Showing papers in "Journal of Water and Health in 2018"
TL;DR: Findings indicated that arsenic, cadmium, lead, and chromium could not cause chronic kidney disease of unknown etiology.
Abstract: Chronic kidney disease of unknown etiology (CKDu) is spreading gradually in Sri Lanka. In the current research, 1,435 well water samples from all 25 districts of Sri Lanka, 91 rice samples, and 84 human urine samples from both CKDu-endemic and non-endemic areas in Sri Lanka were analyzed for arsenic, cadmium, lead, and chromium to detect whether toxic elements could be a cause of CKDu. The liver-type fatty acid binding protein (L-FABP) concentration and arsenic, cadmium, lead, and chromium concentrations of the urine samples were analyzed to determine the relation of L-FABP with arsenic, cadmium, lead, and chromium. High concentrations of arsenic, cadmium, lead, and chromium were not detected in the well water samples from CKDu-endemic areas. Arsenic, cadmium, and lead contents in the rice samples from both CKDu-endemic and non-endemic areas were well below the Codex standard. There were no relationships between the L-FABP concentration and concentrations of arsenic, cadmium, lead, and chromium in urine. In addition, arsenic, cadmium, lead, and chromium concentrations in human urine samples from CKDu-endemic areas were not significantly different from those from non-endemic areas. These findings indicated that arsenic, cadmium, lead, and chromium could not cause CKDu.
58 citations
TL;DR: 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.
Abstract: 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.
50 citations
TL;DR: It is shown that guidelines, regulations, tools and resources, public health support, and context-specific evidence of the feasibility and benefits of WSPs are elements of the enabling environment that encourage adoption and implementation of W SPs in high-income countries.
Abstract: Effective risk management helps ensure safe drinking water and protect public health. Even in high-income countries, risk management sometimes fails and waterborne disease, including outbreaks, occur. To help reduce waterborne disease, the WHO Guidelines for Drinking Water Quality recommend water safety plans (WSPs), a systematic preventive risk management strategy applied from catchment to consumer. Since the introduction of WSPs, international guidelines, national and state legislation, and local practices have facilitated their implementation. While various high-income OECD countries have documented successes in improving drinking water safety through implementing WSPs, others have little experience. This review synthesizes the elements of the enabling environment that promoted the implementation of WSPs in high-income countries. We show that guidelines, regulations, tools and resources, public health support, and context-specific evidence of the feasibility and benefits of WSPs are elements of the enabling environment that encourage adoption and implementation of WSPs in high-income countries. These findings contribute to understanding the ways in which to increase the uptake and extent of WSPs throughout high-income countries to help improve public health.
35 citations
TL;DR: The proportion of the population with access decreased by 13% on average for these 17 countries when collection time was added as a consideration and the effect of adding a 30-minute collection time component to monitor access to drinking water was demonstrated.
Abstract: Despite the reported achievement of the Millennium Development Goals (MDGs) with respect to drinking water, lack of access to water remains widespread worldwide. The indicator used there to measure access to water in the MDGs refers to the use of an improved water source. However, the amount of time spent in collecting water is high in countries where access to drinking water supplies located on premises is not common. 26.3% of the world's population did not have such access in 2015. Thus the need to travel to a water point, possibly queue, fill water containers, and carry them home is prevalent. The amount of time and effort used in water collection can be considerable, and household surveys increasingly provide data on collection time. This study aims to demonstrate the effect of adding a 30-minute collection time component to monitor access to drinking water. This study draws on household surveys from 17 countries to highlight the widespread burden of fetching water and its significant impact on estimates of coverage. The proportion of the population with access decreased by 13% on average for these 17 countries when collection time was added as a consideration.
31 citations
TL;DR: The antimicrobial properties of CNTs are reviewed, diverse mechanisms of action against microorganisms as well as their applicability for water disinfection and microbial control are discussed, and future opportunities for their application in the water remediation process are highlighted.
