Investigation On Water Quality Of Freshwater Aquaculture And Research In Microbial Remediation Of The Organic Pollution In Aquaculture

With the development of economy and society, aquaculture gained flourish progress, and it has become the important support of national economy in our country. It was full of important social meaning and economy value to monitor aquaculture water quality in real-time and seek the corresponding solving measures according to pollution status.Introduction was given to the three typical aquatic cultivation modes of dike-pond system in Huizhou, and monitoring was conducted on the regular indexes of the different aquatic cultivation modes in dry and rainy seasons. The result showed that COD,NH₃-N and TN in the pig-fish mode pond presented increasing trends, piggery wastewater had the most contribution rate; NH₃-N and TN polluted seriously in pig-fish mode pond and singly depending on feed pond during dry season; the ponds were subjected to the pollution of heavy metal with different degree, and the copper pollution was particularly serious. Finally, the improvement measures were proposed for pollution of aquiculture water.According to the pollution problem of organics in the environment of aquiculture, under the laboratories condition, through the enrichment culture of different samples, 188 strains of bacteria were totally isolated on the three kinds of selective mediums. Through the determination of the isolated strains' extracellular enzymes activities,37 strains of bacteria were successfully screened out. The utilization ability of feed medium was measured by COD, the rate of 9 strains of bacteria' removal COD reached 56.67%～78.22% at last. Based on the morphological observation, physiological and biochemical characteristics and the result of sequences alignment of 16S rDNA, 9 strains of functional bacteria were identified,among them there were 6 functional bacteria strains identified as Bacillus sp.,1 strain was identified as Ochrobactrum intermedium,1 strain was identified as Deinococcus sp.,and the last strain was identified as Arthrobacter nicotianae. According to different extracellular enzyme activity, 9 strains of functional bacteria were divided into 3 groups, among them 4 functional bacteria strains had amylase activity, 3 bacteria strains had protease activity, and 2 bacteria strains had lipase activity. Antagonistic experiment was carried out between 3 groups of functional bacteria by using Oxford Cup method. The experimental results indicated that strains G2-2, G3-2 and XNZ4 inhibited the growth of C8D7; G2-2, G3-2, XNZ4 and C8ZH had suppressive effect on the growth of C8D22. 12 groups of multiple microorganisms were constructed by 3 strains of no inhibition effect selected from 3 groups of different extracellular enzyme activity. With the cell density of 0.5mg/ml, inoculation amount 5% and volume ratio 1:1:1, the feed degradation experiments of strains from the multiple microorganisms were done by COD removal rate as screening standard only. At last, 1 group of advantage multiple microorganisms was screened out. The relationship between the growth characterizations of 3 bacteria strains in the advantage multiple microorganisms and COD removal rate was researched. The different concentration and different ratio of functional strains had influence on the COD removal rate, and the result showed that the optimal concentration and the best ratio were 0.25mg/ml and 1:2:2 respectively.The effects of adding microbe of Bacillus into culture—vats concerning conditions of water quality, phase of bacteria, water color and growth of Tilapia were studied. 1.7g wet bacterial sludge was added into the vats each time, and the strain ratio of multiple microorganisms was 2:2:1. The experiments of adding microorganism group two months later showed as follows:â‘ Beneficial micro-organisms of multiple microorganisms could proliferate into dominant microflora, inhibit the reproduction of harmful microbe, and keep a balance of ecology in water better;â‘¡The multiple microorganisms improved the water quality, added the dissolved oxygen and water fatness, built favorable water color namely algae;â‘¢The average weight of fish increased obviously, and the feed coefficient had a certain decrease. Nitrogen and phosphorus pollution loads of vat aquaculture were estimated and investigated by three methods respectively, which are ZHU NEI JUN LANG method (Japan), chemical analysis method and material balance method.