PRELIMINARY STUDY ON APPLICATION OF SLUDGE DENSIFICATION SYSTEM TECHNOLOGY IN AN INVERTED AAO CONTINUOUS FLOW WASTEWATER TREATMENT PLANT
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摘要: 选取无锡市某污水处理厂(设计规模15万m3/d)进行污泥致密系统处理技术(SDST)工艺优化,在外回流工艺段增设污泥致密模块以实现污泥沉降性能的有效提高。该厂采用倒置AAO工艺(缺氧/厌氧/好氧),一期和二期工程分别作为实验组和对照组,设计规模分别为4万,11万m3/d。致密模块以半覆盖式处理(最大处理量为原设计剩余污泥量的50%),成功运行90 d,一期工程TN去除能力显著提升,出水浓度下降14.7%,由6.32 mg/L下降至5.39 mg/L。启动阶段(1~36 d),一期好氧池污泥沉降速度提升至1.92 m/h,稳定提升阶段(42~90 d),其沉降速度和SVI30分别为(3.62±0.52) m/h和(49.3±5.5) mL/g,而二期分别为(1.93±0.35) m/h和(59.3±5.5) mL/g。污泥致密模块具有稳定的污泥致密作用,致密污泥MLSS为(19.3±2.75) g/L,SVI30仅为(36.7±9.0) mL/g。通过镜检成功观察到致密污泥中含有大量的小型颗粒状絮体,但颗粒化程度有限。研究发现,活性污泥中大量的纤维状和惰性无机物质是影响致密模块稳定运行的重要因素,通过增设螺旋式格栅可以保障致密模块的稳定运行,而无机物质中的砂、铁盐和铝盐等对系统的影响仍需进一步探讨。此外,耦合除砂措施并采用全覆盖式处理以优化改造致密模块是进一步提高致密污泥颗粒化程度的关键。该工程案例系SDST在国内倒置AAO连续流污水处理厂的首次成功应用,将为国内存量污水处理厂的升级改造提供重要思路。
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关键词:
- 污泥致密系统处理技术 /
- 倒置AAO /
- 连续流污水处理工艺 /
- 工艺优化 /
- 沉降性能
Abstract: The sludge densification system technology (SDST) was applied in a wastewater treatment plant (WWTP) for engineering modification, located in Wuxi, with a designed treatment capacity of 150000 m3/d, and a sludge densification module was added in the external reflux process section to effectively improve sludge settling performance. The inverted AAO (anoxic/anaerobic/oxic) process was adopted in the WWTP with the Phase Ⅰ project (40000 m3/d) and Phase Ⅱ project (110000 m3/d), acting as the experimental group and control group, respectively. After the engineering modification, the densification module was successfully operated for 90 days in a half-scale mode, which maximum treatment capacity was 50% of the original design surplus sludge volume. The removal capacity of TN in the Phase Ⅰ project was significantly improved, and the effluent concentration decreased by 14.7% (from 6.32 mg/L to 5.39 mg/L). During the start-up stage (day 1 to 36), the settling rate of aerobic sludge increased to 1.92 m/h. In the stable and lifting stage (day 42 to 90), the settling rate and SVI30 were (3.62±0.52) m/h and (49.3±5.5) mL/g, respectively, while the counterparts of sludge in the Phase Ⅱ project were (1.93±0.35) m/h and (59.3±5.5) mL/g. The densification device had a stable sludge densification effect so that the densified sludge MLSS was (19.3±2.75) g/L, and the SVI30 was only (36.7±9.0) mL/g. Many small granular flocs in densified sludge were successfully observed through microscopic examination, but the degree of granulation was limited. This study found that the massive fibrous and inert inorganic matters in activated sludge were important factors affecting the operation of the densification module, while a spiral grating was added to ensure its operation. Moreover, the effects of these inorganic substances such as sand, iron salt, and aluminum salt on the system still need to be further discussed. In addition, coupling sand removal measures and adopting full coverage treatment to optimize and transform the densification module were the key to further improving the granulation degree of densification sludge. Our team has successfully applied the SDST in an inverted AAO continuous flow WWTP in China for the first time, providing an important method for the upgrading and modification of existing wastewater treatment plants. -
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