Assessment of efficiency of a decentralized wastewater treatment plant at Mzuzu University, Mzuzu, Malawi

Abstract

Limited wastewater treatment contributes to water quality degradation of water bodies in Malawi, Lunyangwa River (LR) in Mzuzu is no exceptional. There is lack of comprehensive and regular monitoring of wastewater treatment plants and surface water quality in Malawi mainly due to inadequate funding and laboratory facilities. This study assessed overall performance of Mzuzu University Wastewater Treatment Plant (MUWWTP) and its impacts on receiving waters namely the Luwinga stream (LS) that drains into LR. Representative duplicate grab samples (n = 40) were collected from eight sampling points from the treatment stagess of MUWWTP, upstream (control) and downstream of LS in five sampling campaigns from January to April 2019. Onsite tests were carried out for pH, temperature, Electrical Conductivity (EC), and Dissolved Oxygen (DO), whereas Total Suspended Solids (TSS), Total Solids (TS), Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Nitrate (NO3−), Ammonium (NH4+), and Total Phosphorus (TP) were analyzed at the Government Central Water Laboratory in accordance with the American Public Health Association (APHA) Standards of 2014. Except pH (9.39), the rest of the parameters were within Malawi Effluent Standards (MS691:2005) and Environmental Protection Agency (EPA) Effluent Guidelines of 2014TDS (118.8 mg/L); DO (6.57 mg/L); TSS (18 mg/L); BOD5 (4.5 mg/L); COD (51.4 mg/L); NO3− (0.01 mg/L); TP (0.11 mg/L) and NH4+ (0.003 mg/L). Furthermore, MUWWTP effluent did not impact stream water quality as evidenced by the recommended scores with respect to surface water quality regulation and Water Quality Index. There is need to regularly monitor effluent and stream water quality.