Enhanced Coagulation with Membrane System in Removing Dissolved Organic Matter

Safety drinking water has been an issue in Kin-men for a long term. Because the Tai-lake was polluted, the water plan can’t remove the dissolved organic matter (DOM) successfully. According to the result of investigation, the TOC in Tai-lake is 13~16 mg / L and the average TOC after the rapid filter are 13.5 mg / L in 2013 and 9.49 mg / L in 2014, and treated after slow sand filter are 11.21 mg / L in 2013 and 7.78 mg / L in 2014. It is obviously to see that the filtration units are unable to remove DOM. In my research, I will use powdered activated carbon(PAC) with enhanced coagulation and combine ceramic membrane to build a treatment process, in order to elevate the removal of DOM. By analyzing TOC and UV to determine the best of three kinds of coagulants ( alum, poly aluminum chloride(PACl), ferric chloride) and the adsorption time for powdered activated carbon. Controlling flux when using ceramic membrane to filtrate and observe the change of trans-membrane pressure ( TMP ) and permeability.
From the experiment results, PACl has the best performance in removing DOM, the optimum dosage is 200 mg / L. The adsorption time of PAC is 30 min. By using PAC 150 mg / L with PACl 200 mg / L can successfully eliminate the TOC down to 4 mg / L to meet the standard. In the ceramic membrane system , the flux is 97.5 LMH, the TMP increase 10 kPa and permeability decrease from 8 to 5.4 LMH / kPa for filtrating 160 min. Enhanced chemical backwash is better than back wash in removing membrane fouling.