污水处理厂出水对鱼类影响的试验研究

Research on Influence of Toxicity of Effluent from Sewage Treatment Plant on Fishes

进行了污水处理厂出水对鱼类影响的毒性试验研究 ,对试验结果进行了理论分析 .选取鲤鱼、鲫鱼为试验生物 ,在水温为 2 5℃、原水氨氮浓度为 1 5 mg/L,ρ( DO)为 7.5～ 8.5 mg/L的情况下 ,观察了不同污水体积浓度下鱼的死亡率和生长情况 .并对观察结果进行了理论分析 .结果表明 :鲤鱼对水质毒性敏感性高于鲫鱼 ,鲤鱼的 2 4h LC50 指标为 85 % ,鲫鱼在 1 0 0 %污水体积浓度下 2 4h内死亡率仅为 3 0 % ;鲤鱼、鲫鱼的 96h LC50 指标分别为 69%和 79% .鲫鱼在短时间暴露于高浓度的二沉池出水中不会致死 .出水对养鱼的毒性主要是水中的游离氨引起的 ,在 2 5 %污水体积浓度下养鱼是安全的 ,其安全浓度上限值在 2 5 %～ 40 %之间 .将出水适量引人养鱼水体既可改善鱼类的摄食条件 ,又可改善水体的氧气条件 。

The toxicity of effluent from sewage treatment plants and its influen on fishes were researched and analyzed theoretically. Carp and crucian carp were selected for experiment. The growing and death rate of the fishes were investigated under the conditions of 25℃, 15mg/L ammonia nitrogen and 7.5~8.5mg/L dissolved oxygen φ (DO) in experimental water. The result indicates that carp is more sensitive to the water toxicity than crucian carp; The 96h LC 50 indexes of carp and crucian carp are 69% and 79% respectively; And the 24h LC 50 index of carp is 85% and Crucian carp's death rate is only 30% during the exposure time although the volume fraction of sewage is 100%. The free ammonia in effluent is the key toxic substance to fishes and its safe concentration should be in the range of 25% to 40 %.