Removal of suspended solids from dairy wastewater using flocculation

Dairy industries are considered as the most environmentally unfriendly processes, because they produce wastewater that contains suspended solids. The release of this water into aquatic bodies affects aquatic life and the water quality. This paper investigates coagulation and flocculation processes for the removal of suspended matter from the dairy wastewater. The jar tests were carried out using a polyamine salt coagulant which neutralizes the charge of the particles and polyacryamide flocculent that helps in building the size of the floc. The effective flocculant capacity of the flocculant was determined based on the final turbidity and the suspended solids removal of the wastewater. The capacity was also found as a function of the flocculent types, concentration and pH of the wastewater. A notable decrease in the suspended solids were observed. This was mainly because of the mechanism of electrical double layer formed on the solid surface. By the addition of cationic polyelectrolytes, it neutralises the particles on the outer layer and attracts particles in the inner layer. Thus it leads to the process of charge neutralisation and bridging of smaller floc molecules.