污泥臭氧原位减量工艺中典型抗生素的去除研究
文献类型：学位论文
| 作者 | 汪鲁 |
| 学位类别 | 博士 |
| 答辩日期 | 2016-11 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 强志民 |
| 关键词 | 活性污泥工艺 污泥臭氧处理 污泥原位减量 磷回收 抗生素 |
| 其他题名 | Removal of typical antibiotics during in-situ sludge ozone- reduction process |
| 学位专业 | 环境工程 |
| 中文摘要 | 产量庞大的剩余污泥不仅是抗生素进入自然环境的重要途径，还成为活性污泥法面临的严峻挑战。可以同步实现污泥减量及污泥中抗生素去除的工艺对于控制剩余污泥带来的二次污染具有重要意义。由于传统污泥处理处置能力有限而且成本较高，污泥原位减量已经引起了国内外研究者的广泛兴趣。因此，污泥原位减量工艺中抗生素的去除值得关注，但是目前相关研究还比较有限。臭氧是一种强氧化剂，可以氧化去除水体中多种有机污染物。此外，臭氧处理还是一种有效的污泥溶胞手段，可以与活性污泥系统联合构成基于溶解 -隐性生长机制的污泥原位减量工艺。因此，本文选取 3种四环素类抗生素（TCs：四环素（TCN）、土霉素（OTC）、强力霉素（DOX））、5种氟喹诺酮类抗生素（FQs：诺氟沙星（NOR）、氧氟沙星（OFL）、环丙沙星（CIP）、洛美沙星（LOM）、恩诺沙星（ENR））以及 1种大环内酯类抗生素（阿奇霉素（AZN））作为目标抗生素（TAs），并对它们在污泥臭氧原位减量工艺中的去除规律进行了研究。 首先，通过批次实验及模拟处理系统的连续运行考察了 SBR和 A/A/O污泥臭氧原位减量工艺的污泥减量效果和污水处理性能。其次，通过批次实验研究了TAs在活性污泥工艺中的去除机制、吸附及生物降解特征，深化了对 TAs在活性污泥工艺中迁移转化行为的认识，为 TAs在污泥臭氧原位减量工艺中去除规律的研究奠定了基础。再次，通过批次实验研究了活性污泥中 TAs在臭氧处理过程 中的去除效果、降解过程及影响因素。最后，通过模拟处理系统的连续运行考察了 TAs在 SBR及 A/A/O污泥臭氧原位减量工艺中的去除规律。本文得到的主要结论为： （1）臭氧处理具有良好的污泥溶胞效果，会导致污泥液相中的溶解性COD（SCOD）、总氮（TN）和总磷（TP）浓度大幅上升。污泥初始 pH偏碱性可以促进污泥溶胞，对有机物和氮的溶出有利；但是，过高的初始 pH会对污泥溶胞产生抑制作用；初始 pH偏酸性有利于含磷物质的释放。臭氧处理后污泥回流对SBR系统中的微生物活性、COD、有机氮和氨氮（NH4+-N）的去除未产生明显的不利影响，但导致除磷效率大幅下降。钙磷摩尔比（Ca/P）为 10.0时，臭氧处理后污泥上清液中TP和磷酸盐（PO43- -P）的去除率均超过 80%，滞后于理论Ca/P；经过除磷后，上清液中的 SCOD和 TN浓度有所降低。 （2）A/A/O污泥臭氧原位减量工艺中臭氧处理单元的最佳臭氧投加量约为100 mg O3 g1 MLSS，此时污泥溶解率约为 35.5%。在此臭氧投加量下，该系统取得的最大污泥减量率约为 85%。臭氧处理后污泥回流对 A/A/O单元的 COD和N的去除、MLVSS/MLSS及污泥活性没有显著影响，系统内污泥的沉降性能得到了明显提高，然而 A/A/O单元的除磷效能显著下降。COD和 N的总体质量衡算表明，臭氧处理后污泥回流可以促进 A/A/O单元内有机物矿化和反硝化反应。P的每日质量衡算表明，磷回收单元可以回收入水中 29%的磷，从而使得污泥臭氧原位减量系统的除磷能力得到部分恢复。 （3）TAs的存在（每种浓度 100 μg L–1）没有对污泥生物活性表现出明显的抑制。在活性污泥工艺中，TAs的水解和挥发作用可以忽略；吸附是 TAs的主要去除路径；FQs类抗生素观察到了微弱的生物降解，而 TCs类抗生素和 AZN并未观察到生物降解。TAs在污泥上的吸附是一个自发的、放热的、焓变驱动的、由表面反应控制的可逆过程。TAs在活性污泥上的吸附能力由非疏水分配作用决定。TAs不同离子化形态的吸附能力有所差异。TCs、FQs和 AZN吸附能力最强的离子化形态分别为一价阳离子态、两性离子态和二价阳离子态。与缺氧条件相比，好氧条件有利于 TAs在活性污泥上的吸附。FQs在活性污泥工艺中的生物降解符合伪一级动力学模型，半衰期很长（> 100小时）。 （4）臭氧处理可以有效的去除污泥中的 TAs。臭氧投加量为 102mg O3g–1MLSS，pH = 7.2时，污泥中各种 TAs的总体去除率均在 86%以上。TAs的总体降解及吸附态 TAs的去除均符合伪一级动力学，而溶解态TAs浓度随时间的变化可以用连续反应动力学模型描述。吸附态 TAs脱附及溶解态 TAs的臭氧氧化是污泥臭氧处理过程中 TAs降解的主要途径。初始 pH上升（5.0–9.5）对污泥臭氧处理过程中 TAs的降解具有促进作用。 （5）进水中 TAs（每种浓度 100 μg L–1）的存在没有对 SBR和 A/A/O系统的 COD、TN、NH4+ -N和 TP的去除性能产生明显的影响。SBR及 A/A/O污泥臭氧原位减量工艺出水中 TAs浓度均在一定范围内波动，表明活性污泥系统在长期运行过程中保持了相对稳定的 TAs去除性能，而且臭氧处理后污泥回流及剩余污泥零排放没有对两系统中活性污泥的 TAs吸附能力造成明显影响。污泥臭氧原位减量工艺不仅可以实现污泥的大幅减排，还可以显著降低污泥中 TAs的含量。每日质量衡算表明 TAs在污泥臭氧原位减量工艺中的变化是一个输入和输出渐趋平衡的过程。 |
| 英文摘要 | The large amount of excess sludge not only is an important source of the antibiotic release to the environment, but also has long been a serious challenge to the activated sludge process. The process simultaneously achieving sludge reduction and antibiotic removal from sludge is of great significance to the control of secondary pollution caused by excess sludge. The in-situ sludge reduction has aroused great interest due to the limited capacity and high operation cost of the conventional sludge treatment and disposal. Thus, the antibiotic removal in the in-situ sludge reduction process deserves great attention. However, to date, the relevant studies on this have been still limited.Ozone is a strong oxidant