【作者】 牛曼；

【导师】 张小平；

【作者基本信息】 华南理工大学 ， 环境工程， 2010， 硕士

【摘要】 本课题采用海藻酸盐包埋法对蛋白核小球藻和好氧活性污泥进行混合固定化,在自制的流化床光生物反应器中,将藻菌共生、固定化、流态化等技术组合起来,以达到对高浓度有机废水高效处理的目的。通过采用氯化钡代替部分氯化钙作为固定液和壳聚糖覆膜两种方法,对传统藻酸盐固定化方法进行改进。研究发现采用壳聚糖覆膜的方法,能很好改善固定化小球的稳定性,且对COD、氨氮和磷酸盐的去除影响不大。之后考察了壳聚糖溶液的pH值、质量浓度和覆膜时间对去除率和小球稳定性的影响。结果表明污染物的去除率随着壳聚糖质量浓度和覆膜时间的增加而降低,随着pH值的增加而增大,小球的稳定性则具有相反的变化趋势。因此综合考虑固定化小球的稳定性和对污染物的处理效果,确定最佳的壳聚糖溶液的质量浓度、pH值和覆膜时间分别是:1%、5.5、15min。固定化小球的粒径影响其传质性能,比较了粒径分别约为3 mm、4 mm、6mm的固定化小球对污染物去除效果的影响,发现粒径约为4 mm的固定化小球,对COD、氨氮和磷酸盐的去除率最大,分别为74.8%、83.4%、71.7%。通过测定系统中DO和CO2的浓度发现, DO浓度的增加速度要快于CO2,说明系统中,藻的光合作用占一定的优势。一定时间后,藻菌共生之间可达到一种动态平衡,满足藻菌对二氧化碳和氧气的需求。固定化藻菌对污染物的去除受污水营养比的影响。研究发现,氮磷比为4.6:1时对氨氮的去除率最大,然后随着氮磷比的增加,即氨氮初始浓度的增加,氨氮去除率显著降低,但总去除量不断增加;藻菌共生系统对污染物的耐受性较高,当废水中氨氮浓度为154.3 mg/L时,固定化藻菌对污染物的去除量均达到最大值,藻菌生长良好。流化床床层中固定化小球的膨胀度与液体循环流量之间的关系可以描述床层的膨胀行为,是进行流化床光生物反应器设计的基础。通过测定不同循环流量(Q)下,固定化小球的膨胀度(X),得到二者之间的关系式为Q=62.127Ln(X)+149.68。流化床中固定化小球膨胀度过大或过小,都会降低污染物的去除率。同时考察了系统中无效容积对污染物降解速率的影响,结果表明应尽量减小系统中的无效容积,在提高污染物降解速度的同时,还能降低系统的造价。更多还原

【Abstract】 In this study,Chlorella pyrenoidosa and aerobic activated sludge were immobilized by alginate. In self-made fluidized photobioreactor,the symbiosis of algae and bacteria,immobilization and fluidization technology were combined to achieve efficient treatment of high concentration organic wastewater.The improvement of traditional alginate immobilization method by use of barium chloride instead of part of calcium chloride as fixative,and the immobilized beads coated by chitosan were studied. It was found that the mechanical strength and stability of alginate immobilized beads was improved after coated with chitosan , while the removal efficiency of COD, nitrogen and phosphate was not influenced.Then, impacts of the concentration and pH value of chitosan solution ,and coated time on the removal efficiency of pollutants were studied. The result shows that the removal efficiency of pollutants decreased with the increase of the concentration of chitosan solution and coated time, increased with the increase of pH value of chitosan solution,while the stability of immobilized beads changed in the opposite direction.Considering the stability of immobilized beads and treatment effect of pollutants, the optimal concentration and pH value of chitosan solution ,and coated time are: 1%, 5.5, 15min.The diameter of immobilized beads can influence its mass transter efficiency. Impacts of three different particle size of immobilized beads on removal efficiency of pollutants was investigated. The result shows that the immobilized beads with the particle size about 4mm had the best removal efficiency of COD, nitrogen and phosphate ,The removal efficiency were 74.8%, 83.4%, 71.7% respectively.By testing the the concentration of DO and CO2,it was found that the concentration of DO increased faster than CO2 in immobilized bacterial and algal system, which indicated that algae’s photosynthesis occupy the dominant position. After a certain time, the concentration of DO and CO2 can achieve a dynamic equilibrium ,which can meet the demand of bacteria and algae.The nutrient ratio of wastewater has some influence on removal efficiency of pollutants. In this study,it was found that the system achieved the best removal efficiency of nitrogen ,when the ratio of nitrogen and phosphorus was 4.6:1.Then the removal efficiency of nitrogen decreased evidently with the increase of the ratio of nitrogen and phosphorus,but the total removal increased.The immobilized bacterial and algal system has high tolerance of pollutants,the total removal of pollutants reached the maximum when the ammonia concentration was 154.3mg / L ,and the algae and bacteria grew well.The relationship between expansion degree of immobilized beads and the circular flow of liquid in photobioreactor can describe the expansion behavior of fluidized bed,which is the basis of the design of photobioreactor.By testing the expansion degree of immobilized beads in different flow of liquid ,the relationship can be expressed by Q=62.127Ln(x)+149.68.The removal rate will decrease when the expansion of immobilized beads is large or too small.The effect of invalid volume on removal efficiency of pollutants was also studied. It was found that the invalid volume of fluidized photobioreactor system should be minimized,which not only improves the degradation rate of pollutants ,but also can reduce the cost of the photobioreactor system.更多还原