| Summary: | 碩士 === 國立高雄師範大學 === 生物科技系 === 96 === AbstractTo prevent any damage against aquatic organisms arising from excessively high concentration of organic pollutants in the water, such as: ammonia-nitrogen, nitrite-N and bacteria, water is generally replaced to remove these substances for water tank fish-farming. However, this is rather inconvenient and the adaptability of fishes has to be considered. So, circulating water fish-farming becomes a growing trend, especially for ozone treatment. These studies analyzed the change of ozone residual concentration when ozone was input to water tanks with different capacities and states. In the water tanks of 12.5 L, 25 L and 50 L, the maximum ozone residual concentrations were 0.093, 0.155 and 0.107 mg/l, respectively. When ozone was input to 50 L water in static/dynamic states, the maximum ozone residual concentrations were 0.155 and 0.076 mg/l. When various pollutants prepared with manual reagent were filled into the water tank, and then ozone was input to 50 L static/dynamic water tank, the changing concentrations of pollutants were separately analyzed through ozone treatment. Under 50 L dynamic water state, original concentration 0.387 mg/l of nitrite-N declined below 0.1 mg/l within 40 min; under 50 L static water state, original concentration 0.396 mg/l of nitrite-N declined below 0.1 mg/l within 20 min. Ammonia-nitrogen after ozone treatment couldn’t yield action at pH 8.5. For the change of COD concentration in 50 L static water after ozone treatment, original concentration of COD was 42 mg/l, which declined below 20 mg/l within 40 min. For the change of bacteria quantity in 50 L dynamic water after ozone treatment, the original concentration tested by spectrometer amounted to 106×108 cell/50 L, which declined below 6.3×108 cell/50 L within 18 min; for the change of bacteria quantity in 50 L static water, the original concentration tested by spectrometer amounted to 512.5×108 cell/50 L, which declined below 6.3×108 cell/50 L within 14 min. For the change of concentration of nitrite-N, total ammonia-nitrogen, COD and bacteria in 50 L dynamic water after comprehensive ozone treatment, the original concentration 0.386 mg/l declined below 0.1 mg/l at 60 min; the original concentration of COD was 29 mg/l, which declined below 20 mg/l within 40min; for the change of E. coli quantity, the original concentration tested by spectrometer amounted to 485×108 cell/50 L, which declined below 0.5×108 cell/50L at 60min. Ozone treatment couldn’t oxidize ammonia-nitrogen. For the change of concentration of nitrite-N, total ammonia-nitrogen, COD and bacteria in 50 L static water after comprehensive ozone treatment, the original concentration 0.391 mg/l declined below 0.1 mg/l at 40min; the original concentration of COD was 48 mg/l, which declined below 20 mg/l at 40min; for the change of E. coli quantity, the original concentration tested by spectrometer amounted to 575.5×108 cell/50 L, which declined below 0.5×108 cell/50 L at 60 min. Ozone treatment couldn’t oxidize ammonia-nitrogen. For the toxicity of ozone residual concentration 0.114 mg/l against crucian of different weights, the median lethal time (Lt50) was 15 min (0.67 g/fish), 59 min (0.894 g/fish), 78 min (1.8 g/fish) and 95 min (2.7 g/fish), respectively. For the toxicity of different ozone quantities (0.204 mg/l, 0.114 mg/l, 0.075mg/l) against crucian of the same weight 1.8 g, Lt50 was 12min (0.204 mg/l), 78min (0.114 mg/l) and 97min (0.075 mg/l), respectively. In the 30-day test of the effect of ozone treatment on crucian-breeding, pH value of experiment group ranged between 8.60-7.94, concentration of COD was kept at 50-60 mg/l, concentration of total ammonia-nitrogen was below 2.38 mg/l, concentration of nitrite-N was below 13.348 mg/l, and bacteria quantity amounted to 40-245×1010 cell. pH value of control group ranged between 8.41-6.39, concentration of COD reached 204 mg/l, concentration of total ammonia-nitrogen was 5.07 mg/l, concentration of nitrite-N was below 41.172 mg/l, and bacteria quantity amounted to 30-560×1010 cell. The test results from crucian-breeding showed that, the total amount of experiment group increased by 184 g, that of control group by 103 g, and the mean weight of experiment group increased by 3.07 g, 1.69 times of control group (1.81 g). 30 days after this test with ozone treatment, three types of bacteria were obtained from the water samples of control group and experiment group, then verified by transditional diagnotic system and molecule biotechquie and subjected to nucleotide sequence comparison in NCBI website, with the bacterium of CW1 similar to Leifsonia sp. up to 99% identity, the bacterium of CW12 similar to Aeromonas veronii bv. sobria up to 99% identity, and the bacteria of CW3 similar to Citrobacter freundii strain 6 up to 98% identity.
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