research topics in water purification

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Recent advancements in water treatment

For immediate release, acs news service weekly presspac: january 19, 2022.

Generating clean, safe water is becoming increasingly difficult. Water sources themselves can be contaminated, but in addition, some purification methods can cause unintended harmful byproducts to form. And not all treatment processes are created equal with regard to their ability to remove impurities or pollutants. Below are some recent papers published in ACS journals that report insights into how well water treatment methods work and the quality of the resulting water. Reporters can request free access to these papers by emailing  newsroom@acs.org .

“Drivers of Disinfection Byproduct Cytotoxicity in U.S. Drinking Water: Should Other DBPs Be Considered for Regulation?” Environmental Science & Technology Dec.15, 2021

In this paper, researchers surveyed both conventional and advanced disinfection processes in the U.S., testing the quality of their drinking waters. Treatment plants with advanced removal technologies, such as activated carbon, formed fewer types and lower levels of harmful disinfection byproducts (known as DBPs) in their water. Based on the prevalence and cytotoxicity of haloacetonitriles and iodoacetic acids within some of the treated waters, the researchers recommend that these two groups be considered when forming future water quality regulations.

“Complete System to Generate Clean Water from a Contaminated Water Body by a Handmade Flower-like Light Absorber” ACS Omega Dec. 9, 2021 As a step toward a low-cost water purification technology, researchers crocheted a coated black yarn into a flower-like pattern. When the flower was placed in dirty or salty water, the water wicked up the yarn. Sunlight caused the water to evaporate, leaving the contaminants in the yarn, and a clean vapor condensed and was collected. People in rural locations could easily make this material for desalination or cleaning polluted water, the researchers say.

“Data Analytics Determines Co-occurrence of Odorants in Raw Water and Evaluates Drinking Water Treatment Removal Strategies” Environmental Science & Technology Dec. 2, 2021

Sometimes drinking water smells foul or “off,” even after treatment. In this first-of-its-kind study, researchers identified the major odorants in raw water. They also report that treatment plants using a combination of ozonation and activated carbon remove more of the odor compounds responsible for the stink compared to a conventional process. However, both methods generated some odorants not originally present in the water.

“Self-Powered Water Flow-Triggered Piezocatalytic Generation of Reactive Oxygen Species for Water Purification in Simulated Water Drainage” ACS ES&T Engineering Nov. 23, 2021

Here, researchers harvested energy from the movement of water to break down chemical contaminants. As microscopic sheets of molybdenum disulfide (MoS2) swirled inside a spiral tube filled with dirty water, the MoS2 particles generated electric charges. The charges reacted with water and created reactive oxygen species, which decomposed pollutant compounds, including benzotriazole and antibiotics. The researchers say these self-powered catalysts are a “green” energy resource for water purification.

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Current Water Treatment Technologies: An Introduction

• Reference work entry
• First Online: 11 July 2021
• pp 2033–2066
• Cite this reference work entry

• Na Tian 4 ,
• Yulun Nie 5 ,
• Xike Tian 5 &
• Yanxin Wang 6  

409 Accesses

Water treatment and purification in environmental protection are the worldwide issues to relieve the water shortage. At present, various treatment technologies for drinking water or wastewater have been developed. Hence, in this chapter, we will summarize the available water treatment and purification technologies including their advantages and disadvantages as well as the practical application. The main contents then can be divided into the following parts: Firstly, the purification processes for drinking water are introduced including the efficiency and mechanism of filtration and sedimentation, flocculation, disinfection, and other modern emerging technologies. Secondly, the principles and applications of existed wastewater treatment methods are summarized. Thirdly, the new technologies of water treatment are presented such as water reuse technology, membrane technology, advanced oxidation processes based deep water treatment technologies, etc. We think, by summarizing the recent literature and our preliminary work, the present chapter will give the basic information of various water treatment technologies for readers and further capitalize on these technologies for sustainable water management.

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Wastewater Treatment Technologies

Methods and Characteristics of Conventional Water Treatment Technologies

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Tian, N., Nie, Y., Tian, X., Wang, Y. (2021). Current Water Treatment Technologies: An Introduction. In: Kharissova, O.V., Torres-Martínez, L.M., Kharisov, B.I. (eds) Handbook of Nanomaterials and Nanocomposites for Energy and Environmental Applications. Springer, Cham. https://doi.org/10.1007/978-3-030-36268-3_75

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Research Article

Research on drinking water purification technologies for household use by reducing total dissolved solids (TDS)

Roles Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing

* E-mail: [email protected]

Affiliation Redlands East Valley High School, Redlands, California, United States of America

• Bill B. Wang

• Published: September 28, 2021
• https://doi.org/10.1371/journal.pone.0257865
• Reader Comments

This study, based in San Bernardino County, Southern California, collected and examined tap water samples within the area to explore the feasibility of adopting non-industrial equipment and methods to reduce water hardness and total dissolved solids(TDS). We investigated how water quality could be improved by utilizing water boiling, activated carbon and sodium bicarbonate additives, as well as electrolysis methods. The results show that heating is effective at lower temperatures rather than long boils, as none of the boiling tests were lower than the original value. Activated carbon is unable to lower TDS, because it is unable to bind to any impurities present in the water. This resulted in an overall TDS increase of 3.5%. However, adding small amounts of sodium bicarbonate(NaHCO 3 ) will further eliminate water hardness by reacting with magnesium ions and improve taste, while increasing the pH. When added to room temperature tap water, there is a continuous increase in TDS of 24.8% at the 30 mg/L mark. The new findings presented in this study showed that electrolysis was the most successful method in eliminating TDS, showing an inverse proportion where an increasing electrical current and duration of electrical lowers more amounts of solids. This method created a maximum decrease in TDS by a maximum of 22.7%, with 3 tests resulting in 15.3–16.6% decreases. Furthermore, when water is heated to a temperature around 50°C (122°F), a decrease in TDS of around 16% was also shown. The reduction of these solids will help lower water hardness and improve the taste of tap water. These results will help direct residents to drink more tap water rather than bottled water with similar taste and health benefits for a cheaper price as well as a reduction on plastic usage.

Citation: Wang BB (2021) Research on drinking water purification technologies for household use by reducing total dissolved solids (TDS). PLoS ONE 16(9): e0257865. https://doi.org/10.1371/journal.pone.0257865

Editor: Mahendra Singh Dhaka, Mohanlal Sukhadia University, INDIA

Received: June 22, 2021; Accepted: September 14, 2021; Published: September 28, 2021

Copyright: © 2021 Bill B. Wang. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: The author received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Introduction

The concentration of total dissolved solids(TDS) present in water is one of the most significant factors in giving water taste and also provides important ions such as calcium, magnesium, potassium, and sodium [ 1 – 3 ]. However, water with high TDS measurements usually indicates contamination by human activities, such as soil and agricultural runoff caused by irrigation, unregulated animal grazing and wildlife impacts, environmentally damaging farming methods such as slash and burn agriculture, and the overuse of nitrate-based fertilizer [ 4 , 5 ], etc. Around tourist areas as well as state parks, these factors will slowly add up over time and influence the water sources nearby [ 5 ]. Water that flows through natural springs and waterways with high concentrations of organic salts within minerals and rocks, or groundwater that originates from wells with high salt concentration will also result in higher particle measurements [ 6 ].

Water sources can be contaminated by substances and ions such as nitrate, lead, arsenic, and copper [ 7 , 8 ] and may cause many health problems related to heavy metal consumption and poisoning. Water reservoirs and treatments plants that do not consider water contamination by motor vehicles, as well as locations that struggle to provide the necessary components required for water treatment will be more prone to indirect contamination [ 9 – 11 ]. Many plants are effective in ensuring the quality and reduction of these contaminants, but often leave out the secondary considerations, The United States Environmental Protection Agency(US EPA)’s secondary regulations recommend that TDS should be below 500 mg/L [ 2 ], which is also supported by the World Health Organization(WHO) recommendation of below 600 mg/L and an absolute maximum of less than 1,000 mg/L [ 3 ]. These substances also form calcium or magnesium scales within water boilers, heaters, and pipes, causing excess buildup and drain problems, and nitrate ions may pose a risk to human health by risking the formation of N -nitroso compounds(NOC) and less public knowledge about such substances [ 12 – 15 ]. Nitrates can pose a non-carcinogenic threat to different communities, but continue to slip past water treatment standards [ 15 ]. Furthermore, most people do not tolerate or prefer water with high hardness or chlorine additives [ 16 ], as the taste changes tremendously and becomes unpreferable. Even so, TDS levels are not accounted for in mandatory water regulations, because the essential removal of harmful toxins and heavy metals is what matters the most in water safety. Some companies indicate risks in certain ions and alkali metals, showing how water hardness is mostly disregarded and is not as well treated as commercial water bottling companies [ 17 , 18 ].

In Southern California, water quality is not as well maintained than the northern counties as most treatment plants in violation of a regulation or standard are located in Central-Southern California [ 19 ], with southern counties having the largest number of people affected [ 20 ]. This study is focused on the Redlands area, which has had no state code violations within the last decade [ 21 ]. A previous study has analyzed TDS concentrations throughout the Santa Ana Basin, and found concentrations ranging from 190–600 ppm as treated wastewater and samples obtained from mountain sites, taking into account the urban runoff and untreated groundwater as reasons for elevated levels of TDS but providing no solution in helping reduce TDS [ 22 ]. Also, samples have not been taken directly through home water supplies, where the consumer is most affected. Other water quality studies in this region have been focused on the elimination of perchlorates in soil and groundwater and distribution of nitrates, but such research on chemicals have ceased for the last decade, demonstrated by safe levels of perchlorates and nitrates in water reports [ 23 , 24 ]. In addition to these studies, despite the improving quality of the local water treatment process, people prefer bottled water instead of tap water because of the taste and hardness of tap water [ 25 ]. Although water quality tests are taken and documented regularly, the taste of the water is not a factor to be accounted for in city water supplies, and neither is the residue left behind after boiling water. The residue can build up over time and cause appliance damage or clogs in drainage pipes.

This study will build upon previous analyses of TDS studies and attempt to raise new solutions to help develop a more efficient method in reducing local TDS levels, as well as compare current measurements to previous analyses to determine the magnitude to which local treatment plants have improved and regulated its treatment processes.

Several methods that lower TDS are reviewed: boiling and heating tap water with and without NaHCO₃, absorption by food-grade activated carbon [ 26 , 27 ], and battery-powered electrolysis [ 28 – 30 ]. By obtaining water samples and determining the difference in TDS before and after the listed experiments, we can determine the effectiveness of lowering TDS. The results of this study will provide options for residents and water treatment plants to find ways to maintain the general taste of the tap water, but also preserve the lifespan of accessories and pipelines. By determining a better way to lower TDS and treat water hardness, water standards can be updated to include TDS levels as a mandatory measurement.

Materials and methods

All experiments utilized tap water sourced from Redlands homes. This water is partially supplied from the Mill Creek (Henry Tate) and Santa Ana (Hinckley) Water Sheds/Treatment Plants, as well as local groundwater pumps. Water sampling and sourcing were done at relatively stable temperatures of 26.9°C (80.42°F) through tap water supplies. The average TDS was measured at 159 ppm, which is slightly lower than the reported 175 ppm by the City of Redlands. Permission is obtained by the author from the San Bernardino Municipal Water Department website to permit the testing procedures and the usage of private water treatment devices for the purpose of lowering water hardness and improving taste and odor. The turbidity was reported as 0.03 Nephelometric Turbidity Units (NTU) post-treatment. Residual nitrate measured at 2.3mg/L in groundwater before treatment and 0.2 mg/L after treatment and perchlorate measured at 0.9 μg/L before treatment, barely staying below the standard of 1 μg/L; it was not detected within post-treatment water. Lead content was not detected at all, while copper was detected at 0.15 mg/L.