which could oxidize multiple organic pollutants in water. Moreover, ozonation is also an effective method for sludge solubilization, which could constitute the in-situ sludge reduction process based on lysis-cryptic growth of microbes along with the activated sludge system. This study selected 3 tetracyclines (TCs: tetracycline (TCN), oxytetracycline (OTC), doxytetracycline (DOX)),5 fluoroquinolones (FQs: norfloxacin (NOR), ofloxacin (OFL), ciprofloxacin (CIP),lomefloxacin (LOM), enrofloxacin (ENR)), and 1 macrolide (azithromycin (AZN)) as target antibiotics (TAs), and clarified the removal of TAs in the in-situ sludge ozone-reduction process. The sludge reduction efficiencies and wastewater treatment performance of SBR and A/A/O in-situ sludge ozone-reduction processes were first investigated through a series of batch experiments and the continuous operation of simulated treatment systems. Then, a series of batch experiments were conducted to clarify the mechanisms of TAs removal and the characteristics of TAs sorption and biodegradation in the activated sludge process, which not only provides an insight into the behavior of TAs in the activated sludge procsss, but also lays a foundation for the study on TAs removal during the in-situ sludge ozone-reduction process. Thereafter, batch experiments were carried out to clarify the TAs removal efficiencies, degradation processes, and impact factors during sludge ozonation. Finally, the removal of TAs in the SBR and A/A/O in-situ sludge ozone-reduction processes was investigated through the continuous operation of the simulated treatment systems. The main conclusions are as follows: (1) Ozonation could exhibit good sludge-solubilization performance, resulting in a significant increase in the aqueous concentrations of soluble COD (SCOD), total nitrogen (TN), and total phosphorus (TP). Alkaline initial pH facilitated the sludge solubilization and the release of organic matters and N, while the sludge solubilization was inhibited by highly alkaline pH. Acidic initial pH favored the P release during sludge ozonation. The ozonated sludge recycle did not significantly influence the microbial activity and the removal of COD, organic nitrogen, and ammonia (NH4+ -N) in the SBR, but obviously decreased the P removal. The removal efficiencies of TP and phosphate (PO43- -P) exceeded 80% at Ca/P molar ratio 10.0, which was much higher than the theoretical value. After P recovery, the SCOD and TN concentrations in sludge supernatant were decreased slightly. (2) The optimal ozone dose for the sludge ozonation module in the A/A/O in-situ sludge ozone-reduction process was about 100 mg O3 g1 MLSS, at which the solubilization ratio reached 35.5%. The maximum sludge reduction efficiency of 85% could be achieved under this ozone dose in the A/A/O in-situ sludge ozone-reduction process. Ozonated sludge recycle caused little changes in COD and N removal, MLVSS/MLSS ratio, and sludge activity in the A/A/O module, but enhanced the activated sludge settleability. However，the deterioration of P removal was observed.The overall mass balances of COD and N reveal that the