Keywords: algae removal, coagulation, drinking water, PAC dosing, potable water treatment, powdered activated carbon, prechlorination, water quality
Optimal strategy for algae control in potable water treatment facilities
This paper presents both a current review of the state-of-the-art in algae removal, and an experimental study of algae removal in potable water supply. Established techniques were investigated by jar-testing on surface raw water samples derived from a lowland river, with the dominant species of algae being Scenedesmus sp (a green algae). These tests were conducted both in isolation and in combination to determine the optimum operational strategy for an actual water treatment facility. Employing 1 mg/L of Cu2SO4 could remove algae by up to 50.6%, though this might lead to the release of algal toxin. The most effective single technique was PAC addition, which could reduce the algae population by up to 97.6%, although doses above 30 mg/L created turbidity. The maximum reduction ratio achieved with polyaluminium chloride in the absence of pH control was 79.1%, employing a dosage of 14 mg/L; careful pH control during addition of poly-AlCl3 coagulant increased algae removal by up to 35%.