Impact of Temperature and Coagulants on Sludge Dewaterability

Abstract

Temperature and coagulant types have an important impact on the quantity and quality of the residue (sludge) in water and wastewater treatment processes. Temperature influences water viscosity and the distribution of the coagulant in water. Coagulants can promote the agglomeration of fine particles into larger flocs so that they can be more easily separated from the water. Experiments have been conducted to explore the relationship between temperature (16-26°C), the type of coagulant, and sludge dewaterability (estimated using the capillary suction time (CST)). Alum, Ferric, and Moringa oleifera Lam were used as coagulants. The influences of different mixer shapes, turbidity values, and flocs sizes on sludge dewaterability have been assessed. The results show that ferric chloride was unaffected by temperature, whereas alum and M. oleifera performances were influenced by temperature. CST results using the coagulant ferric chloride, regardless of mixer shape, turbidity, and floc size, were insensitive to temperature differences.

Keywords

• capillary suction time
• coagulants
• floc sizes
• sludge dewaterability
• temperatures.