Aqua (Sep 2021)
Variation of Al species during water treatment: correlation with treatment efficiency under varied hydraulic conditions
Abstract
The concentration of hydrolyzed coagulant ion species is a key factor in determining drinking water treatment efficiency. Direct correlation of water treatment efficiency with changes in species during coagulation has not been addressed. We investigated the correlation under different hydraulic conditions and water treatment efficiencies including changes in removal of turbidity, ultraviolet adsorption at 254 nm (UV254) and dissolved organic carbon (DOC). Results highlighted that Al species (monomeric species as Ala, medium polymeric species as Alb and colloidal species as Alc) behaved differently during coagulation and treatment efficiencies were affected. When varying the mixing speed, the removal of Alc species had a strong negative correlation with water treatment efficiency but under other hydraulic conditions positive correlations were found. The removal of Ala species was positively correlated with water treatment efficiency, but under other hydraulic conditions the low abundance of Ala species meant the correlation was difficult to observe. The Alb species were significantly and positively correlated with water treatment efficiency with the highest correlation coefficient (R2) of 0.87. The correlation of metallic species with removal efficiencies of the DOC and the UV254 produced higher R2 values. Correlation of the rate of removal of Alb species with the removal efficiencies of the DOC or the UV254 was better than for Alc. HIGHLIGHTS Hydrolyzed coagulant ion species is considered as one of key factors in determining drinking water treatment efficiency.; Drinking water treatment efficiency is often correlated with the distribution species in coagulant rather than water.; The variation of the species removal was investigated in the coagulation system.; Under varied hydraulic conditions a positive response in correlation was presented.;
Keywords
