Detection of somatic phages, infectious enteroviruses and enterovirus genomes as indicators of human enteric viral pollution in surface water

In the present study, we aimed to determine whether the concentrations of somatic coliphages, infectious enteroviruses or the detection of enterovirus genomes were associated with the detection of human pathogenic viruses in surface water. Four French rivers were sampled monthly or semimonthly for the quantitative detection of somatic coliphages, infectious enteroviruses and the qualitative RT-PCR detection of enterovirus, hepatitis A virus, Norwalk I viruses, Norwalk II viruses, astrovirus and rotavirus genomes over 12 months. All the 68 water samples tested were positive for the quantitative detection of somatic coliphages (range of concentrations: 4 x 10(2) to 1.6 x10(5) FUl(-1)). Infectious enteroviruses were isolated by a cell culture system in only two (3%) of the 68 concentrated water samples tested, whereas enterovirus genomes were detectable in 60 (88%) of the same samples. A positive RT-PCR detection of the genome of hepatitis A virus, Norwalk-like virus genogroup II, astrovirus, rotavirus and Norwalk-like virus genogroup I was demonstrated, respectively, in 1.5% (1/68), 1.5% (1/68), 3% (2/68), 0% and 0% of the 68 concentrated water samples tested. All of these four water samples were positive for the detection of enterovirus genomes, whereas only one of them was positive for the isolation of enteroviruses on cell culture. Moreover, the genomic detection of human pathogenic viruses appeared not to be statistically associated with the concentration levels of somatic coliphages in the 68 concentrated water samples tested (Wilcoxon rank test; P=0.14). Taken together, our findings indicate that the quantitative detection of somatic coliphages and the isolation of enteroviruses on cell culture are not suitable parameters for the control of the viral contamination in surface water, whereas the detection of enterovirus genomes may be useful for predicting the presence of waterborne viruses.     

Occurrence of rotaviruses and enteroviruses in recreational waters of Oak Creek, Arizona

Recent epidemiological studies have shown a relationship between swimming in recreational waters meeting bacteriological standards and gastroenteritis with a suggested viral etiology. No previous studies have been conducted in the United States on the occurrence of human pathogenic enteric viruses in freshwater recreational areas. The presence of enteroviruses and rotaviruses was investigated in Oak Creek, Arizona, a heavily used recreational area. Water samples were filtered through positively charged filters (168–1555 I.), eluted with beef extract, and assayed for human enteroviruses and rotaviruses. Eighteen of the 41 recreational water samples were positive for enterovirus or rotavirus. Of these, nine samples exceeded the Arizona State recommended limit of 1 PFU 40 l⁻¹ for full body contact in effluent dominated recreational waters. Several virus positive samples met the recommended fecal coliform standards (200 CFU 100 ml⁻¹) for recreational waters indicating the inadequacy of bacterial standards for monitoring viral water quality. The isolation of the pathogenic enteric viruses (i.e., poliovirus 1, echovirus 1, coxsackievirus B1 and B6 and rotavirus) from this popular recreational water demonstrates the potential for transmission of viral disease.     

A new portable virus concentrator for use in the field

A new portable apparatus is described which is usable in the field to concentrate large volumes of environmental water for laboratory purposes. The portable virus concentrator consists of four parts: a sampling unit including a programmable peristaltic pump; a 5 μm prefiltration unit; an ultrafiltration system; and a physicochemical measure area. The ultrafiltration system includes 10⁵ NMWL polysulfonate membranes, is performed at the natural pH of water and is followed by an elution step. By this technique, more than 60 l are concentrated in an hour and the recovery of three types of concentrates is observed: parasites are retained in the prefiltrate; bacteria and 80% of viruses are recovered in the concentrates.     

