Process Safety and Environmental Protection, Vol.92, No.6, 815-821, 2014
A cost effective method for decentralized sewage treatment
The aim of this research was to upgrade the performance of a conventional septic tank (CST) for on-site treatment of sewage with negligible costs. Although CST is known as an inexpensive pre-treatment system, a complementary treatment is required to reuse its output effluent. In this work, the quality of treated wastewater reached to the standard level for irrigation by the innovational changes made in the structure of CST for converting it into an advanced septic reactor (ASR). The modification consists adding some pipe and trays without using any mechanical or electrical equipment. ASR was operated at ambient temperatures in laboratory and pilot-scale. The effects of up-flow velocities (V-up) of 0.4, 0.5, 0.7, 1 and 1.5 m/h and hydraulic retention times (HRT) of 36, 24 and 12 h on the ASR treatment performance were studied. For optimum V-up of 1 m/h and HRT of 24 h and biomass specific methanogenic activity (SMA) of 0.31 mg COD/gVSS d the maximum removal of chemical oxygen demand (COD), biochemical oxygen demand (SODS) and total suspended solids (TSS) were 86.2%, 79.4% and 95%, respectively. The results showed that ASR is an appropriate alternative for CST for sewage on-site treatment by a low cost modification. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Keywords:Decentralized treatment;Anaerobic treatment;Advanced septic reactor;Wastewater treatment;Economy and reuse