For each test, all procedures were done indoors under controlled temperatures, and 20 L of fresh water was retrieved before each test. Water samples were taken before each experimental set and measured for TDS and temperature, and all equipment were cleaned thoroughly with purified water before and after each measurement. TDS consists of inorganic salts and organic material present in solution, and consists mostly of calcium, magnesium, sodium, potassium, carbonate, chloride, nitrate, and sulfate ions. These ions can be drawn out by leaving the water to settle, or binding to added ions and purified by directly separating the water and ions. Equipment include a 50 L container, 1 L beakers for water, a graduated cylinder, a stir rod, a measuring spoon, tweezers, a scale, purified water, and a TDS meter. A standard TDS meter is used, operated by measuring the conductivity of the total amount of ionized solids in the water, and is also cleaned in the same manner as aforementioned equipment. The instrument is also calibrated by 3 pH solutions prior to testing.All results were recorded for and then compiled for graphing and analysis.

Heating/Boiling water for various lengths of time

The heating method was selected because heat is able to break down calcium bicarbonate into calcium carbonate ions that are able to settle to the bottom of the sample. Four flasks of 1 L of tap water were each heated to 40°C, 50°C, 60°C, and 80°C (104–176°F) and observed using a laser thermometer. The heated water was then left to cool and measurements were made using a TDS meter at the 5, 10, 20, 30, and 60-minute marks.

For the boiling experiments, five flasks of 1 L of tap water were heated to boil at 100°C (212°F). Each flask, which was labeled corresponding to its boiling duration, was marked with 2, 4, 6, 10, and 20 minutes. Each flask was boiled for its designated time, left to cool under open air, and measurements were made using a TDS meter at the 5, 10, 20, 30, 60, and 120-minute marks. The reason that the boiling experiment was extended to 120 minutes was to allow the water to cool down to room temperature.

Activated carbon as a water purification additive

This test was performed to see if food-grade, powdered activated carbon had any possibility of binding with and settling out residual particles. Activated carbon was measured using a milligram scale and separated into batches of 1, 2, 4, 5, 10, 30, and 50 mg. Each batch of the activated carbon were added to a separate flask of water and stirred for five minutes, and finally left to settle for another five minutes. TDS measurements were recorded after the water settled.

Baking soda as a water purification additive

To lower scale error and increase experimental accuracy, a concentration of 200 mg/L NaHCO₃ solution was made with purified water and pure NaHCO₃. For each part, an initial TDS measurement was taken before each experiment.

In separate flasks of 1 L tap water, each labeled 1, 2, 4, 5, 10, and 30 mg of NaHCO 3 , a batch was added to each flask appropriately and stirred for 5 minutes to ensure that everything dissolved. Measurements were taken after the water was left to settle for another 5 minutes for any TDS to settle.

Next, 6 flasks of 1 L tap water were labeled, with 5 mg (25 mL solution) of NaHCO₃ added to three flasks and 10 mg (50 mL solution) of NaHCO₃ added to the remaining three. One flask from each concentration of NaHCO₃ was boiled for 2 mins., 4 mins., or 6 mins., and then left to cool. A TDS measurement was taken at the 5, 10, 20, 30, 60, and 120-minute marks after removal from heat.

Electrolysis under low voltages

This test was performed because the ionization of the TDS could be manipulated with electricity to isolate an area of water with lower TDS. For this test, two 10cm long graphite pieces were connected via copper wiring to a group of batteries, with each end of the graphite pieces submerged in a beaker of tap water, ~3 cm apart.

Using groups of 1.5 V double-A batteries, 4 beakers with 40mL of tap water were each treated with either 7.5, 9.0, 10.5, and 12.0 V of current. Electrolysis was observed to be present by the bubbling of the water each test, and measurements were taken at the 3, 5, 7, and 10 minute marks.

Results/Discussion

Heating water to various temperatures until the boiling point.

The goal for this test was to use heat to reduce the amount of dissolved oxygen and carbon dioxide within the water, as shown by this chemical equation: Heat: Ca(HCO 3 ) 2 → CaCO 3 ↓ + H 2 O + CO 2 ↑.

This would decompose ions of calcium bicarbonate down into calcium carbonate and water and carbon dioxide byproducts.

Patterns and trends in decreasing temperatures.

The following trend lines are based on a dataset of changes in temperature obtained from the test results and graphed as Fig 1 .

• PPT PowerPoint slide
• PNG larger image
• TIFF original image

https://doi.org/10.1371/journal.pone.0257865.g001

To predict the precise temperature measurements of the tap water at 26.9°C, calculations were made based on Fig 1 . The fitting equations are in the format, y = a.e bx . The values for the fitting coefficients a and b, and correlation coefficient R 2 are listed in Table 1 as column a, b and R 2 . The calculated values and the target temperature are listed in Table 1 .

https://doi.org/10.1371/journal.pone.0257865.t001

Fig 2 was obtained by compiling TDS results with different temperatures and times.

https://doi.org/10.1371/journal.pone.0257865.g002

The fitting equations for Fig 2 are also in the format, y = a.e bx . The fitting coefficients a and b, and correlation coefficient R 2 values are listed in Table 2 . Based on the fitting curves in Fig 2 and the duration to the target temperature in Table 1 , We calculated the TDS at 26.9°C as listed in column calculated TDS in Table 2 based on the values we reported on Fig 2 .

https://doi.org/10.1371/journal.pone.0257865.t002

Based on the heating temperature and the calculated TDS with the same target water temperature, we obtained the following heating temperature vs TDS removal trend line and its corresponding fitting curve in Table 2 .

In Fig 1 , a trend in the rate of cooling is seen, where a higher heating temperature creates a steeper curve. During the first five minutes of cooling, the water cools quicker as the absorbed heat is quickly released into the surrounding environment. By the 10-minute mark, the water begins to cool in a linear rate of change. One detail to note is that the 100°C water cools quicker than the 80°C and eventually cools even faster than the 60°C graph. Table 1 supports this observation as the duration to target temperature begins to decrease from a maximum point of 94.8 mins to 80.95 mins after the 80°C mark.

As shown in Fig 2 , all TDS values decrease as the temperature starts to cool to room temperature, demonstrating a proportional relationship where a lower temperature shows lower TDS. This can partially be explained by the ions settling in the flasks. Visible particles can also be observed during experimentation as small white masses on the bottom, as well as a thin ring that forms where the edge of the water contacts the flask. When the water is heated to 40°C and cooled, a 3.8% decrease in TDS is observed. When 50°C is reached, the TDS drops at its fastest rate from an initial value of 202 ppm to 160 ppm after 60 minutes of settling and cooling. The TDS measurements in these experiements reach a maximum of 204 ppm at the 60°C mark. However, an interesting phenomenon to point out is that the water does not hit a new maximum at 100°C. meaning that TDS reaches a plateau at 60°C. Also, the rate of decrease begins to slow down after 20 minutes, showing that an unknown factor is affecting the rate of decrease. It is also hypothesized that the slight increase in TDS between the 5–20 minute range is caused by a disturbance in the settling of the water, where the temperature starts to decrease at a more gradual and constant rate. The unstable and easy formation of CaCO 3 scaling has also been the subject of a study of antiscaling methods, which also supports the result that temperature is a significant influence for scale formation [ 12 ].

In Table 2 , calculations for TDS and the time it takes for each test to cool were made. Using the data, it is determined that the test with 50°C water decreased the most by 16% from the initial measurement of 159ppm. This means that it is most effective when water is heated between temperatures of 40–60°C when it comes to lowering TDS, with a difference of ~7–16%. When water is heated to temperatures greater than 80°C, the water begins to evaporate, increasing the concentration of the ions, causing the TDS to increase substantially when cooled to room temperature.

Finally, in Fig 3 , a line of best fit of function f(x) = -0.0007x 3 + 0.1641x 2 –10.962x + 369.36 is used with R 2 = 0.9341. Using this function, the local minimum of the graph would be reached at 48.4°C.

https://doi.org/10.1371/journal.pone.0257865.g003

This data shows that heating water at low temperatures (i.e. 40–50°C) may be more beneficial than heating water to higher temperatures. This study segment has not been presented in any section within the United States EPA Report on water management for different residual particles/substances. However, warmer water temperatures are more prone to microorganism growth and algal blooms, requiring more intensive treatment in other areas such as chlorine, ozone, and ultraviolet disinfection.

Using the specific heat capacity equation, we can also determine the amount of energy and voltage needed to heat 1 L of water up to 50°C: Q = mcΔT, where c, the specific heat capacity of water, is 4.186 J/g°C, ΔT, the change in temperature from the experimental maximum to room temperature, is 30°C, and m, the mass of the water, is 1000 g. This means that the amount of energy required will be 125580 J, which is 0.035 kWh or 2.1 kW.

After taking all of the different measurements obtained during TDS testing, and compiling the data onto this plot, Fig 4 is created with a corresponding line of best fit:

https://doi.org/10.1371/journal.pone.0257865.g004

In Fig 4 , it can be observed that the relationship between the temperature of the water and its relative TDS value is a downwards facing parabolic graph. As the temperature increases, the TDS begins to decrease after the steep incline at 50–60°C. The line of best fit is represented by the function f(x) = -0.0142x 2 + 2.258x + 105.84. R 2 = 0.6781. Because the R 2 value is less than expected, factors such as the time spent settling and the reaction rate of the ions should be considered. To determine the specifics within this experiment, deeper research and prolonged studies with more highly accurate analyses must be utilized to solve this problem.

Boiling water for various amounts of time

Trend of boiling duration and rate of cooling..

Using the same methods to create the figures and tables for the previous section, Fig 5 depicts how the duration of time spent boiling water affects how fast the water cools.

https://doi.org/10.1371/journal.pone.0257865.g005

As seen in Fig 5 , within the first 10 minutes of the cooling time, the five different graphs are entwined with each other, with all lines following a similar pattern. However, the graph showing 20 minutes of boiling is much steeper than the other graphs, showing a faster rate of cooling. This data continues to support a previous claim in Fig 2 , as this is most likely represented by a relationship a longer the boil creates a faster cooling curve. This also shows that the first 5 minutes of cooling have the largest deviance compared to any other time frame.

The cooling pattern is hypothesized by possible changes in the orderly structure of the hydrogen bonds in the water molecules, or the decreased heat capacity of water due to the increasing concentration of TDS.

Effect on TDS as boiling duration increases.

In Fig 6 , all lines except for the 20-minute line are clustered in the bottom area of the graph. By excluding the last measurement temporarily due to it being an outlier, we have observed that the difference between the initial and final TDS value of each test decreases.

https://doi.org/10.1371/journal.pone.0257865.g006

Despite following a similar trend of an increase in TDS at the start of the tests and a slow decrease overtime, this experiment had an interesting result, with the final test measuring nearly twice the amount of particles compared to any previous tests at 310 ppm, as shown in Fig 6 . It is confirmed that the long boiling time caused a significant amount of water to evaporate, causing the minerals to be more concentrated, thus resulting in a 300 ppm reading. Fig 6 follows the same trend as Fig 2 , except the TDS reading veers away when the boiling duration reaches 20 minutes. Also, with the long duration of heating, the water has developed an unfavorable taste from intense concentrations of CaCO₃. This also causes a buildup of a thin crust of CaCO₃ and other impurities around the container that is difficult to remove entirely. This finding is in accordance with the introductory statement of hot boiling water causing mineral buildups within pipes and appliances [ 9 ]. A TDS reading of 300ppm is still well below federal secondary standards of TDS, and can still even be compared to bottled water, in which companies may fluctuate and contain 335ppm within their water [ 1 , 2 ].

This experiment continues to stupport that the cooling rate of the water increases as the time spent boiling increases. Based on this test, a prediction can be made in which an increased concentration of dissolved solids lowers the total specific heat capacity of the sample, as the total volume of water decreases. This means that a method can be derived to measure TDS using the heat capacity of a tap water mixture and volume, in addition to current methods of using the electrical conductivity of aqueous ions.

Adding food-grade activated carbon to untreated tap water

Fig 7 presents a line graph with little to no change in TDS, with an initial spike from 157 to 163 ppm. The insoluble carbon remains in the water and shows no benefit.

https://doi.org/10.1371/journal.pone.0257865.g007

The food-grade activated carbon proved no benefit to removing TDS from tap water, and instead added around 5–7 ppm extra, which settled down to around +4 ppm at 120 minutes. The carbon, which is not 100% pure from inorganic compounds and materials present in the carbon, can dissolve into the water, adding to the existing concentration of TDS. Furthermore, household tap water has already been treated in processing facilities using a variety of filters, including carbon, so household charcoal filters are not effective in further reducing dissolved solids [ 18 ].

