Detection of enteric viruses in treated drinking water.

The occurrence of viruses in conventionally treated drinking water derived from a heavily polluted source was evaluated by collecting and analyzing 38 large-volume (65- to 756-liter) samples of water from a 9 m3/s (205 X 10(6) gallons [776 X 10(6) liters] per day) water treatment plant. Samples of raw, clarified, filtered, and chlorinated finished water were concentrated by using the filter adsorption-elution technique. Of 23 samples of finished water, 19 (83%) contained viruses. None of the nine finished water samples collected during the dry season contained detectable total coliform bacteria. Seven of nine finished water samples collected during the dry season met turbidity, total coliform bacteria, and total residual chlorine standards. Of these, four contained virus. During the dry season the percent removals were 25 to 93% for enteric viruses, 89 to 100% for bacteria, and 81% for turbidity. During the rainy season the percent removals were 0 to 43% for enteric viruses, 80 to 96% for bacteria, and 63% for turbidity. None of the 14 finished water samples collected during the rainy season met turbidity standards, and all contained rotaviruses or enteroviruses.     

Elimination of viruses and indicator bacteria at each step of treatment during preparation of drinking water at seven water treatment plants

Seven drinking water treatment plants were sampled twice a month for 12 months to evaluate the removal of indicator bacteria and cytopathogenic enteric viruses. Samples were obtained at each level of treatment: raw water, postchlorination, postsedimentation, postfiltration, postozonation, and finished (tap) water. Raw water quality was usually poor, with total coliform counts exceeding 105 to 106 CFU/liter and the average virus count in raw water of 3.3 most probable number of cytopathogenic units (MPNCU)/liter; several samples contained more than 100 MPNCU/liter. All plants distributed finished water that was essentially free of indicator bacteria as judged by analysis of 1 liter for total coliforms, fecal coliforms, fecal streptococci, coagulase-positive staphylococci, and Pseudomonas aeruginosa. The total plate counts at 20 and 35 degrees C were also evaluated as a measure of the total microbial population and were usually very low. Viruses were detected in 7% (11 of 155) of the finished water samples (1,000 liters) at an average density of 0.0006 MPNCU/liter the highest virus density measured being 0.2 MPNCU/liter. The average cumulative virus reduction was 95.15% after sedimentation and 99.97% after filtration and did not significantly decrease after ozonation or final chlorination. The viruses isolated from treated waters were all enteroviruses: poliovirus types 1, 2, and 3, coxsackievirus types B3, B4, and B5, echovirus type 7, and untyped picornaviruses.     

Elimination of viruses and indicator bacteria at each step of treatment during preparation of drinking water at seven water treatment plants.

Seven drinking water treatment plants were sampled twice a month for 12 months to evaluate the removal of indicator bacteria and cytopathogenic enteric viruses. Samples were obtained at each level of treatment: raw water, postchlorination, postsedimentation, postfiltration, postozonation, and finished (tap) water. Raw water quality was usually poor, with total coliform counts exceeding 105 to 106 CFU/liter and the average virus count in raw water of 3.3 most probable number of cytopathogenic units (MPNCU)/liter; several samples contained more than 100 MPNCU/liter. All plants distributed finished water that was essentially free of indicator bacteria as judged by analysis of 1 liter for total coliforms, fecal coliforms, fecal streptococci, coagulase-positive staphylococci, and Pseudomonas aeruginosa. The total plate counts at 20 and 35 degrees C were also evaluated as a measure of the total microbial population and were usually very low. Viruses were detected in 7% (11 of 155) of the finished water samples (1,000 liters) at an average density of 0.0006 MPNCU/liter the highest virus density measured being 0.2 MPNCU/liter. The average cumulative virus reduction was 95.15% after sedimentation and 99.97% after filtration and did not significantly decrease after ozonation or final chlorination. The viruses isolated from treated waters were all enteroviruses: poliovirus types 1, 2, and 3, coxsackievirus types B3, B4, and B5, echovirus type 7, and untyped picornaviruses.     