ozonated sludge recycle could enhance the organic mineralization and denitrification in the A/A/O module. The daily mass balance of P indicates that the P recovery module could recover 29% of the input phosphorus, which partially restored the P removal capability. (3) The presence of TAs (100 μg L1 each) exhibited little inhibition on the sludge bioactivity. Sorption was the primary removal pathway of TAs in the activated sludge process, while hydrolysis and volatilization could be negligible. The biodegradation was observed for FQs, but not for TCs and AZN. The sorption of TAs on activated sludge was a spontaneous, exothermic, enthalpy-driven, and reversible process, which was governed by surface reactions. The sorption affinity of TAs with activated sludge was determined by the hydrophobicity-independent mechanisms. Different ionized species of TAs possessed different sorption affinity with activated sludge. For TCs, FQs, and AZN, the ionized species possessing the strongest sorption affinity with activated sludge were monovalent cations, zwitterions, and divalent cations, respectively.Aerobic condition facilitated the sorption of TAs on activated sludge comparing with anoxic condition. The biodegradation of FQs followed the pseudo-first-order kinetic model, with long half-lives (> 100 h). (4) TAs in excess sludge could be effectively removed by sludge ozonation. The total removal efficiencies of TAs in sludge reached over 86% at 102 mg O3 g1MLSS and pH 7.2. Both the total degradation of TAs and the removal of sorbed TAs during sludge ozonation followed the pseudo-first-order kinetic model, whilst the consecutive reaction model could well express the changes of dissolved TA concentrations with reaction time. The desorption of sorbed TAs and their subsequent oxidation by ozone in the liquid phase constituted the main route for TAs degradation during sludge ozonation. The increasing initial pH (5.0–9.5) facilitated TAs degradation during sludge ozonation. (5) The presence of TAs (100 μg L1 each) in the influent exerted little influence on the removal of COD, TN, NH4 + -N, and TP in the SBR and A/A/O systems. The concentrations of TAs in the effluent of the SBR and A/A/O systems fluctuated in a certain range, suggesting that the removal capability of TAs by the activated sludge system remained relatively stable in the long-term operation. Furthermore, the sorption affinity of TAs with activated sludge was not significantly changed by the ozonated sludge recycle and zero sludge discharge. Significant reduction of sludge discharge and TAs concentrations in sludge could be achieved simultaneously in the in-situ sludge ozone-reduction process. The daily mass balance indicates that the variations of TAs in the SBR and A/A/O in-situ sludge ozone-reduction processes were a process in which the balance between TAs input and ouput was achieved gradually. |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/36966]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 汪鲁. 污泥臭氧原位减量工艺中典型抗生素的去除研究[D]. 北京. 中国科学院研究生院. 2016. |
入库方式： OAI收割
来源：生态环境研究中心
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。