【作者】 王辉；

【导师】 黄君礼；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2006， 硕士

【摘要】 随着我国农业的迅速发展以及化肥工业的兴起,化肥工业尿素废水的排放量急剧增加,由此带来的一系列环境问题突显出来,已引起环保领域和全球范围的广泛重视。通过筛选、比较,选择合适的工艺处理尿素废水,使尿素废水中的污染物成分含量降到最低,实现达标排放。该工艺由物理处理单元和生物处理单元两部分组成。物理处理单元选择吹脱技术,可去除尿素废水中大部分的NH3-N,降低生物处理的负荷。生物处理单元采用好氧-缺氧-好氧工艺对废水进一步处理,将NH₃-N的含量降到最低。通过小试的正交试验,分别得出竖向管束填料和球状填料脱氨塔的最佳工艺参数,均为pH值为11.0、气液比为3500∶1、温度为30℃。在最佳条件下,比较了2种填料对吹脱效率的影响。结果表明,竖向管束填料脱氨塔的NH3-N去除率比球状填料脱氨塔的NH₃-N去除率高出约15%,可达90%左右。然后根据小试的最佳工艺参数进行工程调试,综合考虑去除率和经济运行成本,生产运行脱氨塔的最佳工艺参数为pH值为10.5、气液比为3500∶1、温度为废水温度。运行稳定后废水的NH₃-N平均含量由243mg/L降为85mg/L,其吹脱效率可达到65%左右。采用脱氨塔去除尿素废水中的NH₃-N时,脱氨塔产生的废气中NH₃的浓度为37.5mg/m³、排放量为4.50kg/h,满足恶臭排放标准要求。通过对NH3扩散浓度预测,结果认为,本装置产生的NH₃无论是厂界浓度值还是居住区浓度值均满足相应的标准要求。通过对脱氨塔除氮机理的分析,认为竖向管束脱氨塔内为液滴传质,传质的效率高;管束内存在强烈的湍流剪切,可以实现水流的高分散状态,并为实现高传质的工况提供必要条件;而且在竖向管束的气流中充满着高强度的微涡旋,形成了强烈湍动的流态可加速水中的NH₃向空气中的迁移,大幅度增加了传质速率。将脱氨塔出水用好氧-缺氧-好氧工艺进一步进行生物处理,最终出水的NH3-N和COD含量平均为17.9mg/L和63.8mg/L,平均再去除率分别为72.3%和57.6%。用尿素废水对“吹脱+好氧-缺氧-好氧生物处理”工艺进行性能测试,数据显示除出水中的氰化物未达到设计要求之外,其它各项指标均达标。更多还原

【Abstract】 With the rapid development of agriculture and fertilizer industry, quantity of urea wastewater rapidly increased in our country. Environmental problems that brings attached more attention in the field of environmental protection even all the world.The suitable process treating urea wastewater was confirmed by comparing many ones. Pollutants were removed most efficiently and the effluent can be drained under the standard. The process is consists of physical unit and biological unit.NH₃-N in urea wastewater mostly was removed by air stripping as the physical unit and reduced the load of the biological unit. The wastewater was treated further by aerobic-anoxic-aerobic biological process as the biological unit and the content ofNH₃-N was reduced the most lowness.By the orthogonal experiments the optimum parameters of removingNH₃-N in pipe packed stripper and ball packed stripper are obtained that the value of pH, air-liquid ratio and temperature is 11.0, 3500, and 30℃respectively. The influence of the two different fillers to the removal rate is compared under the optimum conditions. The result shows that the removal rate ofNH₃-N in pipe packed stripper is 90%, higher than in ball packed stripper by about 15%. Based on the results we have carried out further study in plant plant. The optimum parameters in plant plant are obtained that the value of pH, air-liquid ratio and temperature is 10.5, 3500, and the same as wastewater respectively. The content ofNH₃-N was reduced from 243mg/L to 85mg/L by air stripping and the removal rate can reach about 65%.TheNH₃ concentration of off gas from ammonia stripper is 37.5mg/m3 and the emmission is 4.50kg/h under emission standards for odor pollutants. The results indicate that the concentration of plant boundary or habitation can meet the standard respectively.It was found that the high mass-transfer efficiency was due to drop mass transfer through mechanism analysis of the removal ofNH₃ in pipe packed stripper. The strong turbulent shear can bring high dispersion of wastewater current in the pipes and make it possible to transfer efficiently. The strong更多还原