Suppression of performance of activated carbon filter due to residual aluminum accumulation

Extending the lifetime of granular activated carbon (GAC) filters with no significant loss in their effectiveness is a considerable challenge for drinking water supply utilities. However, the effects of residual Al from coagulants on GAC performance are rarely considered. Herein, in-service GAC samples obtained from full-scale water treatment plants were investigated to evaluate the amount of accumulated Al. Although the Al concentration in water was two to three times lower than the Ca concentration, Al exhibited considerable accumulation (second to Ca accumulation) in in-service GAC samples (0.68-8.63 mg g(-1)). Surface characterization results indicated that Al accumulation could have been caused by the co-precipitation of Al with Ca and Si to form Ca4Al2Si3O10 center dot H2O and Ca4Al6O12SO4, self-precipitation or complexion with OH/COOH on the GAC or biofilm surfaces. Correlation analysis of the accumulated Al and GAC properties implied that Al accumulation considerably reduced the surface area of GAC by similar to 30%. Lab simulation experiments indicated that the removal of dissolved organic matter was reduced by 6-10% when additional Al was loaded. In addition, results showed that the residual Al (up to 200 mu g L-1) considerably affected the extracellular polymeric substance component and microorganism

Automated summary

Residual aluminum from coagulants has a significant impact on the performance of granular activated carbon (GAC) filters, leading to aluminum accumulation and reduced surface area of GAC, thereby affecting the removal of dissolved organic matter.