Chiang Mai Journal of Science

In the present study, the greywater from the hostel was characterized and treated using the natural coagulation and a hybrid electrocoagulation process. The effects of coagulants and its dosage, i.e. natural (Moringa oleifera and Strychnos potatorum), and synthetic (Alum) in treatment of greywater were compared. Furthermore, the greywater was treated in a hybrid electrocoagulation system and the effluent quality was compared with reusable standards. The greywater collected from the hostel was characterized for various physicochemical parameters: found that pH was 5.76-8.74, turbidity was 185-322 NTU, chemical oxygen demand was 100-500 mg/L, total solids was 1800-2857 mg/L, and the bacterial count was 61000 – 98000 CFU/ 100 mL. In the study, it was observed that Strychnos potatorum seed powder showed an optimal removal with 100 mg/L of coagulant turbidity reduced to 124 NTU. In the hybrid reactor system, the greywater was found to be more effectively treated. The treated water after electrocoagulation – electroflotation (EC-EF) reactor showed turbidity of 1-2 NTU, total solids of 48-54 mg/L, bacterial count of 1-2 CFU/ 100 mL. The greywater was treated effectively in the reactor with 92% removal of hardness, 96% removal of turbidity, 98% removal in the total solids and 5 log reductions in the bacterial count. Therefore, the hybrid system showed better removal efficiency in treating the greywater and can be reused for non-potable applications.