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In the present study, the temperature effects on the organic carbon and nitrogen removal in an activated sludge process are evaluated. Benchmark Simulation Model No.1 (BSM1) based on activated sludge process is used for all the simulation purposes. A steady state simulation is performed to analyze the effluent concentrations with varying kinetic parameters obtained from different temperature coefficients over a wide range of temperatures from 15 °C to 35 °C. The temperature coefficient ‘a’ is assumed to have different set of values specific to the kinetic parameters, namely, Maximum heterotrophic growth rate \left( {{\mu _{mH}}} \right), Maximum autotrophic growth rate \left( {{\mu _{mA}}} \right), Heterotrophic decay rate \left( {{b_H}} \right), Autotrophic decay rate \left( {{b_A}} \right). The effluent concentration defined in terms of Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Total Suspended Solids (TSS), Total Nitrogen (TN) and Ammonia are observed to be significantly changing with a change in the kinetic parameters which are in turn a strong function of temperature coefficient. Emphasis is laid on the temperature range of 25–30 °C as it is commonly the most operated temperature range in a WWTP in India. It is also noticed that at temperatures <20 °C and >30 °C, the effluent limitations are violated from the standard values.

Simultaneous removal of nitrogen and phosphorous is a recommended practice while treating wastewater. In the present study, control strategies based on proportional-integral (PI), model predictive control (MPC), and fuzzy logic are developed and implemented on a plant-wide wastewater treatment plant. Four combinations of control frameworks are developed in order to reduce the operational cost and improve the effluent quality. As a working platform, a Benchmark simulation model (BSM2-P) is used. A default control framework with PI controllers is used to control nitrate and dissolved oxygen (DO) by manipulating the internal recycle and oxygen mass transfer coefficient (KLa). Hierarchical control topology is proposed in which a lower-level control framework with PI controllers is implemented to DO in the sixth reactor by regulating the KLa of the fifth, sixth, and seventh reactors, and fuzzy and MPC are used at the supervisory level. This supervisory level considers the ammonia in the last aerobic reactor as a feedback signal to alter the DO set-points. PI-fuzzy showed improved effluent quality by 21.1%, total phosphorus removal rate by 33.3% with an increase of operational cost, and a slight increase in the production rates of greenhouse gases. In all the control design frameworks, a trade-off is observed between operational cost and effluent quality.

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In every urban infrastructure, Wastewater Treatment Plant (WWTP) requires special attention because of its adverse effects on the environment and also for resource recovery. Therefore, there arises a need to treat the wastewater in order to meet the effluent norms prior to discharge. Different control strategies and various scenarios of plant layout can be tested and evaluated through modelling and simulation studies on the benchmark layouts. In this paper, a feedforward nested loop control structure based on ammonia concentration is implemented on Benchmark Simulation Model (BSM1-P) developed based on Activated Sludge Model No. 3 bioP (ASM3bioP) for controlling the dissolved oxygen in aerobic zones and nitrate level in anoxic zones and nutrient removal by adding two anaerobic zones. By using this control strategy, pumping energy, percentage violations of ammonia and nitrogen concentrations in the effluent, and effluent quality are reduced effectively.