二氧化氯和氯复合消毒剂对城市污水的消毒效果

试验研究了二氧化氯和氯复合消毒剂用于经城市污水处理厂处理后的城市污水消毒的效能 ,结果表明 ,二氧化氯和氯复合消毒剂的使用减低了生成的亚氯酸根离子的浓度 ,增加了残余的二氧化氯的浓度 ,粪大肠菌灭活效果良好。     

水中粪大肠菌群结果不确定度的评定

依据国家标准和测量不确定度的评定方法,评定水中粪大肠菌群的不确定度.认为不确定度的主要来源为样品保存条件、培养条件、人员操作和判定计数等.通过对地表水和海水样品粪大肠菌群操作过程中的不确定度进行分量计算,建立一种简单的水中粪大肠菌群多管发酵法不确定度评定方法.     

高温厌氧消化中底物浓度对病原指示微生物杀灭的影响

剩余污泥中含有大量病原微生物,土地利用之前必须进行适当的处理,降低病原微生物的数量,以降低环境风险.通过研究在不同的底物浓度条件下,剩余污泥高温厌氧消化(55℃)过程对病原指示微生物的杀灭效果,分析厌氧消化前后污泥中病原指示微生物数量变化的原因.结果表明,随着底物浓度的增加,VFAs浓度和累积产甲烷量增加.在底物浓度为28~84 g·L-1、温度为55℃、持续28 d的高温厌氧消化过程中,上清液中总大肠杆菌下降2.0~3.0个数量级、粪大肠杆菌下降1.8~3.3个数量级;消化后污泥中总大肠杆菌和粪大肠杆菌杀灭率均达到99%以上;且上清液中和消化污泥中均未检测到沙门氏菌的存在.在研究底物浓度范围内,当底物浓度大于45 g·L-1时,消化液和污泥中总大肠杆菌和粪大肠杆菌的杀灭效果下降.     

Septic tank and agricultural non‐point source pollution within a rural watershed

This investigation addresses the problem of Non‐Point Source (NPS) pollution in the rural Lake Weatherford watershed in Parker County, Texas. This reservoir is the primary municipal water supply for the City of Weatherford, Texas. The principal method of wastewater disposal is the on‐site system or septic tanks for the small residential areas surrounding the reservoir.

Sources of NPS pollution of interest in this watershed include agricultural operations as well as the residential areas. These sites were identified with the aid of aerial photography and field investigation. Suspected NPS problems were substantiated through a sampling program involving chemical and biological testing of the reservoir. Results indicate that there is significant NPS pollution contamination of Lake Weatherford from agricultural sources and seepage from on‐site wastewater disposal systems. Excessive fecal coliform and fecal streptococcus counts (>500 bacteria/100 ml) were generally associated with rainfall events and several samples showed values > 100000 bacteria/100 ml. The fecal coliform/fecal streptococcus ratios indicated contamination from human sources, animal sources, and a combination of both. Nutrient concentrations fluctuated from quite low to high with ammonia as the most consistent problem. High ammonia values were also associated with rainfall events.     

水质标准中指示微生物的发展及现状

饮用水病原微生物污染是公共卫生面临的主要威胁之一,微生物监测在水质监测中的必要性日益受到人们的认可。在实际工作中,一般是通过检测指示微生物间接反映病原微生物的存在。通过调研国内外各组织、机构颁布的水质标准发现,近年来,我国环境质量标准和污染物排放标准中对于指示微生物的选择有从总大肠菌群向粪大肠菌群和大肠埃希氏菌(E.coli)转变的趋势,而美国环保署、欧盟、世界卫生组织、澳大利亚国家健康与医疗研究委员会等根据最新的流行病学证据,强调了大肠埃希氏菌(E.coli)、肠球菌(Enterococci)与粪便污染的相关性更强,可用于替代大肠菌群。建议我国在后续水质标准中对微生物指标进行增补修订时,参考国外经验,形成集成多种指示微生物与多种特定病原体的监测指标体系,以更好地保护环境功能和民众健康。     

多管发酵法与其改进法检测水中粪大肠菌群的比较

粪大肠菌群是水体中粪便污染的重要指示菌，对于评价水质污染程度具有重要的卫生学意义。多管发酵法是传统的粪大肠菌群检测方法，但其步骤繁杂、周期长。目前，已有部分监测及科研人员对其进行了改进，笔者采用改进法与国标多管发酵法进行比较验证，认为Ec培养法可完全替代国标多管发酵法，纸片法亦可用于除酸性水样及菌量大的原污水外的其他环境水样中粪大肠菌群的检测。     

