【作者】 管凤伟；

【导师】 赵庆良；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2010， 博士

【摘要】 煤气废水是一种水质成分复杂、污染物种类繁多、生物毒性大的高浓度有机废水,具有COD浓度高、可生化性差、水质水量变化大、色度高等特点,是一种极难处理的工业废水。目前,生物法是煤气废水处理的主要方法,采用的工艺主要是活性污泥法,该工艺在处理过程中存在的主要问题是系统运行不稳定、对难降解有机物和NH₄⁺-N去除效果差等。本研究试图通过增加物理化学预处理法、改善生物处理的生化环境、添加固体矿物材料（硅藻土）、改变系统反应器构型及采用臭氧预氧化等方法,强化传统煤气废水生物处理效果。根据煤气废水的水质特征,本文提出:“酸化预处理-强化A/O-BAF-O₃-固定化生物活性炭（IBAC）”组合工艺处理煤气废水工艺路线,并开展了长时间的小试和中试实验研究。该工艺较好的解决了煤气废水中毒性物质对NH₄⁺-N和难降解有机物降解的抑制作用,提高了COD和NH₄⁺-N的总体去除效果。强化A/O-BAF生物处理工艺中,第一级好氧单元采用的是普通活性污泥法,在运行中稳定性较差,处理效果不理想,需要采取强化措施。本文采用硅藻土添加剂强化普通活性污泥工艺。由于煤气废水COD和NH₄⁺-N含量高、浓度变化幅度大,本研究采用以颗粒活性炭和沸石为生物载体的生物膜反应器构型作为缺氧池和二级好氧反应器构型,利用其对污染物吸附-生物再生和吸附-脱附原理,提高了COD和NH₄⁺-N的去除效果,减小了出水COD和NH₄⁺-N浓度的变化幅度。煤气废水生物处理出水可生化性较差,而单独采用物理化学法处理成本较高,需要通过化学法预氧化提高废水的可生化性,再接续生物处。本文采用O₃-固定化生物活性炭（IBAC）深度处理煤气废水生物处理出水,取得良好效果。煤气废水小试实验结果表明,酸化除油预处理可以有效地去除煤气废水中难生物降解的乳化焦油,改善污泥性状,强化后续生物处理效果;在废水酸化除油过程中添加少量小颗粒矿物材料,可以改善析出有机絮体的结构和密度,加速絮体的沉降,提高沉淀物的脱水率,强化废水处理效果。“强化A/O-BAF”生物处理段在进水COD较高的条件下可以稳定运行,其中一级好氧单元起到至关重要的作用。系统在平均进水COD为2210mg·L^-1、NH₄⁺-N含量为244mg·L^-1的条件下,COD和NH₄⁺-N去除率分别可达87.6%和80%,提高了常规的煤气废水生物处理功效;减少系统水力停留时间（HRT）后,对系统COD去除率影响不大,但影响NH₄⁺-N去除效果,NH₄⁺-N去除率降为67%。臭氧预氧化可以有效地去除废水的色度,对COD有一定的去除作用,在240mg·L^-1的投量下可以提高废水的可生化性;废水O₃-IBAC系统对COD去除效果较好,出水平均为87mg·L^-1,可以达到废水排放标准对COD的要求;对NH₄⁺-N的去除效果一般,处理出水的NH₄⁺-N平均浓度为45mg·L^-1,总去除率为49%。煤气废水生物处理中试实验表明,生物处理系统运行稳定,有机污染物去除效果好。其中,一级好氧单元的挥发酚的去除率可以达到99%,出水一般低于0.5mg·L^-1,已达国家一级排放标准,而该单元的COD和总酚的去除效果也很好,分别可达到80%和85%,强于小试实验结果;在进水COD大于2000mg·L^-1的条件下,系统总体COD和总酚的去除效果较好,去除率分别为83%和87%;系统COD容积负荷的变化对COD和酚类的去除率影响不大,然而提高负荷后,生物处理反应器中的水温应注意控制;生物处理系统NH₄⁺-N去除效果较差,总去除率为45%左右,低于小试实验结果,其中一级好氧单元NH₄⁺-N去除率降低了22%,二级好氧单元NH₄⁺-N去除率降低了36%,推测主要原因由于曝气生物滤池的操作控制问题引起的。本文通过实验考查了硅藻土添加剂对降解煤气废水微生物活性的强化效果,并研究了其强化机制。实验表明,硅藻土添加剂对微生物的活性具有明显的强化作用,每分钟溶解氧消耗量最高可增加27%左右;通过对比分析添加硅藻土及粉末活性炭对废水COD、挥发酚、pH、总酚和溶解氧浓度的影响特征,认为硅藻土对酚类物质的吸附及固体表面对溶解氧的富集作用是其强化微生物活性的主要机制。色谱-质谱联机（GC-MS）测试结果表明,废水生物处理过程中,有机物种类明显减少。缺氧单元主要去除一些结构复杂的有机物;废水中的有机污染物经过一级好氧单元处理后,大部分的短链烃和结构较简单的酚、酮、羧酸和脂类被降解,而一些结构复杂的杂环烃类和芳香烃类则残留下来;废水经二级好氧单元处理后,有机物种类进一步减少,主要残留下一些芳香酮和芳香酯类化合物。更多还原

