Research and Application of Activated Sludge Models

With the growing demands on better effluent quality and higher cost-effectiveness wastewater treatment systems, the traditional methods to design and manage the Wastewater Treatment Plant (WWTP) by experiences and current standards could not meet rapidly developing wastewater industry. As a result, it is an inevitable trend to develop mathematical models and corresponding simulating software for wastewater treatment processes to improve the performance and cost-effectiveness of critical environmental protections. Based on International Water Association (IWA)'s activated sludge models (ASMs), an Activated Sludge Process Simulator — Carbon Oxidation (ASPS-CO) program is developed to simulate and optimize the design, operation, and management of WWTPs. With the focus on the carbon oxidation only, the ASPS-CO program models three typical biological processes: aerobic growth of heterotrophs, death and lysis of heterotrophs, and "hydrolysis" of particulate organics. This ASPS-CO program also develops its own sub-modules to calibrate model parameters, convert traditional measured data, and replace commonly missing data, etc. Therefore, it can simulate not only the water quality of influent and effluent in WWTPs, but also the operating conditions of series continuous stirred-tank reactors (CSTRs): for example, concentration and composition of biomass, and quality and composition of the wastewater, etc. The simulations of the Tianjin Ji-zhuang-zi WWTP using the ASPS-CO program indicate that the results closely match the measured data, which proves to be a reliable method to simulation other WWTPs. In conclusion, this method can provide a reliable theoretical foundation for engineers and researchers to design, operation, and management of wastewater treatment processes. Furthermore, it provides confidences in decision-makers to use this method as an important reference to make critical decisions.