高有机负荷对好氧颗粒污泥形成和稳定性能的影响

为探究高有机负荷(organic loading rate，OLR)对好氧颗粒污泥在序批式反应器(sequencing batch reactor，SBR)中的形成和稳定性能的影响及高OLR条件下微生物群落结构的特征，采用连续监测方法对运行过程中颗粒污泥形貌、水质、沉降性能以及EPS的变化进行探究。结果表明：在OLR为14.4 kg·(m³·d)⁻¹的条件下，颗粒化进程较快，43 d完成颗粒造粒；并且高OLR引起丝状菌在颗粒表面大量附着，造成颗粒沉降性能和水质处理能力不稳定；通过改变进水中蛋白胨的占比来抑制丝状菌生长，使好氧颗粒污泥系统重新恢复稳定；在此过程中，混合液悬浮固体质量浓度(mixed liquid suspended solids，MLSS)、混合液挥发性悬浮固体质量浓度(mixed liquid volatile suspended solids，MLVSS)随OLR的增加而增加，但受丝状菌增加的影响会下降，而在丝状菌消除之后，MLSS和MLVSS恢复增长；SVI随OLR的增加不断下降，而受丝状菌增加的影响会呈现上升趋势，在丝状菌消除后，颗粒沉降性能恢复，SV₃₀/SV₅在1.0左右波动；胞外聚合物(extracellular polymeric substances，EPS)受OLR和丝状菌影响较大，尤其是紧密结合型的EPS；恢复正常的颗粒污泥可高效去除进水中的COD、NH₄⁺-N和TN，去除率分别为91.5%、92.0%和79.4%；采用MiSeq高通量测序的方法发现高OLR下好氧颗粒污泥中去除有机物和氮的优势菌门为Saccharibacteria、Bacteroidetes和Proteobacteria；异养硝化、好氧反硝化菌丰度较高。由此可以看出，异养硝化-好氧反硝化可能是好氧颗粒污泥的主要脱氮方式。本研究结果可为SBR系统控制好氧颗粒污泥中丝状菌的生长，维持好氧颗粒污泥稳定性提供参考。

Effect of high organic loading rate on the formation and stability of aerobic granular sludge

In order to study the effect of high organic loading rate (OLR) on the formation and stability of aerobic granular sludge in sequencing batch reactor (SBR) and the characteristics of microbial community structure under high OLR conditions, continuous monitoring method was used to explore the changes in granular sludge morphology, water quality, sedimentation performance and EPS during operation. The experimental results showed that under the high OLR condition of 14.4 kg·(m3·d)−1, the granulation process was fast and completed in 43 days. And high OLR stimulated the growth of filamentous bacteria attaching to the surface of granules, which resulted in the instability of sedimentation performance and effluent quality. Through changing the proportion of peptone in the influent, the growth of filamentous bacteria was inhibited and the aerobic granular sludge system recovered the stability. During this process, mixed liquid suspended solids (MLSS) and mixed liquid volatile suspended solids (MLVSS) increased with the increase of OLR, but decreased with the increase of filamentous bacteria. After filamentous bacteria were eliminated, both MLSS and MLVSS increased again. SVI decreased with the increase of OLR, while it showed an upward trend due to the effect of filamentous bacteria increasing. The sedimentation performance of granular sludge also recovered when filamentous bacteria were eliminated, and its SV30/SV5 fluctuated around 1.0. Extracellular polymeric substances (EPS) fluctuated greatly under the influence of OLR and filamentous bacteria, especially for tightly bound EPS. The recovered granular sludge could effectively remove COD, NH4+-N and TN, and the corresponding removal efficiencies were 91.5%, 92.0% and 79.4%, respectively. Through MiSeq high-throughput sequencing method, it was found that Saccharibacteria, Bacteroides and Proteobacteria were the dominant bacteria for removing organic matter and nitrogen in aerobic granular sludge at high OLR, and high abundance of heterotrophic nitrifying and aerobic denitrifying bacteria occurred. The main nitrogen removal mode of aerobic granular sludge was heterotrophic nitrification-aerobic denitrification. The results of this study can provide reference for SBR system to control the growth of filamentous bacteria in aerobic granular sludge and maintain the stability of aerobic granular sludge.