Adding sodium bicarbonate solution to boiled tap water

As seen in Fig 8 , after adding 1 mg of NaHCO 3 in, the TDS rises to 161 ppm, showing a minuscule increase. When 4 mg was added, the TDS drops down to 158 ppm. Then, when 5 mg was added, a sudden spike to 172 ppm was observed. This means that NaHCO 3 is able to ionize some Ca 2+ and Mg 2+ ions, but also adds Na + back into the water. This also means that adding NaHCO 3 has little to no effect on TDS, with 4mg being the upper limit of effectiveness.

https://doi.org/10.1371/journal.pone.0257865.g008

To examine whether or not the temperature plays a role in the effectiveness in adding NaHCO 3 , a boiling experiment was performed, and the data is graphed in Fig 9 .

https://doi.org/10.1371/journal.pone.0257865.g009

Fig 9 presents the relationship between the amount of common baking soda(NaHCO₃) added, the boiling time involved, and the resulting TDS measurements. After boiling each flask for designated amounts of time, the results showed a downward trend line from a spike but does not reach a TDS value significantly lower than the initial sample. It is apparent that the NaHCO₃ has not lowered the TDS of the boiling water, but instead adds smaller quantities of ions, raising the final value. This additive does not contribute to the lowering of the hardness of the tap water. However, tests boiled with 5 mg/L of baking soda maintained a downward pattern as the water was boiled for an increasing amount of time, compared to the seemingly random graphs of boiling with 10 mg/L.

In some households, however, people often add NaHCO₃ to increase the pH for taste and health benefits. However, as shown in the test results, it is not an effective way of reducing TDS levels in the water [ 10 , 16 ], but instead raises the pH, determined by the concentration added. Even under boiling conditions, the water continues to follow the trend of high growth in TDS, of +25–43 ppm right after boiling and the slow drop in TDS (but maintaining a high concentration) as the particles settle to the bottom.

Utilizing the experimental results, we can summarize that after adding small batches of NaHCO3 and waiting up to 5 minutes will reduce water hardness making it less prone to crystallizing within household appliances such as water brewers. Also, this process raises the pH, which is used more within commercial water companies. However, the cost comes at increasing TDS.

Using electrolysis to treat TDS in tap water

Different voltages were passed through the water to observe the change in TDS overtime, with the data being compiled as Fig 10 .

https://doi.org/10.1371/journal.pone.0257865.g010

The process of electrolysis in this experiment was not to and directly remove the existing TDS, but to separate the water sample into three different areas: the anode, cathode, and an area of clean water between the two nodes [ 19 ]. The anions in the water such as OH - , SO 4 2- , HCO 3 - move to the anode, while the cations such as H + , Ca 2+ 、Mg 2+ 、Na + move to the cathode. The middle area would then be left as an area that is more deprived of such ions, with Fig 10 proving this.

As shown in Fig 10 , electrolysis is effective in lower the TDS within tap water. Despite the lines being extremely tangled and unpredictable, the general trend was a larger decrease with a longer duration of time. At 10 minutes, all lines except 10.5 V are approaching the same value, meaning that the deviation was most likely caused by disturbances to the water during measurement from the low volume of water. With each different voltage test, a decrease of 12.7% for 6.0 V, 14.9% for 9.0 V, 22.7% for 10.5 V. and 19.5% for 12.0 V respectfully were observed. In the treatment of wastewate leachate, a study has shown that with 90 minutes of electrical treatment, 34.58% of TDS content were removed, supporting the effectiveness of electricity and its usage in wastewater treatment [ 29 ].

This experiment concludes that electrolysis is effective in lowering TDS, with the possibility to improve this process by further experimentation, development of a water cleaning system utilizing this cathode-anode setup to process water. This system would be a more specific and limited version of a reverse osmosis system by taking away ions through attraction, rather than a filter.

The Southern Californian tap water supply maintains TDS values below the federal regulations. However, crystalline scale buildup in household appliances is a major issue as it is hard to clean and eliminate. To easily improve the taste and quality of tap water at home as well as eliminating the formation of scales, the following methods were demonstrated as viable:

• By heating water to around 50°C (122°F), TDS and water hardness will decrease the most. Also, the boiling process is effective in killing microorganisms and removing contaminants. This process cannot surpass 10 minutes, as the concentration of the ions in the water is too high, which poses human health risks if consumed. These, along with activated carbon and NaHCO₃ additives, are inefficient methods that have minimal effects for lowering TDS.
• Electrolysis is one of the most effective methods of eliminating TDS. Experiments have proven that increased current and duration of time helps lower TDS. However, this method has yet to be implemented into conventional commercial water filtration systems.

Also, some observations made in these experiments could not be explained, and require further research and experimentation to resolve these problems. The first observation is that TDS and increasing water temperature maintain a parabolic relationship, with a maximum being reached at 80°C, followed by a gradual decrease. The second observation is that when water is boiled for an increased duration of time, the rate of cooling also increases.

This experiment utilized non-professional scientific equipment which are prone to mistakes and less precise. These results may deviate from professionally derived data, and will require further study using more advanced equipment to support these findings.

Acknowledgments

The author thanks Tsinghua University Professor and PLOS ONE editor Dr. Huan Li for assisting in experimental setups as well as data processing and treatment. The author also thanks Redlands East Valley High School’s Dr. Melissa Cartagena for her experimental guidance, and Tsinghua University Professor Dr. Cheng Yang for proofreading the manuscript.

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The Effectiveness of Home Water Purification Systems on the Amount of Fluoride in Drinking Water

Behrooz eftekhar.

a Dept. of Endodontic, School of Dentistry, Ahwaz Jondishapoor University of Medical Sciences, Ahwaz, Iran.

Masoume Skini

b Postgraduate Student, Dept. of Endodontic, School of Dentistry, Ahwaz Jondishapoor University of Medical Sciences, Ahwaz, Iran.

Milad Shamohammadi

Jaber ghaffaripour.

c DDS, School of Dentistry, Ahwaz Jondishapoor University of Medical Sciences, Ahwaz, Iran.

Firoozeh Nilchian

d Dental Students Research Center, Dept. of Dental Public Health, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.

Statement of the Problem

Water purification systems for domestic use have drawn significant attention over the past few years. This can be related to the improvement of public health and concern for water contamination. 

The aim of this study was to evaluate whether home water purification systems eliminate the essential materials such as fluoride besides filtrating the heavy ions and other unwanted particles out of water.

Materials and Method

In this experimental study, six most frequently used commercial brands of water purifiers were evaluated and compared. Specimens were collected right before and after setting up the device, and 6 months later. Then, spectrophotometry (the Harrison device) was performed to compare fluoride clearance by each home water cleaner device.

Based on the data collected from all water purification devices in different locations, the amount of fluoride was significantly different before and right after using home water purifier and six months later ( p = 0.001 and p = 0.00, respectively).

The filtration of water significantly decreased its fluoride concentration. The fluoride content of purified water was approximately as much as zero in some cases.

Introduction

Fluoride is a natural element branched from Fluorine. This element can be found in all sorts of water and soil. Out of every kilogram of outer layer of earth, 0.3 gram is fluoride. Mineral waters have more amount of this element compared to other sources.( 1 )

About 60 years ago, Grand Rapids in Michigan State was the first city in which fluoride supplement was synthetically added to tap water. In US, adding fluoride to community water supplies of many cities has improved the oral health of millions of American citizens.( 2 )

Fluoridation of community water supplies is adding a specific amount of fluoride (0.7-1.2 ppm) to water in order to reduce the risk of dental caries. By 2002, almost 170 million Americans were provided with this privilege.( 3 )

Since most of the systemic fluoride is provided through tap water to population, many policies have been established to add fluoride to community water regarding its benefits for teeth and bones.( 4 )

In regions and countries that do not have water-fluoridation technology, there are natural supplements as previously mentioned. For example, Iran has many mineral water supplies that contain considerable amounts of fluoride. Amount of fluoride in natural mineral waters depends on weather conditions; the warmer the weather is, the higher the amount of fluoride can be detected. Mineral waters in southern regions that have warmer weather contain more fluoride. In Iran, the highest amount of fluoride has been found in southeast and northeast areas.

Water purification systems for domestic use have drawn much of attention over the past few years. This can be related to improvement of public health and concerns for water contamination. There are several types of home water purification systems that can be categorized into 3 different groups( 5 ) as filtered systems, systems using UV irradiation, and ion-exchange systems.

The aim of this study was to find out whether domestic water purification systems could eliminate the essential materials such as fluoride besides filtrating the heavy ions and other unwanted particles out of water.

In this study, 6 frequently used commercial brands of water purifiers in Ahwaz were compared. The commercial brands evaluated in the current study were CCK (Ceramic and Ceramic/Carbon Cartridges ; RTX-TS DLM filters, Korea), Soft Water (Ceramic Candles; Alpine TJ Series filters, W9332420, USA), Alkusar (Special media cartridges filters; PRB50-IN, USA), Puricom (Special media cartridges filters; Watts 4.5" x 10" Dual Housing, Korea), Water Safe (Granular Carbon Cartridges filters; LCV (Lead, Cysts, VOC's) (Carbon Block Filter Cartridges, Australia), and Aquafresh (Sediment String-Wound; Poly Spun and Pleated Washable Cartridges filters, K5520, USA). The main drinking water supply for Ahwaz is provided by governmental companies. After making arrangement with certain companies that supported these brands, the devices were setup in 6 different regions of Ahwaz. Samples were collected before and right after setting up the device. To reduce the errors and elevate the accuracy of the module, 5 samples were taken from each device. Another sample was collected from each single device 6 months later. A total of 64 samples were collected including 32 unfiltered (control) and 32 filtered samples of tap water (experimental) from 6 regions in Ahwaz. Fluoride sampling kits (Spands; EW-99574-08Hach ® Test Kits, USA) were used to test the amount of fluoride in sample waters. Samples were all collected in polyethylene sampling containers and were then coded. Spectrophotometry (AvaSpec-ULS2048L- USB2 UARS spectrometer, USA) was performed. In order to measure the characteristics of individual molecules, a mass spectrometer converted them to ions so that they could be moved about and manipulated by external electric and magnetic fields.

Atmospheric pressure was around 760 torr (mm of mercury). The pressure under which ions may be handled is roughly 10 -5 to 10 -8 torr (less than a billionth of an atmosphere). By varying the strength of the magnetic field, ions of different mass can be focused progressively on a detector fixed at the end of a curved tube and also under a high vacuum.

Latin alphabetic words were used to code each commercial device. Numbers were used for samples obtained before and after setting the device.( 6 )

The results were analyzed by using paired sample t-test, with alpha (ɑ) set at 0.05.

The amount of fluoride in water before and after using six brands of water purifier device is summarized in Table 1 .

The amount of fluoride before and after installing water purifier devices

Based on the data gathered from all water purification devices set in different regions, the level of fluoride was significantly different before and after using home water purifier ( p = 0.001). It was found that home water purifiers nearly eliminated fluoride from tap water. Table 2 represents the results of t-test.

Comparison of different study groups with t-test

* p< 0.05 is statistically significant.

Another round of sampling was done 6 months later from the same filters of home water purifier. Details are illustrated in Table 3 and 4.

The amount of fluoride in tap water after 6 months of using a water purification filter

Comparison of the study groups after six mounts with t-test

Fluoride absorption is mostly systemic or local; systemic absorption occurs through eating the element with food, water or fluoride pills, and local absorption by toothpastes and other fluoride-containing hygienic products. In many countries, the highest supply for fluoride absorption is systemic absorption through water consumption.( 6 ) In early 20 th century, the first attempts were made to fluoridate public water supplies, which eventually led to 40% decrease of dental caries in the target population.( 7 )Introduction of water fluoridation in the 1950-1960 and fluoride-containing dental products in the 1970 changed the situation. The main sources of fluoride in established market economies (EME) are drinking water, fluoridated salt, foods and beverages, baby cereals and formulas, fluoride supplements, toothpastes, mouth-rinses, and topical fluorides. Additionally, fluoride in water has a diffusion or halo effect; which means that the drinks and foods manufactured in fluoridated areas are also available to whole population including the residents of non-fluoridated areas.

