好氧活性污泥在升流式厌氧污泥床反应器中的厌氧颗粒化过程及机制

 采用升流式厌氧污泥床(UASB)反应器,以城市污水处理厂二沉池活性污泥为种泥,研究好氧絮状污泥的厌氧颗粒化过程及其机制.UASB在污泥负荷(SLR)0.25kg(COD)/(kg(VSS)·d)和水力负荷(HLR)0.1m³/(m²·h)的条件下启动后,通过分阶段缩短水力停留时间(HRT)的方式逐步将SLR和HLR提高到0.52kg(COD)/(kg(VSS)·d)和0.3m³/m²·h,经过150d的连续运行,成功培育出了厌氧颗粒污泥,系统对COD的去除率达到了95%以上.厌氧颗粒污泥的形成过程先后经历了污泥驯化期、微生物聚集体形成期、初生颗粒污泥形成期、次生颗粒污泥形成期、成熟颗粒污泥形成期5个时期.好氧絮状污泥的厌氧颗粒化机制整体上符合二次核学说,其中初生颗粒污泥的形成符合黏液学说,而次生颗粒污泥的形成机制与目前已报道的厌氧颗粒污泥形成机制不同,其内核是由初生颗粒污泥破碎后的碎片组成,产甲烷丝状菌和其他细菌通过插入碎片中或者附着于碎片表面的方式形成聚集体,并逐渐发展成为次生颗粒污泥.

Mechanism and Process of Anaerobic Sludge Granulation in UASB Reactor with Aerobic Activated Sludge as Seed

The mechanism and the process of the anaerobic sludge granulation of the aerobic flocculent sludge in an Upflow Anaerobic Sludge Blanket (UASB) reactor are studied in this paper. The sludge is obtained from a secondary sedimentation tank of an activated sludge plant for treating municipal wastewater. The results show that the anaerobic granular sludge is cultivated successfully after the continuous operation for 150 d and the Hydraulic Retention Time (HRT) is reduced from 24 h to 8 h. During the phase-shortening, the sludge load and the hydraulic load are increased from 0.25 kg COD/(kg(VSS)·d) and 0.1 m³/(m²·h) to 0.52kg COD/(kg(VSS)·d) and 0.3m³/(m²·h), respectively. The process of the granulation contains five stages, including the sludge acclimation, the microbial aggregates formation, the primary granular sludge formation, the secondary granular sludge formation and the mature granular sludge formation. During the mature granular sludge formation stage, the COD is removed approximately by 95%. The mechanism of the anaerobic sludge granulation of the aerobic flocculent sludge is consistent with the second nuclei theory as a whole. The primary granular sludge formation mechanism is consistent with the Extracellular Polymers (ECP) theory, while the secondary granular sludge formation mechanism is consistent with other reported theories. In this study, the secondary granular sludge is formed by the methane filamentous bacteria and other bacteria inserting or absorbing to the fragments while its inner nuclei are composed of primary granular broken fragments.