An evaluation of biogas production from anaerobic digester of a constructed wetland domestic wastewater treatment plant

Abstract

Domestic wastewater treatment using constructed wetlands have been found to be very efficient and cost effective. Primary treatment facilities such as anaerobic digesters have been reported to reduce the organic load of wastewater before entering the constructed wetland systems. It has also been established that biogas is a product of organic matter decomposition under anaerobic condition. In this study, we evaluated quantity of biogas produced from the anaerobic digester of a constructed wetland domestic wastewater treatment plant. After a period of 148 days (15th September, 2015 to 8th February, 2016), the mean of the percentages of methane (CH₄), Carbon dioxide (CO₂), Hydrogen Sulphide (H₂S) and Carbon monoxide (CO) were 60.97±8.38, 33.93±6.31, 1.03±4.45 and 0.25±2.11% respectively. The average rate of production of biogas was found to be 641.83±88.26 m³/day. The study concludes that anaerobic digester pre-treatments do not only assist in reducing organic load for the efficient performance of the constructed wetland but can also serve the purpose of biogas production. It is recommended that further works be carried out to determine the potential of energy recoverable from the anaerobic digester.

Key words: Anaerobic digester, biogas, constructed wetland, domestic sewage, renewable energy.