| In recent years, the pollution of coastal water was worsening in our country. Eutrophication, red tides were still increased. The pollutions have seriously hindered the rapid development of mariculture and had great impact on our continuable environment. Nitrogen pollution was the most prominent. Biological nitrogen removal is the main methods of removing nitrogen pollution. It was mainly compelted by nitrification and denitrification. Denitrification is the process that the denitrobacteria changed nitrate nitrogen into nitrogen under anoxic conditions. It could remove nitrogen from seawater and settled nitrogen pollution of seawater radically.This study established a method of enrichment culture of marine denitrobacteria, and observed the characteristic changes of activated sludge during the enrichment and determined the suitable condition of marine denitrobacteria by single-factor test. At the same time, used sodium alginate and polyvinyl alcohol to embed denitrobacteria, carbon source and tested the removal of nitrogen after embedded.The conclusions of the investigation were as follow:1. Under the condition of the temperature 25~30℃, pH7.0~7.5, anaerobic, cultured for 25d, denitrobacteria can be get which has denitrification rate at 4.83mg/(gMLSS·h), denitrification intensity at 110mg/(L·h) and the quantity can reach to 2.5×108MPN/mL. During the cultivation process, denitrification rate, denitrification intensity, SV, SVI and other indicators appeared regularly change. The denitrifying bacteria had a good removal of nitrogen.2. By single factor experiments, made sure that denitrobacteria culture of seawater could use sodium citrate, glucose, lactose, methanol, ethanol, soluble starch as the sole carbon source for denitrification, in which the highest removal rate of nitrogen could be get by using sodium citrate, ethanol. The suitable pH was 7.0~8.0 and temperature was 25℃~40℃. DO was lower, denitrification was more intense and the removal rate of nitrogen was higher. When the DO controlled under 1.5~2.0mg/L, the denitrification could be carried out normally. To increase the amount of denitribacteria, could greatly enhance the removal rate of nitrogen and shorten the processing time. Compared denitrobacteria amount and time, add bacterium 10mL in 350mg/L of nitrogen solution. The initial concentration of nitrogen has no effect on denitrification intensity of denitrobacteria. 3. Using sodium alginate, Oligomeric heterozygosity of PVA as the embedding material embedded denitrobacteria, the nitrogen removal efficiency was better than a high degree of polymerization of PVA. In appropriate environmental conditions, the rate of nitrogen removal of the cells after embedded was worse than those without embedding. However, in adverse environmental conditions (for example, pH5.0, temperature 10℃), the embedded cells can improve the resistance capacity of denitrobacteria. Adding an appropriate amount of soluble starch in the embedded cells could improve well in mechanical strength of sodium alginate and PVA cells and could reduce the adsorption and swelling of PVA cells. The denitrification rate of embedded cells of carbon and denitrobacteria is better than the embedded cells of carbon.
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