Protecting public health from the impact of body-contact recreation.

Population growth and the increasing demand for recreational opportunities have put public and political pressure on water purveyors to make every water body available for multipurpose use. There is increasing evidence that full water-body contact recreation such as swimming, and water/jet skiing may add significantly more microorganisms such as viruses, Giardia, and Cryptosporidium to a water body when compared with non-body contact recreational waters. Body-contact recreation also poses a risk to the consumer inadvertently ingesting contaminated water. Waterborne disease outbreaks caused by recreation are well documented with the endemic rate and the risk level to the public estimated to be very high. Since 1989, 171 outbreaks, associated with recreational water, have been documented in the USA with more than 15,000 individuals infected; these outbreaks occurred in both natural and artificial settings. Discussions on the recently published Long-Term 2 Enhanced Surface Water Treatment Rule (LT2) have focused on varied treatment goals related to microbiological quality and source water protection methods at the heart of this discussion. This paper highlights new studies on risk from recreation, proposed beach standards, modeling to assess the risk of infection, political issues associated with limiting recreation, and what water utilities can do to reduce risk.     

QMRA (quantitative microbial risk assessment) and HACCP (hazard analysis and critical control points) for management of pathogens in wastewater and sewage sludge treatment and reuse.

Hazard Analysis and Critical Control Points (HACCP) was applied for identifying and controlling exposure to pathogenic microorganisms encountered during normal sludge and wastewater handling at a 12,500 m3/d treatment plant utilising tertiary wastewater treatment and mesophilic sludge digestion. The hazardous scenarios considered were human exposure during treatment, handling, soil application and crop consumption, and exposure via water at the wetland-area and recreational swimming. A quantitative microbial risk assessment (QMRA), including rotavirus, adenovirus, haemorrhagic E. coli, Salmonella, Giardia and Cryptosporidium, was performed in order to prioritise pathogen hazards for control purposes. Human exposures were treated as individual risks but also related to the endemic situation in the general population. The highest individual health risk from a single exposure was via aerosols for workers at the belt press for sludge dewatering (virus infection risk = 1). The largest impact on the community would arise if children ingested sludge at the unprotected storage site, although in the worst-case situation the largest number of infections would arise through vegetables fertilised with sludge and eaten raw (not allowed in Sweden). Acceptable risk for various hazardous scenarios, treatment and/or reuse strategies could be tested in the model.     

隐孢子虫和贾第鞭毛虫的成套分析方法介绍

城市供排水系统中的隐孢子虫和贾第鞭毛虫直接威胁饮用水安全,同时对城市水环境带来生态和健康风险,因此对水体中的两虫进行调研,掌握其污染现状有重要意义。对两虫问题的系统研究离不开有效的检测手段,分别对两虫的密度检测、活性分析和种类鉴定方法进行了系统介绍,并对各种检测方法的优缺点进行说明和比较,进而提出了两虫的成套分析方法。     

Quantification and genotyping of Cryptosporidium spp. in river water by quenching probe PCR and denaturing gradient gel electrophoresis.

A new detection method was developed for the simultaneous quantification and genotyping of Cryptosporidium spp. in river water. Several modifications made to the US EPA Method 1623 enabled high and stable recovery of Cryptosporidium from 40 L of river water (geometric mean = 35%, standard deviation = 8.7%). Quenching probe PCR (QProbe PCR) was used to quantify the 18S rRNA gene of Cryptosporidium spp. This method could successfully detect single oocysts in a sample, and the lower quantitation limit was as low as 2.5 oocysts/sample. In addition, denaturing gradient gel electrophoresis (DGGE) followed by DNA sequencing was used to identify the genotypes. These methods were applied to detect Cryptosporidium spp. in the Koyama River, Japan. The positive ratio was 69% (11/16) with the maximum concentration of 59 oocysts/100 L. Seven genotypes including two novel ones were identified. These results showed that this detection method could provide valuable information on Cryptosporidium in river water, both in the concentration and in the genotypes, which is essential for the precise assessment of waterborne risk to human health.     

