Development of a simple and low-cost method for the elimination of indicator bacteria from domestic wastewater discharges to the Huacapa River in Guerrero, Mexico

Fecal material is one of the principal components in domestic wastewater (DWW). In this sense, Escherichia coli is a recognized indicator of fecal pollution due to its low-cost monitoring in DWW. Moreover, DWW are a pathogen reservoir that become a health hazard when its discharges are poured to water bodies without treatment. In this study, a simple and low-cost method was developed to functionalize the leaves (LC), peel (PC), and seeds (SC) of Moringa oleifera (MO), with an saline extract (NaCl 0.35 M), to obtain coagulants capable to reduce the presence of bacteria indicating fecal contamination and other pollution indicators in Guerrero, Mexico. The optimal doses were determined with a surface response using Sigma Plot® 8.10 software through a factor design of mixed levels. The optimal conditions for the reduction of the microbiological and physicochemical parameters were PC and SC, with concentrations of 70 g/l of the grinded material used to prepare the MO-coagulants, with doses of 1 and 6 mL, respectively, evaluated for the pollutant’s removal in the wastewater samples. The results showed the removal of fecal coliforms (99.3%), E. coli (92%), nitrates (47.9%), total dissolved solids (63%), turbidity (90%) and a dissolved oxygen concentration (DO) of 7.1 g/l in the treated wastewater. The developed method, using MO, is a simple and efficient tool for the reduction of bacteria indicating fecal contamination and other pollution indicators present in DWW.