Abstract

Effective use of biodegradable substrates as an internal carbon sources (ICS) for denitrification and EBPR and predicting performance of aeration systems during nitrification in activated sludge bioreactors, may be useful in realization the sustainable development by potentially saving energy consumption at WWTPs. A large number of WWTPs use activated sludge systems with an integrated removal of carbon, nitrogen and phosphorus under anaerobic-aerobic conditions. Therefore, the aeration control in activated sludge bioreactors is very important, because it is one of the most energy-consuming processes in the wastewater treatment. The aeration system can absorb from 50% to 90% of the electricity consumed by the WWTP (depending on size and technological solutions of plant), which generate 15-40% of the total cost for energy consumption in budget of the wastewater treatment. Challenges with optimization of aeration systems in existing WWTP and ongoing process in the bioreactors depended mostly from the complexity of the process and the impact of various factors on the maintenance of stability and high efficiency of wastewater treatment. The aim of this study was to determine the correctness of the modernization carried out at a large biological nutrient removal (BNR) Debogorze WWTP, which serves Gdynia agglomeration (northern Poland), to optimizing energy consumption by the predictive control of the aeration system in bioreactors. The comparative experimental and modeling study confirmed, that using predictive aeration control (maintaining even a relatively low concentration of oxygen in the bioreactor), has not affected the condition of activated sludge as well as biochemical processes rates such as AUR/OUR and COD utilization. Moreover energy consumption at WWTP was lower after the modernization of biological step completed in 2009, obtaining stable quality of treated wastewater, which meet the requirements (N=10, P=1 mg/dm3) of effluent according to EU Directive.

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