Assessing the health implications of turbidity and suspended particles in protected catchments.

The supply of unfiltered disinfected drinking water from Melbourne's fully protected catchments means that the water-quality managers must ensure that the source water poses no public health risk. High turbidity is currently used as a surrogate of pathogens, and harvesting of water is based on its measurement. The work presented here summarises suspended particle and associated pathogen, microbial indicator and faecal biomarker concentrations collected to (a) quantify turbidity in an Australian water supply system and (b) assess the possibility of increasing water harvesting from selected tributaries. Pathogens and microbial indicators were present in low numbers in these source waters; increased turbidity during storm events was not associated with an increase in pathogen concentration. The results confirmed that protected catchments, along with good management, were effective barriers to pathogen contamination. Aesthetic issues still need to be addressed, but no measurable increase in microbiological risk was associated with storm-generated particles.     

浙江饮用水源地水环境状况及存在问题分析

为了对浙江省饮用水水源地的水质状况进行全面评价,依据相关资料,从水质类别、富营养化状态,水体中微囊藻毒素含量、有机物及农药污染状况,酸雨和水体pH值等方面,对浙江省饮用水水源地水环境状况进行了全面分析。分析结果表明：目前影响水源地水质的主要因子是氮和磷,水源地营养化程度呈逐渐加重趋势;有机污染引起的健康风险较小,但剧毒型氨基甲酸酯农药（涕灭威、克百威）检出率较高;水体pH值呈中性偏碱性,酸雨对水体的直接影响表现不明显,但其间接及持续影响不可忽视。针对浙江省饮用水水源地水质安全问题,提出了相应的水质保护建议。     

Genotyping of single Cryptosporidium oocysts isolated from sewage and river water.

The study was designed to genotype individual Cryptosporidium oocysts using an 18S rRNA gene-based semi-nested PCR and direct sequencing procedure. Positive PCR amplification was observed in all single C. parvum HNJ-1 oocyst samples tested. Semi-nested PCR and direct sequencing was applied to Cryptosporidium oocysts isolated from sewage and river water. The procedure could genotype 54% of FITC-stained single oocysts isolated from sewage and 32% from river water. The predominant genotype in both sewage and river water was C. parvum genotype 1, accounting for 33 and 25%, respectively, of all the FITC-stained intact Cryptosporidium oocysts present.     

In-house contamination of potable water in urban slum of Kolkata, India: a possible transmission route of diarrhea

We have investigated and determined the potentiality of different water sources, both for drinking and domestic purposes, in diarrheal disease transmission in diarrhea endemic foci of urban slums in Kolkata, India in a one and half year prospective study. Out of 517 water samples, collected from different sources, stored water (washing) showed higher prevalence of fecal coliforms (58%) (p < 0.0001) in comparison with stored (drinking) samples (28%) and tap/tubewell water (8%) respectively. Among different sources, stored water (washing) samples had the highest non-permissible range of physico-chemical parameters. Fecal coliform levels in household water containers (washing) were comparatively high and almost 2/3 of these samples failed to reach the satisfactory level of residual chlorine. Interestingly, 7% stored water (washing) samples were found to be harboring Vibrio cholerae Improper usage of stored water and unsafe/poor sanitation practices such as hand washing etc. are highlighted as contributory factors for sustained diarrheal episodes. Vulnerability of stored water for domestic usage, a hitherto unexplored source, at domiciliary level in an urban slum where enteric infections are endemic, is reported for the first time. This attempt highlights the impact of quality of stored water at domiciliary level for fecal-oral contamination vis-à-vis disease transmission.     

Significance of bacteria associated with invertebrates in drinking water distribution networks.

