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题名: 活性污泥快速去除污染物机制与高效工艺研究
作者: 郭旋
学位类别: 博士
答辩日期: 2016-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 刘俊新
关键词: 污水处理,活性污泥,快速转移,高效工艺 ; wastewater treatment, activated sludge, rapid removal and transfer, efficient process
其他题名: Rapid removal mechanism of wastewater pollutants by activated sludge and development of efficient organic-transfer process
学位专业: 环境工程
中文摘要:       目前的污水二级生物处理工艺以水质达标为目标,重视利用微生物的作用将不同类型污染物降解去除,存在能耗高、排放温室气体、产生大量剩余污泥等问题,而且剩余污泥中有机质含量偏低导致其可资源化的潜能较低。为降低污水处理能耗、实现污水中可资源化物质的分类回收,本文针对活性污泥与污水接触初期能快速去除污染物的性能,对活性污泥的结构特征、快速去除污水中污染物的机制、强化物质转移的调控方法等进行了研究。在此基础上,研发出活性污泥法污水处理新工艺,为发展能耗低和资源回收型污水处理系统探索新的途径。主要研究结果如下:
      对北京市5个生活污水处理厂(站)细格栅后的污水进行采样分析,污水中颗粒物粒度范围为0.1-100 μm,其中>1 μm的颗粒物占90 %以上;有机质主要以颗粒态和胶体态存在,氮和磷则主要以溶解态存在;COD浓度与悬浮固体(SS)浓度有良好的相关性。批量实验结果表明,在活性污泥与污水混合后10 min,污水中SS去除率达到95 %以上,比转移量为60-70 mg SS/g MLSS;COD去除率在80 %左右,比转移量为90-120 mg COD/g MLSS;而TN和TP的去除率较低。由此可见,活性污泥能够快速去除污水中的颗粒态和胶体态物质,但对溶解态的物质去除率较低。污水中有机物质转移至污泥中,使得污泥的挥发性固体与总固体的比值(VS/TS)提升5%-10 %。以上结果为污水中不同类型物质的分类回收和低能耗快速去除技术的研发提供了科学依据。
      研究了污泥絮体中胞外聚合物(EPS)的组分特征及其在污泥絮体聚集中的作用。三维荧光图谱和红外光谱图显示,溶解性EPS(S-EPS)、松散结合型EPS(LB-EPS)和紧密结合型EPS(TB-EPS)中均存在一些蛋白质和多聚糖对应的强频段,其中,TB-EPS具有更多的C-O、N-O等基团,有更强的氢键缔合趋势。键能测定的结果表明,污泥絮体之间的结合键以氢键为主。基于此,本研究提出了通过水力剪切分离外层S-EPS和LB-EPS,暴露了内层TB-EPS的强化污泥絮体聚集的调控方法和最佳控制条件:采用较大的水力剪切力(G=400-500 s-1)将污泥絮体破碎为更小的絮体,在暴露内层TB-EPS的同时不会导致EPS的表面侵蚀;破碎后,采用较小的水力剪切力(G=40-60 s-1),使破碎后的絮体重新聚集起来,重聚集后的平衡粒径d0.5可由原污泥的600-700 μm增大至800 μm左右。
      通过分层剥离实验,比较了微生物和EPS在快速去除污染物过程中的作用,结果发现,快速去除性能受微生物活性影响较小,TB-EPS起重要作用,其表面官能团以氢键的方式和污染物相结合。另外,污染物的去除率与污泥絮体的聚集性能存在很好的相关性。污泥对污水中污染物的快速去除主要依靠的是基于氢键的化学吸附+絮体的“聚集”作用:颗粒态和胶体态的污染物首先以氢键附着在小颗粒污泥絮体上,再随着絮粒之间的相互碰撞聚集而去除。活性污泥絮体在反复的破碎-重聚集和资源分离回收后,其聚集性能降低。本研究采用曝气的方式对污泥进行再生,结果表明,2-3 d水解和2-4 h、0.01 m3/h·L曝气再生可以同步实现污泥中的资源回收和污泥絮体性能的恢复。
      在上述研究的基础上,研发了新型活性污泥高效转移工艺。转移-再生模式(I)的最佳运行条件为:破碎强度GT=~32850,物质转移池污泥浓度~2000mg/L,再生时间2 h,污泥龄10 d。在此条件下,污染物的转移量为200-300 mg COD/g MLSS,较原污泥提升了20%以上;转移-分离-再生模式(II)可以高浓度有机废水的形式回收污泥中的有机质。相比于传统的好氧生物处理工艺(活性污泥法和吸附再生法),新工艺污泥的VS/TS由0.5-0.6提升至0.7以上,耗能水平降低50%左右,能源回收水平为0.4-0.5 kWh/m3,实现了污水中碳资源的有效回收。
英文摘要:       At present, the main target of sewage secondary biological treatment process is to meet the water quality discharge standards. The biodegradation of pollutants using microorganisms has been drawn great attention due to its excellent performance in pollutants removal. As a result, some serious problems such as high energy consumption, greenhouse gas emissions and low organic matter content of the excess sludge have begun to emerge. In order to reduce the energy consumption of sewage treatment and actualize the recycle of resource in wastewater, the rapid removal performance of pollutants in wastewater by activated sludge was investigated. Addtionally, the structural characteristics of the activated sludge, mechanism and enhanced method of rapid removal of pollutants were also explored. Furthermore, a new transfer process based on activated sludge was developed to explore new ways for the development of waste water treatment system with lower energy consumption and higher potential of resource recovery. The main results are as follows:
      Wastewater samples (after fine screens) from five wastewater treatment plants (station) in Beijing were analysed. The particle size distributions of the samples were between 0.1-100 m, with more than 90% of particulates’ size larger than 1 μm Organic matters presented mainly in particulate and colloidal, whereas nitrogen and phosphorus were presented mainly in dissolved. There was good correlation between COD and suspended solids (SS). Batch experiments showed that after 10 min mixture of activated sludge and wastewater, the removal of SS reached more than 95%, and the transfer amount was 60-70 mg SS/g MLSS; the removal of COD about 80%, and the transfer amount to 120 mg COD/g MLSS. However, the removal of TN and TP were 20-50% and 20-30%, which were rather low compared to those of SS and COD. It can be seen that the rapid removal of matters in wastewater by activated sludge were mainly in the forms of granular and collide. As the organic matters in the sewage were transferred to the sludge, the ratio of volatile solids to total solids (VS/TS) of the sludge was increased by 5%-10%. These results provided a scientific basis for the recycle of different types of substances in wastewater and the development of low energy consumption and rapid removal technology.
