Development and evaluation of treatment options for recycling ablution greywater

This study aimed to develop and evaluate five simplified AGW treatment options with or without low-cost ceramic filters, including direct ceramic filtration, alum coagulation–sedimentation, alum coagulation–sedimentation–ceramic filtration, alum coagulation–sedimentation–activated carbon, adsorption–sedimentation, and ceramic filtration–activated carbon adsorption–sedimentation. In raw AGW, concentrations of turbidity (14.8 NTU), TSS (24 mg/L), COD (63.2 mg/L), BOD (37.0 mg/L), and fecal coliform (884 MPN/100 mL) exceeded the greywater reuse standards for unrestricted irrigation, toilet flushing, and firefighting. In laboratory experiments, first three treatment options produced almost similar effluent with residual turbidity 1.5 NTU, COD 35 mg/L, and BOD 20 mg/L. Addition of the activated carbon to the last two treatment options enhanced the BOD and COD removals (< 12 mg/L). Multicriteria decision-making was performed to evaluate all the AGW treatment options against effluent water quality, treatment cost, land requirements, and need of skilled operators. Criteria weights were estimated using Entropy method, while the technique for order preference by similarity to ideal solution was used to final ranking of AGW treatment options. Results found direct filtration as the most feasible option to reuse AGW for restricted irrigation, and for unrestricted irrigation, toilet flushing, and firefighting, the ceramic filtration–activated carbon adsorption–sedimentation treatment process would be the more feasible option.