AquaNL Trade Fair: Day 3

Online monitoring of microbiological water quality

by Nienke Koeman-Stein

At AquaNL, I discussed the results of the TKI project on the online monitoring of microbiological water quality. At present, water quality is monitored by taking water samples and then analysing them in the laboratory. The drawbacks of this approach include changes to the water during transport, the long delay before results are known, and infrequent measurements. The benefit is that there is a lot of experience with the laboratory methods and, as far as drinking water quality is concerned, the statutory standards are based on the laboratory methods.

Even so, there is a need for online monitoring. During this project, experience has been acquired with four monitors based on different measurement principles: the BACTcontrol, which is based on enzyme activity, the BactSense, which uses flow cytometry, the Bugcount Guardian based on ATP analysis for measuring microbiology in the aqueous phase, and the CBM, a biofilm monitor. Work has begun on the validation of the monitors using laboratory results. During that process, we have seen that, when we use the same measurement principles, such as flow cytometry online or in the lab, the analyses are a good match. When we used different measurement principles, such as a monitor based on enzyme activity and one using flow cytometry, it was not possible to achieve similar matches. This was to be expected.

A range of pilot studies were then conducted at both drinking water utilities and industrial sites. They showed that the sensors all have the potential for practical application for research purposes and continuous monitoring. Some of the measured change in water quality could be clearly linked to changes in the process. The changes in microbiological water quality did not result in exceedances of the statutory limits at the drinking water utilities and so there was not yet any cause for alarm. The establishment of alarm values will require a longer testing period. The experiences with sensors were positive.

Belissima: Modelling Organic Micropollutant Removal in Activated Sludge and Advanced Oxidation Systems

door Julian Muñoz Sierra

I recently had the opportunity to present our work on modeling the removal of organic micropollutants (OMPs) in activated sludge and advanced oxidation systems at AQUANL. This presentation was a synthesis of the outcomes from our TKI project Belissima.

As many of you are aware, the issue of micropollutants in the water cycle has gained significant attention in recent years. Increasing awareness has led to growing regulatory pressure to minimize their environmental impact, emphasizing the need for more efficient treatment and monitoring in urban wastewater systems. Conventional wastewater treatment plants (WWTPs) were not originally designed to remove OMPs, although they do contribute to their partial reduction. However, for many WWTPs that rely primarily on secondary or tertiary treatments, effluent micropollutant concentrations remain largely unknown. This knowledge is crucial for the potential implementation of quaternary treatments, such as advanced oxidation processes (AOPs) or adsorption.

Within the Belissima project, we quantified the biotransformation rate constants and removal efficiencies of 16 targeted micropollutants in bioreactors operating under aerobic, anoxic, and anaerobic conditions. These rates were incorporated into an Activated Sludge Digestion Model (ASDM) using BioWin software to predict micropollutant concentrations in WWTP effluents. The model was applied to the Walcheren WWTP in the Netherlands and calibrated with the plant’s design and operational data.

The predicted output concentrations from this model served as input for coupling to AOP models. Several laboratory experiments and two AOP pilot plants (UV/H₂O₂ and O₃) were tested as potential quaternary treatments. The coupling of these models provides a valuable tool for optimizing quaternary treatment implementation, facilitating technology selection and operational cost savings in micropollutant removal.

Image 1: KWR-stand

Image 2: Nienke Koeman

Image 3: Julian Munoz Sierra

Image 4: Frank Oesterholt

Image 5: Frank Oesterholt