Polyaluminium chloride coagulation in drinking water treatment

Abstract

Dissolved organic matter, DOC [mg C/L], is a representative parameter for the content of organic matter in natural waters. Along the A254 absorbance as a measure or organic compounds determined at λ = 254 nm UV [cm-1], DOC underlies the calculation of SUVA (Specific Ultraviolet Absorbance) = A254/DOC x 100 [L m-1 mg-1]. SUVA can be used to describe the composition of the water in terms of hydrophobic/hydrophilic character. The study results are presented in the coagulation process with pre-hydrolyzed aluminum salt, as a polyaluminum chloride (PACl), a simple salt of Al, as an Al sulfate (Alum), applied to surface water intended for drinking water. From SUVA values DOC removal efficiency in the coagulation process is estimated. SUVA= 2-4 estimated efficiency of 25-50% removal in DOC. When using PACl, DOC removal efficiency is within the range of 27-53%, and slightly lower when using Alum. SUVA values < 2 indicate DOC removal efficiencies < 25%. DOC removal efficiencies obtained from the use of Alum are within the range 5.6- 8.4% and those obtained used as ciagulation agent PACl are in the range 20.8-23.8%.