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CASS工艺在寒冷地区城市污水处理中的优化运行研究

Optimal Operation of Cyclic Activated Sludge System (CASE) in Cold Areas for Municipal Wastewater Treatment

【作者】 郑飞

【导师】 陈志强; 申玉坤;

【作者基本信息】 哈尔滨工业大学 , 环境工程, 2011, 硕士

【摘要】 齐齐哈尔市是我国纬度较高的城市之一,气温较低并且冰封期长。整个城市只有一座10万m3/d的城市污水处理厂和一个20万m3/d的氧化塘。随着城市面积的不断扩大,城市污水量日益增加,高峰时水量远远超过了氧化塘所能承受的负荷。经过经济技术论证污水处理厂的二期工程选择了CASS工艺。目前,CASS工艺多用于工业废水的处理和纬度较低的城市污水处理。CASS工艺在寒冷地区应用的具体运行参数和运行方式需要进一步研究。本课题的研究以城市生活污水为处理对象,构建CASS工艺的小试系统以模拟齐齐哈尔市南郊污水处理厂的二期工艺,通过试验研究,考察运行参数的改变对CASS工艺处理效果的影响,以得到CASS工艺在寒冷地区运行的优化参数,掌握CASS工艺特性,探寻其降解有机物及脱氮除磷的规律。试验调节了进水历时、污泥回流比、曝气时间、反应区配比、充水比、污泥龄、溶解氧这7个因素。试验结果显示COD和氨氮受各因素的影响最小,两者的去除效率都很高并且十分稳定。总氮和总磷的去除效果受各因素的影响较大,其中污泥回流比、曝气时间和曝气末段溶解氧对总氮的去除效果影响最大,污泥龄和曝气末段溶解氧对总磷的去除效果影响最大。生物脱氮除磷是两个相互冲突的过程,综合各个因素的影响最优运行参数为:进水历时4h,污泥回流比100%,曝气时间2h(进水2h后开始曝气),生物选择区、预反应区和主反应区的容积比例1:8:27,污泥龄15d,曝气末段溶解氧3.0mg/L。在该运行条件下温度降到10℃左右时出水各项指标仍可以稳定达标。对整个周期连续取样,试验结果表明进水不曝气的2h中整个反应器中的硝酸盐氮得到了大量的去除。另外硝酸盐氮浓度的降低使得聚磷菌可以更充分的进行释磷,主反应区也发生了明显的释磷现象,最终污泥的释磷量达到进水总磷含量的9.5倍。长时进水短时曝气的运行模式有利于硝化细菌的生长。

【Abstract】 Qiqihar is one of our cities with higher latitudes, low temperatures and long period of ice. The whole city has only a 100 thousands m3/d of municipal wastewater treatment plant and a 200 thousands m3/d of the oxidation pond. With the continuous expansion of urban areas, increasing the amount of, the peak of urban sewage far beyond the oxidation pond can bear the load. After the economic and technical feasibility studies of the second phase of the sewage treatment plant is selected CASS.Currently, CASS process used for industrial wastewater treatment and municipal sewage treatment in lower latitudes. CASS process in the cold regions of the specific operating parameters and operation mode needs further study. The research project of urban sewage was treated, building a small test system of CASS process to simulate the Phase II for the southern suburbs of the sewage treatment plant in Qiqihar. Through experimental research, changes in operating parameters investigated on the effect of CASS Process. Get the optimization parameters for CASS process running in the cold regions. Master the characteristics of CASS process, exploring the law for degradation of organic compounds and nitrogen and phosphorus removal.Test regulates influent time, sludge return ratio, aeration time, ratio of reaction zone, water filling ratio, SRT and DO. The results showed that COD and ammonia nitrogen by the minimal impact of various factors, both the removal efficiency is very high and very stable. Removal of total nitrogen and total phosphorus greatly influenced by various factors. Sludge return ratio, aeration time and last paragraph of dissolved oxygen aeration of greatest impact on total nitrogen removal. SRT and last paragraph of dissolved oxygen aeration of greatest impact on total phosphorus removal. Biological nitrogen and phosphorus removal is two conflicting processes. Comprehensive impact of various factors, the optimal operating parameters for the influent time 4h, sludge return ratio 100%, aeration time 2h (2h influent after aeration), biological selection, pre-reaction zone and the main reaction zone volume ratio 1:8:27, SRT 15d , the last paragraph of dissolved oxygen aeration 3.0mg/L. Under the operating conditions when the temperature dropped to around 10℃effluent standards of the indicators can still be stable. Continuous sampling of the entire cycle, the results show that two hours without aeration for influent make a lot of nitrate nitrogen removal in the reactor. Also the reducing for the concentration of nitrate nitrogen make that the Phosphate accumulating bacteria can be more fully phosphorus release. The main reaction zone also has an obvious phenomenon of phosphorus release. The total amount of phosphorus released can reach 9.5 times as large as the amount of influent phosphorus. The mode of long influent and short aerobic is conducive to the growth of nitrifying bacteria.

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