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题名: 微波及其组合工艺强化污泥厌氧消化及改善脱水性能研究
作者: 刘吉宝
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: 魏源送
关键词: 预处理,剩余污泥,微波,脱水,厌氧消化,流变性 ; Pretreatment, Waste activated sludge, Microwave, Dewatering, Anaerobic digestion, Rheology
其他题名: Application of microwave and its hybrid processes for enhancing sludge anaerobic digestion and dewatering
学位专业: 环境工程
中文摘要:       污泥脱水、厌氧消化是污泥处理处置尤为重要的两个技术单元。污泥中水和有机物复杂的分布形态导致污泥脱水和厌氧消化的效率低,而如何经济高效地强化污泥脱水和厌氧消化,目前在强化机制上仍然认识不足。本文应用中温常压微波加热技术,结合酸、碱、H2O2 投加和长期厌氧消化的运行试验研究,考察了不同预处理工艺对污泥脱水性能和厌氧消化的影响,优化了基于微波预处理的强化污泥脱水调质工艺和强化污泥厌氧消化工艺,探索了预处理影响污泥脱水性能以及强化厌氧消化的作用机制。
      比较了微波及其不同组合工艺(微波-酸,微波-碱,微波-H2O2,微波-H2O2-碱)对污泥脱水性能和产甲烷潜势的影响,分别优化确定了强化污泥脱水的微波-酸预处理工艺和强化污泥厌氧消化的微波-H2O2-碱预处理工艺。强化污泥脱水的预处理调质工艺优化条件为:先调节污泥的pH 为2.5,然后加入生石灰30~60mg/g TS(3~6%),立即微波加热到80~90℃,加热过程保持搅拌混合。经该工艺调质后,污泥经隔膜压滤机压滤,污泥含水率降低到约74%。机制研究表明,微波加热温度与pH 对污泥脱水性能产生重要影响。温度升高可以更大程度地破解污泥,利于结合水的释放;低pH 利于污泥颗粒团聚长大,避免释放的大分子有
机物对水分子的束缚。有机物分子量分布和三维荧光光谱分析的结果表明,分子量在104~105 Daltons 的大分子蛋白质类有机物含量及其性质是影响污泥脱水性能的关键因素。
      微波-H2O2-碱预处理工艺可使污泥厌氧消化产甲烷潜势提高25~30%。但由于H2O2 在微波处理过程中分解不完全,残留H2O2 抑制后续的厌氧消化,主要表现为:1)残留H2O2 抑制了厌氧消化水解酸化微生物的代谢活性,导致蛋白质、多糖等大分子有机物的水解速率降低;2)残留H2O2 在厌氧消化初期显著抑制了产甲烷古菌的活性,在高剂量H2O2(>0.6 g/g TS)投加时,厌氧消化初期产甲烷停止,但随着厌氧消化的进行,产甲烷古菌的活性能够恢复。此外,高剂量H2O2投加导致大量惰性物质的生成,降低了污泥产甲烷潜势。
      综合考虑残留H2O2 的抑制和预处理的能量消耗,确定了基于微波-H2O2-碱部分预处理的强化污泥中温厌氧消化工艺。长期半连续运行结果表明,尽管该预处理导致了较高的氨氮释放,但并未发生明显的氨氮抑制现象,该工艺能够长期稳定运行,强化厌氧消化的效果明显。当SRT=20 d,日产甲烷量提高了约20%,VS 去除率提高了30%;SRT 为15d 时,日产甲烷量提高了26~36%。预处理不仅利于缩短污泥厌氧消化的停留时间,提高了反应器内功能性细菌、古菌的相对丰度,而且提高了污泥的流动性,降低了污泥粘弹性,利于污泥的搅拌传质。
      综上所述,基于中温常压的微波预处理能够强化污泥脱水和厌氧消化,今后需进一步加强基于微波预处理的强化污泥脱水和厌氧消化的应用研究,为污泥减量化、资源化和稳定化提供新途径。
英文摘要:       Sludge dewatering and anaerobic digestion are important technologies in sewage sludge treatment and disposal. Due to the complex structures of sewage sludge, water and organics are highly tied in sludge flocs or microbial cells, resulting the limited efficiency of sludge dewatering or anaerobic digestion. In addition, the mechanism of sludge dewatering and anaerobic digestion enhanced by pretreatment is still unclear. Thus, the purposes of this study were to detemine and optimize microwave and its hybrid pretreatment processes for enhancing sludge dewatering and anaerobic digestion,respectively, through investigating the impacts on sludge dewatering and anaerobic digestion, as well as exploring the mechanisms for enhancing sludge dewatering and anaerobic digestion.
