Microbiological Reduction Strategy of Treated Wastewater for Safe Vegetable Production in Accra, Ghana

The reuse of wastewater comes with the risk of exposure to pathogens. As part of the goals of the Wideruptake Project aimed at promoting the safe reuse of wastewater in Accra, Ghana, the effectiveness of a combination of storage tanks and shallow reservoirs imitating the performance of anaerobic reactors and algal-based maturation ponds was assessed. Stored treated wastewater received from a treatment plant (of SSGL Ltd) located 10 km away, were monitored over the dry and rainy seasons and the microbial and parasitological quality of vegetables irrigated with this water were also determined using the membrane filtration technique. Results showed that treated wastewater from SSGL exhibited relatively good quality, with E. coli concentrations ranging from 0 to 2.8 log units. The storage anaerobic polytanks and the shallow reservoir showed E. coli concentrations of 0–2.5 log units and 0–1.3 log units respectively. In comparison, the drain or culvert which receives runoff exhibited higher E. coli concentrations ranging from 2.6 to 3.7 log units, while Vibrio concentrations were 0–1.4 log units. The bacteriological quality of the reservoir effluent met the EU guidelines of <10 cfu/100mL. All the vegetables were of good quality showing E. coli concentrations of <1 log unit and devoid of intestinal parasites. The study underscores the effectiveness of the improvised combined wastewater storage systems as an effective option for urban and peri-urban farmers for ensuring the safe irrigation of vegetables.