Although adding fluoride to almost all oral hygienic products has restricted the effect of fluoride water (Halo effect), it is still common to fluoridate the city water supply.( 6 ) In many areas of the world, there is no systematic plan for fluoridation of community water and only the natural sources supply it. Therefore, sometimes the hardness of water and aggregation of different and sometimes poisonous elements drive the population to use bottled water or use home purification devices.

The findings of the present study revealed that all the 6 devices reduced the fluoride in tap water and most of them nearly eliminated it. Different home purification devices have been marketed each of which is claimed to eliminate certain kinds of elements from water.( 9 ) JK Mwabi et al. (2011) used 4 different filters to reduce the hardness and chemical contamination of water in poor villages in Africa, and reported that all of the four filters reduced the fluoride significantly. Bucket filter had the most significant effect and reduced fluoride element 99.9%. These results also indicated that fluoride was the most reduced element of all. Likewise, silver-impregnated porous pot (SIPP) filter reduced 90%-100% of elements.

Clasen et al. ( 5 ) in their study reported that 3 different home purification systems ,the ceramic candle gravity filter, iodine resin gravity filter, and iodine resin faucet filter, reduced bacterial contamination by four logs and decreased ions such as fluoride and arsenic, as well.

Moreover, there are certain methods to reduce the excessive amount of fluoride in the water. One of the best-known methods is absorption technique.( 7 ) Evaluation of 6 different commercial water purifiers has not been done in any other study; therefore, there is no similar study to compare the results exactly. More evaluations are suggested to be performed on home water purification systems, and more strategies should be devised to preserve the essential elements of tap water.

The current study found considerable differences between the amount of fluoride before and after filtration with home purification device; that is filtration significantly decreased the fluoride concentration even as much as 100% in some cases.

Conflict of Interest: None declared

LET THE MAGIC OF PURE WATER TOUCH YOUR LIFE...

The science behind water filtration: how it really works, promo video, introduction.

Have you ever considered the intricate path a single droplet of water takes, navigating through the labyrinth of filtration systems? In today’s fast-paced and ever-changing world, grasping the science behind water filtration is more than satisfying curiosity; it’s about recognizing a vital process integral to our everyday existence. This exploration goes beyond just providing safe drinking water; it delves into the transformation of unfiltered water laden with harmful contaminants and unpleasant odors into something pure and safe. From the complexities of different types of filters to the essential removal of impurities, this article unravels the mysteries of water filtration.

Join us as we simplify and illuminate the science behind water filtration, offering clear explanations and captivating insights into a process that ensures the water in our bottles and from our taps is clean and wholesome.

What is Water Filtration?

Water filtration, in its essence, is the guardian of our water quality. Imagine a complex, multi-layered defense system designed to capture and eliminate various contaminants – that’s what water filtration does. It’s not merely a physical barrier. It incorporates a blend of physical, chemical, and biological processes to remove everything from visible particles to microscopic threats. The goal? To transform water from its raw, uncertain state into a clear, safe, and drinkable resource.

Tracing the Roots: The History of Filtration

Embarking on a historical journey – The science of water filtration is as old as civilization itself. Ancient civilizations like the Greeks, Egyptians, and Indians were pioneers in early water purification techniques. Their rudimentary methods, ranging from boiling water to using sand and gravel as filters, laid the groundwork for today’s sophisticated systems. This historical perspective is not just about acknowledging their ingenuity but understanding how our current practices are rooted in these ancient wisdoms.

The Invisible Foes: Understanding Contaminants

Unveiling the hidden enemies – Water, in its journey from source to tap, encounters various contaminants. These include physical particles like dirt and rust, biological threats like bacteria and viruses, and chemical pollutants like pesticides and heavy metals. Each type of contaminant presents a unique challenge and requires a specific approach to filtration. Recognizing these adversaries is crucial in selecting the appropriate filtration method to ensure safe, clean water.

Activated Carbon: The Silent Purifier

The unsung hero in our faucets – Activated carbon filters, found in many household water purifiers, are akin to a dense forest trapping unwanted travelers. These filters use a process called adsorption, where contaminants are trapped inside the pore structure of the carbon substrate. Activated carbon is exceptionally adept at removing chlorine, improving taste and odor, and reducing certain harmful chemicals. It’s the first line of defense in many filtration systems, providing an essential barrier against a range of impurities.

Reverse Osmosis: The Fine Sieve of Filtration

A deeper dive into molecular purity – Reverse osmosis (RO) takes filtration to a microscopic level. It involves forcing water through a semi-permeable membrane that acts like an ultra-fine sieve, allowing only water molecules to pass through. This process is effective at removing a wide range of contaminants, including dissolved salts, bacteria, and viruses. Think of it as a meticulous editor, ensuring that only the purest water gets through.

UV Purification: Nature’s Disinfectant

Emulating the sun’s sterilizing power – UV purification is a marvel of mimicking nature. By exposing water to ultraviolet light, this method effectively neutralizes bacteria and viruses without adding chemicals or altering the water’s taste and odor. It’s a swift, effective, and environmentally friendly way to disinfect water, akin to bathing it in a beam of pure sunlight.

The Gravity of Sedimentation

Letting gravity do the work – Sedimentation is a simple yet effective process where gravity helps in the filtration journey. Here, heavier particles in the water settle to the bottom over time, akin to leaves settling at the bottom of a still pond. While not a complete filtration method on its own, sedimentation is a crucial preliminary step that prepares water for further purification.

Filtration vs. Purification: The Nuances

Deciphering the subtle differences – Filtration and purification, while often used interchangeably, have distinct roles. Filtration primarily removes physical impurities, while purification goes a step further to eliminate microscopic contaminants, including bacteria and chemicals. It’s the difference between cleaning the surface and performing a deep, thorough cleanse.

Environmental Footprints of Filtration

Treading lightly on the planet – Water filtration isn’t just about human health; it has significant environmental implications too. By reducing our reliance on bottled water, we diminish plastic waste and conserve natural resources. Moreover, advancements in filtration technology are continuously seeking more sustainable and energy-efficient methods, underscoring the importance of environmental stewardship in water filtration.

Home Filtration: Myths and Realities

Navigating the DIY landscape – While DIY water filtration can be an interesting home project, it’s important to recognize its limitations. Homemade filters might not be effective against all contaminants and cannot replace professionally designed systems. It’s vital to approach home filtration with a blend of curiosity and caution, ensuring that safety and effectiveness aren’t compromised.

The Next Wave in Water Filtration

Innovations shaping our future – The future of water filtration is a canvas of innovation and improvement. Emerging technologies promise more efficient, effective, and environmentally-friendly filtration systems. From nanotechnology to bio-filtration, the horizon is bustling with possibilities that could revolutionize how we access clean water.

Selecting Your Shield: Filtration Systems

Tailoring your defense against contaminants – Choosing the right water filtration system is a personalized decision. It requires understanding the specific contaminants in your water and selecting a system that effectively targets those concerns. With a range of options available, from under-sink filters to whole-house systems, finding the right fit is about matching your needs with the right technology.

The Lifeline: Maintenance and Care

Ensuring enduring purity – Regular maintenance is the heartbeat of any water filtration system. Neglecting it can lead to decreased efficiency, potential contamination, and a shortened lifespan of the system. Adhering to maintenance schedules and understanding the care requirements of your system is crucial for ensuring its ongoing effectiveness.

Debunking Filtration Myths

Separating fact from fiction – In the realm of water filtration, myths and misconceptions abound. From overestimating the capabilities of certain filters to misunderstanding the nature of contaminants, it’s essential to be well-informed. Debunking these myths not only enhances our understanding but also guides us towards making better choices for our water needs.

How exactly does a water filter improve the taste of water?

Water filters remove contaminants like chlorine and heavy metals, which can cause unpleasant tastes and odors, resulting in cleaner and more pleasant-tasting water.

Are there any health risks associated with not changing a water filter on time?

Yes, a clogged or old filter can harbor bacteria and let contaminants back into the water, posing health risks.

Can water filtration systems remove beneficial minerals from water?

Some systems, like reverse osmosis, can remove minerals, but many are designed to retain beneficial minerals while removing harmful substances.

Is filtered water as effective as boiling water for purification?

Filtered water is effective for removing contaminants, but boiling is recommended for killing pathogens in areas with unsafe water supplies.

How do I know which water filtration system is right for my home?

It depends on your water source, the specific contaminants present, and your household needs. Testing your water and consulting with a filtration expert can help determine the best system for you.

The Crystal Clear Conclusion

In conclusion, understanding the science behind water filtration is more than a deep dive into a technical subject; it’s about embarking on a journey towards purity and responsibility. As we explore the various ways to remove impurities from water, including biological contaminants and substances that cause bad tasting water, we become better equipped to protect ourselves from the dangers of contaminated water . This knowledge empowers us to make well-informed choices about the water we drink, whether it comes from municipal water supplies or other sources. By familiarizing ourselves with different filtration types and their roles in purifying water, we not only enhance our own health but also contribute to environmental conservation and responsible living. Ultimately, as we unravel and understand the complexities of water quality and the science behind its filtration, we step up as guardians of one of Earth’s most vital resources.

Take the Step Towards Pure, Healthy Water Today!

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Inorganics Treatment: Arsenic and Nitrate Webinar

• June 25, 2024 from 2 to 3:30pm ET
• The webinar recording will be posted to this page within two weeks of the live broadcast.
• Small Drinking Water Systems Webinar Series

About the Webinar

1. Biological Nitrate Treatment: Innovations and Challenges

This presentation will focus on a biological nitrate treatment pilot study conducted at a water treatment plant. The study used an innovative denitrification system and nitrogen gas sparging to lower dissolved oxygen concentration, and it sometimes achieved complete denitrification. This discussion will also focus on the challenges of matching the acetic acid feed to a variable influent nitrate concentration and addressing clogging by bacterial flocs. The treatment approach showed promise; however, reactor design enhancements are needed to bring this technology to small systems.

Presenter: Asher Keithley, EPA Office of Research and Development.  Asher is a general engineer with EPA’s Office of Research and Development, Center for Environmental Solutions and Emergency Response, Water Infrastructure Division. Their research focuses on drinking water treatment of inorganics and contaminants of emerging concern, such as manganese and nitrate. They are particularly interested in biological drinking water treatment processes. Asher is a licensed Professional Engineer in the state of Ohio.

2. Arsenic Refresher

This presentation will provide an overview of arsenic chemistry and treatment considerations. Arsenic accumulation in the distribution system and potential release back to the water will also be discussed, based on retrospective data analysis from EPA’s arsenic demonstration program.

Presenter: Simoni Triantafyllidou, EPA Office of Research and Development.  Simoni is an environmental engineer with EPA's Office of Research and Development, Center for Environmental Solutions and Emergency Response, Water Infrastructure Division. Her research and technical support efforts revolve around aquatic chemistry, drinking water quality and treatment, corrosion science, inorganic contaminants, and sustainable drinking water infrastructure such as premise plumbing and distribution systems.

3. An Arsenic Case Study in California: Oasis Mobile Home Park

This presentation will provide an overview of EPA Region 9’s enforcement case with Oasis Mobile Home Park for violation of the Arsenic Rule. Key topics will include environmental justice, enforcement, technical conditions, and community and stakeholder engagement. The unique challenges and successes of trying to bring a small public water system back into compliance will also be discussed.

Presenter: Maria Alberty, EPA Region 9.  Maria is an environmental protection specialist with EPA Region 9, Enforcement and Compliance Assurance Division in San Francisco, California. Maria is a credentialed drinking water inspector, and she leads cross-organizational teams to evaluate public water systems and ensure that those systems achieve and maintain public health and environmental compliance under the Safe Drinking Water Act. Prior to enforcement, she was a contracting officer for 18 years at EPA and NASA.

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Dissertations / Theses on the topic 'Water purification'

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Kent, Laura. "Photocatalysts for water purification." Thesis, University of Surrey, 2018. http://epubs.surrey.ac.uk/850035/.

Lacoursière, Stéphanie. "Water purification by membrane distillation." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26112.

Davies, R. H. "Semiconductor photocatalysis for water purification." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636399.

Choi, Siwon (Siwon Chloe). "Microfluidic engineering of water purification." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111415.

