Water Treatment Practices Research Articles

Powdered activated carbon enhanced Manganese(II) removal by chlorine oxidation

Chlorine is not effective in the oxidative removal of soluble manganese(II) ions at neutral pH. Powdered activated carbon (PAC) also has a very limited capacity for Mn(II) removal through adsorption in drinking water treatment practice. This study explored the combined use of PAC and chlorine for Mn(II) removal and found that PAC dramatically catalyzed Mn(II) oxidation by chlorine under diverse conditions. At a dose as low as 5.0 mg/L, two different commercial PACs increased Mn(II) oxidation rate by two orders of magnitude respectively and reduced Mn(II) concentration from 200 μg/L to < 10 μg/L in tens of minutes. First-order kinetics with respect to aqueous Mn(II) concentration were observed. Typically, homogeneous Mn(II) oxidation by chlorine depends strongly on alkaline pH. In the presence of PAC, however, the reaction was still rather fast at pH 6.0. Increasing PAC doses linearly increased Mn(II) oxidation rate, indicating that the reaction was highly PAC surface active sites dependent. The efficacy of PAC was further corroborated in removing Mn(II) from natural water. SEM-EDS and XPS demonstrated that a MnO2 coating was formed on PAC surface after reaction, which resulted from heterogeneous oxidation of Mn(II) on PAC surface rather than the precipitation of Mn oxides formed through homogeneous oxidation in solution. Adsorption of free Mn(II) ions onto PAC surface was proved to directly correlate with Mn(II) oxidation rate. Two kinds of electron transfer pathways from adsorbed Mn(II) species to chlorine, enhanced by surface-complexation and electrically-conductive carbon surface respectively, were hypothesized.

Degradation of metronidazole by UV/chlorine treatment: Efficiency, mechanism, pathways and DBPs formation

Metronidazole (MET) is a widely used antibiotic but is recalcitrant in aquatic environment. This study investigated elimination of MET by UV/chlorine process systematically. The degradation of MET in the process well fitted pseudo first-order kinetics. Decreasing pH from 9 to 5 raised the rate constant from 0.0199 min-1 to 0.1485 min-1, possibly ascribed to change in species distribution and apparent quantum yields of radicals. Scavenging experiments indicated that both HO and Cl contributed to the degradation of MET, and that HO was the dominant species in the pH range studied. The second-order rate constant between Cl and MET was determined to be (5.64 ± 0.1) × 109 M-1 s-1. Three products were identified by UPLC-Q-TOF MS and degradation pathway was thus proposed. Significant amounts of chlorinated disinfection by-products (DBPs) were produced and 1,1,1-TCP was the dominant (83.6%-92.3%) in the UV/chlorine process. The kinetic model developed fitted well with experimental results, and was used to examine the effects of typical water parameters, such as chorine dosage, pH, inorganic anions, NOM and real water matrix. Furthermore, removal efficiency of MET by the UV/chlorine process were assessed in terms of electrical energy per order (EE/O). The efficiency was about 0.43 kWh m-3 order-1, 0.54 kWh m-3 order-1, 0.57 kWh m-3 order-1, respectively, for the removal of MET in ultrapure water (UPW) and two types of real water samples, indicating that UV/chorine was a practical method for authentic drinking water treatment practices.

Mineral Composition of Kentucky Bluegrass under Recycled Water Irrigation on Golf Courses

