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A calibrated ASM 2d model of a full scale MBR is modified as to include the soluble microbial products (SMPs) fractions and study their dynamics in full scale. Batch tests were conducted to estimate the SMP kinetics. The biomass associated products (BAPs) kinetics were estimated with results in tune with previous experiments. The utilization associated products (UAP) kinetics estimation was instead complicated by two aspects which regularly occur when spiking readily biodegradable COD: storage phenomena (not accountable in ASM 2d); the non-uniformity between the polysaccharide fraction, easily biodegradable, and the protein fraction, which proved to be refractory to biodegradation. The procedure for UAP kinetics estimation would thus require further analysis. UAPs were found in full scale markedly predominant compared to the BAPs. The data analysis revealed that the membrane rejection mechanism was identified as SMP loading rate dependent, emphasizing the need of a more careful consideration towards this parameter when working in a dynamic environment. The work discusses the feasibility of the SMP extension studies in dynamic conditions. Fine tuning of the membrane rejection factor, the necessity of more frequent sampling, and experimental determination of the additional kinetics SMP parameters become necessary and burdensome adaptations of the ASM calibrations. However both nutrients removal, sludge production and energy consumption modelling were not improved by including the SMP fraction in the modelling. SMPs did not correlate with fouling rates in this full scale MBR, indicating a strong drawback, since the main drive for these models is thus not accomplished.

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This work provides a case study on how activated sludge modelling and computational fluid dynamics (CFD) can help to optimize the energy consumption of a treatment plant that is already equipped with an advanced control based on online nutrient measurements. Currently, aeration basins on wastewater treatment plant Antwerp-South are operated sequentially while flow direction and point of inflow and outflow vary as a function of time. Activated sludge modelling shows that switching from the existing alternating flow based control to a simultaneous parallel feeding of all aeration tanks saves 1.3% energy. CFD calculations also illustrate that the water velocity is still sufficient if some impellers in the aeration basins are shutdown. The simulations of the Activated Sludge Model No. 2d indicate that the coupling of the aeration control with the impeller control, and automatically switching off some impellers when the aeration is inactive, can save 2.2 to 3.3% of energy without affecting the nutrient removal efficiency. On the other hand, all impellers are needed when the aeration is active to distribute the oxygen.

An ASM2da model of the full-scale waste water plant of Bree (Belgium) has been made. It showed very good correlation with reference operational data. This basic model has been extended to include an accurate calculation of environmental footprint and operational costs (energy consumption, dosing of chemicals and sludge treatment). Two optimisation strategies were compared: lowest cost meeting the effluent consent versus lowest environmental footprint. Six optimisation scenarios have been studied, namely (i) implementation of an online control system based on ammonium and nitrate sensors, (ii) implementation of a control on MLSS concentration, (iii) evaluation of internal recirculation flow, (iv) oxygen set point, (v) installation of mixing in the aeration tank, and (vi) evaluation of nitrate setpoint for post denitrification. Both an environmental impact or Life Cycle Assessment (LCA) based approach for optimisation are able to significantly lower the cost and environmental footprint. However, the LCA approach has some advantages over cost minimisation of an existing full-scale plant. LCA tends to chose control settings that are more logic: it results in a safer operation of the plant with less risks regarding the consents. It results in a better effluent at a slightly increased cost.

This study presents the development of an Early Warning System (EWS) called EPIGONE focusing on the detection of dry weather overflows in the vicinity of throttle structures in sewer systems. Throttle structures are considered as vital parts of a sewer system as they are control sections limiting flow rates to a designed operational value. Because these structures are by definition prone to potential clogging or blockages, a close follow-up of the daily operation by an EWS facilitates increased vigilance or even alarm. Primary goal of EPIGONE is to alert operators and thus allow fast intervention in case of suspected failures of these structures within a settled timeframe. EPIGONE combines overflow water level measurements with rainfall radar information to determine Combined Sewer Overflow (CSO) activity during dry weather as this dual condition will indicate malfunctioning. This combination of measurements was found to be the most cost effective set-up to deploy on a large scale. Water level data are recorded and logged on-site and sent to a central controller via GSM/GPRS, where an algorithm determines dry weather overflow conditions. Rainfall radar data are used as criterion to decide on dry weather conditions. From there on alarms are sent out to multiple recipients via e-mail and/or text messages (SMS). Next to this, it is obvious that this system can also be used for ‘regular’ wet weather CSO monitoring.