Lyu, Shicheng. "Membraneless Water Purification via diffusiophoresis." Digital WPI, 2020. https://digitalcommons.wpi.edu/etd-theses/1360.

Jones, Samuel Casey. "Static mixers for water treatment : a computational fluid dynamics model." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20718.

Yang, Zi. "INORGANIC MEMBRANES FOR WATER PURIFICATION APPLICATIONS." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1588556057684163.

Schillo, Melissa C. "Mesoporous Inorganic Membranes for Water Purification." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313586746.

Baruah, Arabinda. "Smart nanostructured materials for water purification." Thesis, IIT Delhi, 2016. http://localhost:8080/iit/handle/2074/7002.

Wong, Kit Iong. "Chemical removal of dichloromethane (DCM) from contaminated water using advanced oxidation processes (AOPs) :Hydrogen Peroxide Ozone UV." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3868740.

Mangombo, Zelo. "The electrogeneration of hydroxyl radicals for water disinfection." Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5745_1190373027.

This study has shown that OH˙ radicals can be generated in an Fe/O2 cell from the electrode products via Fenton&rsquo s reaction and used for water disinfection. The cell system in which the experiments were carried out was open and undivided and contained two electrodes with iron (Fe) as the anode and oxygen (O2) gas diffusion electrode. Typically, 100 ml of Na2SO4.10H2O (0.5M) solution was used as a background electrolyte. OH˙ radicals were produced in-situ in an acidic solution aqueous by oxidation of iron (II), formed by dissolving of the anode, with hydrogen peroxide (H2O2). The H2O2 was electrogenerated by reduction of oxygen using porous reticulated vitreous carbon (RVC) as a catalyst.

Siguba, Maxhobandile. "The development of appropriate brine electrolysers for disinfection of rural water supplies." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=init_6284_1180438520.

A comparative study of electrolysers using different anodic materials for the electrolysis of brine (sodium chloride) for the production of sodium hypochlorite as a source of available chlorine for disinfection of rural water supplies has been undertaken. The electrolyser design used was tubular in form, having two chambers i.e. anode inside and cathode outside, separated by a tubular inorganic ceramic membrane. The anode was made of titanium rod coated with a thin layer of platinum and a further coat of metal oxide. The cathode was made of stainless steel wire. An assessment of these electrolysers was undertaken by studying the effects of some variable parameters i.e.current, voltage and sodium chloride concentration. The cobalt electrolyser has been shown to be superior as compared to the ruthenium dioxide and manganese dioxide electrolysers in terms of hypochlorite generation. Analysis of hydroxyl radicals was undertaken since there were claims that these are produced during brine electrolysis. Hydroxyl radical analysis was not successful, since sodium hypochlorite and hypochlorous acid interfere using the analytical method described in this study.

Hardy, Scott Andrew. "Effectiveness of static mixers for disinfection of cryptosporidium oocysts." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20925.

Belghazi, A. "Heterogeneous semiconductor UV-photocatalysis for water purification." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636072.

Harries, Richard R. "Water purification by ion exchange mixed beds." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/18591.

Shen, Junjie. "Application of membrane technologies in water purification." Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3147.

Yang, Jingming. "Characteristics of a novel anaerobic fluidized bed reactor for waste water treatment." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/25318.

Li, June Yonghong. "A study of ozonation kinetics of phenolic compounds in single and solute systems." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/20821.

Kulati, Thanduxolo Cullinan. "Evaluation of physiochemical qualities and heavy metal levels of the final effluents of some wastewater treatment facilities in the Eastern Cape Province of South Africa." Thesis, University of Fort Hare, 2016. http://hdl.handle.net/10353/1547.

Khan, Wesaal. "Microbial interactions in drinking water systems." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/53751.

Lam, Chun-wai Ringo, and 林俊偉. "Development of photocatalytic oxidation technology for purification ofair and water." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38572382.

Hastie, Michele. "Energy and Water Conservation in Biodiesel Purification Processes." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20384.

Ahmed, Abd El-Safey Ibrahim. "Novel N-halamine Biocidal Polymers for Water Purification." Thesis, University of Surrey, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505994.

Mole, Jonathan Michael. "Titanium dioxide as a photocatalyst in water purification." Thesis, University of Kent, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309747.

Choong, Looh Tchuin (Looh Tchuin Simon). "Application of electrospun fiber membranes in water purification." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98153.

Koura, Mbadinga Pauline Joella. "A solar water purification system for rural areas." Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/2612.

Mechelhoff, Martin. "Electrochemical investigation of electrocoagulation reactors for water purification." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/8896.

Boahen, Anthony Kwaku. "Purification of oily water with cross flow microfiltration." Thesis, University of Bath, 1999. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311233.

Neba, Alphonsus. "The Rhodes BioSURE process and the use of sustainability indicators in the development of biological mine water treatment." Thesis, Rhodes University, 2007. http://hdl.handle.net/10962/d1004043.

Richman, Marjorie Timmerly. "Particle and biomass detachment during biological filter backwashing : impact of water chemistry and backwash method." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19519.

Skeens, Brian Michael. "Pilot scale evaluation and comparison of static mixers for coagulation in water treatment." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19522.

Conley, LuAnne Simpson. "Removal of complexed iron by chemical oxidation and/or alum coagulation." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-03172010-020643/.

Jeffcoat, Stuart Blakely. "The importance of hydrophobicity/hydrophilicity on particle removal in deep bed filtration and macroscopic filtration modeling." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/20149.

Weinberg, Marla Kaye. "The effectiveness of an electrochemical treatment process and its applications in textile wastewater treatment." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/8697.

Shah, Anup G. "Fate and effect of the antioxidant ethoxyquin on a mixed methanogenic culture." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/19904.

Omoniyi, Emmanuel Oluseyi. "Comparative study of brine treatment using a functionalized nanofibre and an ion exchange resin." Thesis, Cape Peninsula University of Technology, 2015. http://hdl.handle.net/20.500.11838/2334.

Liu, Jinlin, and 刘金林. "Wastewater organic as the precursors of disinfection byproducts in drinking water: characterization,biotransformation and treatment." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46289562.

Santoyo-Gutierrez, Socrates. "Absorption heat pump assisted effluent purification." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245055.

Bach, Altai. "Water purification by advanced oxidation processes using nano particles." Online version, 2010. http://dds.crl.edu/CRLdelivery.asp?tid=13238.

Rodríguez, Rodríguez Juan Martín. "Sputter deposited titanium oxide films for photoelectrochemical water purification." Universidad Nacional de Ingeniería. Programa Cybertesis PERÚ, 2000. http://cybertesis.uni.edu.pe/uni/2000/rodriguez_rj/html/index-frames.html.

John, Wilson. "Synthesis, properties and analysis of polydadmac for water purification." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/19531.

De, Villiers David. "Design and evaluation of photocatalytic reactors for water purification." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52178.

Vasylchenko, D. "The study and analysis of various water purification methods." Thesis, Sumy State University, 2016. http://essuir.sumdu.edu.ua/handle/123456789/45938.

Haikola, Matilda, and David Fridlund. "District Heat-driven Membrane Distillation for Drinking Water Purification." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232824.

Shafieian, Dastjerdi Abdellah. "A solar‐driven membrane‐based water desalination/purification system." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2020. https://ro.ecu.edu.au/theses/2323.

Isaeva, Margarita, and Castro Natasha Montes. "Water Treatment for the Removal of Iron and Manganese." Thesis, Högskolan i Skövde, Institutionen för teknik och samhälle, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-5357.

Wang, Po-Yang, and 王伯洋. "Water purification of brackish water aquaculture." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/85210277667013176328.

Loeb, Stephanie. "Nanostructured Photocatalysis for Water Purification." Thesis, 2013. http://hdl.handle.net/1807/43101.

Lin, Jia-Bao, and 林嘉寶. "DMAIC PLUS-Water purification Case." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/07088727433805232391.

CHEN, WEI-LIN, and 陳威霖. "Water purification of freshwater aquaculture." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/88b6rz.

Articles on Water purification

Displaying all articles.

What can fish mouths teach us about engineering clog-free  filters?

S. Laurie Sanderson , William & Mary

Why Africans must join forces to protect scarce water resources

Cameron Harrington , University of Cape Town

It’s public attitudes to recycled sewage that need better treatment, not the water

Jonathan Bridge , University of Liverpool

Tree seeds used to purify water

Uppsala University

Solving the toilet shortage needs a bottom-up  approach

Dani Barrington , Monash University

Filtering out the poisons

University of South Australia

Portable purification filter could provide safe drinking water

Related topics.

• Biologically inspired design
• Biomechanics
• Biomimetics
• Fluid dynamics
• Water management
• Water quality

Delivering hydrogen to EU’s industry: which are the greenest options?

Using hydrogen produced from abundantly available renewables on-site is the most sustainable option. Delivering compressed renewable hydrogen via pipelines or shipping liquid renewable hydrogen could still be environmentally friendly, research says.

Renewable hydrogen is expected to play a crucial role in reducing carbon emissions in Europe. Previous JRC  research revealed that sourcing it from regions with cheaper renewable energy can prove to be more cost-effective than local production. 

However, environmental concerns arise from transporting large quantities of hydrogen over long distances, as the environmental impact varies significantly according to the production technology and the method of delivery. 

To address these concerns, a  new study compares the life cycle environmental impacts of on-site production through steam methane reforming (SMR) or electrolysis with three different delivery methods, including compression, liquefaction, and chemical bonding to other molecules.  Transportation by both ship and pipeline was considered.

The distance used to compare the different methods of delivery is 2,500 km, compatible with the extent of EU territory and equivalent to the distance between Portugal and the Netherlands. The two countries were considered based on a proposal in an EU funded project which examined the feasibility of sustainable hydrogen transportation.

The results show that the environmental performance of hydrogen supplied to large industries can vary significantly based on the production technology and delivery pathway. 

The study was carried out by the JRC for the  Clean Hydrogen Partnership , a public-private partnership supporting research and innovation (R&I) activities in hydrogen technologies in Europe. The findings result in key recommendations for policymakers and stakeholders to help countries and industries to accelerate the transition towards a more sustainable hydrogen economy.

On-site production versus long-distance delivery

The most environmentally sustainable approach is on-site production using efficient renewable sources, such as wind power in the Netherlands. If on-site production is not viable using local abundant renewable sources, importing renewable hydrogen can still lead to a significant reduction in greenhouse gas (GHG) emissions compared to on-site production with fossil fuels. However, focusing solely on GHG emissions may lead to other, unintended environmental impacts. 

Shipping liquid hydrogen and transporting compressed hydrogen through pipelines appear to have the least environmental impact when delivering hydrogen over long distances. 

Meanwhile, the process of packing and unpacking hydrogen into chemical carriers such as ammonia, liquid organic compounds, methanol, and synthetic natural gas demands larger amounts of energy and resources. It makes these options less desirable to minimise environmental impact. But no significant difference was noticed in comparative environmental impact of delivery methods when comparing chemical carriers one with another. 

Role of renewable energy infrastructure 

The report emphasises the close relationship between the environmental impact of delivered hydrogen and renewable energy infrastructure. 

For imported solar-generated hydrogen to have an environmental advantage over conventional hydrogen production from fossil fuels, the environmental impact of generating electricity through photovoltaic panels must be significantly reduced. 

This can be achieved by improving the efficiency of photovoltaic panels in terms of materials use and utilising renewable energy for their production.

Impact of water use

Water use is another crucial factor to consider. The availability of freshwater affects the impact of hydrogen production. On-site hydrogen generation in water-rich countries proves to be a more sustainable option in terms of water use compared to importing hydrogen from water-scarce nations. 

Hydrogen loss

Hydrogen losses during the delivery chain can significantly increase the environmental impact of delivered hydrogen. However, options that are more susceptible to losses, such as liquid and compressed hydrogen, still have lower environmental impacts than using hydrogen carriers.

When on-site production of hydrogen using local renewable sources is not feasible, importing renewable hydrogen from closer regions becomes the more environmentally sustainable choice. When transporting hydrogen over long distances within Europe, delivering compressed hydrogen through pipelines or liquid hydrogen via ships stands out as the preferred option in terms of environmental impact.