Golf courses in the western United States increasingly are being irrigated with recycled water. Research was conducted on eight golf courses in a semiarid region, including three courses with recycled water irrigation for 10 years, three courses with recycled water irrigation for 18 to 26 years, and two courses with surface water for irrigation for 15 and 18 years. Turf quality of kentucky bluegrass (Poa pratensis) (KBG), the most widely used turfgrass species in the United States, was evaluated on 25 roughs from the aforementioned golf courses. Concurrently, KBG shoot samples and soil samples from these sites were collected. Shoots of KBG were analyzed for mineral concentrations, including sodium (Na), calcium (Ca), magnesium (Mg), potassium (K), chlorine (Cl), boron (B), sulfur (S), phosphorus (P), manganese, iron, zinc, copper, and molybdenum. Electrical conductivity (EC) and sodium absorption ratio (SAR) of soil saturated paste were determined. Recycled water irrigation for 10 and &gt;18 years increased clipping Na by 4.3 and 9.9 times and Cl by 1.5 and 1.3 times, respectively. Compared with surface water irrigation, B concentration in KBG shoots increased by 3.5 times and K concentration reduced by 16% on sites with recycled water irrigation for &gt;18 years. Multiple regression analysis was conducted to identify the relationships between mineral concentration in shoots and turf quality. There was a negative linear relationship between turf quality and Na concentration in the shoots (R2 = 0.65). Soil SAR in 0 to 20 cm depth was highly associated with KBG shoot Na, as documented by a logarithmic regression of R2 = 0.70. Stepwise regression indicated that Na accumulation in the shoots was the leading plant variable causing the decline of turf quality under recycled water irrigation. Therefore, it is reasonable to believe that water treatment and management practices that can reduce soil SAR and Na concentration in KBG shoots would improve turf quality and plant health.

Водоподготовка в пищевой промышленности

The author considered the contemporary state of the issue of water treatment in food and beverages production. The article presents regulated water quality parameters for drinking and bottled water, for dairy industry, beer and soft drinks production, as well as for production of vodka, vodka for export, and baby food. The article shows that water from central utility and drinking water supply needs additional treatment to produce food and beverages. It should be cleaned from hardness salts, iron, manganese, mineral salts, organic compounds and microbial contamination. Besides, many companies use groundwater sources (from wells). That makes water treatment procedure even more complicated. The author considered such treatment methods as ion exchange, magnetic water treatment, catalyzed oxidation, deferrization using sorption-filtering materials from mineral raw materials, aeration, reverse osmosis, electrodialysis, activated carbon adsorption. The author shows the treatment mechanisms, their advantages and disadvantages. The article indicates which materials and equipment can be used to apply these methods in water treatment practice. It describes new techniques for effective water treatment such as radiolysis, cavitation and advanced oxidation treatment techniques. It gives flow diagram of bottled water production depending on its origin and content of impurities which is used by the companies working in Gelendzhiksky district, Lipetsk and Kemerovo. The author analyzed the contemporary state of the issue of water treatment in food and beverages production companies based on the available information and assessed the technical level of water treatment systems. The article reveals that only companies which produce alcoholic drinks such as vodka, liquors, and beer use a number of water treatment procedures which meet modern requirements. In general, food production companies face water treatment issue. Labor intensive, expensive and non-environmentally friendly water treatment methods are used everywhere. But they do not always guarantee required water quality. For that reason water treatment schemes in food industry should be revised. The author gives recommendations to replace traditional technologies with modern ones.

Users’ Perceptions on Drinking Water Quality and Household Water Treatment and Storage in Small Towns in Northwestern Tanzania

Despite recent progress in increasing the world’s population with sustainable access to safe drinking water, hundreds of millions still rely on unimproved sources. To improve the quality of drinking water, various household water treatment and safe storage methods have been developed, adopted and promoted as alternative interventions. However, there is paucity of information regarding drinking water quality and prevalence of HWTS practices especially from the users’ perspectives in Tanzania. This paper examines users’ perceptions on drinking water quality and household water treatment and storage practices in the selected towns of Misungwi, Magu and Lamadi in Northwestern Tanzania. The specific objectives of the study were 1) to examine users’ perceptions on drinking water quality, and 2) to identify household water treatment and storage methods used in the study towns. The paper is based on empirical primary and secondary data collected from 417 households, through survey, key informant interviews, observation and documentary review, and analysed for descriptive statistics, chi-square tests and qualitative content analysis. The study found that water supply coverage in the study towns was generally low. Households drew water from various sources, including ones which were not suitable for drinking. This necessitated households to improve the quality of their drinking water through HWTS practices. Although a combination of adequate and inadequate treatment methods was used to improve water quality and aesthetics, prevalence of HWT practices was generally low. Similarly, safe storage was rarely practiced. Therefore, interventions aimed at improving access to domestic water supply should also incorporate elements of water treatment and safe storage at the point of use to contribute to improved health outcomes.