The implication of invertebrates found in drinking water distribution networks to public health is of concern to water utilities. Previous studies have shown that the bacteria associated with the invertebrates could be potentially pathogenic to humans. This study investigated the level and identity of bacteria commonly associated with invertebrates collected from the drinking water treatment systems as well as from the main pipelines leaving the treatment works. On all sampling occasions bacteria were isolated from the invertebrate samples collected. The highest bacterial counts were observed for the samples taken before filtration as was expected. There were, however, indications that optimal removal of invertebrates from water did not always occur. During the investigation, 116 colonies were sampled for further identification. The isolates represent several bacterial genera and species that are pathogenic or opportunistic pathogens of humans. Diarrhoea, meningitis, septicaemia and skin infections are among the diseases associated with these organisms. The estimated number of bacteria that could be associated with a single invertebrate (as based on average invertebrate numbers) could range from 10 to 4000 bacteria per organism. It can, therefore, be concluded that bacteria associated with invertebrates might under the worst case scenario pose a potential health risk to water users. In the light of the above findings it is clear that invertebrates in drinking water should be controlled at levels as low as technically and economically feasible.     

Effect of climate changes on waterborne disease in The Netherlands.

Effects of climate change in The Netherlands in the 21st century on the microbiological quality of water for drinking water production and recreation were evaluated. The following was concluded: increased temperature leads to significant additional inactivation of enteric pathogens in surface waters with residence times of more than a month, but not in waters with residence times of up to ten days. Increased precipitation, runoff and storm water overflow lead to more peak concentrations of waterborne pathogens in surface water. Peak concentrations strongly determine the infection risk through drinking water consumption. Drought lowers and increased precipitation elevates groundwater tables, but an effect on the risk of groundwater contamination with waterborne pathogens is not clear. Climate effects are not noticeable near a groundwater well, where the groundwater table and flow rate are mainly determined by the pumping rate. Exposure of recreants to waterborne pathogens that can grow in the water is expected to increase due to increased recreation and increased growth opportunities of these pathogens. Due to warmer summers, pathogens, like amoeba, that have not caused problems up to date in The Netherlands, may now emerge in recreational waters.     

Giardia and Cryptosporidium in source waters of S?o Paulo State, Brazil.

Giardia lamblia and Cryptosporidium parvum are two protozoan intestinal parasites responsible for many drinking-water-related disease outbreaks in recent years. They are very resistant to conventional water treatment processes, can persist for long times in the environment and are, therefore, of great concern for public health. This work aimed to evaluate the presence of Giardia and Cryptosporidium in water sources from S?o Paulo State, Brazil, as part of the "Evaluation of Inland Waters from S?o Paulo State" project from CETESB. Over a period of 19 months, 278 water samples from 28 sites located in 10 watersheds were analysed. The immunofluorescence assay was used after concentration of the samples by the calcium carbonate flocculation technique. Thermotolerant (faecal) coliforms, faecal streptococci and Clostridium perfringens were also determined in order to verify the existence of correlation between these bacterial indicators and the protozoa. Giardia and Cryptosporidium were detected in 27% and 2.5% of the samples, respectively, a lower figure compared with the results reported by other authors, especially for Cryptosporidium. A Spearman rank correlation test demonstrated a significant correlation between Giardia and faecal indicator concentrations. According to the American Regulation of Monitoring (ICR), treated water from 16 of these 28 collection sites should also be analysed to evaluate whether the treatment process could remove the parasites. Some technical deficiencies of these methods still limit the utilisation of the monitoring results for public health decisions, but the data here reported will help to improve the quality of drinking water in S?o Paulo State.     

Canal networks as extended waste stabilization ponds: fate of pathogens in constructed waterways in Pathumthani Province, Thailand.

The occurrence and fate of surface water and wastewater pathogens (faecal coliforms, Escherichia coli, Giardia lamblia and Cryptosporidium parvum) in two constructed waterways and a pond-based AIT wastewater treatment plant (AIT WWTP) in Pathumthani, Thailand were studied in the context of several biogeochemical factors and in relation to pollutional pressure and seasonal phenomena with a view to proposing potential mechanisms for their removal. More data on pathogen removal in a given local context would provide assurance that some pathogens could serve as suitable indicator organisms and predict removal of different pathogenic microorganisms such as protozoan parasites covered in this study. The enumeration technique for protozoan pathogens was improved in terms of application of emerging novel molecular technologies for the development of a fast but affordable microbiological method. Potential risk of waterborne disease outbreak in pertinent communities was then characterized using established infection probability models and the compiled pathogen occurrence data. Overall, we have addressed several strategic priorities of pathogen research in waste stabilization ponds in developing tropical countries like     

Cryptosporidium monitoring system at a water treatment plant, based on waterborne risk assessment.

