Physical Abrasion Of Ultrafiltation Membrane By Powdered Activated Carbon And The Performance Of The Hybrid Process

Under the condition that water pollution cannot be rapidly improved and thatnational drinking water standard becomes increasingly stringent, the conventionalprocess has been difficult to meet current drinking water treatment requirements.Ultrafiltration, which is a key technology of enhanced drinking water treatment, hasbegun to be applied to large-scale waterworks in our country. However, two born defectsof UF tecnology, membrane fouling and low efficiency in retaining organics, become thegreatest obstacle to the promotion of UF in water purification area. The powderedactivated carbon adsorption, which can effectively retain small organic molecules, can beformed with ultrafiltration complementary. Thus, they have been widely studied andapplied. However, powdered activated carbon membrane itself whether there is pHysicalwear as well as its effect on membrane fouling has not yet formed a conclusion. Thispaper focuses on the pHysical damage of powdered activated carbon on ultrafiltrationmembrane surface, water purification performance of the combined process andmembrane fouling.First of all, an ultrafiltration membrane pHysical damage assessment method basedpressure decline was created. It was demonstrate through experiments that the pressuredecay method could be used to evaluate micron membrane damage, with strongsensitivity. Moreover, the initial pressure is not significantly affected. While anothermehtod based on water quality was also established to investigate ultrafiltrationmembrane pHysical damage, using water indexs such as turbidity, UV254, DOC and thetotal count of bacteria. It was found that water turbidity and total number of bacteria werevery sensitive to the ultrafiltration membrane damage, while that UV254and DOC wasnot sensitive enough and could only served as auxiliary index. Pressure decline and waterquality-based UF membrane pHysical damage evaluation method was used tosystematically analyze the long scratch damage of membrane by powdered activatedcarbon. It was found that powdered activated carbon and ultrafiltration contact with eachother would not cause pHysical damage in the contact time of0-30d and the aerationintensity of0-10L/min.Then, this detailed study of powdered activated carbon adsorption and ultrafiltrationcombined process treating Songhua River water was performed. Powdered activatedcarbon adsorption parameter optimization results show that powdered activated carbonwas the key measures to controll the organic content in Songhua River water. Whentreating winter Songhua River raw water with powdered activated carbon, the mostappropriate contact reaction time was about3-5min, and the optimal dose was between20-30mg/L. Long run results showed that combined process could control effluent turbidity less than0.1NTU wiht removal efficiency above98%under the powderedactivated carbon dosage30mg/L. The s CODMNand UV254removal rates of thecombined proces were increased by an average11%-19%and18%-23%percentage,repectively. Powdered Activated Carbon displayed no significant effect on removingmicroorganisms by UF with the total number of bacteria in the treated water between0-3CFU. However, due to bacteria breed in water tanks and water lines, small amounts ofbacteria was detect in treated water after by UF membrane.Membrane fouling formation mechanism consisted of membrane pore narrowing,membrane pore clogging, blockage and cake layer formation. Membrane pore narrowingand pore blockage were generally caused by the organic pollutants, while cake layerwasmainly composed of colloidal blocking material, particulate matter accumulated onthe membrane surface. Powdered activated carbon adsorption ultrafiltration pretreatmentprocess could make the critical flux Songhua River water increase from the10-13L/(m2h) to20-28L/(m2h). Aeration, filtration and pretreatment on ultrafiltration membranetreatment Songhua River water pollution greater impact by optimizing aeration, filtrationand pre-treatment can effectively reduce membrane fouling during ultrafiltration.Ultrafiltration processes to achieve sustainable and stable operation. Dosage of25mg/Lpowdered activated carbon, ultrafiltration membrane water purification treatment aftersettling, the "fouling" level was lower than when not adding powdered carbon pollutionlevels. Laboratory tests in the course of its process of operating results good and stable.Under the same conditions, no powdered activated carbon dosing ultrafiltrationmembrane, a membrane fouling pHenomenon earlily occurred and pollution was veryserious.