Related links

Environmental life cycle assessment (LCA) comparison of hydrogen delivery options within Europe

Clean Hydrogen Partnership

EU Hydrogen strategy

More news on a similar topic

• General publications

• 6 March 2024

• 24 November 2023

• News announcement
• 11 September 2023
• 10 min read

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• Open access
• Published: 06 July 2020

Public health benefits of water purification using recycled hemodialyzers in developing countries

• Jochen G. Raimann   ORCID: orcid.org/0000-0002-8954-2783 1 , 2 , 3 , 4 ,
• Joseph Marfo Boaheng 4 , 5 ,
• Philipp Narh 4 , 6 ,
• Harrison Matti 4 ,
• Seth Johnson 1 , 4 ,
• Linda Donald 1 , 4 ,
• Hongbin Zhang 7 , 8 ,
• Friedrich Port 1 , 9 &
• Nathan W. Levin 1 , 4  

Scientific Reports volume  10 , Article number:  11101 ( 2020 ) Cite this article

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In rural regions with limited resources, the provision of clean water remains challenging. The resulting high incidence of diarrhea can lead to acute kidney injury and death, particularly in the young and the old. Membrane filtration using recycled hemodialyzers allows water purification. This study quantifies the public health effects. Between 02/2018 and 12/2018, 4 villages in rural Ghana were provided with a high-volume membrane filtration device (NuFiltration). Household surveys were collected monthly with approval from Ghana Health Services. Incidence rates of diarrhea for 5-month periods before and after implementation of the device were collected and compared to corresponding rates in 4 neighboring villages not yet equipped. Data of 1,130 villagers over 10 months from the studied communities were studied. Incidence rates showed a decline following the implementation of the device from 0.18 to 0.05 cases per person-month (ppm) compared to the control villages (0.11 to 0.08 ppm). The rate ratio of 0.27 for the study villages is revised to 0.38 when considering the non-significant rate reduction in the control villages. Provision of a repurposed hemodialyzer membrane filtration device markedly improves health outcomes as measured by diarrhea incidence within rural communities.

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Introduction.

Estimates from the World Health Organization and the World Bank place around 1.1 billion people in the world in a position of having to drink unsafe water. Water and sanitation, specifically access to clean water for the world population, were adopted as the Sustainable Development Goal-6 (SDG-6) by all member states of the United Nations. The deserved, widespread attention emphasizes the importance of the issue and the need for more improvement. Industrialized countries have to a large extent solved the problem and a majority of their populations has access to safe drinking water. This is mainly due to the effort of governments, strict laws, regular monitoring, efficient handling and cleaning of sewage, centralized and monitored provision of clean drinking water and lastly to a generally higher level of hygiene (including the use and provision of sanitary facilities). Due to high population growth rates, lack of economic development, and inadequate political efforts this remains a major problem in many countries with limited resources.

Rural areas in developing countries present problems of greatest magnitude. Water is still mainly carried from continually contaminated surface water such as ponds and rivers. Water is often polluted by coliform bacteria and viral pathogens. Factors such as a lack of sanitary facilities, inadequate hygiene practices and substantial flooding during rainy seasons aggravate the problem. Not only surface but also centralized, processed water are at high probability of being contaminated 1 . Wells may also be susceptible to pollution particularly when they are shallow or intermittently overcome by raising water tables. Further, in some low-income countries a flourishing business of sachet water exists, which is assumed to be safe for consumption. However, as shown in work from Nigeria these sachets are also in many cases contaminated due to improper packaging and storage, or inadequate hygiene in the processing. The incidence of diarrhea and its life threatening complications such as dehydration and acute kidney injury correlate with these factors 2 . Non-infectious contaminants in drinking water such as lead and other heavy metals, arsenic, and also organophosphates from pesticides and insecticides contribute to health hazards, problems that are not addressed with our work at present.

Since the first epidemiological studies by the physician John Snow in the nineteenth century, the deleterious effect of microbial pathogens in water has been well established. Estimates of the World Health Organization suggest that 88% of all diarrheal diseases are caused by the consumption of unsafe drinking water and the lack of adequate sanitation facilities 3 . A recent publication of the initiative has identified that a majority of cases of acute kidney injury in the developing world are (in contrast to the most frequently reported pathogenesis in first world countries) are associated with community-acquired disease and to a major part with diarrhea 4 . This is particularly evident in children 2 to 5 years of age in whom mortality is very high 5 . Overall, these data strongly corroborate why it must be a prime goal for the world community to jointly aim to achieve the SDG-6. These data provide a powerful stimulus for widespread joint action by the world community to achieve this goal.

Common approaches to counteract microbial pollution include various filtration devices: Microfiltration, ultrafiltration, nanofiltration and reverse osmosis. Membrane filtration has long been recognized as an effective and likely efficient approach to partly solve the problem in rural regions, however membranes and filtration devices are expensive, and filters are prone to clogging without proper functioning flushing methodologies. The great need that is also building the basis of the SDG-6 of the United Nations, will require an affordable solution to be made available that is not overly prone to malfunction, can sustain functionality over a long period of time and does not require too extensive maintenance in terms of parts and labor. Surface water is often polluted with parasites, bacteria and viruses that can cause serious health issues 6 . Of note, all these pathogens are larger than the pore size of the hemodialyzer that is approximately 0.003 µm. This pore size notably is smaller than most commercially available purification devices, the operation of which has been claimed to be a feasible technique for water purification 2 .

Hemodialysis is a renal replacement therapy modality that uses hemodialyzers in those suffering from renal failure to counteract the consequences of not having kidney function and to ultimately save them from dying. These hemodialyzers are mainly comprised hollow fibers in a plastic casing. This allows, after cannulation of the patient, to pass the patient’s blood inside the fibers, and along the semipermeable membrane of the fiber, until it leaves the hemodialyzer and is returned to the patient. At the same time, dialysis water, containing anions and cations in specifically defined concentrations, passes, in a countercurrent fashion, on the other side of the membrane resulting in gradient-driven diffusion allowing for toxin removal from the blood and by producing a hydrostatic pressure also removes excess water from the patient through volumetric ultrafiltration. These hemodialyzers were commonly being reused after sterilization, a practice that has changed since earlier days of dialysis and current clinical practice commonly uses hemodialyzers only once and discards them after use. Of note, this alone results in approximately 30 kg of annual waste for every (out of approximately 2 million worldwide) dialysis patient 7 . It was shown recently that used and re-sterilized hemodialyzers (a process possible at less than $2 per hemodialyzer) are effective in producing clean water from microbiologically contaminated water when pushed through these hemodialyzers under high hydrostatic pressure.

We, Easy Water for Everyone (EWfE), report here the experience and some preliminary data from the use of this relatively simple technique for preparation of drinking water from polluted river water in rural villages in Ghana that have no electricity. We provided villages with devices containing re-sterilized hemodialyzers uniquely repurposed from their hemodialysis past, which are capable of producing large volumes of water (up to 500 L/h) free of bacteria and viruses for domestic use. Here we report public health outcomes based on prospectively collected self-reported public health information on diarrhea incidence collected before and after implementation of this device in several villages.

Material and methods

Easy Water for Everyone (EWfE) is a 501(c)(3) non-profit, non-governmental organization (NGO) in the United States, Ghana (and with other countries in progress). With the help of local politicians and stakeholders a need for water purification in the estuary of the Volta River in Ghana was identified. For those living in this region the river is the main source for drinking water even though it is known to carry pathogens. Under the supervision of local committees and administrators, EWfE started to install and maintain a device in each of the villages. The chronological order was arbitrary and data collection was commenced on the islands around Ada Foah since 02/2018.

Water purification method

The membrane filtration device (NUF500; NUFiltration, Israel), consists of a set of 8 hollow-fiber hemodialyzers, appropriate tubings and a faucet. These hollow fiber hemodialyzers in this project have been used as hemodialyzers once, then reprocessed and sterilized according to FDA/AAMI standards before installation into the water-purification device. Each hemodialyzer contains around 12,000 capillaries providing a membrane surface area of nearly 2 square meters per hemodialyzer. The membrane pore size is 0.003 µm, notably preventing passage of bacteria, parasites and notably also of pathogenic viruses. The output of pure water can be as high as 500 L/h when actively pumped into the device or up to 250 L/h passed into the device by gravity after being pumped into an overhead tank as used in this study. The pressure by gravity is caused by a height of about 12 feet from which the polluted water enters the eight dialyzers placed in parallel (see Fig.  1 a, b).

Hemodialyzer membrane filtration device used for our project. Setting with ( a ) a manual pump (up to 500 L/h) and ( b ) gravitational force (up to 250 L/h) for driving the contaminated into the re-sterilized and repurposed hemodialyzer filters.

Contaminated river water enters the inside of the capillaries (“blood” compartment) while clean water collects outside of the capillaries (“dialysate” compartment in clinical hemodialysis). Only water (and dissolved salts) passes through the pores. Organic matter that accumulates on the inside of the capillary fibers needs to be rinsed away by intermittently reversing the pressures and filtering clean water back across the membranes (backwashing) through manual pumping. It takes less than 5 min for the backflow to change from dirty to clean appearance and then regain full efficiency for providing clean water.

Data collection

Following the approval of our research project, embedded in the non-profit endeavor, by Ghana Health Services, we initiated data collection with trained local community members to support our endeavor. Next to demographic data and water results before and after passing through the filter, we collected data monthly from the heads of households on self-reported diarrhea events in 8 villages during the months February through November 2018. This was a subset of villages served by EWfE.

In late June 2018, the hemodialyzer filtration devices became operational in 4 of these villages so that this ongoing monthly data collection started 5 months before the installation. It was concluded 5 months after the installation of the hemodialyzer filtration device. Simultaneously the same data was collected in the 4 villages without the device. For each village and each month, the count of diarrhea events and the number of persons exposed to the data collection were analyzed to estimate the monthly diarrhea incidence rates. Monthly data were summarized for each of the two groups of villages, the control group of 4 villages never exposed to the hemodialyzer water treatment and the group of 4 villages exposed to the water treatment during their second 5 months of the 10-months study period. This approach allowed comparison of the incidence rates during the first and second 5-months periods and incidence rate ratios (second/first 5 months) for the study group and the control group. Having this concomitant data allows us, in a univariate fashion, to use village populations as their own controls and consider the potential confounding effect of seasonality.

The results of water testing showed coliform bacteria at 558 CFU/100 mL in the source water (Volta River) and zero CFU in the filtrate water at the beginning of our installations in the villages of Big Ada. We studied 8 villages (4 were designated control villages and 4 were study villages) in rural Ghana. Table 1 shows the population characteristics of the study arms. Of the village populations studied in this cohort study, 11% and 8% were younger than 5 years of age and notably showed a remarkably high proportion of villagers (96% and 99%) had to resort to open defecation.

Monthly diarrhea incidence rates averaged 0.18 counts per exposure month during the baseline period of the study villages and 0.11 for the same 5 months of the control group. During the first 5 months after the installation of the hemodialyzer filtration device, the rate reduced to 0.05, yielding a rate ratio for the study group of 0.28. For the control group the second 5 months gave an average rate of 0.08, showing modest non-significant reduction from the prior 5 months period with a rate ratio of 0.73 (Table 2 ). Figure  2 a and b show the monthly data for the two periods in both village groups. The control villages of the same region and during the same calendar months allow consideration of a seasonal effect on the diarrhea incidence in the study group. Thus, using the incidence rate ratio for the second 5 months over the first 5 months gives a seasonally adjusted rate ratio of 0.38 (0.28/0.73), which translates to a diarrhea incidence rate that is reduced by 62% following initiation of the hemodialyzer filtration device in the study villages.

Monthly diarrhea incidence rates between February (Month − 5) and November (Month + 5) 2018 in ( a ) study villages, where the device was installed in late June 2018 and ( b ) control villages with no device installation during the same months.

In many countries microbiologically contaminated water is the underlying cause of gastrointestinal disease, mainly diarrhea, associated with deleterious consequences such as acute kidney injury resulting in a high mortality rate, particularly in weaned children younger than five and the elderly. Our data, collected in 4 rural communities in the Ada-East distric of Greater Accra Region in Ghana, before and after the implementation of a hemodialyzer membrane filtration device to produce clean drinking water, shows a substantially reduced risk (rate) of self-reported diarrhea by 72%. This is a major public health outcome particularly since diarrhea is well known to be associated with deleterious consequences such as acute kidney injury and death, particularly in younger children and the elderly. This finding is striking and the rigorous analytic design where each community serves as their own control allows for drawing solid conclusions. Studying and comparing our data to that of a control group which presented only with modest reduction in the incidence of diarrhea over the same time period, corroborates an effect that can be attributed to implementation of our approach. The only modest reduction of diarrhea incidence in the control villages also reduces concerns of seasonality in the incidence rates confounding our interpretation.

