煤气化废水是典型的高毒性难降解工业废水。生物处理工艺承担了大部分有机和含氮污染物去除的任务，然而实际生物处理工艺运行不佳，导致出水污染物浓度较高，对零排放工艺的运行成本和效率造成较大压力。针对上述问题，本论文在对实际生物处理工艺关键问题解析的基础上，探究微氧强化厌氧水解的效果和机理，考察剩余污泥吸附及耦合厌氧水解的预处理效果，最后构建基于剩余污泥吸附耦合微氧水解强化预处理的实际煤气化废水新型生物处理工艺。通过解析国内典型实际煤气化废水生物处理工艺沿程，发现传统厌氧水解对污染物去除率低且毒性削减效果较差，导致生化出水COD、NH4+-N和总酚（Tph）浓度分别高达500-600、70-100 mg/L和50-80 mg/L。强化厌氧水解提高煤气化废水中污染物的去除和毒性的削减能力是保证生物处理工艺效率的关键。构建小试微氧强化厌氧水解的长期连续运行装置，探究其对实际煤气化废水的处理效果和机理。当溶解氧浓度为0.2-0.3 mg/L时，COD和Tph的去除率分别提高了14.9和24.0%。证实了微生物和功能酶的活性的增加，胞外聚合物和蛋白含量的增加，及相关功能微生物和功能酶基因的富集是其主要作用机理。进一步以特征毒性难降解有机物邻苯二酚为研究对象，在短期和长期作用两个维度分别探究了微氧强化水解的机理。短期作用机制中，微氧参与邻苯二酚开环反应，邻苯二酚加氧酶等关键功能酶活性显著提高，氧气作为电子受体参与降解反应加速了有机物降解的电子传递。长期作用中，微氧环境富集了与酚类降解相关的微生物，同时增加了与邻苯二酚有氧代谢相关的功能酶基因丰度。为进一步提高对实际煤气化废水毒性的缓冲能力，探究了剩余污泥吸附预处理及耦合厌氧水解的效果。发现剩余污泥吸附对煤气化废水中COD和NH4+-N去除率分别为20.4%和15.1%。同时，剩余污泥吸附耦合厌氧水解后对污染物的去除效率显著提高（COD去除率提高了17.7%），同时显著提高了废水可生化性。最后构建基于剩余污泥吸附耦合微氧水解强预处理的耦合生物处理工艺。传统工艺生化出水COD、NH4+-N、Tph和TN平均浓度分别为：427.9、37.5、46.8和65.5 mg/L，而耦合工艺生化出水各污染物浓度显著降低，分别为：262.8、14.2、6.32和41.2 mg/L。新型耦合工艺相较传统工艺效率显著提升具有实际应用潜力。
Coal gasification wastewater is a typical highly toxic industrial wastewater. The biological treatment process undertakes most of the organic and nitrogenous pollutant removal tasks, however, the poor operation of the actual biological treatment process leads to high pollutant concentration in the effluent, which puts more pressure on the operation cost and efficiency of the zero discharge process. To address the above problems, this thesis explores the effect and mechanism of microaerobic enhanced anaerobic hydrolysis based on the analysis of key issues of the actual biological treatment process, investigates the pretreatment effect of residual sludge adsorption and coupled anaerobic hydrolysis, and finally constructs a new biological treatment process for actual coal gasification wastewater based on residual sludge adsorption coupled with microaerobic hydrolysis enhanced pretreatment.By analyzing the biological treatment process of typical domestic coal gasification wastewater, it is found that the traditional anaerobic hydrolysis had low pollutant removal and poor toxicity reduction performance, resulting the COD, NH4+-N and total phenol (Tph) concentrations in biochemical effluent were as high as 500-600, 70-100 mg/L and 50-80 mg/L, respectively. Toxicity reduction ability is the key to ensure the efficiency of biological treatment process.A small pilot micro-oxygen-enhanced anaerobic hydrolysis with long-term continuous operation was constructed to investigate the treatment effect and mechanism on actual coal gasification wastewater. When the dissolved oxygen concentration was 0.2-0.3 mg/L, the removal rates of COD and Tph were increased by 14.9 and 24.0%, respectively. It was confirmed that the increase of microbial and functional enzyme activities, the increase of extracellular polymer and protein content, and the enrichment of related functional microorganisms and functional enzyme genes were the main mechanisms of action.The mechanism of enhanced hydrolysis by micro-oxygen was further investigated in two dimensions of short-term and long-term effects, respectively, using the characteristically toxic and refractory organic catechol as the target. In the short-term action mechanism, micro-oxygen participated in the ring-opening reaction of catechol, the activity of key functional enzymes such as catechol oxygenase was significantly increased, and oxygen participated in the degradation reaction as an electron acceptor to accelerate the electron transfer for organic degradation. In the long-term action, the micro-oxygen environment enriched microorganisms related to phenol degradation, while increasing the abundance of functional enzyme genes related to the aerobic metabolism of catechol.To further improve the buffering capacity against the toxicity of actual coal gasification wastewater, the effects of residual sludge adsorption pretreatment and coupled anaerobic hydrolysis were investigated. It was found that residual sludge adsorption removed 20.4% and 15.1% of COD and NH4+-N, respectively, from the coal gasification wastewater. Meanwhile, the removal efficiency of pollutants was significantly improved by residual sludge adsorption coupled with anaerobic hydrolysis (COD removal rate increased by 17.7%), while the wastewater biochemically was significantly improved.Finally, a coupled biological treatment process based on residual sludge adsorption coupled with strong pretreatment by micro-oxygen hydrolysis was constructed. The average concentrations of COD, NH4+-N, Tph and TN in the biochemical effluent of the conventional process were 427.9, 37.5, 46.8 and 65.5 mg/L, respectively, while the concentrations of each pollutant in the biochemical effluent of the coupled process were significantly reduced to 262.8, 14.2, 6.32 and 41.2 mg/L. The new coupled process has practical potential to improve the efficiency compared with the conventional process. The new coupling process has practical potential for application.
