Reduction of excess sludge and characterization of microbial community in biopolymer-using biological wastewater treatment processes

研究了在活性污泥法中投加可生物降解塑料(PHBV、PCL和PIA)对微生物生长和反硝化活性的影响。多相活性污泥系统由标准曝气工艺和PHBV二相反硝化工艺组成，与常规活性污泥法相比，剩余污泥量减少了20-30%。同时，该多元体系具有较高的脱氮活性。通过非选择性琼脂平板计数法定量分离出的大多数优势反硝化菌不能降解PHBV，通过研究16S rRNA基因序列信息NIRS和nosZ基因克隆库被鉴定为β蛋白杆菌类的成员。基于反应器微生物群落的NIRS和nosZ克隆分析表明，大多数NIRS和nosZ克隆来自于软单胞菌科的成员和其他β蛋白细菌的系统发育类群。在活性污泥反应器中投加3，5-DCP后，剩余污泥显著减少，而BOD的去除却没有明显降低。但在使用3，5-DCP的反应器长时间运行过程中，这种影响被消除。在这一操作过程中，发生了从β蛋白细菌到甲蛋白细菌和放线菌的种群转移。投加PHBV等可生物降解塑料可消除3，5-DCP对微生物生长的抑制作用。当活性污泥在pH为4的条件下加入矿物质基质时，在此过程中会发生嗜酸硝化作用，生物量随着运行时间的延长而逐渐减少。

Effects of the addition of biodegradable plastics (PHBV, PCL, and PIA)on microbial growth and denitrifying activity in activated sludge process were investigated. A multi-phase activated sludge system consisting a standard aeration process and a sold-phase denitrification proems with PHBV produced 20-30% reduced excess sludge compared to the normal activated sludge process. Also, this multi-system had a high denitirication activity. Most of the predominant denitrifiers isolated quantitatively by the plate-counting method using non-selective agar medium were unable to degrade PHBV and were identified as members of genera of the class Betaproteobacteria by studying 16S rRNA gene sequence information nirS and nosZ gene clone library-based analyses of the microbial community from the reactor showed that most of the nirS and nosZ clones proved to be derived from members of the family Comamonadaceae and other phylogenetic groups of the Betaproteobacteria.Effects of the addition of a chemical uncoupler; 3,5-dichlorophenol (DCP), on microbial growth in activated sludge were also investigated. The addition of 3,5-DCP in an activated sludge reactor resulted in the significant reduction of excess sludge without a great decrease in BOD removal. However, this effect was eliminated during the prolonged operation of the reactor with 3,5-DCP. Population shifts from Betaproteobacteria to Alphaproteobacteria and Actinobacteria took place during this operation. The inhibition of microbial growth by 3,5-DCP was eliminated by the addition of biodegradable plastic such as PHBV.When activated sludge was gown with mineral medium at pH 4, acidophilic nitrification took place In this process, the biomass decreased gradually with operation time.