Discussion of our approach in comparison with other approaches

The methods used in the present study have been effective in removing pathogens from consistently polluted river or lake water sources. During the past 3 years the on-site implementation of the hemodialyzer filtration device have allowed us to demonstrate the success of providing clean and pathogen-free drinking water to villages where the source of drinking water had been consistently contaminated. This system works well even in remote areas without requiring electricity or other external power sources. No restrictions on water use need to be imposed and use of clean water can be encouraged also for handwashing with soap. When more water is needed, the filling of the main water tank can be increased from weekly to two to three times a week (or even daily). There are several key elements that contrast our approach to other methods to produce drinking water: (1) Rejection of pathogens is highly effective and includes particles as small as pathogenic viruses, given the pore size of 0.003 µm, (2) no need to add bactericidal agents such as chlorine to kill remaining pathogens in drinking water, (3) the simplicity of this design allows its use in isolated rural villages even in areas that have no electricity, (4) this system becomes almost self-sufficient after a few villagers have been trained to do the thrice daily backwashing, (5) excellent filtration rates have been observed with this setup for over one year, (6) visits by a trained technician once or twice weekly or more frequently when necessary for refilling the large water tanks using a gas-driven pump provide some monitoring of the continued function and service and (7) relatively low cost since the reprocessed hemodialyzers are inexpensive and have shown in our 3-year experience to maintain high output rates of nearly 250 L/h (by gravity feed) for over one year. Furthermore, in circumstances where larger volumes of purified water are needed, an expanded device, employing far more dialyzers could be utilized. It would also be feasible to equip the device with solar panels which would increase water production substantially but would add to the cost.

Comparison of efficacy with other approaches

Attempts to purify water from microbiological contamination have been undertaken in a multitude of studies discussing purification of water from springs, boreholes, and wells, all sources with many opportunities for contamination to occur between sources and point of use. The source water is detoxified and infectious agents are reduced or removed by methods such as chlorination, membrane filtration, flocculation and others. Direct systems include conventional filtration, for example using sand through granular media which removes parasites, bacteria and possibly some viruses. Conventional filtration also includes chemical coagulants such as potassium alum added to source water which produce clots (flocs) which are in turn filtered. These processes are not easy and require expert handling by trained individuals.

Quite commonly reported is household chlorination which is a simple technique with widespread use. It improves water quality and effectively prevent diarrheal diseases. Quantity and acceptance (because of the resultant taste of the water) are downsides of this approach 5 .

With direct filtration, water passes through a medium such as sand or diatomaceous earth, a process which removes giardia lamblia, cryptosporidia, and bacteria from the water. These methods also remove color and turbidity. Filtration bags are warm bags or cartridges containing a filament to strain the water. These bags are however not useful for anything smaller than the giardia. Ceramics may be impregnated with tiny colloidal particles and allows for eradication of most bacteria and protozoan parasites. However, also this method is not adequate for virus removal. Most of these methods however are laborious, require specialized knowledge and infrastructure, and also time.

Membranes are widely used to produce safe drinking water and are the only means available to produce water free of parasites, bacteria and all pathogenic viruses.

Membranes can be divided into groups largely defined by their characteristics in regard to pore sizes. Depending on the degree of pore size, they can also produce water free of many chemical components. In the case of biologically contaminated water some membranes can produce water free of bacteria, parasites and viruses.

Hemodialyzers that are contained in the device we have chosen to implement in village structures have a semi-permeable membrane made of polysulphone and polyethersulphone. The pore size is around 0.003 µm and will not let parasites, bacteria and viruses pass, while still providing an output as large as 500 L/h.

Decreased microbial quantity in drinking water is effective in decreasing diarrhea. Effectiveness does not solely depend on the presence of improved water supplies but will also be affected by the use of sanitization facilities and handwashing with diligent soap procedures. In concert with appropriate education, these interventions will play a powerful role in improving public health outcomes. Also important in the context of effectiveness is the amount of water that is being produced over a defined period of time. In this context it is of note that our approach, even with the use of the gravitational device where water is pumped into an overhead tank and gravitation is being used to transfer contaminated water into the filter, allows for up to 250 L/h.

Household efforts

Household efforts include: improved water storage, chlorination, solar exposure, filtration by filter media in relationship to pore size, combined flocculation and disinfection methods. A combination of efforts including improved water supply and storage, and improved sanitation results in better water supplies thus reducing the risk of developing diarrhea. Various authors provide a range of figures for reduction of diarrhea but overall it is expected that household interventions will provide a risk reduction for diarrhea incidence 8 . The WHO promotes water treatment and safe storage of household water. Affordability, acceptability, sustainability and scale ability are all important factors and these small-scale solutions do provide improvement.

A current technology comparable to our approach are the “Aqua Towers”, an approach that also uses gravitational forces to pass water through the filter. More than 1,000 of these are active in Asia Pacific and Latin America. It utilizes ultrafiltration but the manufacturer does not reveal the membrane type. Activated carbon is used to enhance the quality of the drinking water. In addition, part of the water supply is used for hand washing. The authors claim that viruses larger than 0.01 microns are removed. However, a membrane with pore sizes as large will not exclude the rotavirus (a causative pathogen of diarrhea in up to 40% in some reported populations), and hepatitis B and C viruses, unlike the hollow fiber hemodialyzer membrane as discussed above. Of note, no outcome data have been published for the communities using the “Aqua Towers”, to the best of our knowledge.

Strengths and limitations of our study

Surveys of diarrhea in households may be considered soft data, however the magnitude of a relative 72% reduction in the incidence of diarrhea per monitored population is strikingly large. It is also corroborated by many mothers reporting a sudden virtual absence of diarrhea in their children after availability of the hemodialyzer-filtered water. The marked reduction in the diarrhea incidence may be due to using sterile water instead of river water polluted with known pathogens, such as E. coli , as the main source of drinking water. Additionally, handwashing with clean water may be an important contributor to our observations. While our study cannot prove causation with certainty, the nearly stable rates in the control group suggests a causative role of the change in the water source from river water to filter-sterilized water.

Of note, we decided to not adjust for population characteristics for two reasons: the same population served as their own controls for each household and the groups of villages and secondly the incidence rates during the initial 5 months were similar for the two groups of villages.

Further considerations beyond water purification

The effectiveness of pure drinking water, sanitation and hygiene by the Campbell/Cochrane collaboration showed 66 rigorous evaluations and 71 interventions (accounting for 30,000 children in 35 countries). Point of use water quality was associated with positive outcomes and so did hand-washing with soap. The Cochrane data base of systemic reviews discussed the effect of hand washing promotion for preventing diarrhea induced nutritional deficiency 9 , retarded child development 10 and deaths in low- and middle-income countries. The list of interventions to improve water quality by eliminating or reducing pathogens with the objective of preventing diarrhea is substantial.

Our results on markedly reduced incidence of diarrhea after implementation of the hemodialyzer filtration device agree with prior studies. In Clasen’s data synthesis paper 11 on 42 studies in 21 countries showed that all interventions to improve the microbial quality of drinking water were effective in reducing diarrheal incidents even though variations in design and application of water cleansing systems limit comparability of their cited studies. Results are less consistent for the role of other common environmental interventions (such as sanitation, or instruction in hygiene) 12 .

Our study using monthly surveys of diarrhea in households may be considered soft data, however the magnitude of a relative 72% reduction in the incidence of diarrhea per monitored population is strikingly large. It is also corroborated by many mothers reporting spontaneously a sudden virtual absence of diarrhea in their children after availability of the dialyzer-filtered water. The marked reduction in the diarrhea incidence is likely due to using sterile water instead of using river water polluted with known pathogens, such as E. coli , as the main source of drinking water. It may be expected that combination of installing a membrane filtration device and combining it with WASH initiatives will have a strong amplified effect as compared to clean water provision alone. This however remains to be shown in further prospective research.

The hemodialyzer membrane filtration device used in this study was clearly associated with a substantial reduction in the incidence of self-reported diarrhea compared to the prior period and compared to a control group without the device. Use of repurposed hemodialyzers, that had already saved lives once in their initial purpose in renal replacement therapy, can again serve as an affordable means of water purification to again save lives within entire communities. Our hemodialyzer membrane filtration approach using hollow fibers with pore size as tight as 0.003 µm in the a surface-maximizing configuration used in the technology of the device described in this paper is highly effective and unique. This renders it not only eligible but potentially highly effective to allow the world population to successfully accomplish the United Nations’ Sustainable Development Goal 6.

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Acknowledgments

First and foremost, we would like to thank those who have made this study possible by their generous donations. We further would like to thank all those that supported our work and helped us to get to the point we currently are. Last but certainly not least we would like to thank the village committees and everybody in the studied villages (Adzakeh, Agamakope, Alewusedekope, Amekutsekope, Anazome, Azizakope, Baitlenya and Tornyikope).

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Easy Water for Everyone, 10 Bank Street, Suite 560, White Plains, NY, 10606, USA

Jochen G. Raimann, Seth Johnson, Linda Donald, Friedrich Port & Nathan W. Levin

Research Division, Renal Research Institute, New York, USA

• Jochen G. Raimann

Katz School at Yeshiva University, New York, USA

Easy Water for Everyone, Accra, Ghana

Jochen G. Raimann, Joseph Marfo Boaheng, Philipp Narh, Harrison Matti, Seth Johnson, Linda Donald & Nathan W. Levin

Department of Field Epidemiology and Applied Biostatistics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

• Joseph Marfo Boaheng

Ghana Health Services, Big Ada, Ghana

Philipp Narh

Department of Epidemiology and Biostatistics, CUNY Graduate School of Public Health and Health Policy, City University of New York, New York, USA

Hongbin Zhang

CUNY Institute for Implementation Science in Population Health, New York, USA

Departments of Medicine (Nephrology) and Epidemiology, University of Michigan, Ann Arbor, MI, USA

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Contributions

Conceptualization: J. R., S. J., L. D. and N. L.; Data curation: J. R., J. M. B., P. N. and F. P.; Formal analysis: J. R., J. M. B., H. Z. and F. P.; Funding acquisition: L. D. and N. L.; Investigation: J. R., J. M. B., H. Z., F. P. and N. L.; Methodology: J. R., J. M. B., H. Z., F. P. and N. L.; Project administration: P. N., L. D. and N. L.; Resources: J. R., P. N., S. J., H. Z. and N. L.; Software: J. R. and J. M. B.; Supervision: N. L.; Validation: J. R., H. Z., F. P. and N. L.; Visualization: J. R., J. M. B. and F. P.; Writing—original draft: J. R., F. P. and N. L.; Writing—review & editing, J. R., J. M. B., P. N., S. J., L. D., H. Z., F. P. and N. L.

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Jochen Raimann and Seth Johnson are employees of Renal Research Institute/Fresenius Medical Care. All other authors have no financial disclosure.

