Modelling and simulation of full-scale Sequential Batch Reactor (SBR) biological process operation using GPS-X

Abstract

Sequencing Batch Reactors (SBR) have become a popular wastewater treatment technology and are now used widely for the removal of nitrogen and carbon compounds from reject water (i.e. water from sludge dewatering process) and high-strength industrial wastewater. SBR is a fill-and-draw wastewater treatment system where the biological activities are identical to the conventional activated sludge process. The two different biological processes in SBR are the nitrification and denitrification process which takes place within one reactor. The reject water at the municipal wastewater treatment plant in Porsgrunn, Norway, contains 2500 mg/L of total chemical oxygen demand (COD) and 600 mg/L ammonium nitrogen (NH4-N) concentration which cause disturbances in the treatment process when it is mixed with the receiving wastewater. Hence, the wastewater treatment plant recently upgraded with two similar SBRs operating in 24-hour cycles with a working volume of 115 m3 and 100.4 m3, respectively. Modelling and simulation of the simultaneous nitrification/denitrification (SND) process using key control parameters, such as dissolved oxygen (DO), alkalinity and pH, helps to understand more about the processes as well as to monitor and regulate plant operations efficiently. The objective of this research was to model and simulate the nitrification-denitrification process in these SBRs with simple and advanced cycle settings using GPS-X tool, a modelling and simulation software designed for planning and optimizing both new and upgraded municipal and industrial wastewater treatment plants. The complete treatment process in the plant was modelled integrating the in-built SBR model in GPS-X. The built model was simulated with key inputs parameters such as inflow rate, total carbon, total nitrogen, and aeration. In conclusion, the GPS-X model helps to understand the biological process in the SBR reactor which enables to improve the process efficiency by adjusting the different operating parameters.