Distribution of enteric bacteria in Antarctic seawater surrounding a sewage outfall

The spatial distribution and movement of the sewage plume from McMurdo Station, Antarctica, was investigated in the ocean under the early summer sea ice. Ocean currents were also examined to determine their effect on the movement of the plume. Samples of sea water were obtained via holes drilled through the ice and analyzed for coliform bacteria. Coliform densities in ice cores were also determined. Densities of coliform bacteria as high as 10(5)/100 ml were found along the c. 1 km shoreline of McMurdo Station and the plume extended 200-300 m seaward. The relocation of the outfall from a surface configuration to the subsurface (11 m deep) had little influence on the distribution of the plume that sometimes reached the seawater intake station, 400 m to the south. Ocean current measurements in the study area confirmed that, while the prevailing advection was to the north and away from the intake area, episodic reversals of flow at some current meter stations coincided with pulses of sewage that moved to the intake. These findings support the use of bacterial indicators as one means to map the distribution and movement of recent sewage contamination in cold (-1.8 degrees C) sea water and provide evidence that the disposal and movement of domestic wastes deserves attention in coastal [correction of costal] polar environments.     

Backfilling missing microbial concentrations in a riverine database using artificial neural networks

Predicting peak pathogen loadings can provide a basis for watershed and water treatment plant management decisions that can minimize microbial risk to the public from contact or ingestion. Artificial neural network models (ANN) have been successfully applied to the complex problem of predicting peak pathogen loadings in surface waters. However, these data-driven models require substantial, multiparameter databases upon which to train, and missing input values for pathogen indicators must often be estimated. In this study, ANN models were evaluated for backfilling values for individual observations of indicator bacterial concentrations in a river from 44 other related physical, chemical, and bacteriological data contained in a multi-year database. The ANN modeling approach provided slightly superior predictions of actual microbial concentrations when compared to conventional imputation and multiple linear regression models. The ANN model provided excellent classification of 300 randomly selected, individual data observations into two defined ranges for fecal coliform concentrations with 97% overall accuracy. The application of the relative strength effect (RSE) concept for selection of input variables for ANN modeling and an approach for identifying anomalous data observations utilizing cross validation with ANN model are also presented.     

Modeling fecal coliform bacteria—II. Model development and application

The episodic nature of their origin and the transience of the receiving water response make the modeling of fecal coliform bacteria contamination events particularly challenging. A two-layer mass balance model was developed to simulate spatial and temporal variability in fecal coliform bacteria concentrations in a polluted, urban lake. Independently validated submodels were used to estimate bacteria loads from tributary and point source discharges, to quantify mass transport and to determine losses due to sedimentation and death. The overall model was validated by successfully simulating spatial and temporal dynamics for dry weather conditions and two wet weather events. Sensitivity analyses indicate that the likelihood of violating public health standards is influenced by environmental conditions, e.g. light intensity and wind mixing. Model simulations are used to illustrate the impact of water quality management actions on bacteria levels at various locations in the lake. The general approach presented here and the techniques used to quantify model inputs may be of value in application to other systems.     

Ecological impact of application of wastewater biosolids to agricultural soil

There has been little investigation of the ecological interactions between major organisms brought about by the application of wastewater biosolids to agricultural soil. This paper provides an overview of the possible effects of biosolids application on these ecosystems by using what is known about the ecology and diversity of microbial populations in soil and biosolids. Areas considered include interactions between indigenous and introduced bacterial populations, impacts of biosolids application on soil protozoa and the role of phages in bacterial population dynamics. These ecological processes are particularly relevant, for instance, to increase an understanding of the fundamental mechanisms responsible for inactivation of potentially infectious enteric microorganisms in biosolids‐amended agricultural soil.     

回收污水中肠道病毒方法的改进

介绍了一种城市污水中肠道病毒的浓集方法:病毒浓集前在污水中加入带阳电荷的物质聚氯化铝,30mg/L的聚氯化铝可使f2噬菌体回收率达到(92.06±8.65)%,pH值为6.5时f2回收率达(92.15±6.02)%,温度对回收率没有影响。该方法不仅对病毒的回收率高(>80%),且浓集污水量较大(20L)、效果稳定。     

Water Quality Changes in a Septic Tank Effluent Discharged to the Chalk

B ucket-type samplers were installed in the unsaturated zone to intercept septic tank effluent descending through the Chalf at Snowdown, Kent. Better than 90 per cent removal of BOD and COD, and of the order of 99 per cent removal of coiform bacteria, were observed after downward percolation through 2.1 m of Chalk. Nitrification of ammonia had begun at that depth, but not at intermediate depth. The results, though limited, suggest that septic tank effluent is purified in the Chalk in a similar way to settled sewage.     