Human enteric viruses in groundwater indicate offshore transport of human sewage to coral reefs of the Upper Florida Keys

To address the issue of human sewage reaching corals along the main reef of the Florida Keys, samples were collected from surface water, groundwater and coral [surface mucopolysaccharide layers (SML)] along a 10 km transect near Key Largo, FL. Samples were collected semi‐annually between July 2003 and September 2005 and processed for faecal indicator bacteria (faecal coliform bacteria, enterococci and Clostridium perfringens) and human‐specific enteric viruses (enterovirus RNA and adenovirus DNA) by (RT)‐nested polymerase chain reaction. Faecal indicator bacteria concentrations were generally higher nearshore and in the coral SML. Enteric viruses were evenly distributed across the transect stations. Adenoviruses were detected in 37 of 75 samples collected (49.3%) whereas enteroviruses were only found in 8 of 75 samples (10.7%). Both viruses were detected twice as frequently in coral compared with surface water or groundwater. Offshore, viruses were most likely to be found in groundwater, especially during the wet summer season. These data suggest that polluted groundwater may be moving to the outer reef environment in the Florida Keys.     

Bacteriological water quality effects of hydraulically dredging contaminated upper Mississippi River bottom sediment.

Bacteriological effects of hydraulically dredging polluted bottom sediment in the navigation channel of the Upper Mississippi River (river mile 827.5 [about 1,332 km] to 828.1 [about 1,333 km]) were investigated. Bottom sediment in the dredging site contained high total coliform densities (about 6,800 most-probable-number total coliform index per g [dry weight] and 3,800 membrane filter total coliforms per g [dry weight]), and fecal coliforms comprised an average 32% of each total coliform count. Total coliform and fecal coliform densities in water samples taken immediately below the dredge discharge pipe were each approximately four times corresponding upstream values; fecal streptococcus densities were approximately 50 times corresponding upstream values. Correlation analysis indicated that mean turbidity values downstream to the dredging operation were directly and significantly (r greater than 0.94) related to corresponding total coliform, fecal coliform, and fecal streptococcus densities. Salmonellae and shigellae were not recovered from either upstream or downstream water samples. Turbidity and indicator bacteria levels had returned to predredge values within less than 2 km below the dredge spoil discharge area at the prevailing current velocity (about 0.15 m/s).     

Virological examination of drinking water: a Canadian collaborative study

A collaborative virological survey of drinking water was initiated in three major Canadian urban areas, Montreal, Ottawa, and Toronto. In each selected area, three water purification plants were sampled monthly for up to 18 months. The total population served by all nine plants was about 1 500 000. Samples of raw (100 L) and treated (1000 L) water were examined by virus concentration procedures based on adsorption-elution. Sample concentrates were assayed for cytopathic viruses on BS-C-1 cells and the results were expressed as the most probable number of cytopathic units (MPNCU). Viruses were detected in 57% (0-15.35 MPNCU/L) of the raw water samples from Montreal, 37% (0-46.0 MPNCU/L) in Ottawa, and 33% (0-4.91 MPNCU/L) in Toronto. The majority of isolates were reoviruses, but picornaviruses were also found. All finished waters (177 samples) met bacteriological, turbidity, and residual chlorine standards and were free of detectable viruses.     

Virus occurrence in municipal groundwater sources in Quebec, Canada

A 1 year study was undertaken on groundwater that was a source of drinking water in the province of Quebec, Canada. Twelve municipal wells (raw water) were sampled monthly during a 1 year period, for a total of 160 samples. Using historic data, the 12 sites were categorized into 3 groups: group A (no known contamination), group B (sporadically contaminated by total coliforms), and group C (historic and continuous contamination by total coliforms and (or) fecal coliforms). Bacterial indicators (total coliform, Escherichia coli, enteroccoci), viral indicators (somatic and male-specific coliphages), total culturable human enteric viruses, and noroviruses were analyzed at every sampling site. Total coliforms were the best indicator of microbial degradation, and coliform bacteria were always present at the same time as human enteric viruses. Two samples contained human enteric viruses but no fecal pollution indicators (E. coli, enterococci, or coliphages), suggesting the limited value of these microorganisms in predicting the presence of human enteric viruses in groundwater. Our results underline the value of historic data in assessing the vulnerability of a well on the basis of raw water quality and in detecting degradation of the source. This project allowed us to characterize the microbiologic and virologic quality of groundwater used as municipal drinking water sources in Quebec.     

