Study On Nitrogen Removal Of Aquaculture Wastewater By Microbial And Microbial-Plants Combined Stystem

China’s acquaculture in mudflat along the coast rapidly developed in recent decades, the problemes were hidden in the back the fact that acquaculture contributes significantly to the economic should not ignored. The serious problems of environment pollution are more serious caused by some factors,for example, there is no enough amounts and species of primary producers and in order to prevention and treatment of diseases,too much artificial feed and chemicals were put in aculture water,which causes the substantial amounts uneated feedstuff and chemicals are generated in the process,and other factors such as excrement and death cultivate organism body. Nitrogen compounds,especially ammonia nitrogen and nitrite nitrogen,are not only likely to cause environment pollution and eutrophication,but also harmful for aquaculture organisms themselves. Therefore,to develop a highly efficient and economic method of denitrification becomes the focus of the work.The reseach is carried out through aspects as nitrogen removel characteristics of microbial and microbial-plants combined nitrite-removel.the main results obtained are as followes:(1) Isolations and identifications and effects of factors on the degradation of nitrite-N of aerobic denitrifying strainThe aerobic denitrifying strain named DF-1were screened and isolated from the sediment and water sample from fish ponds in Dafeng,Yanchen.DF-1were found to belong to Klebsiella oxytoca. Strain DF-1could degrade the nitrite-N from6.5mg/L to zero in22h. Strain DF-1growed well at pH7、 temperature35℃and salinity5, the denitrification of strain DF-1reached the peak at pH9、 temperature35℃and salinity0. strain DF-1growed well and nitrite-N degradation rate reached to peak when it used sucrose or sodium acetate as carbon source.(2) Isolations and identifications and effects of factors on the ammonia removel capability of heterophic and autotrophic nitrifiers.The autotrophic nitrifiers named DFA-1and heterophic nitrifiers DFY-1were were screened and isolated from sample from fish ponds,Dafeng.Two strains belong to Enterobacter cloacae and Enterobacter aerogenes. Strain DFA-1has a short Dynamics of growth and strong tolerance characteristic. Strain DFA-1growed well at pH from3to7temperature from15℃to30℃and salinity from1to20, the ammonia removel capability of strain DFA-1reached the peak at pH7、 temperature from25to35℃and salinity7(>90%). Strain DFY-1has a long Dynamics of growth and low tolerance characteristic. Strain DFY-1growed well at pH from7to8、 temperature from20℃to25℃, the ammonia removel capability of strain DFY-1was positive correlate with the groeth conditions. Two strains able to use the single carbon source, strains DFA-use glucose, strains DFY-1mainly use glucose and sodium citrate.(3) Microbial-plants combined nitrite-removel in simulated field conditionBuild a microbial system in simulated field condition:design orthogonal experiment by three factors and four levels:ammonia(1、5>10mg/1)、 nitrate(1、5、10mg/1)、 nitrite(15、10mg/1).Adding strains DF-A、DFA-1、 DFY-1to the test groups. Jerusalem artichoke was planted2mouths before the test beginning in the modified barrel,and the plant grow to60-75cm without fertilizing.The test results show that different forms of N removal rate were affectde by the concentration of different forms of N. There is obvious effection of N-removal by three strains after6days cultured;part of N added to the plant system was absorped by Jerusalem artichoke, part of N residues in the soil.The proportion of the amount that be absorped in two ways wanegative correlation with the amount of added to the plant system...