The water volume required for daily monitoring of Cryptosporidium (which can statistically ensure an annual risk of infection below 10(-4)), was assessed by evaluating the applicability of the Poisson lognormal (PLN) distribution in microbial risk assessment. PLN showed as good a fit to the observed data as to the negative binomial distribution. From the estimated PLN distributions for the source and finished water, the efficacy of the oocyst removal by the conventional water treatment process was estimated to follow log-normal distribution (median = 3.16 log10, 95% CI = 4.27-2.05 log10). The 365 consecutive negative results of daily monitoring for 180 L of finished water were found to be statistically equivalent to the annual risk of infection below 10(-4). This research also suggested the possibility of applying a qualitative detection method, such as CC-PCR, as a routine monitoring method for the quantitative risk management.     

Aerobic bacterial spores as process indicators for protozoa cysts in water treatment plants.

The possibility of using aerobic spores as indicators (surrogates) of water treatment efficiency for the removal of Giardia cysts and Cryptosporidium oocysts was evaluated in a water treatment plant that supplies the Barcelona area of Spain. The water treatment consists of pre-chlorination, flocculation-sedimentation, double filtration (sand and granular activated carbon, GAC) with intermediate ozonation and post-chlorination. Aerobic spores significantly increased after GAC filtration, which indicated an active propagation of aerobic spore-formers. However, anaerobic (Clostridium) spores could be a good surrogate for Cryptosporidium oocysts, especially if their detection in samples at low concentrations was improved.     

Impact of Raw Water Quality and Climate Factors on the Variability of Drinking Water Quality in Small Systems

Drinking water quality is mainly influenced by the variable quality of source water, which is affected by both meteorological and climate factors. Contrary to medium and large municipalities, small systems do not have appropriate equipment to face important variations of raw water quality, and they do not have enough information either on the impact of these alterations. The objective of this study is to develop a decision-making tool to small system operators allowing the determination of risk periods, based on easily accessible measures. The impact of several raw water quality parameters and climate factors on drinking water quality was under study. A stepwise regression analysis was applied to determine the most important factors. Two of them were retained: the level of UV₂₅₄ of raw water and average maximal air temperature of 15 days before measurement. These factors are representative of raw water quality or meteorological conditions and are easily accessible to systems with restricted financial capacities. A logistic regression analysis contributed to the estimation of the probability to provide drinking water of bad quality (defined by a drinking water quality index). Finally, results of the analysis were synthetized in a visual tool, allowing the identification of risk periods using the known values of UV₂₅₄ and average maximal air temperature of 15 days. This tool may strongly contribute to the improvement of drinking water management in small systems, as it provides easily accessible information on the risks of deterioration of drinking water quality using two simple parameters.     

Evaluation of activated sludge treatment and the efficiency of the disinfection of Giardia species cysts and Cryptosporidium oocysts by UV at a sludge treatment plant in Campinas, south-east Brazil.

Among many waterborne diseases the giardiasis and cryptosporidiosis are of particular public health interest, because Giardia cysts and Cryptosporidium oocysts can persist for long periods in the environment, and both pathogenic protozoa have been implicated as the cause of many outbreaks of gastroenteritis in the last 25 years. In order to evaluate the efficiency of cysts and oocysts' removal by the activated sludge process, and by UV reactor in inactivating cysts and oocysts in one wastewater treatment plant (WWTP) of Campinas, three sampling points were selected for study: (1) influent, (2) treated effluent without UV disinfection and (3) treated effluent with UV disinfection. Giardia spp. cysts prevailed with higher density in the three different sample types. Cryptosporidium spp. oocysts were observed in only two samples of influent and just one sample of treated sewage with UV disinfection. In the animal infectivity assay for Giardia spp, one mouse of the UV treated group revealed trophozoites in intestinal scrapings. The results of the present study indicate that treatment by activated sludge process delivered a reduction of 98.9% of cysts and 99.7% of oocysts and UV disinfection was not completely efficient regarding the inactivation of Giardia cysts in the case of the WWTP studied.     

