紫外/氯氧化预处理对超滤膜污染的控制研究

Effect of UV/Chlorine Pretreatment on the Ultrafiltration Membrane Fouling

以紫外/氯氧化为预处理工艺,研究了该工艺预处理腐殖酸与高藻水对后续膜污染的影响。结果表明,紫外/氯氧化预处理对两种不同类型污染物引起的膜污染有显著不同的影响。预氧化后,腐殖酸引起的超滤膜污染得到有效控制,在次氯酸钠投加量为0.5 mmol/L时,可逆膜污染阻力降低了81.3%。高藻水经过紫外/氯预氧化后,膜污染反而加重,在次氯酸钠投加量为1 mmol/L时,不可逆污染阻力增大7.65倍。紫外/氯预氧化能够使进水溶液中腐殖酸发生矿化,使进水DOC显著降低;高藻水经预氧化后,溶液中大分子有机物转化为小分子有机物,使滤液DOC显著升高。扫描电镜结果表明,预氧化后腐殖酸在膜表面形成的滤饼层显著减少;尽管预氧化后藻细胞发生破裂,但破裂的藻细胞仍然会在膜表面形成滤饼层。模型拟合结果表明,紫外/氯氧化预处理能够缓解腐殖酸引起的膜污染主要是由于滤饼层过滤与膜孔堵塞的控制;而高藻水经紫外/氯氧化预处理后,滤饼层过滤与膜孔堵塞仍然占主导地位。

In this study, the effect of UV/chlorine pretreatment on the ultrafiltration membrane fouling caused by humic acid(HA) and algaecontaining water was studied. The results showed that membrane fouling trends were different after UV/chlorine pretreatment. The membrane fouling caused by HA was effectively controlled by UV/chorine pretreatment, and the membrane fouling resistance was reduced by 81.3% with the chlorine dose of 0.5 mmol/L However, the algal fouling was aggravated when UV/chlorine pretreatment was applied, the irreversible fouling resistance increased by 7.65 times with the chlorine dose of 1 mmol/L compared with the raw solution. The HA was mineralized after the UV/chlorine pretreatment, resulting in a decreased DOC value in the permeate. The UV/chlorine pretreatment reduced the molecular weight in the feed of algaecontaining water, thereby increasing the DOC in the permeate. The scanning electronic microscope(SEM) results showed that the cake layer on the membrane surface significantly decreased after the UV/chlorine pretreatment. The algal cell was broken after the pretreatment, which accumulated on the membrane surface during the filtration process. The modeling results indicated that the alleviation of HA fouling was attributed to the ease of cake filtration and pore blocking, while these mechanisms still played dominant roles during the filtration of algal water with UV/chlorine pretreatment.