Coagulation / flocculation - ceramic membrane filtration for removal of natural organic matter (NOM) under Norwegian conditions

Coagulation / flocculation using two different coagulants based on polyaluminium chloride (PAX-18) and iron chloride (PIX-111) was applied as pre-treatment for microfiltration with an inside out dead-end ceramic membrane for the removal of natural organic matter (NOM). The influence of coagulant dose and pH value were investigated. The applied treatment process combination is an efficient possibility for the removal of colour and DOC from surface water with high NOM concentrations. The removal strongly depended on the pH and coagulant dose. At lower pH values, the DOC removal was higher due to a better formation of polyhydroxocomplexes. However, an increase in residual metal concentrations at lower pH values has to be taken into account when defining the optimal operating conditions.