丝状菌膨胀对无纺布生物反应器处理效果及膜污染特征的影响

Impacts of Filamentous Bulking on Treatment Effect and Fouling Characteristics of Nonwoven Bioreactor

研究了丝状菌膨胀状态和正常污泥状态下无纺布生物反应器的污泥絮体形态、出水水质对比,膜通量变化,膜阻力分析和胞外聚合物(EPS)含量分析.结果表明,膨胀污泥的平均粒径为448.6μm,正常污泥的平均粒径为234.8μm;丝状菌膨胀状态下的平均COD去除率、NH+4-N去除率、出水浊度分别为90.1%、93.1%、1.33 NTU,较之正常污泥状态下的91.4%、97.0%、0.99 NTU,丝状菌膨胀对COD去除几乎没有影响,对NH+4-N去除有一定的抑制,对出水浊度略有影响;膨胀污泥状态和正常污泥状态下的平均膜通量衰减速率分别为3.29 L·(m2·h2)-1、4.87 L·(m2·h2)-1,膨胀状态下的膜污染较轻,膨胀状态下的膜污染以可逆污染为主,正常状态下以不可逆污染为主,优先发生可逆污染可以减少不可逆污染的发生,从而减缓膜通量的下降;正常污泥和膨胀污泥混合液中溶解性微生物产物(SMP)含量分别为21.369 mg·L-1、10.182 mg·L-1,蛋白质/多糖(P/C)分别为0.370、0.497,SMP的总量与膜污染阻力有关系,P/C与可逆污染所占的比例有关系,混合液污泥的松散附着性EPS与膜污染的关系同SMP相似;EPS含量较高的污泥更易于在膜表面累积,并且累积于膜表面的EPS主要是蛋白质,混合液污泥EPS总量、膜面污泥EPS以及它们的P/C都与膜表面可逆污染存在正相关性.

Sludge flocs morphology and effluent qualities of nonwoven bioreactor during filamentous bulking and normal sludge status were compared. Flux variations,analysis of filtration resistances and extracellular polymer substances( EPS) contents during filamentous bulking and normal sludge status were studied. The results showed that the average particle size of bulking sludge flocs and normal sludge flocs was 448. 6 μm and 234. 8 μm,respectively. During the bulking sludge status,the average COD and NH+4-N removal rate and effluent turbidity were 90. 1%,93. 1% and 1. 33 NTU,respectively,compared with 91. 4%,97. 0% and 0. 99 NTU during the normal sludge status. Filamentous bulking had little impact on COD removal,while it inhibited NH+4-N removal to a certain extent and had slight impact on effluent turbidity. Average membrane flux decay rates during the bulking sludge status and the normal sludge status were 3. 29 L·( m2·h2)-1and 4. 87 L·( m2·h2)-1,respectively,and the fouling during bulking sludge status was slighter. Reversible fouling was the main fouling when sludge was bulking while irreversible fouling was the main fouling when the sludge was in normal status. The prior occurrence of reversible fouling could reduce irreversible fouling therefore slow down the flux decline. Soluble microbial products( SMP) contents in normal sludge mixed liquid and bulking sludge mixed liquid were 21. 369mg·L-1and 10. 182 mg·L-1,respectively,protein/polysaccharide( P/C) was0.370 and0.497,respectively,SMP gross was related to fouling resistance and P /C was associated with reversible fouling proportion. The relation between loosely bound EPS in mixed liquid sludge and membrane fouling was similar to SMP. Sludge with more EPS could accumulate on membrane more easily,and the EPS that accumulated on membrane was mainly protein. EPS gross in mixed liquid sludge,EPS in membrane surface sludge and their P /C all had positive correlations to reversible fouling.