Clostridium perfringens and somatic coliphages as indicators of the efficiency of drinking water treatment for viruses and protozoan cysts.

To find the most suitable indicator of viral and parasitic contamination of drinking water, large-volume samples were collected and analyzed for the presence of pathogens (cultivable human enteric viruses, Giardia lamblia cysts, and Cryptosporidium oocysts) and potential indicators (somatic and male-specific coliphages, Clostridium perfringens). The samples were obtained from three water treatment plants by using conventional or better treatments (ozonation, biological filtration). All samples of river water contained the microorganisms sought, and only C. perfringens counts were correlated with human enteric viruses, cysts, or oocysts. For settled and filtered water samples, all indicators were statistically correlated with human enteric viruses but not with cysts or oocysts. By using multiple regression, the somatic coliphage counts were the only explanatory variable for the human enteric virus counts in settled water, while in filtered water samples it was C. perfringens counts. Finished water samples of 1,000 liters each were free of all microorganisms, except for a single sample that contained low levels of cysts and oocysts of undetermined viability. Three of nine finished water samples of 20,000 liters each revealed residual levels of somatic coliphages at 0.03, 0.10, and 0.26 per 100 liters. Measured virus removal was more than 4 to 5 log10, and cyst removal was more than 4 log10. Coliphage and C. perfringens counts suggested that the total removal and inactivation was more than 7 log10 viable microorganisms. C. perfringens counts appear to be the most suitable indicator for the inactivation and removal of viruses in drinking water treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Investigation of some physical,chemical, and bacteriological parameters of water quality in some dams in Albaha region,Saudi Arabia

This study was conducted to evaluate the quality of water in selected dams in Albaha region, Kingdom of Saudi Arabia. Water samples from eight dams were subjected to physical, chemical, and bacteriological assessment using standardized procedures of conductivity, total dissolved solids, ions, acidity & alkalinity, and EC blue 100® coliform detection. About three fourth (75%) of dams’ water samples exceeded the permissible levels of pH, total dissolved solids, turbidity, Mn and NO₃ set by Saudi standards. Average levels of total dissolved solids, Fe, Mn, SO₄, NO₃, and NO₂ were 3065.00, 0.10, 0.89, 68.25, 17.91 and 0.016 mg/L, respectively. However, the average pH of water samples was 7.95 ± 0.66 which still within the accepted range set by national and global standards. Moreover, total dissolved solids also exceeded regular standards of Food and Agriculture Organization for irrigation water quality. Coliform bacteria were detected in 37.5% of dams without any significant spatial differences between dams and sites as groups. Correlations were found between pH & NO₃, SO₄ & NO₃, coliform bacteria & turbidity, coliform bacteria & NO₂ levels. Increased concentrations of assessed parameters in dams may be attributed to agricultural activities as well as animal and human wastes deposited into dams via rainfalls and flash floods. Proper treatment of dams needs to be taken into account before consumption and irrigation.     

Human enteric viruses–potential indicators for enhanced monitoring of recreational water quality