【Abstract】 Coal gasification wastewater is a kind of high concentrated organic wastewater, which contains complicated ingredients and a great variety of pollutants and which is great toxic. It has the characteristics of high COD, being hard to biodegrade, great diversity quality and quantity and high color. As an industrial wastewater, it is very difficult to treat. At present, biological wastewater treatment method is the primary method used. The main process is mainly activated sludge process. In the process the main problems include the unstable system operation and low removal of persistent organic matters, NH₄⁺-N, etc. In this paper, we attempts to use the following ways to enhance biological treatment ratio of coal gas wastewater: to increase physical and chemical pretreatment method, to improve chemical and biological environment of the biological treatment, to add the solid mineral substance （diatomite）, to change the configuration of the system reactor, to use ozone pre-oxidation, etc.According to the characteristics of coal gasification wastewater, in the paper it is presented that: Combined Treatment Process Route of Coal Gasification Wastewater including acidification pretreatment enhanced A/O-BAF-O₃-immobilized biological activated carbon （IBAC）, and Laboratory-scale and pilot-scale experiments were carried out for long time. In the process solution, the inhibition of the decomposition of NH₄⁺-N and persistent organic substances due to toxic substances in coal gasification wastewater is resolved. Thus the total removal ratio of the COD and NH₄⁺-N is improved. In the enhanced A/O-BAF biological treatment process, aerobic unit in the first stage utilizes conventional activated sludge method which is less stable in operation without satisfactory treatment effect. Thus it is necessary to adopt the enhanced measures. In this paper, diatomite additives are used to enhance the conventional activated sludge process. As the content of COD and NH₄⁺-N in coal gasification wastewater is high and the concentration ranges are wide, in this study biofilm reactor configuration with the biological carrier made with the granular activated carbon and zeolite is used as the configurations of anoxic reactor and two-stage aerobic reactor: through the principle of the adsorption of pollutants biological regeneration and adsorption desorption, removal ratio of COD and NH₄⁺-N is increased and their concentration ranges in the output water are reduced. For biological degradability of coal gas wastewater is low and the single use of physical-chemical treatment is high in the cost, it is necessary to improve biological degradability of coal gasification wastewater through chemical pre-oxidation method, and then go on biological treatment. In this paper, advanced treatment of O₃-immobilized biological activated carbon （IBAC） achieved good results.Laboratory-scale experiment results show that acidification and degreasing pretreatment can effectively remove persistent emulsified tar in coal gasification wastewater, improve the sludge characteristics and strengthen the follow-up biological treatment ratio; in wastewater acidification and degreasing process, adding a small amount of small mineral particles can improve the structure and density of precipitated organic floc, speed up the settlement of floc, improve the dehydration rate of sediment and strengthen wastewater treatment effect.“Enhanced A/O-BAF”biological treatment section can remain stable operation under conditions of high COD in the input wastewater and the first-stage aerobic unit plays a crucial role. Under the conditions of the average 2210mg·L^-1 COD and 244mg·L^-1 NH₄⁺-N in the input wastewater, in the system removal ratios of COD and NH₄⁺-N are respectively 87.6% and 80%, and performance of conventional biological treatment of coal gasification wastewater is increased; reducing system hydraulic retention time （HRT） has little effect on the COD removal ratio of the system, but removal ratio of NH₄⁺-N is affected, reduced to 67%. Ozone pre-oxidation can effectively remove the chroma of wastewater and it is helpful to the removal of COD. With the dosage of 240mg·L^-1, bilogical degradability of wastewater can be increased; wastewater O₃-IBAC system has good COD removal ratio with the average 87mg·L^-1 in output water and COD emission standard can be met. While it has ordinary treatment ratio on NH₄⁺-N, with the total removal ratio of 49% for 45mg·L^-1 NH₄⁺-N in input wastewater.Pilot-scale experiment results of coal gas wastewater show that the biological treatment system is running stable with good removal ratio of organic pollutants. In the first–stage aerobic unit, removal ratio of volatile phenol can reach 99% and its output concentration in wastewater is generally lower than 0.5mg·L^-1 which has reached the national emission standard, while in the unit also very good, respectively 80% and 85% which is better than the small-scale test results; under the condition of COD exceeding 2000mg·L^-1 in the input wastewater, overall removal ratio of COD and total phenol in the system is very good, respectively 83 % and 87%; in the system change in COD volumetric load has little effect on removal ratio of COD and phenol, but with the increased load, it is necessary to pay attention to control water temperature the biological treatment reactor; NH₄⁺-N removal ratio in biological treatment system is low with a total removal ratio of about 45% which is lower than the results of small-scale experiments: NH₄⁺-N removal ratio in the first-stage aerobic unit was reduced by 22%, and NH₄⁺-N removal ratio in the second-stage aerobic unit was reduced by 36%. It is speculated that it is mainly caused by the control operation of BAF.In the paper the enhanced effect of diatomite additive on biological activity of the microbe which decomposes coal gasification wastewater as well as its enhancing mechanism is studied through tests. Experiments show that the diatomite additive has significantly enhancing role on the microbial at most, the maximum increase of about 27%; by comparative analysis of the effect characteristics of adding diatomite and activated carbon on wastewater COD, volatile phenol, pH, total phenol and dissolved oxygen concentration, it is believed that the adsorption of phenolic substances by diatomite and the accumulation of dissolved oxygen on the solid surface is the primary mechanism of its enhanced microbial activity.GC-MS test results show that in biological wastewater treatment process, the organic substance varieties decrease significantly. Hypoxia unit is mainly used to remove some organic compounds with the complex structure; in organic pollutants in wastewater through an aerobic treatment, most of the short-chain hydrocarbons and phenols, ketones, carboxylic acids and lipids with the relatively simple structure are degraded, while some heterocyclic and aromatic hydrocarbon with complex structure are left; through wastewater treatment in two-stage aerobic units, the organic substance varieties are further reduced with the main residue of some aromatic ketones and aromatic esters.更多还原