Isolation Of Aerobic Denitrification Bacterium And Treatment Of Aquaculture Wastewater By Combination Of Bacteria And Algae

The intensive management and high-density breeding model of China's aquaculture industry have led to the rapid deterioration of the current aquaculture environment,the eutrophication of water bodies is becoming increasingly serious,and the problems of farming animals are frequent.The traditional physical and chemical treatment of aquaculture wastewater will cause irreversible damage to the aquaculture water,so exploring new biological treatment of farming wastewater is the only way for sustainable development of aquaculture.Probiotics can effectively improve the aquaculture environment,maintain the micro-ecological balance of the aquaculture water,and also promote the growth immunity of aquatic animals to a certain extent,and have been recognized by a large number of scholars and farmers in aquaculture.In this study,two pure strains were isolated from freshwater breeding ponds,namely BB1 and BB1-a.The results of 16S rDNA series comparison and phylogenetic tree analysis of strain BB1 showed that the two strains were both Pseudomonas sp.,Named Pseudomonas sp.BB1 and Pseudomonas sp.BB1-a,respectively.Zebrafish(Brachydanio rerio var)were cultured under the conditions of Pseudomonas BB1 and Pseudomonas BB1-a at a concentration of 10~6 CFU/mL.The results showed that Pseudomonas BB1 and Pseudomonas BB1-a at this concentration a No biological toxicity to zebrafish.Pseudomonas BB1 and Pseudomonas BB1-a were cultured at different temperatures(15?,20?,25?,30?,35?)and pH(5,6,7,8).The results showed that When the pH is 7,and the temperature is 25-30?,Pseudomonas BB1 can effectively remove the high concentration of ammonia nitrogen in the cultured water,and the removal rate of ammonia nitrogen is as high as 93%;when the pH is 7,and the culture temperature is 20?,The highest removal rate of Pseudomonas BB1-a for ammonia nitrogen was 86.73%.Then selected Rhodotorula,Rhodosporidium sphaercarpum,Pseudomonas BB1(Pseudomonas sp.BB1),Pseudomonas BB1-a(Pseudomonas sp.BB1-a),selected When the above four strains were cultured individually,the optimal treatment concentration for simulated farming wastewater was shown.The results showed that the removal rate of ammonia nitrogen in the low concentration group(10~5 CFU/mL)was higher at 34.04%,and the high concentration group(10~7 CFU/mL)Marine red yeast has a high removal rate of nitrite,49.9%.The medium concentration group(106CFU/mL)has the highest removal rate of COD,which is 58.44%.In consideration of economics,marine red is added in subsequent experiments The concentration of yeast is 10~6 CFU/mL in the middle concentration group;the removal rate of ammonia nitrogen,nitrite and COD is the highest in the middle concentration group of Rhodosporium gloeosporioides(10~6 CFU/mL),which are 48.98%,20.83%,74.3%;Pseudomonas BB1 medium concentration(10~6 CFU/mL)has the highest removal rate of ammonia nitrogen and COD,respectively 43.08%and 65.79%,the high concentration group(10~7 CFU/mL)has a removal rate of 45.49 for nitrite in simulated culture water%,Middle concentration group(10~6 CFU/mL)for nitrous acid The removal rate was 38.39%,and the medium concentration group 10~6CFU/mL was used for subsequent experiments;the pseudomonas BB1-a high concentration group(10~7CFU/mL)had the highest ammonia nitrogen removal rate,31.85%,and the medium concentration group(10~6 CFU/mL)The removal rate of ammonia nitrogen is 18.67%,the medium concentration group(10~6 CFU/mL)has the highest removal rate of nitrite and COD,respectively 3.59%and 24.97%,the medium concentration group 10~6CFU/mL is selected for subsequent experiments;The four strains have no obvious effect on the removal of TP in simulated aquaculture water.Algae can absorb and utilize nutrients such as nitrogen and phosphorus in wastewater through photosynthesis and release oxygen.Bacteria use oxygen to absorb nutrients in wastewater and degrade organic pollutants.Combine the ability of algae and bacteria to explore different inoculation ratios(algae-bacteria ratios are 1/1,1/3,1/5,3/1,5/1,respectively)under the chlorella-bacteria co-culture system.Absorption capacity of nitrogen,phosphorus and other nutrients in breeding wastewater to achieve more efficient treatment of wastewater.The results showed that when marine red yeast and chlorella were co-cultured,the growth of bacteria and algae had a mutual promotion effect;when Pseudomonas BB1 and chlorella were co-cultured,the growth of bacteria and algae had a mutual promotion effect;when small When the concentration ratio of chlorella and marine red yeast is 1/1 and 3/1,the final removal rate of ammonia nitrogen is significantly higher than that of the other groups,the concentration ratio of chlorella and marine red yeast is 5/1,at 72h The highest nitrite removal rate in the simulated culture water was 86.93%,and the highest TP removal rate was 86.64%in the simulated culture water at 72h;when the concentration ratio of chlorella and Pseudomonas BB1was 1/1,for The final removal rate of ammonia nitrogen and nitrite was significantly higher than that of the other groups.When the concentration ratio of Chlorella vulgaris and Pseudomonas BB1 was 5/1,the highest TP removal rate was 87.81%in simulated farming water at 72h.The above results show that the two strains of pseudomonas for good removal effect of ammonia water quality indexes such as,bacteria and algae joint system from bacteria,algae pure culture system for the ammonia nitrogen etc in the aquaculture water pollutants has a better removal effect at first,in the aquaculture water quality regulation and aquaculture has potential application prospect and economic value.