Abstract: Waterborne diseases significantly affect human health and are responsible for high mortality rates worldwide Antibiotics have been known for decades for treatment of bacterial strains and their overuse and irrational applications are causing increasing bacteria resistance Therefore, there is a strong need to find alternative ways for efficient water disinfection and microbial control Carbon nanotubes (CNTs) have demonstrated strong antimicrobial properties due to their remarkable structure This paper reviews the antimicrobial properties of CNTs, discusses diverse mechanisms of action against microorganisms as well as their applicability for water disinfection and microbial control Safety concerns, challenges of CNTs as antimicrobial agents and future opportunities for their application in the water remediation process are also highlighted
27 citations
TL;DR: Chlorine dosage recommendations for household water treatment with chlorine can improve the microbiological quality of household water and reduce diarrheal disease and further research on field effectiveness of chlorination is recommended.
Abstract: Household water treatment with chlorine can improve the microbiological quality of household water and reduce diarrheal disease. We conducted laboratory and field studies to inform chlorine dosage recommendations. In the laboratory, reactors of varying turbidity (10–300 NTU) and total organic carbon (0–25 mg/L addition) were created, spiked with Escherichia coli , and dosed with 3.75 mg/L sodium hypochlorite. All reactors had >4 log reduction of E. coli 24 hours after chlorine addition. In the field, we tested 158 sources in 22 countries for chlorine demand. A 1.88 mg/L dosage for water from improved sources of
27 citations
TL;DR: There needs to be a new framing of local water security with the development of tools which engage IK and WS in order to assess local waterSecurity and appropriately inform interventions, policies, regulations and legislation.
Abstract: Indigenous communities in Canada are over-represented with respect to poor water quality and water advisories. To date, approaches to solve this water crisis have been founded in the Western Science (WS) context with little to no consultation or dialogue with those communities most impacted, and without regard for culture. A literature review was undertaken to: (i) document Indigenous Knowledge (IK), and perspectives regarding water and (ii) to identify current local water security tools utilized by Indigenous communities. The aim is to provide sound evidence regarding the value of ownership and leadership by Indigenous communities in the context of current and appropriate resources available to (re)claim these roles. Solutions must remain consistent with, and founded upon, traditional Indigenous worldviews and cultural values to ensure sustainable water security. Literature reviewed from the past ten years revealed one overarching creation theme with three water-specific themes in Indigenous communities; namely, water from natural sources, water as a life-giving entity, and water and gender. Ultimately, there needs to be a new framing of local water security with the development of tools which engage IK and WS in order to assess local water security and appropriately inform interventions, policies, regulations and legislation.
24 citations
TL;DR: The concentrations of water quality parameters are much higher as compared to World Health Organization and Bangladesh Drinking Standards (BDS), which may cause acute public health risks and make water unsuitable for direct human consumption without treatment.
Abstract: Safe water is essential for life. Consumption of arsenic and manganese contaminated water poses a range of health effects to humans. Physico-chemical and bacteriological characteristics of groundwater at five administrative upazillas in Kushtia District, Bangladesh, have been studied to evaluate the potability of water for drinking purpose from 32 randomly selected tube wells (TWs). APHA (2012) standard analytical methods were applied for analyses of the physico-chemical and bacteriological parameters of the water samples. Arsenic, iron, and manganese content were analyzed by atomic absorption spectroscopy (AAS). The investigated parameters of water samples were found as pH 6.81-8.12, electrical conductivity (EC) 520-1,995 μs/cm, total dissolved solids (TDS) 357.8-1,372.6 mg/L, chloride 10-615 mg/L, total hardness 285-810 mg/L, arsenic (As) 0.001-0.098 mg/L, iron (Fe) 0.04-1.45 mg/L, manganese (Mn) 0.01-6.32 mg/L. About 56.25% of TWs were highly contaminated with fecal coliform (FC) and 68.75% were found to be contaminated with total coliform (TC). Results were compared with World Health Organization (WHO) and Bangladesh Drinking Standards (BDS). The concentrations of water quality parameters are much higher as compared to WHO and BDS standards. This may cause acute public health risks and make water unsuitable for direct human consumption without treatment.
24 citations
TL;DR: There is a need for future robust research in this field, with the use of urinary trichloroacetic acid (TCAA) biomarkers as a direct exposure assessment method for this field.
