Nature-based wastewater treatment systems for schools (Zimbabwe)

To evaluate waste water management practices, a case study was undertaken at a boarding school in Goromonzi District. The existing treatment system consisted of a septic tank and wastewater stabilisation ponds. Key informant interviews were employed and wastewater samples were collected from the upstream point of the boarding school, the raw wastewater and at every inlet and outlet of the existing wastewater treatment system. The parameters used to evaluate the prototype were pH, TP, TN, BOD, COD, TSS, TDS, Conductivity, Total Coliform, E. coli, ESBL E. Coli and Salmonella. Nature-based wastewater treatment systems were considered better suited to boarding institutions in Zimbabwe because of their lower capital and maintenance cost. After a variety of options analysis, the selected configuration comprised a septic tank, constructed wetland and vermi-filter in that order which had a score of 81%. Option analysis was based on the technical, economic, environmental and social performance. The raw wastewater was monitored from August 2022 to November 2022 and the results in were used to design and develop a prototype. The prototype displayed better results as compared to the existing treatment system. It was concluded that in order to reduce environmental pollution from this institution, increasing school enrolment should correspond to expanding the potable and wastewater facilities.