Modeling manure-borne bromide and fecal coliform transport with runoff and infiltration at a hillslope

Hillslope vegetated buffers are recommended to prevent water pollution from agricultural runoff. However, models to predict the efficacy of different grass buffer designs are lacking. The objective of this work was to develop and test a mechanistic model of coupled surface and subsurface flow and transport of bacteria and a conservative tracer on hillslopes. The testing should indicate what level of complexity and observation density might be needed to capture essential processes in the model. We combined the three-dimensional FEMWATER model of saturated-unsaturated subsurface flow with the Saint-Venant model for runoff. The model was tested with data on rainfall-induced fecal coliforms (FC) and bromide (Br) transport from manure applied at vegetated and bare 6-m long plots. The calibration of water retention parameters was unnecessary, and the same manure release parameters could be used both for simulations of Br and FC. Surface straining rates were similar for Br and bacteria. Simulations of Br and FC concentrations were least successful for the funnels closest to the source. This could be related to the finger-like flow of the manure from the strip along the bare slopes, to the transport of Br and FC with manure colloids that became strained at the grass slope, and to the presence of micro-ponds at the grassed slope. The two-dimensional model abstraction of the actual 3D transport worked well for flux-averaged concentrations. The model developed in this work is suitable to simulate surface and subsurface transport of agricultural contaminants on hillslopes and to evaluate efficiency of grass strip buffers, especially when lateral subsurface flow is important.     

The effect of environmental conditions on the ability of a constructed wetland to disinfect municipal wastewaters

Constructed wetlands are widely used all over the world for the treatment of municipal wastewaters, which are characterized by high concentrations of pathogens. The objectives of this study were (1) to study the effect of solar radiation and temperature on the ability of a constructed wetland to reduce the concentration of total coliforms (TC), and (2) to evaluate the relationship between the presence of Salmonella spp. in the outflow and the concentration of TC. The results of this study showed that under Mediterranean environmental conditions, the percentage reduction in coliforms was lower during winter compared to all other seasons. Maximum removal of coliforms was achieved under conditions of high solar radiation and temperature. In addition, solar radiation was found to play a greater role in coliform die-off at low temperatures than at high temperatures. Finally, it was found that the probability of Salmonella spp. appearance in the outflow of the wetland was related to the concentration of TC. The increase in coliform bacteria in the effluents also increased the chances of Salmonella appearance. The risk of Salmonella spp. appearance in the outflow is minimized when the concentration of TC is below 10²/100 mL.     

BACTERIAL LEVELS IN CISTERN WATER SYSTEMS OF NORTHERN KENTUCKY1

ABSTRACT: In rural Northern Kentucky, rainwater is commonly collected from rooftops and stored in cement block cisterns as the sole source of drinking water. Although every cistern system is unique in some aspect of design, use, or maintenance, a bacterial survey of 30 rural Northern Kentucky cistern systems suggests that coliforms and heterotrophic bacteria are common to all types of cistern storage systems. An average of 600 coliforms/ml and 3.6 ± 10⁵ heterotrophic bacteria/ml were detected in water samples from the bottoms of the cistern storage tanks. Bacterial levels in water delivered to household cold tap faucets were similar to the levels found in the storage tanks. When detected, fecal coliforms were recovered throughout the entire system including the household cold tap faucet. Current U.S. regulations for drinking water quality are discussed, with a suggestion that fecal coliform levels may be a more appropriate guideline for interpreting the water quality of individually maintained, nonchlorinated, nonpiped water supplies, such as cistern storage systems.     

Faecal Coliforms in Bivalve Harvesting Areas of the Alvor Lagoon (Southern Portugal): Influence of Seasonal Variability and Urban Development

Faecal coliform (FC) levels in surface water and clams (Ruditapes decussatus) and variations in environmental parameters were studied in two bivalve harvesting areas in the Alvor lagoon (southern Portugal). Land use and cover characteristics in adjacent subwatersheds were also analysed to assess their contributions as sources of faecal contamination. High FC levels in clams from the harvesting area in the most urbanized subwatershed (impervious surface coverage ≈ 10.5%) were positively associated with rainfall and with the cooler periods of the year. FC levels in clams from the least urbanized subwatershed were generally very low and did not present any detectable seasonal trend. From these results, it was concluded that the periodic deterioration of the microbiological quality of clams derives from the cumulative impact of the reservoir of faecal contamination created in urbanized areas, entering into the lagoon during storm water runoff.