Development of Effective Biological Treatment Process of Organic and Nitrogenous Substances in Wastewater

在废水生物处理过程中，有机物一般通过好氧微生物去除，而含氮物质则通过好氧硝化和厌氧反硝化相结合的方式去除。硝化器进行的硝化作用将氨转化为亚硝酸盐和硝酸盐，反硝化作用将氮氧化物转化为氮气。本研究旨在开发一种有效的生物工艺，通过好氧和厌氧微生物在多孔颗粒载体中共存，同时去除废水中的有机和氮物质。本研究明确了影响有机和含氮物质同时去除的因素，为该工艺的开发奠定了工程基础。本研究的研究成果总结如下：采用设置一定厚度多孔膜的生物反应器模型，对多孔膜中微生物种类的空间分布进行了较为精确的分析。有机氧化菌、硝化菌和反硝化菌在多孔膜上的分布具有独特的规律。提出了一个考虑微生物生长和死亡动力学的数学模型，并成功地解释了微生物的分布。这些结果表明，好氧微生物和厌氧微生物的共存是可以人工形成的。为了获得同时去除废水中有机物和含氮物质的基础工程数据，构建了由多孔颗粒载体组成的连续流流化床生物反应器处理人工污水。反应器采用喷淋曝气好氧运行（DO=6 ~ 7ml/L），污水连续进料，水力停留时间8h。废水中碳氮比（C/N）在2.5 ~ 10之间变化。稳态时，当进水氮浓度为20 mg/L时，总氮去除率随C/N比从50%提高到85%，当进水氮浓度为40 mg/L时，总氮去除率在40 - 50%之间，与C/N无关。以实验结果为基础，对同时去除有机和含氮物质的微生物反应进行了动力学分析。得到了有机氧化、硝化和反硝化的速率常数，并发现其与有机负荷和进水氮浓度有关。在低C/N条件下，脱氮主要由反硝化作用完成，而在高C/N条件下，脱氮主要依靠微生物对氮的吸收。少

In biological wastewater treatment process, organic compounds are generally removed by aerobic microbes, while nitrogenous substances are removed by a combination of aerobic nitrification and anaerobic denitrification. Nitrification carried out by nitrifiers transfers ammonia to nitrite and nitrate, and denitrification reduces the nitrogen oxides to nitrigen gas. The present research aims to develop an effective biological process for simultaneous removal of organic and nitrogen substances in wastewater by cohabitation of aerobic and anaerobic microbes in porous particle carriers. This research made clear the factors related to the simultaneous removal of organic and nitrogenous substances, and laid the engineering foundation of developing such process. The research results obtained in the present research were summarized as follows.Using a model bioreactor installed with porous sheets of definite thickness, spatial distribution of microbial species in the porous sheets was analyzed qu … More antitatively. The organic oxidizing bacteria, nitrifiers and denitrifiers showed a unique distribution pattern in the porous sheets. A mathematical model taking microbial growth and death kinetics into account was proposed and successfully explained the microbial distribution. These results showed that cohabitation of aerobic and anaerobic microbes could be formed artificially.In order to obtain the basic engineering data for the simultaneous removal of organic and nitrogen substances in wastewater, a continuous-flow fluidized-bed bioreactor consisting of porous particle carriers was constructed to treat artificial sewage. The reactor was operated aerobically by aeration with a sparger (DO=6-7ml/L), and the sewage was fed continuously at a hydraulic retention time of 8h. Ratio of Carbon concentration to nitrogen concentration (C/N ratio) in the wastewater varied from 2.5 to 10. At the steady state, total nitrogen removal ratio increased from 50% to 85% with C/N ratio in case of influent nitrogen concentration = 20 mg/L,while in case of influent nitrogen concentration = 40 mg/L,the total nitrogen removal ratio was between 40 - 50%, independent of C/N ratio.Based on the experimental results, a kinetic analysis of the microbial reactions related to simultaneous removal of organic and nitrogenous substances was performed. The rate constants of orgainc oxidation, nitrification and denitrification were obtained and found to be dependent on the organic loading and influent nitrogen concentration. At low C/N ratio, denitrification contributed largely to the nitrogen removal, while nitrogen removal was mainly dependent on the nitrogen uptake by microbial growth at high C/N ratio. Less