Improving the performance of a 4-stage Bardenpho WWTP by means of decentralized automatic control

The first part of this paper presents the development of a 4-stage Bardenpho wastewater treatment plant simulator model. The simulator model is an adaptation of the Benchmark Simulation Model No. 1 for the 4-stage Bardenpho process, and it consists of seven reactor arranged in series followed by a secondary settler. The bio-kinetic model used to describe the biological processes in the reactors is a modified Activated Sludge Model No. 3 that considers parallel growth of the heterotrophic biomass on both biodegradable substrate and internal storage products. The secondary settler was considered to be reactive and the biological processes that occur in the settler were accounted for. The second part of the paper focuses on the analysis of the benefits that decentralized control has on the operation of the 4-stage Bardenpho process. Four control strategies of the 4-stage Bardenpho are analyzed from a control performance, operational costs and effluent quality perspective. The control strategies are based on PI controller designed using the Internal Model Control principle. In order to make the simulation more realistic the sensors and reactors were not considered being ideal and their complex behavior was considered in the simulator model.