Treatment of dairy wastewater by inorganic coagulants: Parametric and disposal studies

Present study reports treatment of simulated dairy wastewater (SDW) by inorganic coagulants such as poly aluminum chloride (PAC), ferrous sulphate (FeSO4) and potash alum (KAl(SO4)2·12H2O). Batch coagulation experiments were conducted to evaluate the influence of initial pH (pHi: 5–10) and coagulant dosage (m: 100–5000 mg/L) on chemical oxygen demand (COD) removal from SDW. Residual COD and system pH were observed as function of time. Optimum pHi (pHi,op) was found to be 8.0 for all the three coagulants. Optimum m (mop) was found to be 300, 800 and 500 mg/L for PAC, FeSO4 and KAl(SO4)2·12H2O, respectively, giving 69.2, 66.5 and 63.8% COD removal efficiency in 30 min. Heating values of the sludge generated by the coagulants PAC, FeSO4 and KAl(SO4)2·12H2O were found to be 20.7, 29.6 and 17.3 MJ/kg, respectively.