池塘循环水养殖模式的构建及其对氮磷的去除效果

Modeling of Water Circulating Pond Aquaculture System and Its N & P Removal Effect

构建了一个由水源地、养殖池塘、生态沟渠（1级净化）、2级净化塘和3级净化塘组成的淡水池塘循环水养殖模式,研究该模式对池塘养殖废水中氮和磷的去除效果。2010年5—10月的运行结果表明,经过3级净化后,养殖废水中氨氮水平能维持在约0.33 mg.L-1,6月仅为0.010 3 mg.L-1,亚硝酸盐氮含量低于0.02 mg.L-1,总氮含量在各月均能达到GB 3838—2002《地表水环境质量标准》中Ⅴ类标准（≤2.0 mg.L-1）,总磷含量均能达到地表水Ⅲ类标准（≤0.2 mg.L-1）,对叶绿素a的去除效果也很明显,去除率为16.10%~91.22%。可见,该模式能够有效地去除养殖废水中过量的氨氮、亚硝酸盐氮、总氮、总磷和叶绿素a。各级净化模块并不能逐级加倍发挥净化效果,这可能是因为在日常管理过程中由于孽生使得水生植物密度过大,从而引起水质变化反复。近2 a来的试验结果显示新建的淡水池塘循环水养殖模式正处于功能完善阶段,尚未成熟。

A model of water circulating pond aquaculture system for fish rearing was constructed and tested,including water source,fish pond,eco-canal（first-level purification）,second-level purification pond and third-level purification pond,and its effect of removing nitrogen and phosphorous was studied.The test-running of the model from May to October 2010 showed that after three levels of purification,the concentration of ammonia nitrogen in outflowing wastewater from the system was maintained around 0.33 mg·L-1 and even lowered down to 0.010 3 mg·L-1 in June,and the concentration of nitrite nitrogen was kept lower than 0.02 mg·L-1,making the concentration of total nitrogen meet the criteria of Grade V of the Standard for Surface Water Environment Quality（GB 3838—2002）,and the concentration of total phosphorous the criteria of Grade III of the Standard for Surface Water Environment Quality.The effect of the model removing chlorophyll-a was also very obvious,ranging from 16.10% to 91.22% in rate.It is clear that the model could remove surplus ammonia nitrogen,nitrite nitrogen,total nitrogen,total phosphorous and chlorophyll-a from the wastewater.But,in this experiment,the purification ponds did not show their function of effect multiplier level by level,maybe due to the excessive density of aquatic plants as a result of poor management,which led to fluctuation of water quality.The test in the past two years demonstrates that the model of water circulating pond aquaculture system is still in the process of improving functionally,but has not yet got mature.