Floating treatment wetland aided nutrient removal from agricultural runoff using two wetland species

Floating treatment wetlands (FTWs) are an emerging surface water treatment practice for reducing nutrients such as nitrogen (N) and phosphorus (P) in a variety of waste streams. FTWs consist of floating rafts which support wetland plants allowing the plant roots to be submerged below the water surface similar to hydroponic systems. N and P removal is achieved through direct plant uptake and flocculation or sedimentation facilitated by biofilms adhering to plant roots. While research has documented FTW performance for a variety of waste streams, little information is available on runoff from commercial nurseries. Nursery runoff occurs frequently, from storm and irrigation events, and can potentially contain elevated concentrations of total N (TN) and total P (TP) due to crop fertilization and frequent irrigation. Nursery runoff is often captured in large ponds known as tailwater recovery basins (TRBs) for reuse. We assessed the effectiveness of FTWs for treating nursery runoff in TRBs over a 7-day hydraulic retention time across a 19-week growing season using two supplied nutrient concentrations and four treatments with four replicates in a randomized complete block mesocosm experiment. The high nutrient concentration averaged 17.1 mg·L−1 TN and 2.61 mg·L−1 TP and low nutrient concentration averaged 5.22 mg·L−1 TN and 0.52 mg·L−1 TP. Treatments included: 1) Pontederia cordata, 2) Juncus effusus, 3) a raft with no plants, and 4) no raft (open-water). Pontederia cordata removed 90% and 92% of TP and 84% and 89% TN, depending on initial loading; performing better than the other planted and non-planted treatments. Juncus effusus performed better than the mat-only control treatments for TP and TN removal across nutrient concentrations tested, but performed similarly to the open water control when nutrient load was evaluated. Nutrient uptake by Pontederia cordata averaged 0.026 g·m−2·d−1 N and 0.0075 g·m−2·d−1 P. The study demonstrated that FTWs can be very effective, but nutrient removal depends greatly upon plant species selection.

Diffusion of Handwashing Knowledge and Water Treatment Practices From Mothers in an Antenatal Hygiene Promotion Program to Nonpregnant Friends and Relatives, Machinga District, Malawi.

Access to safe drinking water and improved hygiene are essential for preventing diarrheal diseases in low- and middle-income countries. Integrating water treatment and hygiene products into antenatal clinic care can motivate water treatment and handwashing among pregnant women. Free water hygiene kits (water storage containers, sodium hypochlorite water treatment solution, and soap) and refills of water treatment solution and soap were integrated into antenatal care and delivery services in Machinga District, Malawi, resulting in improved water treatment and hygiene practices in the home and increased maternal health service use. To determine whether water treatment and hygiene practices diffused from maternal health program participants to friends and relatives households in the same communities, we assessed the practices of 106 nonpregnant friends and relatives of these new mothers at baseline and 1-year follow-up. At follow-up, friends and relatives were more likely than at baseline to have water treatment products observable in the home (33.3% vs. 1.2%, p < 0.00001) and detectable free chlorine residual in their water, confirming water treatment (35.7% vs. 1.4%; p < 0.00001). Qualitative data from in-depth interviews also suggested that program participants helped motivate adoption of water treatment and hygiene behaviors among their friends and relatives.

Natural organic matter as precursor to disinfection byproducts and its removal using conventional and advanced processes: state of the art review.

