投加氯化铁对SMBR工艺效能及膜污染的影响

EFFECT OF COAGULANT FERRIC CHLORIDE DOSAGE ON EFFICIENCY AND MEMBRANE FOULING OF SMBR

试验研究了浸没式膜生物反应器(SMBR)中FeCl3不同投加量对出水水质以及膜污染的影响。结果表明,不同投加量对于COD、NH3-N的去除效率影响不显著;随着FeCl3投加量的增加,总氮(TN)去除效率略有提高。投加适量FeCl3,可以增强化学和生物协同除磷作用。溶解性胞外聚合物(EPSS)中多糖浓度、松散附着胞外聚合物(LB)中蛋白质和腐殖酸浓度与半透膜压(TMP)的增长存在明显的相关性,说明EPSS中多糖、LB中蛋白质和腐殖酸均是导致膜污染的主要因素。FeCl3最佳投加量范围为15～30mg·L-1,此时活性污泥形成了良好的菌胶团,TMP增长速度最慢,膜污染程度最轻。而当投加量进一步增大到60mg·L-1和120mg·L-1时,生物铁结构变得密实,膜污染程度加剧;其次过多FeCl3本身也增加了的膜污染负荷。

The experiment explored that different doses of FeCl3 affect the effluent quality and membrane fouling for SMBR to treat simulated municipal sewage. The results indicated that the removal efficiency of COD and ammonia nitrogen have a little improvement with increasing FeCl3 dose; the removal of total nitrogen increases gradually when the dose of FeCl3 increases; the removal of total phosphorus increases when the dose of FeCl3 is low. The contents of polysac charide in EPSs, protein and humic acid in LB have obvious correlations with the rise of the trans-membrane pressure, it proved that polysaccharide in EPSs and protein and humic acid in LB are both the main factors of the membrane fouling. The optimal dose of FeCl3 is between 15-30 mg·L^-1, bio-ferric sludge has better floc structure and the trans-membrane pressure rises most slowly in comparison with the others. However, the structure of bio-ferric sludge become compact and the membrane fouling deteriorate when the dose of FeCl3 is between 60 - 120 mg·L^-1; moreover, the FeCl3 itself contributes to the membrane fouling.