【作者】 邓康；

【导师】 黄少斌；

【作者基本信息】 华南理工大学 ， 环境科学， 2010， 硕士

【摘要】 随着中国经济的快速发展,近年来大量的氮、磷排入水体引起严重的水体富营养化,导致水质恶化以至湖泊退化,严重时造成水体黑臭。我国大约有25%的湖泊都受到不同程度富营养化的影响。因此,研究和开发出高效、经济的生物脱氮技术已成为当前研究的热点。通过采用某钢铁厂含氮废水,利用曝气生物滤池工艺,研究了曝气生物滤池的启动与挂膜,并对影响反硝化脱氮的因素(溶解氧、碳氮比、pH、温度等)进行详细的分析研究。结果表明,利用含反硝化菌的富集菌液进行挂膜,16 d基本完成挂膜,脱氮率大于90%。当溶解氧较低时(DO为1.5～4.2 mg/L),随着溶解氧的增大,反硝化效率提高。其中,以DO为3.5 mg/L时的效果最好,脱氮率为95.4%。随着曝气量继续增加,脱氮率有所下降,当DO为8.0 mg/L时,脱氮率仍有44.8%。可推断系统中有好氧反硝化菌,存在以硝态氮和O2作为电子受体的好氧反硝化现象。随着碳氮比(COD/N)增大,反硝化效果提高。当COD/N为6～7时,基本能够满足反硝化所需碳源。此时脱氮率大于93%,亚硝态氮在整个反应过程中几乎没有积累,COD去除率在85%左右。碳源种类对反硝化影响存在差异。其中,以葡萄糖和乙醇作为外加碳源时效果最佳,脱氮率分别是92.9%、95.8%,几乎没有亚硝酸的积累(最高时不超过0.25 mg/L)。乙酸钠做碳源时有亚硝酸的积累,最高达5.79 mg/L,积累率为0.96%。当不投加外部碳源时(内碳源),通过内源呼吸代谢作用进行反硝化效果最差,脱氮率仅有18.8%。将系统的温度控制在22.5℃~33.1℃的范围内将产生比较好的脱氮效果。反硝化最佳pH值为7.0~8.0。研究发现,在反硝化过程中pH不断上升直至反硝化结束,转而持续下降出现拐点;ORP则减速下降,当反硝化结束时保持不变。改变起始pH值、初始硝酸盐的浓度,ORP、pH值的变化规律基本一致,ORP变化曲线、pH变化曲线上出现特征点,出现的时间也很相近。因此,可以通过pH和ORP的变化规律判断反硝化的结束。将反应器内的反硝化菌经选择性培养基初筛,好氧反硝化复筛,得到菌种X1,为短杆菌,革兰氏阴性菌,经16S rDNA序列同源性分析,结合生理生化分析,该菌与恶臭假单胞菌(Pseudomonas putida)最为相似。更多还原

【Abstract】 In recent years ,with the rapid growth of economy in China, ,a large number of nitrogen and phosphorus discharged into the water,which have caused serious eutrophication, resulting in the quality of water depravation or the lake degenerate, seriously the water was black and olid. Probably 25% of the lakes are influenced by eutrophication in various degrees in our country. So, developing high efficiency biofilm Nitrogen-removal method is the hot issues of research.The compound inoculation and startup were investigated, and the influences of nitrogen-removal (such as dissolved oxygen, COD/N ratio, pH, temperature, and so on) in biological aerated filter were tested in details while treating nitrate wastewater from an iron factory. The results showed that the nitrogen removal rate was more than 90% after 16 days’cultivation using enrichment containing, which included denitrifying bacteria. the efficiency of denitrification was improved, when the concentration of dissolved oxygen was increased from 1.5 to 4.2 mg/L .When dissolved oxygen value was 3.5 mg/L, the efficiency was the best, it was 95.4%; but the result was opposite when it were increased. Even through dissolved oxygen value was 8.0 mg/L; the efficiency was still 44.8%.it can be inferred that there were aerobic denitrifer, nitrate and oxygen were the electron accepter during denitrification. The efficiency of aerobic denitrification was improved. When COD /N were 6-7, it can meet the requirement for carbon source during aerobic denitrification, the removal rate of nitrate nitrogen and COD were up to 3%, 85% respectively. Almost no nitrite nitrogen accumulated. Different carbon resource had different effect on denitrification. The nitrogen removal rate were 92.9%,95.8% respectively when using grape sugar and ethanol as carbon resource, there was no nitrite nearly.The accumulation of nitrite was obviously up to 5.79 mg/L(the accumulation rate of nitrite was 0.96%) when using sodium acetate as carbon resource. No accumulation of nitrite was measured when other carbon sources were used. There was low nitrogen removal rate (18.8%) by endogenous respiration without carbon sources added. There was a good denitrification, when temperature was 22.5℃~33.1℃, pH value was7.0~8.0.During experiment, we found that pH increased till denitrification stopped, then decreased, showing a turning point. ORP decreased quickly and then slowly, when denitrification stopped, ORP value was steady. The results showed that initial pH and nitrate concentration were changed; there was no change in the variations of pH and ORP, and the feature points still appeared, and time was also close. So we could judge the end of denitrification by changes of pH and ORP.A special method emphasized on nitrogen removal for cultivating denitrifying bacteria was employed. The strain X1 was gram positive and spherical. The strain X1 was identified as Pseudomonas putida based on its biochemical and morphological characters and phylogenetic analysis of 16S rDNA sequences (genbank accession NO.DQ836052.1).更多还原