封闭循环水系统生物滤池气水比对水质净化效能的影响

Effect of the air-to-liquid ratio on treatment efficiency of wastewater in multistage BAF in a recirculating aquaculture system

通过在全封闭循环水系统中养殖半滑舌鳎（Cynoglossus semilaevis Gunthe），研究了不同气水比对曝气生物滤池净化效能，以及对DO、pH值的影响。结果表明：本试验系统在温度为（19±1）℃，系统循环次数为15次，养殖池DO保持在12mg／L以上的运行条件下，随着气水比由0．75：1～1．50：1的增加，生物滤池氨氮的去除率由35．0％增加至52．0％，N02一N的去除率由8．2％增加至44．6％，气水比对硝化反应影响显著，但对化学需氧量COD的去除率影响并不显著，其平均去除率为10．14％；pH值有增加的趋势，生物滤池进水口到出水ISl的pH值由7．97增加至8．08；气水比最佳运行参数为1．25：1。同时还发现1级生物滤池进水口DO接近饱和，1级到末级滤池间DO仅降低了10％左右，系统pH值在7．9～8．1。本研究所获参数，可供生物膜法处理养殖循环水的条件优化作参考。

The half-smooth tongue-sole （Cynoglossus semilaevis Gunthe） is commonly reared in a recirculating aquaculture system. We evaluated the effect of the air-to-liquid ratio on the purification efficiency, DO, and pH in the biological aerated filters of a recirculating system. The test system was maintained at （19 ~I）~C and 15 cycles. The DO in the tank remained above 12 mg/L. As the air-to-liquid ratio increased from 0.75：1 to 1.50：1, the removal rate of TAN increased from 35.0% to 52.0%, and the removal rate of NO2-N increased from 8.2% to 44.6%. Thus, the air-to-liquid ratio had a significant impact on nitrification, whereas the influence of chemical oxygen demand （COD） removal rate was not significant. The average removal rate was 10.14%. The pH values increased from 7.97 to 8.08 but decreased between the biofilter inlet and the outlet. The optimal air-to-liquid ratio was 1.25：1. This resulted in DO levels at the inlet of the first bio-filter tank that were close to saturation. Between the first bio-filter tank and the final bio-filter tank, DO only decreased by 10%. The recirculation aquaculture system maintained the water pH value between 7.9 and 8.1. Our results provide a reference for optimization of bio-film process culture conditions.