Recreational waters contaminated with human fecal pollution are a public health concern, and ensuring the safety of recreational waters for public use is a priority of both the Environmental Protection Agency (EPA) and the Centers for Disease Control and Prevention (CDC). Current recreational water standards rely on fecal indicator bacteria (FIB) levels as indicators of human disease risk. However present evidence indicates that levels of FIB do not always correspond to the presence of other potentially harmful organisms, such as viruses. Thus, enteric viruses are currently tested as water quality indicators, but have yet to be successfully implemented in routine monitoring of water quality. This study utilized enteric viruses as possible alternative indicators of water quality to examine 18 different fresh and offshore recreational waters on O‘ahu, Hawai‘i, by using newly established laboratory techniques including highly optimized PCR, real time PCR, and viral infectivity assays. All sample sites were detected positive for human enteric viruses by PCR including enterovirus, norovirus genogroups I and II, and male specific FRNA coliphage. A six time-point seasonal study of enteric virus presence indicated significant variation in virus detection between the rainy and dry seasons. Quantitative PCR detected the presence of norovirus genogroup II at levels at which disease risk may occur, and there was no correlation found between enteric virus presence and FIB counts. Under the present laboratory conditions, no infectious viruses were detected from the samples PCR-positive for enteric viruses. These data emphasize both the need for additional indicators for improved monitoring of water quality, and the feasibility of using enteric viruses as these indicators. Electronic Supplementary MaterialSupplementary material is available for this article at 10.1007/s12250-015-3644-x and is accessible for authorized users.     

Potential sources of bacteriological pollution for two bays with marinas in Trinidad

Welcome Bay and Chaguaramas Bay in the northwest peninsula of Trinidad contain large marinas and smaller sections of bathing beaches. Bacteriological surveys were conducted at both bays to assess water quality and to determine potential sources of pollution. These surveys were conducted during the wet season of 1996 and the dry season of 1997. Eleven sample stations were established at Welcome Bay and 12 at Chaguaramas Bay. Freshwater samples were collected from rivers and drains within the survey area. Marine water samples were collected from marinas, bathing beaches and inshore and outer areas at both bays. Five water samples were collected from each sampling station during the wet season of 1996 and six during the dry season of 1997. The membrane filter technique was used to determine faecal coliform and Escherichia coli levels in all samples. There was a seasonal effect on water quality, with significantly higher faecal coliform levels in the wet season, when water quality was not in compliance with international standards. This represents a potential health risk in bathing areas. Water quality was better at the outer area of both bays. Water quality at the inner bay areas was most likely adversely affected by land-based sources of pollution identified in this study. These sources include three drains and two rivers, which discharged into the bays. Yachts were apparently not a source of sewage pollution: there was no significant relationship between yacht number and faecal coliform levels.     

流式细胞仪检测纳帕海高原湿地浮游病毒和浮游细菌丰度

【背景】浮游病毒是水体微生物群落中重要的组成成分,深入研究浮游病毒的时空分布有助于更好地保护和开发当地的微生物资源。【目的】对采集到的纳帕海高原湿地水样中的浮游病毒和浮游细菌进行计数,揭示纳帕海高原湿地浮游病毒的分布规律。【方法】采用流式细胞仪检测2013年12月和2014年9月纳帕海高原湿地7个水样的浮游病毒与浮游细菌丰度,并对影响浮游病毒丰度的因素,如细菌丰度、叶绿素a含量以及其他环境因子进行了相关性分析。【结果】季节分布上,雨季浮游病毒和浮游细菌丰度高于旱季;水平分布上,原水样品的浮游病毒高于湿地水和淤泥水。旱季水样的浮游病毒丰度受到细菌丰度及叶绿素a浓度的影响较大;雨季水样的浮游病毒丰度受到水体的p H值和温度的影响较大。【结论】纳帕海高原湿地的浮游病毒和浮游细菌是比较活跃的。浮游病毒丰度在不同季节、不同采样点受到细菌丰度和叶绿素a浓度等因素的不同影响。在旱季噬菌体而非噬藻体或浮游植物病毒是纳帕海高原湿地中浮游病毒的优势种群。     

Full-scale studies of factors related to coliform regrowth in drinking water.

