水产养殖水体好氧同时硝化-反硝化脱氮的研究

利用筛选和分离的7株脱氮微生物，在好氧条件下将氨氮转化为亚硝酸氮，随即在好氧反硝化茵的作用下还原为氮气排放．将上述菌株固定在PVA凝胶膜中，研究了水产养殖水体中氨氮、硝酸氮和亚硝酸氮在PVA凝胶膜中的扩散性能和转化脱氮过程，结果表明，氨氮、硝酸氮和亚硝酸氮在PVA浓度为15％，细胞浓度为40g／L凝胶膜中，扩散系数分别为0．55m^2／s，0．46m^2／s，0．45m^2／s．整个生物脱氮过程历时较短，36h内对200mg／L的氨氮去除率达99％，而且无中间产物亚硝酸氮的积累，固定化微生物生长的适宜pH范围为7～9，最适温度为30℃；与游离的硝化细菌和反硝化细菌相比，固定化硝化茵是游离硝化茵对氨氧化速率的70％，固定化反硝化茵是游离反硝化茵对亚硝酸氮还原速率的74％．经过20d的连续处理，固定化微生物的稳定性远大于游离微生物，28d后，游离微生物在反应器内的浓度几乎为零，而固定化微生物的浓度和活性几乎不变．

Study on the Water Body of Aquiculture for Aerobic Simultaneous Nitrification-Denitrification

Seven denitrifying bacteria strains were screened,and NH_4~ was converted NO_2~-,NO_2~- by those strains,furthermore, they was reduced to N_2 under aerobic conditions,and NO_2~- was accumulated.200 mg/L of NH_4~ was removed for 36 h.The removal rate of NH_4~ is at 99 %.The appropriate pH and temperature for the growth of mixed bacteria was 79 and 30 ,respectively.pH control policy for the high density mixed culture in 10 L fermentor was proposed.By controlling pH value lower then 8 in the early stage and without controlling pH afterwards,cell growth period was shortened and NH_4~ removal rate was improved,dry cell weight reached at 3.9 g/L,increased 62.5 % higher than that under natural pH conditions.Immobilization of the denitrifying bacteria was more stable and more active cells than the dissociated bacteria.The ratio of the former to the latter in the denitrification rate was at 70 %.