Natural organic matter (NOM) is ubiquitous in the aquatic environment and if present can cause varied drinking water quality issues, the major one being disinfection byproduct (DBP) formation. Trihalomethanes (THMs) are major classes of DBP that are formed during chlorination of NOM. The best way to remove DBPs is to target the precursors (NOM) directly. The main aim of this review is to study conventional as well as advanced ways of treating NOM, with a broad focus on NOM removal using advanced oxidation processes (AOPs) and biofiltration. The first part of the paper focuses on THM formation and removal using conventional processes and the second part focuses on the studies carried out during the years 2000-2018, specifically on NOM removal using AOPs and AOP-biofiltration. Considering the proven carcinogenic nature of THMs and their diverse health effects, it becomes important for any drinking water treatment industry to ameliorate the current water treatment practices and focus on techniques like AOP or synergy of AOP-biofiltration which showed up to 50-60% NOM reduction. The use of AOP alone provides a cost barrier which can be compensated by the use of biofiltration along with AOP with low energy inputs, making it a techno-economically feasible option for NOM removal.

A Review of Ozone Systems Costs for Municipal Applications. Report by the Municipal Committee – IOA Pan American Group

ABSTRACTOzone has proven effective in improving water treatment plant performance, increasing customer satisfaction, and meeting increasingly stringent regulatory requirements. The benefits include disinfection; reducing chlorine disinfection by-products; micro-coagulation; enhanced filter performance; biological filtration; oxidation of iron, manganese, sulfide, taste- and odor-causing compounds, pharmaceuticals and personal care products (PPCPs), and endocrine disrupting compounds (EDCs). Despite the effectiveness of ozone in water treatment, a perception remains that ozone may be too expensive for consideration at many water treatment facilities. This paper presents an evaluation by the Municipal Committee of the International Ozone Association (IOA-MC) that aims to provide a realistic assessment of the current capital and operating costs of ozone in the North American water treatment practice. A general strategy is proposed for developing preliminary estimates of ozone capital and operating costs that could be used by engineers and/or owners for planning purposes. The information presented may benefit utilities, managers, and engineers engaged in the evaluation of treatment options.

Assessment of household water treatment and storage practices

Background: Maintenance of drinking-water quality is a pillar of primary prevention and continues to be the foundation for the prevention and control of waterborne diseases. Improved water supply and sanitation, and better management of water resources, can boost countries’ economic growth and can contribute greatly to poverty reduction. The objective of the study was to assess household water treatment and safe storage (HWTS) practice.Methods: A cross-sectional study was conducted for a period of 2 months. Total of 250 household were surveyed under the UHTC. Data was collected using WHO toolkit for monitoring and evaluating household water treatment and safe storage programme. Descriptive analysis was done.Results: Majority had piped connection (32%) followed by public standpipe (31.2%), hand pump (27.6%) as source of water. 60% had knowledge about boiling followed by chlorination 27%, membrane filters 22.4%. Majority i.e. 63% of the participants had thought boiling as the best method for disinfection of drinking water.Conclusions: Majority had piped connection, Maximum kept water container clean and covered. Only one fourth of the total household surveyed suffered from diarrhea in last 6 months.

Household Water Treatment Practice and Associated Factors Among People Living with HIV, Bahir Dar City Administration, Northwest Ethiopia

