Eau potable

The bacterial growth potential is important to understand and manage bacterial regrowth-related water quality concerns. Bacterial growth potential depends on growth promoting/limiting compounds, therefore, nutrient availability is the key factor governing bacterial growth potential. Selecting proper tools for bacterial growth measurement is essential for routine implementation of the growth potential measurement.
This study proposes a growth potential assay that is universal and can be used for different water types and soil extract without restrictions of pure culture or cultivability of the bacterial strain. The proposed assay measures the sample bacterial growth potential by using the indigenous community as inocula. Flow cytometry (FCM) and adenosine tri-phosphate (ATP) were used to evaluate the growth potential of six different microbial communities indigenous to the sample being analyzed, with increasing carbon concentrations. Bottled mineral water, non-chlorinated tap water, seawater, river water, wastewater effluent and a soil organic carbon extract were analyzed.
Results showed that indigenous bacterial communities followed normal batch growth kinetics when grown on naturally present organic carbon. Indigenous bacterial growth could detect spiked organic carbon concentrations as low as 10 μg/L. The indigenous community in all samples responded proportionally to the increase in acetate-carbon and proportional growth could be measured with both FCM and ATP. Bacterial growth was proportional to the carbon concentration but not the same proportion factor for the different water samples tested. The effect of inoculating the same water with different indigenous microbial communities on the growth potential was also examined. The FCM results showed that the highest increase in total bacterial cell concentration was obtained with bacteria indigenous to the water sample.
The growth potential assay using indigenous bacterial community revealed consistent results of bacterial growth in all the different samples tested and therefore providing a fast, more stable, and accurate approach for monitoring the biological stability of waters compared to the previously developed assays. The growth potential assay can be used to aid in detecting growth limitations by compounds other than organic carbon.

Chemical oxidants have been applied in water treatment formore than a century, first as disinfectants and later to abate inorganic andorganic contaminants. The challenge of oxidative abatement of organicmicropollutants is the formation of transformation products with unknown(eco)toxicological consequences. Four aspects need to be considered foroxidative micropollutant abatement: (i) Reaction kinetics, controlling theefficiency of the process, (ii) mechanisms of transformation product formation,(iii) extent of formation of disinfection byproducts from the matrix, (iv)oxidation induced biological effects, resulting from transformation productsand/or disinfection byproducts. It is impossible to test all the thousands oforganic micropollutants in the urban water cycle experimentally to assesspotential adverse outcomes of an oxidation. Rather, we need multidisciplinaryand automated knowledge-based systems, which couple predictions of kinetics,transformation and disinfection byproducts and their toxicological consequencesto assess the overall benefits of oxidation processes. A wide range of oxidation processes has been developed inthe last decades with a recent focus on novel electricity-driven oxidation processes. To evaluate these processes, they have to becompared to established benchmark ozone- and UV-based oxidation processes by considering the energy demands, economics,the feasibilty, and the integration into future water treatment systems.