An 18-month survey of 31 water systems in North America was conducted to determine the factors that contribute to the occurrence of coliform bacteria in drinking water. The survey included analysis of assimilable organic carbon (AOC), coliforms, disinfectant residuals, and operational parameters. Coliform bacteria were detected in 27.8% of the 2-week sampling periods and were associated with the following factors: filtration, temperature, disinfectant type and disinfectant level, AOC level, corrosion control, and operational characteristics. Four systems in the study that used unfiltered surface water accounted for 26.6% of the total number of bacterial samples collected but 64.3% (1,013 of 1,576) of the positive coliform samples. The occurrence of coliform bacteria was significantly higher when water temperatures were > 15 degrees C. For filtered systems that used free chlorine, 0.97% of 33,196 samples contained coliform bacteria, while 0.51% of 35,159 samples from chloraminated systems contained coliform bacteria. The average density of coliform bacteria was 35 times higher in free-chlorinated systems than in chloraminated water (0.60 CFU/100 ml for free-chlorinated water compared with 0.017 CFU/100 ml for chloraminated water). Systems that maintained dead-end free chlorine levels of < 0.2 mg/liter or monochloramine levels of < 0.5 mg/liter had substantially more coliform occurrences than systems that maintained higher disinfectant residuals. Free-chlorinated systems with AOC levels greater than 100 micrograms/liter had 82% more coliform-positive samples and 19 times higher coliform levels than free-chlorinated systems with average AOC levels less than 99 micrograms/liter. Systems that maintained a phosphate-based corrosion inhibitor and limited the amount of unlined cast iron pipe had fewer coliform bacteria. Several operational characteristics of the treatment process or the distribution system were also associated with increased rates of coliform occurrence. The study concludes that the occurrence of coliform bacteria within a distribution system is dependent upon a complex interaction of chemical, physical, operational, and engineering parameters. No one factor could account for all of the coliform occurrences, and one must consider all of the parameters described above in devising a solution to the regrowth problem.     

Structure and dynamics of phytoplankton in an Amazon lake, Brazil

Natural lake systems represent important reservoirs for residential water supply, fish production, recreational activities and enjoyment of their natural beauty. Nevertheless, human impacts may affect their health status resulting in degradation and loss of biodiversity. The aim of the present study was to obtain data on the health status of a natural lake located in an indigenous reservation in the Brazilian Amazon, using the phytoplankton community changes along the rainy (June) and dry (November) seasons of 2006. We collected water (temperature, pH, Secchi depth and conductivity) and phytoplankton samples from the subsurface, middle of the water column, and approximately 30 cm above the bottom, over 24-hour sampling periods, from a central station in the lake. Samples taken from biotic and abiotic variables were correlated using canonical correspondence analysis (CCA). Results showed that the lake exhibited high temperatures in both seasons, and showed thermal stratification only during the rainy season. Dissolved oxygen exhibited a clinograde pattern in the rainy season and high oxygen in the hypolimnion in the dry season. In the rainy season, the water near the bottom was acidic, turbid and had a greater concentration of phosphorus. Dissolved oxygen, conductivity, pH, nitrite, total phosphorus and total dissolved phosphorus exhibited diel variations in the rainy season, whereas water temperature, dissolved oxygen, total nitrogen and total dissolved phosphorus exhibited significant differences between hours of the day in the dry season. The phytoplankton was represented by 39 taxa, and Chlorophyta showed the greatest species richness, totaling 25 taxa. Among Chlorophyta, desmids were the most diverse, accounting 52%. Bacillariophyta (nine species) was the second most diverse group. Cyanophyta was represented by three species, including Merismopedia tenuissima, the most abundant taxon. Despite the occurrence of taxa that indicate organic pollution, their biomass and frequency indicate that the system is not currently threatened. Lake Caracaran? is an oligotrophic system, with low algal density and isolated blooming episodes due to its shallow depth.     

Preliminary Studies on Membrane Filtration for the Production of Potable Water: A Case of Tshaanda Rural Village in South Africa

