Evaluation of Occurrence, Concentration, and Removal of Pathogenic Parasites and Fecal Coliforms in Three Waste Stabilization Pond Systems in Tanzania

Urban Farm DB summary

This cross-sectional study, conducted from February to August 2018, evaluated three waste stabilization ponds (WSPs) in the Morogoro, Mwanza and Iringa regions of Tanzania, where treated effluent is used for urban agricultural activities despite the disease-transmission risks posed by untreated or partially treated wastewater. Using APHA physicochemical methods, the modified Bailenger method and Ziehl-Neelsen staining for parasites, and membrane filtration for fecal coliforms (FC), analyzed with SPSS version 20, the study found helminth egg removal ranging from 80.8% to 100% and protozoan (oo)cyst removal from 98.8% to 99.9%, with the Mwanza WSP showing the highest FC reduction (3.8 log units per 100 mL). Both parasites and FCs in the effluents of the assessed WSPs were found at concentrations exceeding World Health Organization and Tanzania Bureau of Standards limits, except for helminths in the Morogoro WSP and FCs in the Mwanza WSP. FC counts correlated significantly with protozoa (p<0.01) and predicted protozoa occurrence well (p=0.011), with correlations also found among physicochemical parameters, parasites and FC bacteria. The study attributes the systems' inadequate performance to a lack of regular maintenance and/or operation beyond capacity, and concludes that FC indicators are a reasonable proxy for monitoring protozoa but not for helminths, which should be surveyed independently.