Introduction: PLHIV have substantially greater need for access to safe water, for bathing and washing soiled clothing and linen; safe drinking water is necessary for taking medicines. Therefore household water treatment is one of inexpensive and effective technology to make water safe. However the information of household water treatment practices and associated factors on these groups were inadequate. Objective: the: t aim of the study was to assess household water treatment practice and associated factors among PLHIV who are member of the three associations in Bahir Dar city administration, Northwest Ethiopia. Methods: A Community based cross-sectional study was done among PLHIV from April-May 2013. A Simple random sampling technique was used to select the study participants. Pre-tested and structured questionnaire, observation checks list and residual chlorine test was used to collect the data. Binary and multivariate logistic regression analysis were used to determine the separate and confounding effect for variables with p-value <0.2 in binary analysis. Result: of the total respondents 76.3% reported that they treated their drinking water at home. But only 11% of respondents treated water at home within 24 hours of this study. The main reasons for not treating water at home were psycho-social problem 29 (53.7%), unavailability of treatment methods 17 (31.5%), and lack of knowledge how to use treatment methods 8 (14.8%). Occupational status of the respondents (AOR=2.6; 95% CI 0.162-0.903), duration of water storing time (AOR=2.9; 95% CI 1.471-5.692), and use of separate container for water storing (AOR=3.1; 1.008-9.223) were significantly associated variables with household water treatment practice. Conclusion: Household water treatment practices among people living with HIV were found low. Therefore the PLHIV needs special attention to improve household water treatment practice. fee free water treatment methods availability, promotion of household water treatment practice and participate in income generating activities are supreme important.

Ground Water Quality Assessment of the Rural Administrative, Dire Dawa City, Eastern Ethiopia

The physico-chemical composition of groundwater from handdug wells were assessed in rural administrative of Dire Dawa, Eastern Ethiopia. A total of 22 hand-dug well water samples were collected from the well fields. All the samples were analysed for five physicochemical parameters (conductivity, total dissolved solid, total hardness, pH and turbidity) and primary cations and anions (Ca2+, Mg2+, Na+, K+ and Cl-) using appropriate procedures and outcome of the analysis were counterchecked with the national and international standards. The ground water physicchemical analysis where undertaken in Central laboratory of Haramaya University and result of the selected sample shows that 95.65% for total hardness and 78.26% for turbidity which indicates higher than ES261:2001 and World Health Organization (WHO) recommended values, respectively. Total dissolved solid and electrical conductivity of all the samples were below the WHO and the Environmental Protection Agency (EPA) health based guideline values for drinking water, respectively. 95.65% of the pH values of the samples were within the ES261:2001 permissible pH limits (6.5-8.5). Entirely the samples encompass concentration of sodium (7.31 mg/L-74.94mg/L), potassium (0.55 mg/L-3.33 mg/L) and calcium (2.58 mg/L-19.88mg/L) which indicates lower than the WHO maximum admissible limit. The result indicates less pollution and good drinking water treatment practices in the areas, which is safe for human consumption.

Prevalence and risk factors for intestinal parasite infections in schoolchildren, in the city of Santarém, Pará State, Brazil

Introduction: Intestinal parasites are common in children in poor countries around the world, and are the cause of serious health problems. Objective: To evaluate the prevalence of intestinal parasites in schoolchildren in Santarem, and associated socio-environmental risk factors. Methods: Questionnaires were applied to parents, and fecal exams were performed by direct method and sedimentation. Results: The parasites that prevailed were Entamoeba coli (20.4%) and Ascaris lumbricoides (9.0%). The family income is an important factor related to parasitic infections (χ 2 =21.000/ p =0.001). Other factors such as water treatment (χ 2 =20.15/ p =0.002), health infrastructure (χ 2 =25.40/ p =0.001), and hygiene practices such as hand washing (χ 2 =11.54/ p =0.003) were statistically significant for the presence of intestinal parasites too, some on a lesser scale. Conclusion: The results showed that Entamoeba coli and Ascaris lumbricoides are the prevalent parasites. The family income, water quality, and sanitary infrastructure are the main risk factors for parasitic infections.

