碩士 / 國立中山大學 / 海洋環境及工程學系研究所 / 106 / Aquaculture is widely developed in Taiwan western coast. Brackish water and seawater are common water sources. Aquaculture effluents contain high concentration of nutrients to affect water quality in coastal area and often causing the eutrophication. The process of bring in external water can introduce germs into the culture ponds, which increase the risk of culture objects infect diseases. In order to solve these problems, this research apply the ecological engineering technology to decrease the frequency of replacing water and to decrease the accumulation of nutrients in ponds.
This research used Biofloc Technology (BFT) to improve aquaculture water environment. The differences between traditional method and biofloc technology for aquaculture are identified. Biofloc technology is based on the usage of microorganisms in the water that prefer high C/N ratio environment. Extra organic carbon is added into the pond in order to increase the C/N ratio. Large particles formed by the increasing amount of microorganisms, called biofloc. Floc size range from 0.1 mm to a few millimeters, which consist of algae, protozoa, plankton and rotifers. Many fish and shrimp can ingest the flocs, which size between 0.1 to 3mm. This can be served as an extra protein supply.
Tilapia was selected for this study because its high environmental tolerance, and it is the major domestic breeding species in Taiwan. The study was divided into a control group and two experimental groups, with C / N ratios of 10.71, 15 and 20, respectively. Results show that the experimental groups have higher feed assimilation rate than the control group. TAN and organic nitrogen could be higher than traditional aquaculture pond by using biofloc technology, however the inorganic nitrogen is lower.
Biofloc technology in this study has shown its function on removing total nitrogen in culture water. Heterotrophic microorganisms in flocs degrade organic matter after increase C/N ratio and, thus, the amount of flocs are increased too. When the C / N ratio decreases, the autotrophic microorganisms in the flocs consume inorganic nitrogen. The experimental results show that biofloc treatment is efficient on quick improvement of water quality. Two experimental groups can reduce TAN 61.5% and 40.43% within 6 hours. After filtering, 71.95% of total nitrogen can be removed with C/N=15 and 55.92% can be removed with C/N=20. The death floc will be remineralized that causing the total ammonia concentration increased again, if not filtered.
In this study, it is observed that tilapia did use flocs as food which enhancing the feed assimilation rate and stabilizing the water quality. Therefore, add extra organic carbon and remove part of the flocs can quickly improve the water quality when the water quality become unstable in the aquaculture ponds.
| Identifer | oai:union.ndltd.org:TW/106NSYS5282006 |
| Date | January 2018 |
| Creators | Jung-Wei Yen, 顏榮韋 |
| Contributors | Jason C.S. Yu, 于嘉順 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 114 |
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