       The characteristics of extracellular polymer (EPS) in activated sludge were studied. Three-dimensional fluorescence spectrum and infrared spectrum showed that there were some strong bands binding corresponding to polysaccharides and proteins in soluble EPS (S-EPS), loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS). Additionally, TB-EPS had more C-O, N-O groups, which had a stronger hydrogen bonds association trend, and thus were conducive to aggregation between sludge flocs and particulates in wastewater. The results showed that using larger hydraulic shear stress (G=400-500 s-1) would break the sludge flocs into smaller flocs without erosion of the surface of EPS; after that smaller hydraulic shear stress (G=40-60 s-1) was introduced for the aggregation of the sludge flocs and matters in wastewater. The average particle size after aggregation could increase from 600-700 μm to 800 μm. Based on this, the enhance method and the optimal control condition was proposed by the introducing of hydraulic shear to separate S-EPS and LB-EPS and expose the inner TB-EPS.
      The roles of S-EPS, LB-EPS and TB-EPS in a rapid removal of pollutants and sludge floc aggregation process were studied by a delamination experiment. The results showed that, the rapid removal effect of pollutants was not affected by microbial activity, and a good correlation was found between pollutants removal and sludge floc aggregation performance. It indicated that the mechanism of rapid removal of pollutants in wastewater by activated sludge was similar with that of flocculation of sludge flocs. The particulate and colloidal pollutants were firstly adsorbed and attached on the small granular sludge flocs and then were aggregated by the sludge flocs. Therefore, the rapid removal of pollutants in wastewater by activated sludge was mainly depended on chemical-adsorption based on hydrogen and aggregation by activated sludge flocs. The aggregation performance of activated sludge flocs decreased after repeatedly broken-re-aggregation. A hydrolysis- aeration method was used to regenerate the sludge. The results showed that with 2-3 d hydrolysis and subsquencing 2-4 h of regeneration of 0.01 m3/h·L, the recycling and regeneration of activated sludge could be achieved simultaneously.
      Based on the fundamental research, a transfer process based on activated sludge was developed. The optimal operating conditions under model (I) was: breakge strength GT=~32850, MLSS=~2000 mg/L, regeneration time 2 h and SRT=10 d. Under this condition, the transfer of pollutants was 200-300 mg COD/g MLSS. Under model (II) the transfor of organic matters decreased, but it could be recycled by high concentration organic wastewater. Compared to the traditional aerobic biological treatment process, VS/TS of the new process improved significantly, up to 0.6-0.7, with a higher carbon resource recycling rate (60%). Energy consumption level of the new process was only around 50% of the traditional activated sludge process. Furthermore, net energy recovery of about 0.3-0.4 kWh/m3 could be achieved.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/36799
Appears in Collections:水污染控制技术研究室_学位论文

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Recommended Citation:
郭旋. 活性污泥快速去除污染物机制与高效工艺研究[D]. 北京. 中国科学院研究生院. 2016.
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