Exploring Nature-Based Wastewater Treatment Systems for Ipmproving Waste Water Effluent Quality from Goromonzi Boarding School, Mashonaland East Province, Zimbabwe

Abstract

Due to wastewater treatment efficiencies at Goromonzi Boarding School in Mashonaland East Province a modification of treatment system was proposed. In this paper, experimental research methods were employed to assess the average raw wastewater characteristics and prototype effluent quality. Raw wastewater quality was tested for pH, Total Phosphates, TN, BOD, COD, E. Coli and %ESBL E. Coli and the results were 8.14, 0.82 mg/L, 110.21 mg/L, 220.20 mg/L, 720.00 mg/L, 20,000 CFU/100ml and 50% respectively. These results informed development of the prototype which followed the engineering design process. Possible options were analyzed and the best option configuration comprised a septic tank, constructed wetland and vermifilter in that order with a score of 80.92%. Option analysis was based on the technical, economic, environmental and social criteria. The prototype had a hydraulic retention time for the septic tank and constructed wetland of 2 days respectively and 8 hours for the vermifilter. Final effluent from the prototype was tested for pH, Total Phosphates, TN, BOD, COD, E. Coli, %ESBL E.Coli and the results were 7.49, 0.40mg/L, 8.48mg/L, 9.30mg/L, 10.66mg/L, 3CFU/100ml and 0.13% respectively. The prototype produced better (complied with SI6 0f 2007 Green Band) results as compared to the existing treatment system.

Keywords: Wastewater, Treatment, Prototype, Vermifilter, Constructed Wetland, Septic Tank