Abstract: Epidemiological studies have found that maternal exposure to disinfection by-products (DBPs) may lead to adverse pregnancy outcomes although the findings tend to be inconsistent. The objective of this study was to systematically review the evidence in associated with drinking water DBP exposure in relation to adverse pregnancy outcomes. Peer-reviewed articles were identified using electronic databases searched for studies published in the English language. Studies selected for review were evaluated for exposure assessment, confounders, and analyses risks of bias in the selection, outcomes assessment, and attrition. A comprehensive search and screening yielded a total of 32 studies, of which 12 (38%) reported a statistical association between maternal exposure to DBPs and adverse pregnancy outcomes. A maternal exposure to trihalomethanes (THMs) shows an increased risk of small for gestational age (SGA) and slightly increased risk of pregnancy loss. Risks of bias were low among the studies included in the review. Evidence on association relating to adverse pregnancy outcomes to DBP exposure is still less significant. There is a need for future robust research in this field, with the use of urinary trichloroacetic acid (TCAA) biomarkers as a direct exposure assessment method for this field.
23 citations
TL;DR: This study compares the performance of a novel most probable number (MPN) method (Legiolert™/Quanti-Tray®) with Standard Methods for the Examination of Water and Wastewater 9260 J for the enumeration of Legionella pneumophila from potable and nonpotable waters.
Abstract: This study compares the performance of a novel most probable number (MPN) method (Legiolert™/Quanti-Tray ® ) with Standard Methods for the Examination of Water and Wastewater 9260 J for the enumeration of Legionella pneumophila from potable and nonpotable waters. Data from the study showed that Legiolert exhibited higher sensitivity for the detection of L. pneumophila for potable water and equivalent sensitivity for nonpotable water. The Legiolert medium had a high specificity with no false positive signals reported for either water type. The new method represents a significant improvement in usability and accuracy in the enumeration of L. pneumophila .
22 citations
TL;DR: The effects of extraction mixing speed and extraction time of MO on coagulation activity were evaluated using a distilled water extraction method and more positive charge and higher protein content were observed.
Abstract: The seed of Moringa oleifera (MO) is a well-known coagulant used in water and wastewater treatment, especially in developing countries. The main mechanism of MO seed extract in coagulation is the positive protein component for charge neutralization. The method for efficient extraction of MO seed is very important for high coagulation activity. In this study, the effects of extraction mixing speed and extraction time of MO on coagulation activity were evaluated using a distilled water extraction method. Although the rotation per minute for extraction did not affect the coagulation efficiency, the extraction time strongly affected the coagulation efficiency of the extract. To evaluate the characteristic change of MO extract by extraction time, the charge of MO extract and protein characteristic in MO extract were analysed. As the extraction time was short, more positive charge and higher protein content were observed. For detailed protein analysis, the fluorescence spectroscopic study (EEM analysis) was performed. The tryptophan-like peak increased at longer extraction times. For efficient extraction of MO seed, a short extraction time is strongly recommended.
TL;DR: It is argued that bottled water consumption should be reduced in areas where water quality is not an issue, and there is a need for education among the student population in West Virginia.
Abstract: West Virginia has had a history of water quality issues. In parallel, the world is facing a plastic pollution crisis. In order to better understand behavioral responses to perceived water quality, a survey was conducted at a major research university to ask participants about water quality perceptions and drinking water behaviors. A total of 4,188 students completed the survey during the Spring 2017 semester. Logistic regression analyses were used to predict behaviors. Results indicated that a third of the student population primarily used bottled water for drinking purposes at home, while 39% used a filter at home and 26% drank water directly from the tap. On campus, bottled water use was reported by 36% of the students, water fountain use represented 31%, and 29% of the students brought their own water with reusable cups/bottles. Health risk perceptions, organoleptic perceptions (i.e., taste, odor, color), and environmental concern were predictors of the different behaviors. Students originally from West Virginia had a higher propensity of using bottled water. We argue that bottled water consumption should be reduced in areas where water quality is not an issue. In this sense, there is a need for education among the student population in West Virginia.
TL;DR: Two newer methods have substantial potential, CP Chromo Select agar, which allows better recoveries and greater specificity than mCP, and the Fung double tube method, which creates anaerobic conditions and allows enumeration of colonies in tubes in 5-6 hours.