      With the comparison of effects of microwave and its hybrid pretreatment processes on sludge dewaterability and methane production potential, including microwave, microwave-acid, microwave-alkaline, microwave-H2O2 and microwave-H2O2-alkaline, the microwave-acid pretreatment presented the highest efficiency for enhancing sludge dewaterability, and the microwave-H2O2-alkaline could improve sludge methane production potential obviously. The optimised pretreatment process for enhancing sludge dewaterability was determined as follows. Firstly, H2SO4 solution was added to adjust pH to 2.5. Then, lime was added with dosage of 30-60 mg/g TS (3-6%). Finally,sludge was heated to the target temperature of 80-90℃ with microwave irradiation.The water content of dewatered sludge can be reduced to approximately 74% with filter press. Both microwave heating temperature and pH presented important impact on sludge dewaterability. The high temperature was beneficial for sludge flocs disintegration, but the released soluble polymers would result in high negatively surface charge, and finally deteriorate sludge dewaterability. The acidification treatment could avoid the disadvantage of released soluble polymers and decrease bound water content. According to the analysis of molecular weight distribution and 3D-EEM, the fractions of polymers especially protein-like substances at molecular weight of 104-105 Daltons were the key organics related to sludge dewaterability.
      The biochemical methane production potential of sludge was increased by 25-30% with microwave-H2O2-alkaline pretreament. However, due to the fraction of H2O2 that was not decomposed existed in the pretreated sludge, anaerobic digestion was inhibited in the initial stage. The residual H2O2 inhibited metabolic activity of microorganism. In the hydrolysis-acidification stage, hydrolase activity was inhibited mildly, resulting in decreasing hydrolysis rate of proteins and polysaccharides. In the methanogenesis stage,residual H2O2 especially with high dosage (>0.6 g/g TS) pretreatment had acute toxic effect on methanogens. The methanogenesis process even ceased in the initial period,and could recover in the following period. Moreover, large amounts of refractory compounds generated with high dosage H2O2 pretreatment, which led to the decrease of sludge methane production potential.
      Considering the effect of residual H2O2 inhibition and energy consumption, the part-stream microwave-H2O2-alkaline treatment combined with mesophilic anaerobic digestion for treating concentrated sludge was determined. This process operated stably for more than 3 SRTs, though with high level of ammonia and pH in digesters. At SRT of 20 d, the daily methane production was increased by approximately 20%, and VS reduction efficiency was increased by 30%. At SRT of 15 d, the daily methane production was increased by approximately 26-36%. Both pretreatment and two stage anaerobic digestion were beneficial for decreasing SRT. Moreover, pretreatmeat improved the relative abundance of functional microorganism in anaerobic digestion, as well as the improved flowability of digested sludge and the decreased viscoelastic behavior of digested sludge. These effects were beneficial for sludge pumping or mixing processes.
      It is obvious that sludge dewatering and anaerobic digestion can be effectively enhanced by microwave irradiation under low temperature and ambient pressure combined with acid, alkaline and H2O2 addition, and more application research of enhancing sludge dewatering and anaerobic digestion by microwave and its hybrid pretreatment processes should be carried out in order to promote sludge reduction, resource recovery and stabilization in practice.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/36895
Appears in Collections:水污染控制技术研究室_学位论文

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Recommended Citation:
刘吉宝. 微波及其组合工艺强化污泥厌氧消化及改善脱水性能研究[D]. 北京. 中国科学院研究生院. 2016.
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