Holding-time and method comparisons for the analysis of fecal-indicator bacteria in groundwater

Monitoring Approaches for Faecal Indicator Bacteria in Water: Visioning a Remote Real-Time Sensor for E. coli and Enterococci

A comprehensive review was conducted to assess the current state of monitoring approaches for primary faecal indicator bacteria (FIB) E. coli and enterococci. Approaches were identified and examined in relation to their accuracy, ability to provide continuous data and instantaneous detection results, cost, environmental awareness regarding necessary reagent release or other pollution sources, in situ monitoring capability, and portability. Findings showed that several methods are precise and sophisticated but cannot be performed in real-time or remotely. This is mainly due to their laboratory testing requirements, such as lengthy sample preparations, the requirement for expensive reagents, and fluorescent tags. This study determined that portable fluorescence sensing, combined with advanced modelling methods to compensate readings for environmental interferences and false positives, can lay the foundations for a hybrid FIB sensing approach, allowing remote field deployment of a fleet of networked FIB sensors that can collect high-frequency data in near real-time. Such sensors will support proactive responses to sudden harmful faecal contamination events. A method is proposed to enable the development of the visioned FIB monitoring tool.

Evaluation of Microbiological Quality of Agricultural Water and Effect of Water Source and Holding Temperature on the Stability of Indicator Organisms' Levels by Seven U.S. Environmental Protection Agency-Approved Methods

ABSTRACT

The Food Safety Modernization Act Produce Safety Rule requires covered produce growers to monitor the quality of their agricultural water on a regular basis by some U.S. Environmental Protection Agency (EPA)-approved methods recognized by the U.S. Food and Drug Administration. In this study, we evaluated the changes in the population of indicator organisms in surface water up to 6 months, and the effects of water source and holding temperature on the survival of indicator organisms by seven EPA-approved methods (five methods for Escherichia coli and two methods for Enterococcus). The levels of E. coli and Enterococcus in the surface water were variable with sampling month, ranging from 1.61 ± 0.04 to 2.68 ± 0.15 log most probable number (MPN)/100 mL and from undetectable level to 1.19 ± 0.29 log MPN/100 mL, respectively. At 25°C (holding temperature), there were significant reductions (P < 0.05) in E. coli and Enterococcus populations in surface water after 48 and 24 h, respectively, whereas at 4°C, no significant changes in the bacterial populations were observed up to 48 h. Methods 1603, 1604, 1103.1, 10029, and Colilert showed a comparable sensitivity in quantifying E. coli, whereas method 1600 and Enterolert showed a variable sensitivity with the type of water. The results indicated that regular monitoring of agricultural water is essential to examine whether the microbial quality of water is appropriate for its intended use. Water samples should be maintained at 4°C to minimize the changes in microbial populations between sampling and testing. The comparison of the sensitivity of EPA methods for quantifying indicator organisms could provide growers with useful information for choosing the method for their water quality analysis.

HIGHLIGHTS

The impact of industrial wastewater on the physicochemical and microbiological characteristics of groundwater in Ajao- Estate Lagos, Nigeria

In Ajao Estate, it is believed that poor quality of its groundwater is unconnected to the dislodging of wastewater into the environment by food- and wine-producing industries operating in the area. To ascertain this claim, the impact of this wastewater on microbiological and physicochemical quality of the groundwater was evaluated. Microbiological result of water samples revealed decrease in Staphylococcus aureus, Clostridium spp., Escherichia coli, etc. count from the industrial wastewater dislodging point. Groundwater samples collected from areas under the influence of industrial wastewater showed higher concentration of physicochemical elements than those outside the area of influence (control) except pH (5.96) and Cl (19.80 ppm), while in soil samples, reverse was the case. In groundwater samples, most of the physicochemical parameters were not within the permissible limit for drinking water except zinc (Zn) (0.214 to 1.660 ppm) which falls within World Health and Nigerian limit of 3.0 ppm. The degree of contamination/pollution of all the heavy metals in the soil samples were neither polluted nor contaminated, even though the contamination factor (CF) and geoaccumulation index (I-geo) of cadmium (Cd) was the highest in main soil samples and in control. Negative correlations exist between all the heavy metals in soil samples and those in groundwater except copper (Cu). Reasonable concentrations of all these heavy metals with the exception of manganese (Mn) were seen in the sample of industrial wastewater, suggesting that industrial wastewater may be one of the possible sources of their concentration in groundwater even though there might be other sources.