Drinking water treatment through Optimising Phosphate Coagulation collected from four villages in Srikakulam, India: a Response Surface Methodology approach

Abstract

ABSTRACT The drinking water quality is highly affected by industrialisation and by natural geographical features of the region. This work highlights on the quality survey and treatment of drinking water collected from four villages (Kalyanipeta, Kesavadasupuram, Arinam Akkivalasa, and Chilakapalem) near Nagarjuna Agrichem Limited in Srikakulam district, Andhra Pradesh. Physicochemical parameters of the samples were analysed. The presence of phosphates in the samples (3.15 mg/L P) were found to be above the permissible limits (1 mg/L P) which required instant treatment by coagulation process. Various influencing factors like temperature, dosage, mixing speed, and mixing time were considered for optimization of the process. The statistical experimental design was done using central composite approach of response surface methodology to optimise phosphate removal via coagulation and flocculation technique. An optimised removal of phosphates was determined to be 79.5% and 76.06% at a temperature of 27°C and 28°C, dosage of 13.412 and 14.906 mg/L, mixing speed of 91 and 78 rpm, and mixing time of 14.25 and 11.62 min for coagulants ferric chloride and aluminium sulphate respectively. Ferric chloride was found to be a better coagulant with a removal efficiency of 79.5% and the treated water contained 0.645 mg/L of phosphate.