Abstract: Because Clostridium perfringens spores are both specific to sewage contamination and environmentally stable, they are considered as possible conservative indicators of human fecal contamination and possible surrogates for environmentally stable pathogens. This review discusses the reasons and summarizes methods for monitoring spores in water. Cultural methods are still preferred over qPCR for routine water quality monitoring because of their low costs. Membrane filter (MF) methods are preferred over the more laborious and less accurate most probable number methods. The most commonly used MF media are TSC medium and mCP medium. TSC normally allows higher recoveries than mCP. TSC produces fewer false-positive results than mCP; however, it does produce more false-negatives. Two newer methods have substantial potential, CP Chromo Select agar, which allows better recoveries and greater specificity than mCP, and the Fung double tube method, which creates anaerobic conditions and allows enumeration of colonies in tubes in 5-6 hours. Aerobic spores are not associated with fecal contamination but they can be surrogates for environmentally stable pathogens in monitoring water for treatment efficacy; Bacillus cereus spores are normally measured on nutrient agar by the MF method.
TL;DR: The results of this study confirm the presence of V. parahaemolyticus in the Eastern coast of Saudi Arabia and report the first report of tdh + and trh + isolates from this area.
Abstract: Vibrio parahaemolyticus is a Gram-negative halophilic marine microbe that causes gastroenteritis, wound infections, and septicemia in humans. Since the emergence of the pandemic clone O3:K6, V. parahaemolyticus has become a globally well-known pathogen. In this study, 375 seawater samples collected from the Eastern coast of Saudi Arabia were tested for the presence of V. parahaemolyticus . Three hundred and forty samples were determined positive for V. parahaemolyticus using traditional microbiological techniques. The genes toxR and tlh were detected via polymerase chain reaction (PCR) in 41 isolates from 23 samples (6%). Thermostable direct hemolysin ( tdh ) and thermostable direct hemolysin-related hemolysin ( tdh ) are the most common virulence genes associated with V. parahaemolyticus . As such, four isolates were tdh + (1%) and another four were trh + (1%). No evidence of pandemic clones was detected using group-specific PCR. Samples were tested for antibiotic susceptibility against 28 agents. The vast majority of samples exhibited high resistance to carbenicillin (98%), ampicillin (88%), and cephalothin (76%). The multiple antibiotics resistance index was >0.2 for 35% of the isolates. The results of this study confirm the presence of V. parahaemolyticus in the Eastern coast of Saudi Arabia. This is the first report of tdh + and trh + isolates from this area.
TL;DR: The result shows that households' stored water collected from unprotected wells/springs had higher levels of E. coli than stored water from alternative sources, and distance to water sources and water collection containers are also strongly associated with stored water quality.
Abstract: This study aims at assessing the determinants of microbiological contamination of household drinking water under multiple-use water systems in rural areas of Ethiopia. For this analysis, a random sample of 454 households was surveyed between February and March 2014, and water samples from community sources and household storage containers were collected and tested for fecal contamination. The number of Escherichia coli (E. coli) colony-forming units per 100 mL water was used as an indicator of fecal contamination. The microbiological tests demonstrated that 58% of household stored water samples and 38% of protected community water sources were contaminated with E. coli. Moreover, most improved water sources often considered to provide safe water showed the presence of E. coli. The result shows that households' stored water collected from unprotected wells/springs had higher levels of E. coli than stored water from alternative sources. Distance to water sources and water collection containers are also strongly associated with stored water quality. To ensure the quality of stored water, the study suggests that there is a need to promote water safety from the point-of-source to point-of-use, with due considerations for the linkages between water and agriculture to advance the Sustainable Development Goal 6 of ensuring access to clean water for everyone.
TL;DR: Results obtained evidenced the presence and the great diversity of AdV, mainly of human origin, circulating in Belo Stream and the concentration step performed helped to detect AdV in more samples.
