Study Of The Influence On Ozone Oxidation On Molecular Distribution Of Secondary Effluent And Membrane Resistance

To recycle wastewater was a hot point in the field of water treatment, because that membrane separation techniques have the following virtues: low energy consumption, simple operation, good water quality, and stability, etc. Attention was increasingly paid to it. However, membrane fouling and blocking were still the main factors to limit the universal application of membrane separation techniques. This paper discussed the molecular distribution of organic matter in the secondary effluent from waster water treatment plant with biological treatment and the dynamic process of the reaction of ozone with organic matter within the secondary effluent. Moreover, discussed the influence of different molecular distribution of organic matter which was caused by the pretreatment of ozonation on the resistance of ultrafiltration membrane. The results showed that:(1) the molecular distribution of organic matter in the secondary effluent was a "double peak" one, organic matter with bigger molecular occupied a smaller percentage and a larger spreading range, instead, organic matter with smaller molecular was primarily one which less than <4kDa, whereas the distribution of unsaturated organic matter was more complicated and no apparent regularity.(2) ozone oxidation of organic matter within secondary effluent contained three phases, each of which is first order reaction, and it is appropriate to discriminate them through TOC as indicator. The duration of the three phases are 0~2min 2~20min and >20min respectively. So the dynamic equation of ozone oxidation secondary effluent can be gotten:(3)the relationship between different molecular distribution and the resistance of different part of ultrafiltration membrane was as follows: (1)when 1/3 d/φ >15 (d the molecular size of the organic matter in water ; φ: membrane pore size), the organic matter was inclined to cause adsorption in the surface of membrane pore,while d /φ < 2/15, the organic matter could permeate through the membrane pore easily; (2)when 1 > d/φ > 1/3, the organic matter mainly lead to the block of the surface of membrane and of pores as well, when 5/3 > d /φ> 1, the organic matter mainly caused the block of the surface; (3)when d / φ >1, especially d / φ >5/3, he organic matter (including soluble and particular substance) will be the main parts of the cake.