Coupling ASM3 and ADM1 for wastewater treatment process optimisation and biogas production in a developing country: case-study Surat, India

The overall performance of the Anjana wastewater treatment plant (WWTP) located in Surat, India, was assessed by coupling the Activated Sludge Model No. 3 (ASM3) and the Anaerobic Digestion Model No. 1 (ADM1). Guidelines developed by the Dutch Foundation for Applied Water Research (STOWA) were successfully applied for the determination of wastewater characteristics. Concerning the fractionation of primary and secondary sludge, the approach proved to be adequate for the application of ADM1. A satisfactory description of the performance of the plant was obtained in terms of effluent quality, biogas generation and sludge production. This was achieved through coupling ASM3 with ADM1 and adjusting four default values (the growth of autotrophic bacteria from 1 to 0.46 day⁻¹, influent fraction of unbiodegradable particulate chemical oxygen demand (COD) to 0.14 gCOD/gCOD, and the anaerobic disintegration factors for soluble and particulate unbiodegradable COD in ADM1 to 0.01 and 0.29 gCOD/gCOD, respectively). The model was applied to optimise the plant performance and to assess the potential influence of the return of high strength reject effluents through the implementation of an ADM1-ASM3 interface. This study underlines the feasibility, advantages and benefits of mathematical modelling as a reliable tool for process optimisation, plant upgrade and resource recovery in developing countries.