Chemically Enhanced Primary Treatment-Trickling Filter with iMoringa oleifera/i Seeds for Improved Energy Recovery from Wastewater Treatment Plants in Malawi

摘要

Only 10% of the population in Malawi has access to electricity and there is increasing surface water pollution especially in urban areas. This research was conducted with the objectives of improving electricity generation and reducing water pollution in Malawi. A chemically enhanced primary treatment-trickling filter (CEPT-TF) system with iMoringa oleifera/i (MO) seeds as a coagulant is proposed for municipal wastewater (WW) treatment to achieve both objectives. CEPT improves energy recovery by increasing the proportion of captured raw COD whose anaerobic digestion gives higher CHsub4/sub yield than secondary COD. The COD removal efficiency of MO was investigated by conducting jar tests and COD tests using WW samples from three different WWTPs in Suzhou New District, China. The amount of energy recoverable was estimated using an equation derived from COD removal efficiencies and the stoichiometric relationships between COD and CHsub4/sub. The results showed a COD removal efficiency of 74% with MO concentration of 50mg/l for 880mg/l COD which is an average COD for municipal WW in Malawi. It is found that the WWTPs in Malawi’s two big cities of Blantyre and Lilongwe have the potential of producing 9,781.86kWh/d of electricity. CEPT-TF will offer sustainable solutions in Malawi, MO can be planted on sites creating closed loop systems as it provides the coagulant and gets watered and nourished with the effluent from the WWTP.