Abstract: Adenoviruses (AdV) are related to respiratory and gastrointestinal diseases in animals and human beings. Its wide genetic diversity in water bodies and its resistance to environmental conditions allows the use of AdV as a reliable marker for detection of fecal contamination. In this work, the diversity of AdV along Belo Stream – in the city of Caxias do Sul, Rio Grande do Sul, Brazil – was evaluated. Samples were compared both in concentrated and unconcentrated forms. The identification of different AdV species was performed by amplifying a partial sequence of the DNA polymerase gene. AdV was detected in 24 out of 55 concentrated samples (43.6%) and the following species were identified: human adenovirus (HAdV) species C (4/55; 7.2%), D (6/55; 10.9%), E (2/55; 3.6%), and F (9/55; 16.3%). AdV related to other mammalian hosts, such as bovine adenovirus (1/55, 1.8%) and murine adenovirus (2/55, 3.6%) have also been identified; 23.6% (13/55) of the unconcentrated samples were positive, and identified as HAdV species C (6/55, 10.9%), D (1/55, 1.8%), and F (6/55, 10.9%). Results obtained evidenced the presence and the great diversity of AdV, mainly of human origin, circulating in Belo Stream. As expected, the concentration step performed helped to detect AdV in more samples.
TL;DR: The water quality was heterogeneous among wells, and all of them were found to have conditions that caused water to be unfit for human consumption.
Abstract: Vegas-Las Palmas is a rural settlement located in the southern Caribbean region of Costa Rica on the border with Panama. Its population does not have access to potable water, and inhabitants depend on water from wells at the water table level to meet their needs. These wells lack basic infrastructure to protect this water from contamination. In this study, water quality was evaluated at 12 wells from 2014 to 2016 (n = 72). The results revealed high concentrations of faecal coliforms and Escherichia coli with maximum values of 4.6 × 104 MPN/100 mL and 1.1 × 104 MPN/100 mL, respectively. In addition, maximum values of pH, conductivity, turbidity, Ca, Mg, K, Fe, Mn, Cd and Pb were found to be outside the standard limits (nationally and internationally) for potable water. Possible sources of water contamination are associated with the geomorphological characteristics of the area, as well as with hydrometeorological and anthropogenic factors such as the lack of sewerage, the presence of latrines, animals near the wells and the use of agrochemicals. The water quality was heterogeneous among wells, and all of them were found to have conditions that caused water to be unfit for human consumption.
TL;DR: Irrespective of temperature, bottled water from SA contained chemicals with acceptable health risks, and EEqs and BPA concentrations were higher in bottled water stored at 40 °C compared to 20 °C, samples posed an acceptable risk for a lifetime of exposure.
Abstract: Potential endocrine disrupting chemicals (EDCs) are present in bottled water from various countries. In South Africa (SA), increased bottled water consumption and concomitant increases in plastic packaging create important consequences for public health. This study aimed to screen SA bottled water for estrogenic activity, selected target chemicals and assessing potential health risks. Ten bottled water brands were exposed to 20 °C and 40 °C over 10 days. Estrogenic activity was assessed using the recombinant yeast estrogen screen (YES) and the T47D-KBluc reporter gene assay. Solid phase extracts of samples were analyzed for bis(2-ethylhexyl) adipate (DEHA), selected phthalates, bisphenol-A (BPA), 4-nonylphenol (4-NP), 17β-estradiol (E2), estrone (E1), and ethynylestradiol (EE2) using gas chromatography-mass spectrophotometry. Using a scenario-based health risk assessment, human health risks associated with bottled water consumption were evaluated. Estrogenic activity was detected at 20 °C (n = 2) and at 40 °C (n = 8). Estradiol equivalent (EEq) values ranged from 0.001 to 0.003 ng/L. BPA concentrations ranged from 0.9 ng/L to 10.06 ng/L. Although EEqs and BPA concentrations were higher in bottled water stored at 40 °C compared to 20 °C, samples posed an acceptable risk for a lifetime of exposure. Irrespective of temperature, bottled water from SA contained chemicals with acceptable health risks.
TL;DR: Analyzing the results of ICP-MS of parental rocks and aquifer sediments shows that unweathered volcanic rocks were the primary source for lead mobilizing to groundwaters.
Abstract: Geochemical and hydrogeochemical studies were conducted to assess the origin and geochemical mechanisms driving lead enrichment in groundwaters of semi-arid regions in Central Iran. In this study, 149 water samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Concentrations of Pb and As in about 68% and 27% of the samples, respectively, exceeded WHO guidelines. Analyzing the results of ICP-MS of parental rocks and aquifer sediments shows that unweathered volcanic rocks were the primary source for lead mobilizing to groundwaters.
TL;DR: The variation in pH dependent hydrophobicity suggests increased propensity for bioaccumulation and alternate environmental fates for differing microcystin forms, requiring further investigation.