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Raimann, J.G., Boaheng, J.M., Narh, P. et al. Public health benefits of water purification using recycled hemodialyzers in developing countries. Sci Rep 10 , 11101 (2020). https://doi.org/10.1038/s41598-020-68408-1

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Radioactive Substances Containment Technology Developed for Hitachi-GE Highly Innovative Advanced Boiling Water Reactor (HI-ABWR)

Uses an original noble gas filter plus an organic iodine filter to minimize impact on the external environment

March 22, 2024

The HI-ABWR (Highly Innovative Advanced Boiling Water Reactor) *1 developed by Hitachi-GE Nuclear Energy, Ltd . (“Hitachi-GE”) will be equipped with a radioactive substance containment system consisting of a noble gas filter and an organic iodine filter with improved removal effectiveness, in addition to the conventional filter vent system *2 (Figure 1, center). Up to now, radioactive noble gases *3 that are one class of radionuclides have undergone decay prior to release; but the decay process has the problem of requiring a large amount of equipment. Hitachi, seizing on the difference in polarity and molecular size *4 between radioactive noble gases and the steam and hydrogen released from a plant, is developing technology using an original membrane filter to separate and remove the radioactive gases (Figure 1 (a)). For radioactive organic iodine, *5 Hitachi developed organic iodine adsorption technology with improved removal efficiency, by replacing the conventional zeolite *6 adsorbent with an ionic liquid-based material *7 (Figure 1 (b)). Making use of electrostatic interaction *8 with the ionic liquid, organic iodine can be selectively removed. Moreover, since solid zeolite material is not used, pressure drop in the filter vent system are reduced and the noble gas filter (membrane filter) can be made compact. It is expected that the combination these technologies enables this system to be installed in the limited space in existing nuclear power plants while minimizing the impact on the external environment. Hitachi intends to continue working closely with Hitachi-GE, contributing to enhanced nuclear safety through the realization of HI-ABWR with its low environmental impact.

Development of the organic iodine filter in this project was partially funded by a grant from the Agency for Natural Resources and Energy of Japan’s Ministry of Economy, Trade and Industry, given for technology development contributing to enhanced nuclear safety.

Figure 1. Radioactive substances containment system

For more information, use the enquiry form below to contact the Research & Development Group, Hitachi, Ltd. Please make sure to include the title of the article.

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Research shows GLP-1 receptor agonist drugs are effective but come with complex concerns

Drugs like Ozempic, Wegovy and Mounjaro have been around for years, but they’ve recently been making headlines due to a rise in popularity as weight loss agents. They all belong to a class of drugs known as glucagon-like peptide-1 receptor agonists (GLP-1RAs), which mimic a hormone (GLP-1) in the body that helps control insulin and blood glucose levels and promotes feelings of satiety.

These drugs are extremely effective for blood glucose control and weight management, which, combined with their relatively limited side effect profile, makes them very appealing for diabetes treatment — the purpose for which they originally received FDA approval.

However, off-label use fueled by celebrities and social media is a growing concern. And even when physicians are prescribing GLP-1RAs for their intended uses, it’s not a magic formula — there are complex considerations such as dosages, costs, side effects and comparisons between specific drugs.

“The current fervor for GLP-1RAs in the capital markets as well as in the general public, especially in terms of weight reduction, is probably going to result in overuse,” said Chun-Su Yuan, MD, PhD , the Cyrus Tang Professor of Anesthesia and Critical Care at the University of Chicago. “This should raise a red flag.”

Living up to the hype

While experts caution against overusing GLP-1RAs or viewing them as a universal cure-all for obesity, physicians and researchers agree that the drugs are highly effective for weight management and Type 2 diabetes treatment.

“Some other treatments for Type 2 diabetes can actually cause weight gain, whereas GLP-1RA drugs effectively control blood glucose levels while also reducing body weight,” Yuan said.

Yuan and a group of other researchers recently published a paper comparing the effectiveness of different GLP-1RAs. Different drugs performed better in different areas, but all 15 GLP-1RAs they analyzed were very successful in lowering blood glucose and achieving weight loss. They also identified some secondary benefits, such as lowering cholesterol.

Similarly, Eric Polley, PhD , a UChicago data science and public health expert, recently led a study published in Nature Cardiovascular Research that used statistical modeling to simulate a clinical trial comparing the effects of four different classes of diabetes medication in patients with moderate cardiovascular risk. GLP-1RA drugs came out on top, not only controlling blood glucose and weight but also reducing the risk of major heart-related events and the risk of death overall.

Not a silver bullet: making nuanced decisions for each patient

However, GLP-1RAs are not universally effective for all patients, and Yuan said that even after deciding to prescribe this drug class, physicians should consider multiple factors when selecting a specific drug and dosage. For example, co-morbid conditions like hyperlipidemia could tip the scale and make one drug more suitable for a specific patient.

Polley pointed out that even patients with similar clinical profiles might prioritize different aspects of their health or quality of life.

“If cardiovascular health is what you think is important for deciding between these drug classes, I think our most recent study provides some strong evidence. But if there are other outcomes that your patient is concerned about, then you have to consider the effect size for those other outcomes,” Polley said. He and other experts are working on subsequent research examining the effects of different diabetes treatments on other health outcomes and concerns, including a patient’s risk of cancer, blindness or amputation.

Another key consideration is side effects, which can vary significantly from patient to patient. While Yuan’s recent study confirmed the efficacy of GLP-1RAs, the researchers also found that some patients did experience adverse side effects, especially related to gastrointestinal issues like nausea and vomiting. They highlighted the need to consider potential tradeoffs between efficacy and side effects, finding that higher doses can have stronger efficacy but also induce more severe side effects.

“It’s also important to note that the long-term side effects of these drugs are not yet well-studied,” Yuan said. “If large swathes of the general public start taking them off-label for weight loss and then we find out years later that there are bad side effects, it could be a real issue.”

Rethinking long-term weight management strategies to overcome cost barriers

Yet another dimension affecting the use of GLP-1RAs is cost. The drugs are expensive, and experts say the recent spike in popularity has already led to shortages and increased hesitancy among insurance providers to cover these drugs.

“We know these drugs represent a massive breakthrough in our long fight against obesity-related clinical conditions, but their high cost has been the subject of substantial debate,” said David Kim, PhD , a UChicago health economist. “It presents a key barrier to equitable access to this great innovation.”

In pursuit of more equitable and cost-effective approaches to leveraging GLP-1RAs, Kim and a group of other researchers analyzed the potential impact of alternative weight loss programs. Specifically, they proposed an approach in which GLP-1RAs could be prescribed for an initial period of weight loss before patients transitioned to cheaper alternative interventions for weight maintenance such as lower-cost medications, behavioral health programs and support from nutritionists.

“We wanted to challenge the assumption that once you’re on a GLP-1RA drug, you have to keep taking it forever,” Kim said. “That’s where some of the affordability concerns are coming from: large populations are potentially eligible to take these drugs, and we can’t pay for a lifetime supply for everyone.”

The researchers’ model suggested that even though the alternative weight-maintenance programs might be slightly less effective than long-term, full-dosage GLP-1RA use, the clinical benefits would only decrease slightly, while lifetime healthcare spending would decrease substantially.

“We argue that this alternative framework is a viable solution that provides greater flexibility for managing a limited drug supply and giving healthcare payers financial headroom to support more patients accessing effective weight management treatment,” Kim said.

“ Comparative effectiveness of GLP-1 receptor agonists on glycaemic control, body weight, and lipid profile for type 2 diabetes: systematic review and network meta-analysis ” was published in The BMJ in January 2024. Authors included Haiqiang Yao, Anqi Zhang, Delong Li, Yuqi Wu, Chong-Zhi Wang, Jin-Yi Wan and Chun-Su Yuan.

“ Effectiveness of glucose-lowering medications on cardiovascular outcomes in patients with type 2 diabetes at moderate cardiovascular risk ” was published in Nature Cardiovascular Research in April 2024. Authors included Rozalina G. McCoy, Jeph Herrin, Kavya Sindhu Swarna, Yihong Deng, David M. Kent, Joseph S. Ross, Guillermo E. Umpierrez, Rodolfo J. Galindo, William H. Crown, Bijan J. Borah, Victor M. Montori, Juan P. Brito, Joshua J. Neumiller, Mindy M. Mickelson and Eric C. Polley.

“ Balancing Innovation and Affordability in Anti-Obesity Medications: The Role of Alternative Weight Maintenance Program ” was published in Health Affairs Scholar in May 2024. Authors included David D. Kim, Jennifer H. Hwang and A. Mark Fendrick.

Altering cancer treatment dosing could reduce climate impact, study finds

Model estimates potential to reduce greenhouse gas emissions by delivering treatment every 6 weeks.

Changing how often a popular cancer therapy is delivered would reduce greenhouse gas emissions and improve environmental impact without decreasing cancer survival, according to a new analysis from researchers at the University of Michigan Health Rogel Cancer Center.

The team looked at 7,813 veterans receiving the immunotherapy treatment pembrolizumab through the Veterans Health Administration. Pembrolizumab is an intravenous treatment that is often given every three weeks at a standard, one-size-fits-all dose of 200 milligrams. Researchers estimated the environmental impact of patients coming in for this care every three weeks: carbon dioxide emissions from patients' transportation to and from the clinic, manufacturing of the drug, and medical waste like needles, tubing and bags used during the compounding and infusing process.

Then they considered alternative scenarios. What if patients received 400 milligrams of pembrolizumab every six weeks, a dose approved by the U.S. Food and Drug Administration? What if they received a dose proportionate to their weight instead of the standard dose, as pembrolizumab was originally approved by FDA? Data suggests these approaches achieve cancer outcomes equivalent to the standard three-week flat dosing and likely reduce the burdens of cancer treatment that patients face.

They found that for this cohort of patients, extending treatments to every six weeks instead of every three weeks would have required 15,000 fewer infusions. That means 15,000 fewer trips to the clinic and 15,000 fewer incidents of compounding and infusing treatments. In total, this change would reduce greenhouse gas emissions in just the VHA by 200 tons per year. Results are published in The Lancet Oncology .

"As providers, every time we're with a patient we're faced with this litany of decisions that both we and the patient have to make. Those decisions -- every three week dosing or every six week dosing -- seem small but they really add up," said study author Garth W. Strohbehn, M.D., M.Phil., assistant professor of internal medicine at Michigan Medicine.

Next, researchers looked at the impact that the reduced carbon emissions could have on climate change and human health -- not just for the person with cancer, but for all of us, due to rising global temperatures. The model indicates that by continuing the current trends in pembrolizumab dosing instead of changing to less-frequent dosing, about three more people will die per year between now and 2100 because of the extra greenhouse gas emissions.

"There will more than likely be folks completely uninvolved in cancer care who are harmed by choosing to dose this medicine the way that we do. It doesn't need to happen," said Strohbehn, who is also a member of the U-M Institute for Healthcare Policy and Innovation and early career research scientist at the VA Ann Arbor Center for Clinical Management Research.

"That's the point we're trying to make here: There are likely to be health costs that non-patients in a society can expect to bear when we choose to practice cancer care the way we do. Do we have a moral obligation to change the way we're doing things if the patient in front of us is not harmed by it?"

Patient transportation to and from appointments was the biggest driver of carbon emissions, researchers found, which suggests that less-frequent infusion treatments would not only help the environment but also potentially improve patient quality of life due to fewer trips to the hospital. Researchers also estimated significant cost savings for VHA from the alternative dosing regimens since the total amount of drug used with the weight-based doses is lower than the one-size-fits-all approach, echoing earlier findings from Strohbehn's team.

The study authors suggest that multiple policy actions would need to be aligned to facility this change. They suggest payers could develop targeted incentives around environmentally conscious care. Professional societies could alter guidelines with environmental sustainability in mind, where patient outcomes are not expected to be impacted by the adoption of more sustainable care. Requiring environmental report cards for individual drugs at the time of approval could also increase awareness.

"I think there's value in holding a mirror up to the conventional system and encouraging self-reflection," Strohbehn said.

• Today's Healthcare
• Patient Education and Counseling
• Diseases and Conditions
• Personalized Medicine
• Environmental Policy
• Global Warming
• Environmental Issues
• Environmental Awareness
• Environmental impact assessment
• Cervical cancer
• Colorectal cancer
• Breast cancer
• United Nations Framework Convention on Climate Change
• Mammography
• Prostate cancer
• Automobile emissions control

Story Source:

Materials provided by Michigan Medicine - University of Michigan . Original written by Nicole Fawcett. Note: Content may be edited for style and length.

Journal Reference :

• Alex K Bryant, Jacqueline R Lewy, R Daniel Bressler, Zoey Chopra, Derek J Gyori, Brian G Bazzell, Julie A Moeller, Sofia I Jacobson, A Mark Fendrick, Eve A Kerr, Nithya Ramnath, Michael D Green, Timothy P Hofer, Parth Vaishnav, Garth W Strohbehn. Projected environmental and public health benefits of extended-interval dosing: an analysis of pembrolizumab use in a US national health system . The Lancet Oncology , 2024; 25 (6): 802 DOI: 10.1016/S1470-2045(24)00200-6

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