| As the nitrogen pollution of circulating water is somewhat serious in China,thus in this paper,I carried out research to study the denitrification effect and mechanism of corncob reinforced bioreactor on aquaculture wastewater based on the principle of biological nitrification and denitrification.The main results are as follows:?1?The results of water quality monitoring of 5 typical circulating aquaculture systems showed that the existence form of nitrogen in circulating wastewater is mainly nitrogen nitrate,which is about 77 % of the total nitrogen content?90 % at the highest level?,followed by ammonia nitrogen,about 2 4 % of the total nitrogen with nitrite takeup the lowest percent.?2?Under the laboratory conditions,the reactor is not only easy to operate,cost-effective,short start-up time,but also has good denitrification effect,which can effectively remove nitrate and ammonia nitrogen in aquaculture wastewater.Ammonia nitrogen can decrease to 3.50 mg·L-1 from the original?8.00 ± 2.22?mg·L-1,and nitrates change from?31.50 ± 1.57?mg·L-1 to 0.5 mg·L-1.The reactor was able to realize the simultaneous nitrification and denitrification in the high dissolved oxygen surroundings,and the removal rate of total nitrogen was over 85 %.?3?The results of high flux analysis indicate,by using corncob as carrier and carbon source biofilm,the dominant species are Proteobacteria,Bacteroidetes,Firmicutes and Chloroflexi,in which nitrobacteriare mainly composed of Nitrosospira,Nitrosomonas and Nitrosococcus.Denitrifying bacteriaare mainly composed of Alcaligenes,Paracoccus,Pseudomonas and Thiobacillus denitrificans.And with the extension of running time,the species and the quantity are reduced.?4?The microbial apparent attachment results show the rough surface and large porosity of corncob is conducive to the growth of microbial flora.The surface of the membrane is obviously growing with the growth of the membrane.And the microbes on the biofilm are mainly cocci.The microbial spatial distribution results showed that the microbial species and quantity decreased with the increase of the depth of the carrier;while with the extension of time,the microbial species and quantities of the same level also showed a downward trend,especially during the late microbial attachment.?5?From the perspectives of internal material changes in the carrier,it was found that the surface DO of the biofilm was 2.82 mg·L-1 after the succession of the corncob,and the DO decreased slowly with the increase of the membrane depth,for which the dissolved oxygen content of biofilm decreased to 0.23 mg·L-1,and the whole process of change was inverted "S" type curve.With the increase of depth,DO concentration gradually decreased from aerobic state to anaerobic state;biofilm internal N2 O,with deeping of biofilm,change stability,almost no accumulation phenomenon.It can also indirectly learn that the biofilm thickness is about 2300 ?m.?6?The effect of the new reactor in the practice base shows that the wastewater treatment device can effectively realize the denitrification function of the wastewater.During the annual operation,the average removal rate of nitrate is above 80 %,up to 84.75 % and the lowest can evenreach 81.90 %.The average removal rate of total nitrogen is also higher than 78 %,up to 80.75 % and the lowest is about 78.25 %.It can be said that the effect of total nitrogen removal is good and can be widely applied to aquaculture water purification areas. |
PDF Full Text Request