Online flow cytometric monitoring of microbial water quality in a full-scale water treatment plant

The ever-increasing need for high-quality drinking and process waters, and growing public awareness about possible contamination, drive efforts for the further development of automated control of water treatment plants. For example, membrane filtration processes and reverse osmosis in particular are generally regarded as a safe barrier for inorganic, organic, and microbial contamination. Yet, to ensure the final water quality and to increase the confidence of the end-user, intensive and preferably online monitoring should be further implemented as an early-warning tool to control membrane integrity and to prevent microbial regrowth in the distributing network. In this paper, we test the applicability of flow cytometry and cytometric fingerprinting for a full-scale water treatment plant. We demonstrate in a full-scale water treatment plant that flow cytometry can be used as online monitoring tool and that changes in water quality can be observed, which are not monitored by commonly used online quality parameters. Furthermore, we illustrate with ultrafiltration that process conditions impact the flow cytometric cell counts

Safeguarding the microbial water quality from source to tap

Anthropogenic activities and climate change can deteriorate the freshwater quality and stress its availability. This stress can, in turn, have an impact on the biostability of drinking water. Up to now, the microbiological quality of drinking water has been maintained through the selection of high-quality water sources allied to the use of disinfectants and the removal of organic carbon. But as freshwater becomes richer in other nutrients, strategies used so far may not suffice to keep a steady and high-quality supply of drinking water in the future. This article readdresses the discussion on drinking water biostability. We need to reframe the concept as a dynamic equilibrium that considers the available nutrients and energy sources (potential for growth) relative to the abundance and composition of the bacterial community (potential to consume the available resources)

Biogenic palladium enhances diatrizoate removal from hospital wastewater in a microbial electrolysis cell

decrease the load of pharmaceuticals to the environment, decentralized wastewater treatment has been proposed for important point-sources such as hospitals. In this study, a microbial electrolysis cell (MEC) was used for the dehalogenation of the iodinated X-ray contrast medium diatrizoate. The presence of biogenic palladium nanoparticles (bio-Pd) in the cathode significantly enhanced diatrizoate removal by direct electrochemical reduction and by reductive catalysis using the H(2) gas produced at the cathode of the MEC. Complete deiodination of 3.3 mu M (2 mg L(-1)) diatrizoate from a synthetic medium was achieved after 24 h of recirculation at an applied voltage of -0.4 V. An equimolar amount of the deiodinated metabolite 3,5-diacetamidobenzoate (DAB) was detected. Higher cell voltages increased the dehalogenation rates, resulting in a complete removal after 2 h at -0.8 V. At this cell Voltage, the MEC was also able to remove 85% of diatrizoate from hospital effluent containing 0.5 mu M (292 mu g L(-1)), after 24 h of recirculation. Complete removal was obtained when the effluent was continuously fed at a volumetric loading rate of 204 mg diatrizoate m(-3) total cathodic compartment (TCC) day(-1) to the MEC with a hydraulic retention time of 8 h. At -0.8 V, the MEC system could also eliminate 54% of diatrizoate from spiked urine during a 24 h recirculation experiment. The final product DAB was demonstrated to be removable by nitrifying biomass, which suggests that the combination of a MEC and bio-Pd in its cathode offers potential to dehalogenate pharmaceuticals, and to significantly lower the environmental burden of hospital waste streams

A review of nature-based solutions for resource recovery in cities

Our modern cities are resource sinks designed on the current linear economic model which recovers very little of the original input. As the current model is not sustainable, a viable solution is to recover and reuse parts of the input. In this context, resource recovery using nature-based solutions (NBS) is gaining popularity worldwide. In this specific review, we focus on NBS as technologies that bring nature into cities and those that are derived from nature, using (micro)organisms as principal agents, provided they enable resource recovery. The findings presented in this work are based on an extensive literature review, as well as on original results of recent innovation projects across Europe. The case studies were collected by participants of the COST Action Circular City, which includes a portfolio of more than 92 projects. The present review article focuses on urban wastewater, industrial wastewater, municipal solid waste and gaseous effluents, the recoverable products (e.g., nutrients, nanoparticles, energy), as well as the implications of source-separation and circularity by design. The analysis also includes assessment of the maturity of different technologies (technology readiness level) and the barriers that need to be overcome to accelerate the transition to resilient, self-sustainable cities of the future