Formalin: its toxicity to Aeromonas hydrophila, planktons and degradation
The toxicity of formalin at the concentrations of 25, 50 and 75 ppm to Aeromonas hydrophila was studied. A formalin concentration of 25 ppm killed 99.90 percent of bacteria within 24 hours. Concentrations at 50 and 75 ppm killed 100 percent of A. hydrophila within 24 and 12 hours, respectively. Degradation of formalin was studied at the water temperature 27–30°C in aerated and non-aerated aquaria with and without fish. In the aerated aquaria with fish, formalin degraded more rapidly than in ot her groups. At 25, 50 and 75 ppm, formalin completely degraded within 36, 48 and 54 hours in aerated group. In the non-aerated group, it did not degrade until after 36, 54 and 60 hours, respectively. In fiberglass containers, the degradation of formalin at the concentrations of 25 and 50 ppm was similar in the early hours (P<0.05). However 25 ppm formalin degraded more quickly and completely within 48 hours compared to 60 hours for a concentration of 50 ppm (P>0.05). Formalin at 25 and 50 ppm significantly reduced the amount of plankton and dissolved oxygen during the exposure time of 48 hours. The results also showed that the total ammonia concentration slightly decreased in the early hours. Other water quality parameters did not change.
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| Format: | Project biblioteca |
| Language: | English |
| Published: |
1988
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| Online Access: | https://openknowledge.fao.org/handle/20.500.14283/AC276E http://www.fao.org/3/a-ac276e.htm |
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