碩士 / 國立中興大學 / 生物產業機電工作學系 / 91 / In this study, an outdoor brackish-water pond culture system was designed according to the presently conditions of cultivating pond. The biological filter of nitrification treatment system having the effective volume of 140 m3 utilized an S-type submerged filter which was stuffed with honeycomb medium of volume 72 m3 to obtain the total treatment surface area of 7776 m2. The effects of the biological filter in the nitrides removal were investigated by processing circulating water, which came from the cultivating pond rearing milkfish and mullet at different testing periods under various hydraulic retention time (HRT).
During the cultivating trials of milkfish, three sets of HRT, 4, 7 and 10 hr were chosen for the biological filter. The biological filter could attain the highest total average removal rate when HRT was 4 hr, and the average removal rates of NH4+ and NO2- were 8.12 and 8.02 g/hr, respectively. In addition, concentrations of NH4+ and NO2- in the cultivating pond could also be kept under the upper limits of the conformability conditions. The result of the repeated trial using mullet was the same as milkfish when HRT was 4 hr. The cultivating pond showed that during the testing period, the concentrations of NH4+ and NO2- were steady and did not have a rising trend as well. According to the trials results of milkfish and mullet, the optimum HRT of the biological filter was 4 hr which could keep a conformable nitrides concentration for the aqua-organism growing in the cultivating pond of the system.
The test results of urgent removal of nitrides at high concentrations demonstrated that under 2, 3, 4 and 5 hr of different HRT, the average removal efficiencies of NH4+ and NO2- of the biological filter rose with HRT increased. The average removal rates of NH4+ and NO2- also had a positive relation with the flow rate of the biological filter when the average concentrations of NH4+ and NO2- of the influent of biological filter were the same respectively at different HRT. Therefore, when HRT of the biological filter was 2 hr, the system could achieve the optimum operation condition to get the highest urgent removal rates of NH4+ and NO2-.
When HRT of the biological filter was fixed at 4 hr, the effects of nitrification removal under three average aeration rates 0, 0.3 and 0.55 m3/min, were explored. According to the test results, the nitrides removal efficiency raised when the amount of aeration of the biological filter increased, yet the nitrides removal efficiencies of the average aeration rates 0.3 and 0.55 m3/min were close to each other. Both could also keep conformable concentrations of NH4+ and NO2- for aqua-organism growing in the cultivating pond. In order to save the cost of mechanical aeration, 0.3 m3/min of the average aeration rate was applicable for the biological filter. This result could be the reference for the aeration adjustment of the biological filter under different HRT operation conditions.
| Identifer | oai:union.ndltd.org:TW/091NCHU0415024 |
| Date | January 2003 |
| Creators | Meng-wei Hung, 洪孟瑋 |
| Contributors | Chung-Chyi Yu, 尤瓊琦 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 0 |
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