Abstract: Hazardous algal blooms can generate toxic compounds with significant health impacts for exposed communities. The ubiquitous class of algal toxins known as microcystins exhibits significant heterogeneity in its peptide structure, which has been minimally studied, given the significant impact this has on hydrophobicity, acid/base character and related environmental fate and health effects. Octanol-water partition coefficients for the microcystin congeners MCLR, MCRR, MCLY, MCLF, and MCLA were calculated over an environmentally and physiologically relevant pH range. Microcystin-LR log(Kow) partition coefficient values were found to be consistent with previously established literature values, 1.67 to -1.41 between pH 1 and 8. Microcystin RR was found to be pH insensitive with a log(Kow) of -0.7. The remaining congeners exhibit similar pH dependence as MCLR, with systematic increases in hydrophobicity driven by the introduction of more hydrophobic residues to their variable amino acid region. The variation in pH dependent hydrophobicity suggests increased propensity for bioaccumulation and alternate environmental fates for differing microcystin forms, requiring further investigation.
TL;DR: A simple co-precipitation technique is proposed for synthesis of tin oxide (SnO2) microrods, which demonstrate that RB5 shows high catalytic degradation at high concentrations of hydrogen peroxide and catalyst.
Abstract: A simple co-precipitation technique is proposed for synthesis of tin oxide (SnO2) microrods. Stannous chloride and urea were used during synthesis. X-ray powder diffraction (XRD) analysis revealed that the annealed product consists of SnO2 microrods having tetragonal unit cells, while scanning electron microscopy (SEM) analysis revealed the rod-like morphology of a synthesized product. These synthesized microrods are used as photocatalyst for the degradation of reactive black 5 (RB5). Degradation kinetics of RB5 are monitored under daylight in different concentrations of hydrogen peroxide (H2O2) and catalyst. The percentage of RB5 conversion is also calculated at various concentrations of hydrogen peroxide and catalyst which demonstrate that RB5 shows high catalytic degradation at high concentrations of hydrogen peroxide and catalyst.
TL;DR: Water quality index indicates the increase of ion concentrations due to the agricultural effect along with the rainwater in the region, and the study area is at high risk in terms of the health risk assessment.
Abstract: Groundwater is a major water source for drinking, domestic and agricultural activities in the Korkuteli district. However, the intensive agricultural activities in the region negatively affect the groundwater quality. In this study, 30 water samples were collected from springs, wells, and tap waters in dry and wet seasons. Ca-Mg-HCO3 and Mg-Ca-HCO3 were dominant water types in the study area. According to the Gibbs diagrams, which were prepared to determine the mechanism controlling the groundwater geochemistry, samples from both seasons fell in the rock-dominance zone. The water quality index indicates the increase of ion concentrations due to the agricultural effect along with the rainwater in the region. Also, according to WHO standards, water samples are not appropriate to use as drinking water in terms of the heavy metal and fertilizers analysis results. In terms of the irrigation usage, most groundwater samples are suitable in dry and wet seasons. According to HCO3 and SO4 results, the mentioned samples can induce incrustation on metal surfaces and therefore are not recommended for industrial use. Groundwater chemistry in the study area is affected with water-rock interaction and dense agricultural activities. In conclusion, the study area is at high risk in terms of the health risk assessment.
TL;DR: After inactivation at 297 nm (UVA), bacteria regained viability through photoreactivation, and repair increased with increase in photoreactivating light exposure time, which implies additional doses above inactivation thresholds are required to cause irreversible damage.
Abstract: UVA and UVB can be applied to solar disinfection of water. In this study, the inactivation and photoreactivation of viruses and bacteria in the UVA-B range were analyzed. MS2 and T4 bacteriophages, and Escherichia coli were used as surrogates to quantify dose-response behaviors. Inactivation in UVC was used to validate the methodology and to expand the inactivation action spectra. The results showed log-linear inactivation for MS2 and T4 in the 254-320 nm wavelength range. T4 inactivation was consistently faster than MS2 (except at 320 nm), and for both phages, inactivation decreased with increasing wavelength. The dose-response of bacteria exhibited a lag at low doses, possibly because the photons must strike a discrete number of critical targets before growth stops. A tail was present at high doses for some wavelengths, perhaps due to clumping or the presence of subgroups with higher resistance. The inactivation action spectra for bacteria exhibited a reduction in inactivation as wavelength increased. No bacterial inactivation was observed beyond 320 nm at doses applied. After inactivation at 297 nm (UVA), bacteria regained viability through photoreactivation, and repair increased with increase in photoreactivating light exposure time. This implies additional doses above inactivation thresholds are required to cause irreversible damage. These results are useful for designing solar disinfection systems.
