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| Evaluation of Effect of Chlorine Dioxide Disinfection in a Recirculating Aquaculture System (RAS) |
| HAN Houwei,WANG Xianping,ZHANG Lili,LIU Hao,HU Jiaping,WANG Shunkui,YU Kaisong,JIANG Xin,ZHAO Lili,SHAO Wei,WANG Zhenyang |
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Abstract T he effect of chlorine dioxide (ClO2 ) disinfection in a recirculating aquaculture system (RAS ) was evaluated to direct the disinfection work in daily production practice .The ClO2 disinfection work was carried out in 2 successive days once a month using at a dose of 1 mg/L . To evaluate the disinfection effect ,the perniciousness to biological film and the effect on state of fishes′life after using ClO2 were ana‐lyzed .Firstly ,water sampling was conducted before the first and second disinfection ,and 24 h after disin‐fection ,respectively .Heterotrophic bacteria (HB) population detection of each water sample showed that HB had a significant decrease 24 h after the first disinfection(P<0 .01) ,without significant dfference at 48 h(P> 0 .05) ,and then the second disinfection had no significant change (P> 0 .05) .Meanwhile ,the change in the concentrations NH4‐N and NO2‐N in the water during the final and initial 2 months of ClO2 disinfection was also monitored to indirectly evaluate the perniciousness of ClO 2 to the biological film in RAS .The results showed that NH4‐N and NO2‐N concentration increased from 1 .0 mg/L ,0 .30 mg/L 7 days after the disinfection to 1 .25 mg/L ,0 .36 mg/L ,for 10 days and then reduced to the normal level . The ClO2 disinfection indicated that there was no harm to the fish behavor and daily feeding .The findings indicate that ClO2 disinfection at a dose of 1 mg/L in RAS could significantly decrease the heterotrophic bacterial (HB) populations ,with no harm to the fish behavor and daily feeding ,but cause a slight damage to the biological film ,so it should be used carefully .
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Received: 25 June 2016
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