Quantitative evaluation and application of Cryptosporidium parvum inactivation with ozone treatment.

Despite a wealth of studies concerning the factors affecting the inactivation of Cryptosporidium parvum on ozone disinfection, practical approaches for predicting the inactivation level on ozone treatment system and determining the required ozone dose or contact time to achieve the required inactivation level remain unclear. When modified version of the "Delayed Chick-Watson model" was applied, the results show that Cryptosporidium parvum inactivation was well fitted with one unique line as "CTlag" and "inactivation slope" for several water parameters and water types. Thus, this study suggests quantitative methodology for predicting the Cryptosporidium parvum inactivation level with observation for the contact time of ozone and Cryptosporidium parvum and ozone residual.     

集中式地下水水源地环境风险评价方法研究及应用

随着经济的发展,城市不断扩张,很多水源地环境风险日益增加。现今,关于集中式地表水域或湖库型饮用水水源地环境风险评估的研究很多,但对集中式地下水源地环境风险评价研究较少。综合考虑潜在风险源、地下水水源地脆弱性和水源地环境风险防控与应急能力等方面建立了适用于地下水类型的集中式饮用水水源地环境风险评价指标体系和评价方法,并对沈阳市沈北新区7处地下水水源地进行评价。结果表明:潜在风险源和脆弱性分别作为外因和内因,是影响地下水水源地环境风险的主要因素;CLJPSC水源地(2.793)、YJ水源地(2.322)和HJ水源地(2.082)3处水源地为中等风险水源地,NCGSB水源地(1.969)、HJJSC水源地(1.790)、SMJT水源地(1.551)以及GGSYGLC水源地(1.464)为低环境风险水源地。     

南宁市主要饮用水源地水环境健康风险分析

为了解南宁市主要饮用水源水环境质量,分析其对人体健康产生风险水平,对2008—2012年南宁市饮用水源水环境质量进行了分析,并采用美国国家环境保护局(USEPA)推荐的健康风险模型对其所引起的健康风险做了初步评价。结果表明,南宁市主要水源地各污染物环境健康风险水平大小顺序为砷氟化物硝酸盐氨氮铁锰,化学致癌物引起的健康风险水平比非致癌物所致的健康风险水平高4个数量级。水源地水环境健康风险水平主要取决于致癌物质健康风险水平。2008—2012年邕江水源地致癌物质总风险水平较高,空间变化不明显,年际变化呈逐年下降趋势。南宁市主要水源地水环境健康风险水平应受到足够的重视,化学致癌物砷应当作为邕江水源地饮用水源需优先治理的污染物,必须在人们饮用之前将其去除,降低环境健康风险。     

基于RS和GIS的湘江长沙段水域风险评估方法研究

利用2016年9景Landsat影像以及相应时期的实测水质参数数据对湘江长沙段进行水质参数的遥感反演,并引入灾害风险中的危险性及易损性相关概念,通过Arc GIS软件的空间分析功能对湘江长沙段水域风险进行了分析。结果表明:高风险区主要分布于湘江的两岸,并且位于风险源较密集的区域;较高风险区主要位于湘江的两侧以及饮用水源区桥梁所处的位置;中等风险区主要分布于饮用水源区;较低风险区和低风险区主要位于过渡区以及景观娱乐用水区。在传统的水域风险评估中引入遥感技术使得评估方法更为多样且影响因子考虑的更为全面。研究结果对于河流水利管理部门进行水域风险评估、相关水域风险预警与整治方案的制定具有一定的参考价值。