TL;DR: Proper management of these governing factors could significantly reduce DBPs formation, thereby, contributing towards a healthy swimming pool environment.
Abstract: This paper investigates disinfection by-products (DBPs) formation and their relationship with governing factors in chlorinated swimming pools. The study compares concentrations of DBPs with WHO guidelines for drinking water quality recommended to screen swimming pool water quality. The statistical analysis is based on a global database of 188 swimming pools accumulated from 42 peer-reviewed journal publications from 16 countries. The mean and standard deviation of dichloroacetic acid and trichloroacetic acid were estimated as 282 ± 437 and 326 ± 517 μg L-1, respectively, which most often surpassed the WHO guidelines. Similarly, more than half of the examined pools had higher values of chloral hydrate (102 ± 128 μg L-1). The concentration of total chloramines (650 ± 490 μg L-1) was well above the WHO guidelines in all reported cases. Nevertheless, the reported values remained below the guidelines for most of the studied pools in the case of total trihalomethanes (134 ± 160 μg L-1), dichloroacetonitrile (12 ± 12 μg L-1) and dibromoacetonitrile (8 ± 11 μg L-1). Total organic carbon, free residual chlorine, temperature, pH, total nitrogen and bromide ions play a pivotal role in DBPs formation processes. Therefore, proper management of these governing factors could significantly reduce DBPs formation, thereby, contributing towards a healthy swimming pool environment.
TL;DR: Inhalation exposure was estimated and found to be the most relevant, however, different mass transfer models from water measurements significantly under- or overestimated the health burden compared to direct calculation from the concentration in air.
Abstract: While disinfection of swimming pools is indispensable for microbiological safety, it may lead to the formation of disinfection by-products. Most studies agree that inhalation exposure is the predominant pathway of the associated health risks, but assumptions are based on concentrations measured in water and evaporation models. Pool water and air were sampled in 19 swimming pools. Trihalomethanes were detected in all sites; chloroform being the most abundant species. Concentrations ranged between 12.8-71.2 μg/L and 11.1-102.2 μg/m3 in pool water and air, respectively. The individual lifetime carcinogenic risk associated with chloroform in swimming pools exceeded 10-6 in all age groups for recreational swimmers and 10-5 for elite swimmers and staff, even if the pool complied with the national standards. Inhalation exposure was estimated and found to be the most relevant, however, different mass transfer models from water measurements significantly under- or overestimated the health burden compared to direct calculation from the concentration in air. The observed health risks call for defining regulatory values and monitoring requirement of indoor air quality in swimming pools.
TL;DR: Two of the three isolated strains were identified as Elizabethkingia anophelis, the first reported isolation of the pathogen in water supply systems in Greece.
Abstract: After the Elizabethkingia anophelis outbreak in Wisconsin, USA, an active search for the detection of the microorganism in hospital water systems from Central and Northern Greece was performed from June to December 2016. In total, 457 water samples from 11 hospitals were analyzed. Elizabethkingia spp. was detected in three samples collected from two hospitals, both of which are located in Northern Greece. Two of the three isolated strains were identified as Elizabethkingia anophelis . No cases of Elizabethkingia infection were reported in either hospital during 2016. This is the first reported isolation of the pathogen in water supply systems in Greece.
TL;DR: The application of a MST toolbox using both culture-dependent bacteriophage and molecular-dependent 16S rRNA assays at spring and well sites in the karstic St Imier Valley, Switzerland reveals differences in microbial water quality between well and spring karst sites.
