Process selection and design of Bishmizzine wastewater treatment plant

Abstract

Bichmizine Municipality has agreed to treat the domestic wastewater generated from Kfarhazir village that still pass through a channel without any treatment. So it is required to construct a Wastewater Treatment Plant (WWTP) with sufficient capacity to treat this increased sewage. The project takes into consideration all aspects of Kfarhazir and its population growth rate for the next 25 years, as well as the proposed available land that has an area of 438 m 2 while designing the facility. By the execution of the project the entire wastewater of the village will be treated effectively. Decentralized aerobic wastewater treatment was considered in this study since Kfarhazir village is a small community and it is not connected to the planned WWTP for the Koura region. Different small WWTP systems such as: extended aeration (EA), sequence batch reactor (SBR), membrane bio reactor (MBR) and moving bed biofilm reactor (MBBR) were studied and the best selection was the use of the MBBR based on the weighted matrix score analysis. The Bishmizzine WWTP is designed to treat 637 m3 /day. This flow is the estimated daily wastewater flow for the year 2038. Moreover, the WWTP Effluent quality should meet the standards of wastewater reuse for crops irrigation set by the Environmental Protecting Agency (EPA). The WWTP consists of preliminary, secondary, tertiary, disinfection, and sludge treatment processes. The preliminary treatment system contains: screens, grit chamber and equalization tank; the secondary treatment contains: post-anoxic tank, aerobic tank (MBBR unit), Clarifier and chemical injection for phosphorus removal; Tertiary treatment contains: multimedia sand and carbon filters; Disinfection consist of chlorine contact tank while the last system is the sludge treatment and consist of sludge aerobic digester. After designing the WWTP, the GPS-X software version 6.1.1 is used to confirm calculation, optimize the wastewater treatment capacity and investigate the overall plant performance by running four different steady state scenarios. The activated sludge model (ASM2d) was used for biological processes and the biochemical oxygen demand (BOD) based influent model was used for influent characterization. After the GPS-X confirmation on the design, the Piping and Instrumentation Diagram (P&ID) and the lay-out of the plant was drawn by using AutoCAD 2011 software for detail dimensions and process operation.