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Supervisory control configurations design for nitrogen and phosphorus removal in wastewater treatment plants
Author(s) -
Sheik Abdul Gaffar,
Seepana Murali Mohan,
Ambati Seshagiri Rao
Publication year - 2021
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.1002/wer.1512
Subject(s) - effluent , model predictive control , anoxic waters , sewage treatment , aeration , phosphorus , wastewater , environmental science , environmental engineering , activated sludge , water quality , ammoniacal nitrogen , pulp and paper industry , waste management , chemistry , computer science , engineering , control (management) , environmental chemistry , ecology , organic chemistry , artificial intelligence , biology
Abstract Model predictive control (MPC) and Fuzzy controllers are designed in a two‐level hierarchical supervisory control framework for control of activated sludge‐based wastewater treatment plants (WWTP) in order to efficiently remove nitrogen and phosphorus. Benchmark simulation model No.3 with a bio‐phosphorus (ASM3bioP) module is used as a working platform. The hierarchical control framework is used to alter the dissolved oxygen in the seventh reactor (DO 7 ) to control ammonia. Lower‐level PI, MPC, and Fuzzy are used to control the nitrate levels in the fourth reactor ( S NO4 ) by manipulating internal recycle ( Q intr ) and DO 7 in the seventh tank by manipulating mass transfer coefficient ( K L a 7 ). MPC and Fuzzy are designed in the supervisory layer to alter the DO 7 set‐point based on the ammonia composition in the seventh reactor (NH 7 ). From the analysis, it is observed that the effluent quality is improved with a decrease in ammonia, TN, and TP. Though a little difference was observed in the cost for all the control strategies, a trade‐off is maintained between cost and percentage improvement of effluent quality. MPC‐MPC combination showed significant removal in ammonia and better effluent quality when compared to other control strategies. Practitioner points Developed novel strategies in hierarchical configurations for better nutrient removal with optimal costs in an A 2 O process. Lower level control strategies deals with dissolved oxygen in last aeration tank and nitrate in fourth anoxic tank (PI/MPC) Higher level control strategy deals with ammonia in the last aeration tank (MPC/Fuzzy). Average and violations of nutrient removal, economy and overall effluent quality for three weather conditions (Dry, Rain and Strom) are studied. A trade‐off is observed between EQI and OCI.