Abstract: Water resources situated in areas with underlying karst geology are particularly vulnerable to fecal pollution. In such vulnerable systems, microbial source tracking (MST) methods are useful tools to elucidate the pathways of both animal and human fecal pollution, leading to more accurate water use risk assessments. Here, we describe the application of a MST toolbox using both culture-dependent bacteriophage and molecular-dependent 16S rRNA assays at spring and well sites in the karstic St Imier Valley, Switzerland. Culture-dependent and molecular-dependent marker performance varied significantly, with the 16S rRNA assays displaying greater sensitivity than their phage counterpart; HF183 was the best performing human wastewater-associated marker while Rum2Bac was the best performing ruminant marker. Differences were observed in pollution regimes between the well and spring sampling sites, with the spring water being more degraded than the well site. Our results inform the choice of marker selection for MST studies and highlight differences in microbial water quality between well and spring karst sites.
TL;DR: Data presented here indicate that bacteriophage enumeration by plaque assay and RT-qPCR (reverse transcription quantitative polymerase chain reaction) can be affected by these water treatment chemicals.
Abstract: Research on microorganism reduction by physicochemical water treatment is often carried out under the assumption that the microbiological enumeration techniques are not affected by the presence of coagulants. Data presented here indicate that bacteriophage enumeration by plaque assay and RT-qPCR (reverse transcription quantitative polymerase chain reaction) can be affected by these water treatment chemicals. Treatment of water samples with an alkaline protein-rich solution prior to plaque assay and optimization of RNA extraction for RT-qPCR were implemented to minimize the interference. The improved procedures were used in order to investigate reduction of three viral pathogens and the MS2 model virus in the presence of three coagulants. A conventional aluminium coagulant was compared to alternative agents (zirconium and chitosan) in a coagulation-filtration system. The highest virus reduction, i.e., 99.9-99.99%, was provided by chitosan, while aluminium and zirconium reduced virus by 99.9% in colour-rich water and by 90% in water with less colour, implying an effect of coagulant type and raw water quality on virus reduction. Although charge characteristics of viruses were associated with virus reduction, the results reveal that the MS2 phage is a suitable model for aggregation and retention of the selected pathogens.
TL;DR: It is shown that E. coli and visual clarity are inversely related overall in NZ rivers, and more strongly related in many individual rivers, while similar (but positive) correlations apply also to turbidity, suggesting that visual clarity should be a valuable indicator of faecal contamination status and swimming suitability.
Abstract: Swimming is a popular activity in Aotearoa-New Zealand (NZ). Two variables that strongly influence swimming suitability of waters are faecal contamination, as indicated by the bacterium Escherichia coli, and visual clarity as it affects aesthetics and safety with respect to submerged hazards. We show that E. coli and visual clarity are inversely related overall in NZ rivers (R = -0.54), and more strongly related in many individual rivers, while similar (but positive) correlations apply also to turbidity. This finding, apparently reflecting co-mobilisation of faecal contamination and fine sediment, suggests that visual clarity, measured or estimated from appearance of submerged features, should be a valuable indicator of faecal contamination status and (more generally) swimming suitability. If swimmers were to avoid river waters <1.6 m black disc visibility (a long-established NZ guideline for swimming) they would also avoid microbial hazards (E. coli <550 cfu/100 mL about 99% of the time in NZ rivers). However, urban-affected rivers might sometimes be microbially contaminated when still clear. Water management agencies should measure visual clarity together with E. coli in river surveillance. Real-time information on swimming suitability could then be based on continuous monitoring of turbidity locally calibrated to both visual clarity and E. coli.
TL;DR: The growth of bacteria in drinking water can be inhibited after the addition of SM1/SMZ, and bacterial community diversity in Drinking water declined, and the resistance gene sul2 was induced by SM1 in the drinking water.
Abstract: The abuse of antibiotics is becoming more serious as antibiotic use has increased. The sulfa antibiotics, sulfamerazine (SM1) and sulfamethoxazole (SMZ), are frequently detected in a wide range of environments. The interaction between SM1/SMZ and bacterial diversity in drinking water was investigated in this study. The results showed that after treatment with SM1 or SMZ at four different concentrations, the microbial community structure of the drinking water changed statistically significantly compared to the blank sample. At the genus level, the proportions of the different bacteria in drinking water may affect the degradation of the SM1/SMZ. The growth of bacteria in drinking water can be inhibited after the addition of SM1/SMZ, and bacterial community diversity in drinking water declined in this study. Furthermore, the resistance gene sul2 was induced by SM1 in the drinking water.