| Industrialized and intensive aquaculture will become an important trend in thefuture development of marine fish farming, fish farming aquaculture process waterdischarged directly in the coastal farming areas, to create a regional sea pollution. Partof the industrialized aquaculture recirculating aquaculture enterprises have becomethe industry a pillar industry, and has made great achievements in the fishery waterpurification treatment. In this thesis, intensive farming in recirculating aquaculturephilosophy is based on the constructed wetland treatment system model as a coretechnology of sewage treatment breeding process, and then replace the previoustraditional purification devices. First constructed wetland wastewater treatmenttechnology has good effect, water quality and stability, nitrogen, phosphorus removalability, easy operation and maintenance management,engineering infrastructure andlow operating costs, ability to adapt to changes in load, suitable for intermittentdischarge of sewage and other major characteristics. Meanwhile, the constructedwetland to protect wildlife and improve the aesthetic value of the landscape of thelocal area also has benefits. Therefore, great efforts to develop constructed wetlandwastewater treatment technology has great significance for Chinese water pollutioncontrol in our country has a broad development prospects. To constructed wetlandsystem combines mariculture for wetland drainage experimental treatment outside ofmariculture, produces a wetland-turbot farming and circulating water system. Selectsreeds and aquatic plants Spartina, and densities are64plants per square meter. Selectsthree wetland system matrix material coral, vermiculite and sand. Substrate enzymeactivity and microbial distribution are important factors affecting the degradation ofpollutants in constructed wetland systems. In this study, we examined the removaleffects of nitrogen in mariculture wastewater, and the relationship of the removalefficiency, substrate enzyme activity and microbial distribution with constructedwetlands. Once again produces a constructed wetland treatment system, Selects theplanting density of64per square Spartina, and the matrix filler are yarn, blast furnaceslag and coral. Sets different HRT of16h,24h,36h. The main conclusions are asfollows: 1. In the experiment on the water wetland system to explore the effect ofnitrogen:with the increased salinity,Removal of NH4-N differences was not significantby reed wetland (P>0.05). Reeds has some salt tolerance, and plants grows well insalinity between18to19. Spartina alterniflora wetland salinity maintains between28to31, more tolerant than the reed. Choose a different way water, constructed wetlandsfor the removal of ammonia nitrogen difference was significant (P<0.05).With theincrement of intermittent water ways HRT, Constructed wetlands for removal ofammonia nitrogen shows a rising trend, and the change is significant (P<0.05).Considering reasonable and efficiency of the system operation, obtains underreasonable operating conditions for24h intermittent water and adds a small amount ofnitrifying bacteria in probiotics, and the system runs continuously for a month. Theresults shows that both systems have a better nitrogen removal and Spartina systemhandles better than the reed system. So choose Spartina alterniflora wetland system,and combines with recirculating aquaculture turbot. Chooses natural conditions(intermittent water24h) is more reasonable, efficient and simple way of recirculatingaquaculture conditions60days. After a wetland system treats the aquaculturewastewater effluent concentration of ammonia nitrogen, nitrite nitrogen, nitratenitrogen is significantly lower than the concentration of them in the aquarium (P <0.05). Ammonia nitrogen average removal rates is (89.88±0.17)%by constructedwetland system. In the circulating water system, turbot average daily weight gainsweighs2.42grams, and the feed conversion ratio is1.68.In the conventional wayturbot farming, the average daily weight gains weighs2.27grams, the feed conversionratio is1.98.The results shows that selecting circulation patterns have greateradvantages.2. In the experiment on turbot, flounder aquaculture:comprehensives comparisonof two farming operation,and combines with turbot physiological habits and breedingenvironmental factors, and the constructed wetlands-circulating water aquacultureway1as a green cheap turbot farming projects suitable for high-density breedingselection. In the way a farming systems in order to meet the breeding pool waterpremise, takes the form of a three-day cycle, Not only eliminates the appearance offarming systems in the past anaerobic period is too long to inhibit aerobic microbiallife phenomenon, and intermittent work also improves the life of farming equipment,more important is to reduce the concentration of ammonia nitrogen in wastewateraquaculture. Inadequate supply of oxygen in the system as1way of adverseconsequences of uninterrupted water generated in the farming operation way2, makesall kinds of microorganisms in the anaerobic environment long term in constructedwetlands system. Produces oil wall phenomenon, and escapes the pungent odor,abnormal metabolic activity of microorganisms, which greatly reduces the aquaculture wastewater for ammonia, chemical oxygen demand and other removal. Inoperation mode1, the highest concentrations of ammonia and chemical oxygendemand are0.149mg/L,4.25mg/L in aquaculture wastewater, finally reduces to0.001mg/Land2.06mg/L. In operation mode1, the highest concentrations of ammoniaand chemical oxygen demand are0.143mg/L,4.35mg/L, finally reduces to0.005mg/L and2.47mg/L. Datas shows that the final effect of a farming operation1isbetter than2.3. In the experiment to explore the sea on wetland treatment nitrogen removalefficiency and the matrix activity, community characteristics of microbial systems:theresults shows that under conditions of different hydraulic retention time constructedwetland system for ammonia nitrogen removal rate changes significantly (P<0.05),and total nitrogen removal rate differences is not significant (P>0.05). the averageremoval rate of total nitrogen and ammonia nitrogen are (25.02±12.69)%,(82.91±17.51)%by the system respectively. The quantities of aerobic microbes andthe activities of urease and dehydrogenase in the upper and middle layers aresignificantly higher than in the lower layer. The numbers of nitrite bacteria and nitratebacteria in the upper and middle layers of the up-flow tank are significantly greaterthan in the lower layer, while, denitrifying bacteria have the opposite distributiontrend. There are positive correlations between the total number of bacteria and theremoval efficiency of ammonia nitrogen and total nitrogen. Also, the activity ofsubstrate urease has the significant positive relation with the removal efficiency oftotal nitrogen. The study results will help to understand the transport andtransformation mechanism of nitrogen in mariculture wastewater treatment system ofconstructed wetlands. |
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