Ultrafiltration (UF) systems have been used globally for treating water from resources including rivers, reservoirs, and lakes for the production of potable water in the past decade. UF membranes with a pore size of between 0.1 and 0.01 micrometres provide an effective barrier for bacteria, viruses, suspended particles, and colloids. The use of UF membrane technology in treating groundwater for the supply of potable water in the impoverished and rural village, Tshaanda (i.e., the study area) is demonstrated. The technical and administrative processes that are critical for the successful installation of the pilot plant were developed. Given the rural nature of Tshaanda, the cultural and traditional protocols were observed. Preliminary results of the water quality of untreated water and the permeate are presented. Escherichia coli in the untreated water during the dry season (i.e., June and July) was 2 cfu/100 ml and was <1 cfu/100 ml (undetected) following UF, which complied with the WHO and South African National Standards and Guidelines of <1 cfu/100 ml. During the wet/rainy season (February) total coliform was unacceptably high (>2419.2 cfu/100 ml) before UF. Following UF, it dramatically reduced to acceptable level (7 cfu/100 ml) which is within the WHO recommended level of <10 cfu/100 ml. Additionally, during the wet/rainy season E. coli and enterococci were unacceptably high (40.4 cfu/100 ml and 73.3 cfu/100 ml, respectively) before UF but were completely removed following UF, which are within the WHO and SANS recommended limit. The values for electrical conductivity (EC) and turbidity were constantly within the WHO recommended limits of 300 µS/cm corrected at 25°C and <5 NTU, respectively, before and after UF, during dry season and wet season. This suggests that there is no need for pre-treatment of the water for suspended particles and colloids. Considering these data, it can be concluded that the water is suitable for human consumption, following UF.     

Water quality and public health in northern Sudan: a study of rural and peri-urban communities

Access to adequate supplies of good quality drinking water continues to be limited among many rural and peri-urban communities in Africa, despite several decades of water improvement programmes. The present study investigated water quality at the source and point of consumption among rural and peri-urban communities in northern Sudan. Faecal coliform counts were determined by the membrane filtration technique and geometric mean counts compared in different seasons and among the different communities. Among nomadic pastoralists and riverine villages, both water sources and water stored for consumption had faecal coliform counts grossly in excess of WHO standards, with higher counts at the end of the rainy season. In the peri-urban community on the outskirts of Omdurman, while water quality from the distribution system had faecal coliform counts generally below 10 dl - 1, after storage, water was of considerably lower quality, with faecal coliform counts up to 1000 d1 - 1. The highest counts again occurred in the rainy season. Rates of diarrhoeal disease for Khartoum province were also greatest towards the end of the rainy season. The study has shown that poor quality water continues to be a major risk factor for public health in these communities.     

Real-Time PCR Detection of Enteric Viruses in Source Water and Treated Drinking Water in Wuhan, China

A total of 48 water samples were collected from six water treatment plants in Wuhan and analyzed by real-time PCR assay for viral identification of enterovirus (EV), rotavirus group A (RVA), human adenovirus (HAdV) as well as human adenovirus subgroup F (HAdVF) during the period from December 2010 to October 2011. HAdV, HAdVF, and RVA were all positively detected in the samples of source water and treated drinking water. EV could be found in 46 % (11/24) of all the source water samples, but only 21 % (5/24) positive in treated drinking water. The concentrations of these three kinds of enteric viruses detected were as follows: HAdV > RVA > EV. The highest removal rate was EV (97 %), followed by RVA (82 %), HAdV (73 %), and HAdVF (72 %). HAdV and RVA have been abundant in untreated river water and finished water after conventional processes of water treatment plants, while bacterial indicators could not be detected in tap water, which met the standard of China for drinking water bacterial quality. Some factors that could affect the accuracy of qPCR detection are also discussed in this study.     

宁波市城区内河肠道病原细菌定量 PCR 分析

了解城市内河中病原菌含量对城市生态安全具有重要意义。应用定量PCR（ qPCR）方法,对宁波市城区6条重要内河水体中的病原菌含量及主要水质指标进行分析。结果表明,祖关山河、苏家河、南北河、后西河、史魏家河和直落河每升水体中含有病原菌基因的拷贝数分别为：3.34×105、1.47×105、4.68×105、1.75×106、9.65×106和1.33×106;且病原菌基因的含量与水体溶解氧负相关,与总氮、氨氮、浊度、总磷、高锰酸钾指数、叶绿素a和电导率呈正相关关系,但与水体透明度、温度和酸碱度无明显关系。定量PCR分析结果可望为评价城市内河水体质量提供重要参考。