Effects of a behavior change campaign on household drinking water disinfection in the Lake Chad basin using the RANAS approach

Worldwide, an estimated 700 million people rely on unimproved drinking water sources; even more consume water that is not safe to drink. Inadequate drinking water quality constitutes a major risk factor for cholera and other diarrheal diseases around the globe, especially for young children in developing countries. Household water treatment and safe storage systems represent an intermediate solution for settings that lack infrastructure supplying safe drinking water. However, the correct and consistent usage of such treatment technologies rely almost exclusively on the consumer's behavior.This study targeted at evaluating effects of a behavior change campaign promoting the uptake of household drinking water chlorination in communities along the Chari and Logone rivers in Chad. The campaign was based on formative research using health psychological theory and targeted several behavioral factors identified as relevant. A total of 220 primary caregivers were interviewed concerning their household water treatment practices and mindset related to water treatment six months after the campaign. The Risks, Attitudes, Norms, Abilities, and Self-regulation (RANAS) model was used to structure the interviews as the RANAS approach had been used for designing the campaign.Results show significantly higher self-reported drinking water chlorination among participants of the intervention. Significant differences from a control group were identified regarding several behavioral factors. Mediation analysis revealed that the intervention positively affected participants' individual risk estimation for diarrheal disease, health knowledge, perceived efforts and benefits of water treatment, social support strategies, knowledge of how to perform chlorination, and perceived ability to do so. The campaign's effect on water treatment was mainly mediated through differences in health knowledge, changes in norms, and self-efficacy convictions.The findings imply that water treatment behavior can be successfully promoted using health psychological theory. However, they also indicate opportunities for improvement in the campaign design and implementation.

A survey of domestic wells and pit latrines in rural settlements of Mali: Implications of on-site sanitation on the quality of water supplies.

On-site sanitation is generally advocated as a means to eradicate the health hazards associated with open defecation. While this has provided a welcome upgrade to the livelihoods of millions of people in low-income countries, improved sanitation facilities are increasingly becoming a threat to domestic groundwater-based supplies. Within this context, a survey of pit latrines, domestic wells and improved water sources was carried out in a large rural village of southern Mali. All households were surveyed for water, sanitation and hygiene habits. Domestic wells and improved water sources were georeferenced and sampled for water quality (pH, electric conductivity, temperature, turbidity, total dissolved solids, thermotolerant coliforms, chloride and nitrate) and groundwater level, while all latrines were inspected and georeferenced. A GIS database was then used to evaluate the proportion of water points within the influence area of latrines, as well as to underpin multiple regression models to establish the determinants for fecal contamination in drinking supplies. Moreover, an appraisal of domestic water treatment practices was carried out. This revealed that nearly two-thirds of the population uses bleach to purify drinking supplies, but also that domestic-scale treatment as currently implemented by the population is far from effective. It is thus concluded that existing habits could be enhanced as a means to make water supplies safer. Furthermore, population, well and latrine density were all identified as statistically significant predictors for fecal pollution at different spatial scales. These findings are policy-relevant in the context of groundwater-dependent human settlements, since many countries in the developing world currently pursue the objective of eliminating open defecation.

Knowledge, Attitude, and Practice of Mothers/Caregivers on Household Water Treatment Methods in Northwest Ethiopia: A Community-Based Cross-Sectional Study.

In Ethiopia, ensuring safe drinking water remains a big challenge where waterborne diseases, including diarrhea cause a great harm in many rural communities. Limited knowledge, misinformation, negative attitude, and lack of experience toward best practices of alternative water treatment technologies were among the leading challenges. A community-based cross-sectional study was conducted from June 23 to 30, 2015, in Dabat District. The study participants were selected by using simple random sampling method. Questionnaire-based face-to-face interview technique of data collection was used by 20 data collectors under close supervision with six supervisors. From the total of 845 participants with mother-child paired 49.3%, 95% confidence interval [CI] (45.8, 52.5%) had good knowledge, and 54.8%, 95% CI (51.6, 58.3%) had favorable-attitude toward household water treatment. Only 23.1%, 95%CI (20, 26%) of the study participants had practiced household water treatment. Being an urban resident (adjusted odds ratio [AOR]: 2.58, 95% CI: [1.62, 4.11]), having good-knowledge (AOR: 2.62, 95% CI: [1.81, 3.79]), favorable attitude (AOR: 1.45, 95% CI: [1.01, 2.08]), and used unimproved water source (AOR: 1.67, 95% CI: [1.11, 2.50]) were factors associated with household water treatment practices in the district. Despite mothers/caregivers having a fairly good knowledge and positive attitude, their practice of treating drinking water at household level was quite low. Thus, well designed strategy for health education on effective water treatment methods through the national health extension program is recommended.

