College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, PR China.
Yangzhou Polytechnic Institute, Yangzhou, 225127, PR China.
J Environ Manage. 2020 May 15;262:110391. doi: 10.1016/j.jenvman.2020.110391. Epub 2020 Mar 6.
Granule formation has been recognized as a promising biotechnology in denitrifying phosphorus removal (DPR) systems by facilitating phosphorus accumulation organisms (PAOs) especially denitrifying PAOs (DPAOs), and hydraulic selection made this a more difficult task in continuous operation. This study aimed at exploring the microscopic mechanism and putting forward an effective strategy for DPR granulation under the impact of hydraulic retention time (HRT) (12 h, 10 h, 8 h) in a novel Anaerobic Anoxic Oxic - Moving Bed Biofilm Reactor (A/O - MBBR) system. With the reduction of intracellular carbon storage (COD) efficiency (88.58%-78.53%), nitrogen (N) (85.45%-79.11%) and phosphorus (P) (96.55%-92.47%) removals both dropped, but it exhibited a growth of anoxic phosphorus uptake rate (PUR) (3.79-5.68 mg P/(gMLVSS·h)). The batch tests associating with substrate transformation of poly-β-hydroxyalkanoates (PHA), glycogen (Gly) agreed well with the corresponding stoichiometry of phosphorus release rate (PRR) (4.83-7.53 mg P/(gMLVSS·h)), PUR (3.55-5.43 mg P/(gMLVSS·h)), oxic phosphorus uptake rate (PUR) (6.08-6.21 mg P/(gMLVSS·h)), and DPAOs/PAOs ratios (57.17%-89.31%), indicating a shift of microbial community. DPR granules gradually stabilized with low sludge volume index (SVI/SVI ratio = 1.1-1.2), dense and compact structure, higher P content (11.63%), more extracted extracellular polymeric substances (EPS) (111.40-160.31 mg/gMLVSS) as proteins/polysaccharides (PN/PS) ratios (1.70-3.47) increased, leading to better sludge settleability and cell hydrophobicity. Fluorescence in situ hybridization (FISH) results showed that PAOs (mainly Cluster I: 20.20%) were the dominant bacteria in the A/O reactor although a small amount of Defluviicoccus (3.18-3.48%) was responsible for nitrite accumulation, while ammonium-oxidizing bacteria (AOB) (mainly Nitrosomonas: 10.75%) and nitrite-oxidizing bacteria (NOB) (mainly Nitrospira: 15.06%) were enriched in the MBBR.
颗粒形成已被认为是一种有前途的生物技术，可用于反硝化除磷（DPR）系统，促进磷积累微生物（PAOs），特别是反硝化除磷菌（DPAOs）的生长，而水力选择使得这在连续运行中变得更加困难。本研究旨在探索在新型厌氧缺氧好氧-移动床生物膜反应器（A/O-MBBR）系统中，水力停留时间（HRT）（12 h、10 h、8 h）变化对 DPR 颗粒化的微观机制，并提出一种有效的策略。随着细胞内碳储存（COD）效率（88.58%-78.53%）、氮（N）（85.45%-79.11%）和磷（P）（96.55%-92.47%）去除率的降低，缺氧吸磷率（PUR）（3.79-5.68 mg P/（gMLVSS·h））却有所增加。批处理试验与聚β-羟基烷酸（PHA）、糖原（Gly）的基质转化相结合，与相应的磷释放率（PRR）（4.83-7.53 mg P/（gMLVSS·h））、PUR（3.55-5.43 mg P/（gMLVSS·h））、好氧吸磷率（PUR）（6.08-6.21 mg P/（gMLVSS·h））和 DPAOs/PAOs 比值（57.17%-89.31%）吻合较好，表明微生物群落发生了变化。DPR 颗粒逐渐稳定，污泥体积指数（SVI/SVI 比值=1.1-1.2）较低，结构致密，磷含量较高（11.63%），提取的胞外聚合物（EPS）较多（111.40-160.31 mg/gMLVSS），蛋白质/多糖（PN/PS）比值（1.70-3.47）升高，污泥沉降性能和细胞疏水性较好。荧光原位杂交（FISH）结果表明，A/O 反应器中 PAOs（主要为 Cluster I：20.20%）是优势细菌，尽管少量 Defluviicoccus（3.18-3.48%）负责亚硝酸盐积累，而氨氧化菌（AOB）（主要为 Nitrosomonas：10.75%）和亚硝酸盐氧化菌（NOB）（主要为 Nitrospira：15.06%）在 MBBR 中得到富集。
