Novel helical or coiled flocculator for turbidity reduction in drinking water treatment: a performance study

Abstract

Helical or spiral coiled flocculator have not been applied in drinking water treatment yet in Indonesia. Only a few articles discussed it with different themes like hydrodynamic, floc characteristics, and performance. This study was done to know the efficiency (performance) of helical flocculator with parameters velocity gradient, pipe, helical diameter, flowrate, detention time, and coagulant dose. The study was divided into two steps: Jar test to determine the optimum dosage of coagulant and flocculation experiments to evaluate the helical flocculator efficiency. Efficiencies were in the range of medium to high. On flowrate, 13 ml/second was obtained good results for two pipe sizes but different in helical diameters. In a 0.5 inch pipe with 0.8 m helical diameters, the turbidity reduction efficiencies were 72.4% and 73.9%, and sediment volume was 18.3 ml and 20.0 ml. In a 0.625 inch pipe with 0.4 m helical diameters, the turbidity reduction efficiencies were 76.7% and 78.5%, and sediment volume was 14.3 ml and 19.7 ml. The optimum velocity gradient about 64.9–69.6 per second, and detention time about 438–649 seconds. The results showed that helical flocculator was effective for floc formation. Flowrate, pipe diameter, helical diameter were three key parameters to perform helical flocculator.