再生水利用中肠道病毒的健康风险

介绍了国内外对再生水利用中肠道病毒健康风险的评价方法和案例。评价结果表明,再生水经深度处理且投氯量≥10mg/L、使肠道病毒去除率在 5-lg以上时,用于高尔夫球场、食用庄稼灌溉和地下水回灌,可使肠道病毒的感染风险降低至可接受水平 (10-4 ),但用于接触性娱乐用水(如游泳等)还需提高再生水处理深度和加强消毒效果。     

A water quality index for lake beaches

Discriminant analysis of ten years of data from seven beaches located on three lakes in Gatineau Park (Québec) leads to a canonical vector accounting for most of the variability of the three microbial count variables recorded. This discriminant axis orders the beaches along a cline of increasing pollution. It is then transformed into a microbial water quality index calibrated for the given set of beaches, which is in turn used to study the medium-term variability and the long-term evolution of water quality of the beaches.     

The Occurrence of Coliform Bacteria in the Surface Soils of Two Catchment Areas in the Yorkshire Dales

The levels of total coliform and Escherichia coli bacteria were determined within the surface soils of two upland catchments in North Yorkshire. The results indicated that enteric bacteria can survive for a sufficient period outside parent faecal material to provide a semi-permanent land store that might then be capable of contaminating upland waters following transport by hydrological processes. Significant differences in bacterial counts were found between broadly wet and dry soil moisture/vegetation zones in both catchments. This was explained by the more favourable survival conditions found where the soil moisture content was high enough to prevent the rapid desiccation and death of enteric bacteria. Significant differences were also found between the counts of total coliform and Escherichia coli bacteria in surface soils. It was concluded that the use of the total coliform group alone, as an indicator of the degree of sanitary bacterial contamination of soils, may over-estimate the true extent of contamination.     

Sequential modeling of fecal coliform removals in a full-scale activated-sludge wastewater treatment plant using an evolutionary process model induction system

We propose an evolutionary process model induction system that is based on the grammar-based genetic programming to automatically discover multivariate dynamic inference models that are able to predict fecal coliform bacteria removals using common process variables instead of directly measuring fecal coliform bacteria concentration in a full-scale municipal activated-sludge wastewater treatment plant. A sequential modeling paradigm is also proposed to derive multivariate dynamic models of fecal coliform removals in the evolutionary process model induction system. It is composed of two parts, the process estimator and the process predictor. The process estimator acts as an intelligent software sensor to achieve a good estimation of fecal coliform bacteria concentration in the influent. Then the process predictor yields sequential prediction of the effluent fecal coliform bacteria concentration based on the estimated fecal coliform bacteria concentration in the influent from the process estimator with other process variables. The results show that the evolutionary process model induction system with a sequential modeling paradigm has successfully evolved multivariate dynamic models of fecal coliform removals in the form of explicit mathematical formulas with high levels of accuracy and good generalization. The evolutionary process model induction system with sequential modeling paradigm proposed here provides a good alternative to develop cost-effective dynamic process models for a full-scale wastewater treatment plant and is readily applicable to a variety of other complex treatment processes.     

静电除菌技术在污水再生处理中的应用

在某再生水回用工程中,以污水厂二沉池出水为进水,采用了混凝沉淀-静电除菌处理技术,出水细菌总数<100+/mL、大肠菌群<3个/L、SS<0.5 mg/L、浊度<1 NTU、SDI<3,稳定达到<城市污水再生利用城市杂用水水质>(GB/T 18920-2002).出水回用作冲厕、绿化、景观及车辆冲洗用水.     

The Fate of Enteric Bacteria in Relation to Suspended Particles in Sea Water

The investigation was carried out to determine the effect of suspended particles on the survival of selected enteric bacteria (i.e. Escherichia coli and enterococci) which are important indicators of faecal pollution in marine waters. Rates of bacterial removal under varying experimental conditions (i.e. particle concentration, sewage content, and degree of mixing) were determined. The combined effect of the factors concerned with the removal rate of bacteria was evaluated by statistical analyses carried out on the experimental data utilizing the 'complete factorial' experimental design, and a good correlation between bacteria and particles was obtained.     