Rural and Urban Differences in Air Quality, 2008-2012, and Community Drinking Water Quality, 2010-2015 - United States.

Problem/ConditionThe places in which persons live, work, and play can contribute to the development of adverse health outcomes. Understanding the differences in risk factors in various environments can help to explain differences in the occurrence of these outcomes and can be used to develop public health programs, interventions, and policies. Efforts to characterize urban and rural differences have largely focused on social and demographic characteristics. A paucity of national standardized environmental data has hindered efforts to characterize differences in the physical aspects of urban and rural areas, such as air and water quality.Reporting Period2008–2012 for air quality and 2010–2015 for water quality.Description of SystemSince 2002, CDC’s National Environmental Public Health Tracking Program has collaborated with federal, state, and local partners to gather standardized environmental data by creating national data standards, collecting available data, and disseminating data to be used in developing public health actions. The National Environmental Public Health Tracking Network (i.e., the tracking network) collects data provided by national, state, and local partners and includes 21 health outcomes, exposures, and environmental hazards. To assess environmental factors that affect health, CDC analyzed three air-quality measures from the tracking network for all counties in the contiguous United States during 2008–2012 and one water-quality measure for 26 states during 2010–2015. The three air-quality measures include 1) total number of days with fine particulate matter (PM2.5) levels greater than the U.S. Environmental Protection Agency’s (EPA’s) National Ambient Air Quality Standards (NAAQS) for 24-hour average PM2.5 (PM2.5 days); 2) mean annual average ambient concentrations of PM2.5 in micrograms per cubic meter (mean PM2.5); and 3) total number of days with maximum 8-hour average ozone concentrations greater than the NAAQS (ozone days). The water-quality measure compared the annual mean concentration for a community water system (CWS) to the maximum contaminant level (MCL) defined by EPA for 10 contaminants: arsenic, atrazine, di(2-ethylhexyl) phthalate (DEHP), haloacetic acids (HAA5), nitrate, perchloroethene (PCE), radium, trichloroethene (TCE), total trihalomethanes (TTHM), and uranium. Findings are presented by urban-rural classification scheme: four metropolitan (large central metropolitan, large fringe metropolitan, medium metropolitan, and small metropolitan) and two nonmetropolitan (micropolitan and noncore) categories. Regression modeling was used to determine whether differences in the measures by urban-rural categories were statistically significant.ResultsPatterns for all three air-quality measures suggest that air quality improves as areas become more rural (or less urban). The mean total number of ozone days decreased from 47.54 days in large central metropolitan counties to 3.81 days in noncore counties, whereas the mean total number of PM2.5 days decreased from 11.21 in large central metropolitan counties to 0.95 in noncore counties. The mean average annual PM2.5 concentration decreased from 11.15 μg/m3 in large central metropolitan counties to 8.87 μg/m3 in noncore counties. Patterns for the water-quality measure suggest that water quality improves as areas become more urban (or less rural). Overall, 7% of CWSs reported at least one annual mean concentration greater than the MCL for all 10 contaminants combined. The percentage increased from 5.4% in large central metropolitan counties to 10% in noncore counties, a difference that was significant, adjusting for U.S. region, CWS size, water source, and potential spatial correlation. Similar results were found for two disinfection by-products, HAA5 and TTHM. Arsenic was the only other contaminant with a significant result. Medium metropolitan counties had 3.1% of CWSs reporting at least one annual mean greater than the MCL, compared with 2.4% in large central counties.InterpretationNoncore (rural) counties experienced fewer unhealthy air-quality days than large central metropolitan counties, likely because of fewer air pollution sources in the noncore counties. All categories of counties had a mean annual average PM2.5 concentration lower than the EPA standard. Among all CWSs analyzed, the number reporting one or more annual mean contaminant concentrations greater the MCL was small. The water-quality measure suggests that water quality worsens as counties become more rural, in regards to all contaminants combined and for the two disinfection by-products individually. Although significant differences were found for the water-quality measure, the odds ratios were very small, making it difficult to determine whether these differences have a meaningful effect on public health. These differences might be a result of variations in water treatment practices in rural versus urban counties.Public Health ActionUnderstanding the differences between rural and urban areas in air and water quality can help public health departments to identify, monitor, and prioritize potential environmental public health concerns and opportunities for action. These findings suggest a continued need to develop more geographically targeted, evidence-based interventions to prevent morbidity and mortality associated with poor air and water quality.

