title: Balancing effluent quality, economic cost and greenhouse gas emissions during the evaluation of (plant-wide) control/operational strategies in WWTPs.
abstract: The objective of this paper was to show the potential additional insight that result from adding greenhouse gas (GHG) emissions to plant performance evaluation criteria, such as effluent quality (EQI) and operational cost (OCI) indices, when evaluating (plant-wide) control/operational strategies in wastewater treatment plants (WWTPs). The proposed GHG evaluation is based on a set of comprehensive dynamic models that estimate the most significant potential on-site and off-site sources of CO₂, CH₄ and N₂O. The study calculates and discusses the changes in EQI, OCI and the emission of GHGs as a consequence of varying the following four process variables: (i) the set point of aeration control in the activated sludge section; (ii) the removal efficiency of total suspended solids (TSS) in the primary clarifier; (iii) the temperature in the anaerobic digester; and (iv) the control of the flow of anaerobic digester supernatants coming from sludge treatment. Based upon the assumptions built into the model structures, simulation results highlight the potential undesirable effects of increased GHG production when carrying out local energy optimization of the aeration system in the activated sludge section and energy recovery from the AD. Although off-site CO₂ emissions may decrease, the effect is counterbalanced by increased N₂O emissions, especially since N₂O has a 300-fold stronger greenhouse effect than CO₂. The reported results emphasize the importance and usefulness of using multiple evaluation criteria to compare and evaluate (plant-wide) control strategies in a WWTP for more informed operational decision making.
authors: Division of Industrial Electrical Engineering and Automation (IEA), Department of Measurement Technology and Industrial Electrical Engineering (MIE), Lund University, Box 118, SE-221 00 Lund, Sweden; Center for Process Engineering and Technology (PROCESS), Department of Chemical and Biochemical Engineering, Technical University of Denmark, Building 229, DK-2800 Kgs. Lyngby, Denmark.
authors: Xavier
authors: X
authors: Flores-Alsina
authors: Magnus
authors: M
authors: Arnell
authors: Youri
authors: Y
authors: Amerlinck
authors: Lluís
authors: L
authors: Corominas
authors: Krist V
authors: KV
authors: Gernaey
authors: Lisha
authors: L
authors: Guo
authors: Erik
authors: E
authors: Lindblom
authors: Ingmar
authors: I
authors: Nopens
authors: Jose
authors: J
authors: Porro
authors: Andy
authors: A
authors: Shaw
authors: Laura
authors: L
authors: Snip
authors: Peter A
authors: PA
authors: Vanrolleghem
authors: Ulf
authors: U
authors: Jeppsson
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000693:Anaerobiosis; D018407:Bacterial Physiological Phenomena; D056804:Biofuels / Q000032:analysis*; D005740:Gases / Q000032:analysis; D017752:Greenhouse Effect; D008962:Models, Theoretical; D014865:Waste Disposal, Fluid / Q000191:economics / Q000379:methods*
chemical_list: D000393:Air Pollutants; D056804:Biofuels; D005740:Gases
keywords: Benchmarking; Global warming; Model-based evaluation; Multi-criteria decision making; Process control; Sustainability