Performance Evaluation of Coagulants for Water Treatment in Emergency

Abstract

Natural disasters frequency has increased over the past decades. These disasters lead to substantial loss of life and property and render the affected population homeless many times with little or no resources for survival. The short-term effects of the disasters can last for 1–2 weeks, but the long-term effects can last for months. Water is one of the most important requirements for survival in case of a disaster. For the people to survive, they urgently need food and water. Drinking water and water for general use like washing, cooking and maintaining hygiene are essential for the survival. Under normal circumstances water requirement may be more, but in case of emergency, certain minimum amount of water is required for every individual. Availability of adequate quantity of water is crucial for survival, to maintain adequate hygiene and to avoid ill health. Coagulation is one of the most widely used treatment process for removal of suspended solids. Batch coagulation-based water treatment system like the Oxfam up-flow clarifier has been used by relief organizations on various occasions for emergency treatment. In this study the performance of commercially available chemical coagulants, poly-aluminium chloride (PAC), alum (Aluminum Potassium Sulfate) and natural coagulant, Strychmos Potatorum was studied. These coagulants were studied for their effectiveness in treatment of highly turbid water. The effective optimum dosage of PAC was 10–20 mg/L, alum was 70–80 mg/L and Strychnos Potatorum was 30 mg/Lfor treatment of water under different turbidity ranges under laboratory conditions. PAC was found to be the best coagulant among the three studied. PAC effectively reduced the turbidity of raw water by 99% and was found to be best suited for use for emergency water treatment.