An Investigation of Sanitary Indicator Bacteria in a Macrophyte Wastewater-Treatment System

During recent years, many studies have attempted to determine the efficiency of macrophyte systems in removing a wide range of chemical substances and in the amelioration of wastewaters to attain effluent-quality standards. However, despite the importance of microbiological indicators of water quality for determining the suitability of water for recreational and public-supply purposes, little research has focused on the dynamics of sanitary indicator bacteria in macrophyte systems. This study reports the initial findings of such an investigation for a macrophyte raft-lagoon system which was used in the treatment of sewage at Sowerby Bridge, West Yorkshire, England.     

Modeling and efficiency of ultraviolet disinfection systems

Modeling can play a particularly useful role in ultraviolet (u.v.) disinfection because of difficulties in measuring u.v. dose and the immediate results of disinfection. This model predicts bacterial survival in flow-through systems. The calculation takes into account the complex intensity patterns, non-ideal flow patterns, and non-linear curves of log survival vs u.v. dose. Based on the organismal dose-response, the number of survivors in each fraction of the residence time distribution is calculated separately and summed to calculate the average survival. The model uses as input data: the average u.v. intensity within the system, the residence time distribution, and an experimentally determined dose-survival curve in a simplified system where dose can be directly measured. The predictions of the model corresponded well with measured survival in a u.v. pilot plant study. The model was used to show the effects of flow dispersion on average survival by varying residence time distribution. Measures of capacity and efficiency of u.v. systems were derived and illustrated experimentally in simple cylindrical batch units and in two multiple lamp units.     

The Bacterial Quality of an Upland Stream

Faecal coliform concentrations were determined at stream and water inflow sampling sites within an upland catchment in North Derbyshire containing rough, semiimproved and improved pastures. The results indicated that, during its passage through the catchment, the faecal indicators of the stream increased, and this may constitute a health risk to cavers using a popular recreational cave into which the stream drains. The decline in streamwater quality suggests that a semipermanent store of bacteria existed in catchment soils, and hydrological processes operated to transfer bacteria from the land to the stream channel. Contrary to expectations, intra-catchment differences in the bacterial quality of water at inflow and stream sampling sites could not be related to the intensity of agricultural land use in adjacent areas. This is explained with reference to changes in the nature of hydrological transport pathways associated with the improvement of pastures.     

地下水生物除铁效果及其动力学研究

采用生物滤柱进行了地下水除铁的试验研究。当原水中Fe^2＋的质量浓度为4．3mg／L,pH值为6．4～6．6,水温为23～25℃,DO为1．5mg／L,滤速为8m／h时,出水中Fe^2＋〈0．1mg,／L。通过灭菌试验得出,滤柱对铁的去除主要通过生物氧化完成,而非物理化学作用。通过分析不同高度滤层水中铁的含量研究了生物氧化除铁动力学规律,得出铁含量与空床接触时间之间的函数关系。     

SARS-CoV-2, other respiratory viruses and bacteria in aerosols: Report from Kuwait's hospitals

The role of airborne particles in the spread of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is well explored. The novel coronavirus can survive in aerosol for extended periods, and its interaction with other viral communities can cause additional virulence and infectivity. This baseline study reports concentrations of SARS-CoV-2, other respiratory viruses, and pathogenic bacteria in the indoor air from three major hospitals (Sheikh Jaber, Mubarak Al-Kabeer, and Al-Amiri) in Kuwait dealing with coronavirus disease 2019 (COVID-19) patients. The indoor aerosol samples showed 12–99 copies of SARS-CoV-2 per m³ of air. Two non-SARS-coronavirus (strain HKU1 and NL63), respiratory syncytial virus (RSV), and human bocavirus, human rhinoviruses, Influenza B (FluB), and human enteroviruses were also detected in COVID-positive areas of Mubarak Al Kabeer hospital (MKH). Pathogenic bacteria such as Mycoplasma pneumonia, Streptococcus pneumonia and, Haemophilus influenza were also found in the hospital aerosols. Our results suggest that the existing interventions such as social distancing, use of masks, hand hygiene, surface sanitization, and avoidance of crowded indoor spaces are adequate to prevent the spread of SARS-CoV-2 in enclosed areas. However, increased ventilation can significantly reduce the concentration of SARS-CoV-2 in indoor aerosols. The synergistic or inhibitory effects of other respiratory pathogens in the spread, severity, and complexity of SARS-CoV-2 need further investigation.