Ozonation pretreatment for ultrafiltration of the secondary effluent

摘要

In this study, the secondary effluent is used as raw water, the apparent molecular weight distribution (AMWD) of organic substances in water is changed with preozonization, and flat UF membrane (PVDF) is adopted to filtrate the raw water with different AMWD of organic substances, then the influence of AMWD of organic substances in water on membrane resistances is discussed. The results show preozonization can effectively improve the biodegradability of secondary effluent, AMWD of organic substances in water is different in different ozone contact time, AMWD of organic substances has great influence on membrane resistances, blocking and cake layer resistances have controlling force over fouling resistance, the relationship between AMWD of organic substances and membrane resistances is as follows (ⅰ) when d/φ < 2/15 (d: molecular weight of the organic substances in water, φ: membrane pore size), organic substances can easily permeate the membrane pore, while 2/15< d/φ<1/3, organic substances tend to be absorbed in the interior of membrane pore; (ⅱ) when 1/3< d/ φ < 1, organic substances mainly cause the interior membrane pore blocking, when 1< d/ φ < 5/3, organic substances mainly cause the block in membrane surface; (ⅲ) when d/φ > 1, especially d/φ > 5/3, organic substances are the main part forming membrane surface cake.