Palladium nanoparticles supported on amine-functionalized glass fiber mat for fixed-bed reactors on the effective removal of hexavalent chromium by catalytic reduction

Palladium nanoparticles were deposited on the amine-grafted glass fiber mat (GFM-NH2) catalyst support by a conventional impregnation process followed by the borohydride reduction in aqueous solution at room temperature to create the designed Pd/GFM-NH2 catalyst. By the use of large size glass fiber mat without nano/mesopores as the catalyst support, the internal mass transfer limitations due to the existence of nano/mesopores on the catalyst support were eliminated and the Pd/GFM-NH2 catalyst could be easily separated from treated water due to the large size of the catalyst support. Batch experiments demonstrate its good catalytic reduction performance of Cr(VI) with formic acid as the reducing agent. It also demonstrated an efficient Cr(VI) removal and stability in a lab-prepared, packed fixed-bed tube reactor for the continuous treatment of Cr(VI)-containing water. Thus, it has a good potential for the catalytic reduction of Cr(VI) in the water treatment practice.

Removal of sulfide ions from aqueous solutions using carbon- and silicon-containing sorbents

ABSTRACTSulfide ions are among the most common pollutants in natural waters. Sulfide sorption methods are widely used in the waste water treatment practice. The most promising sorbents for removing sulfide ions are porous carbon materials. In the present study we researched sorption capacity of the carbon- and silicon-containing samples of rice and buckwheat processing wastes, as well as the activated carbon, carbon fiber, chitosan and natural silicates toward the sulfide ions in aqueous solutions. It was found that the most effective sorbent from the studied ones is the carbon fiber Aktilen B (99%) and from plant wastes – carbonaceous sorbents obtained from rice straw (77–98%) and buckwheat (94%). We studied the physico-chemical and structural properties of the carbonaceous sorbent based on rice straw and it was found that this sample is amorphous and has a predominant microporous structure. At the concentration of sulfide ions ranging from 140 to 800 µg l−1, the studied sorbent reduces the amount of sulfide ions to 0.4–1.4 of the maximum permissible concentration and can be used for treating natural and post-treating waste waters.

Socio-psychological determinants for safe drinking water consumption behaviors: a multi-country review

The effectiveness of household water treatment practices relies heavily on consumers' compliance. However, what is driving these behaviors from a health psychological perspective is not well understood. A review of studies on safe water collection, treatment, handling and storage practices was conducted to identify important socio-psychological determinants. The objectives are to show which determinants commonly explain safe water consumption practices and how well they do so, and to identify behavior- and population-specific determinants to be targeted in different contexts. The results of the review reveal that all the practices studied can be explained well, with a mean of 62% explained variance between performers and non-performers. Social norms, action knowledge, and perceived self-efficacy were shown to be the most common influential factors for safe water practices. Instrumental beliefs around costs and benefits as well as affective beliefs such as taste are important in a majority of cases but varied more strongly, both for different target behaviors and between specific settings and populations, and are thus to be evaluated from case to case. The review gives clear recommendations on which behavioral factors to address with priority and corresponding behavior change techniques to be made use of in contexts where formative research is not possible.