Performance investigation of the slaughterhouse wastewater treatment facility: a case of Mwanza city slaughterhouse, Tanzania

Abstract

The present study engaged onsite operations and laboratory analysis for Mwanza City Slaughterhouse (MCS) wastewater to improve the efficiency of wastewater treatment of a newly installed facility. The MCS wastewater treatment facility integrated with various unitsbiodigester

(Batch Stirred Tank Bio-reactor), aeration unit, retention, clarifier, and a constructed wetland. During the initial runs, the MCS facility removed 87.5%, 92.2%, 43%, and 65.4% of effluent biochemical oxygen demand (BOD 5 ), chemical oxygen demand (COD), ammonium, and nitrate, respectively. Also, the parameters including pH, temperature, dissolved oxygen (DO) were used to control the system operations. After conducting effective plant operations for five months, the removal efficiencies of BOD 5 , COD, ammonium, and nitrate improved to 97.4%, 98.3%, 97.4%, and 97.6%. In the present study, the unit-by-unit performance values achieved as a result of alterations of the facility‟s running conditions presented. The MCS wastewater treatment facility found to be energy-positive, as it produced an average of 158.2 m 3 biogas per day. This amount of biogas, if converted to electricity, would be sufficient to run the facility operations. Generally, the MCS wastewater treatment facility attained the best performance as per design, achieving the effluent levels recommended by the Tanzania Standards (TZS). Also, the MCS treatment facility takes care of the environment and human health because of effluents released to the surrounding area are now within recommended standards.