镉污染应急处置含镉絮体稳定性实验研究

Experimental Studies on Stability of Flocs from Cadmium Pollution Emergency Treatment

以广西龙江河镉污染应急处置过程中产生的含镉絮体为研究对象,在探讨扰动及pH对絮体稳定性影响的基础上,考察了絮体在模拟静态水库和酸性洪水中的稳定性.结果表明,扰动及pH对絮体稳定性的影响较大,扰动条件下,Cd2+浓度随河水初始pH变化规律为:pH 5.0>>pH 6.0>pH 7.0≈pH 8.0>pH 9.0,当pH为5.0时,Cd2+浓度较高,超标19～58倍;当pH为6.0、7.0、8.0和9.0时,Cd2+浓度不超标至超标11倍.含镉絮体在扰动水环境中释镉量较大,大部分样品的Cd2+浓度高于5.0μg.L-1,最大超标1倍;而在模拟静态水库中的释镉量较小,所有样品中Cd2+浓度均低于5.0μg.L-1,未超标,可见含镉絮体在模拟静态水库中稳定性较好.含镉絮体在模拟酸性洪水中释镉量大,Cd2+浓度超标14～25倍,稳定性差.因此,在龙江河的生态环境影响后评估工作中应加强洪水期的监测.

Taking the flocs from cadmium pollution emergency treatment of Longjiang River in Guangxi province as the research object,the stability of the flocs in the simulated static reservoirs and acidic floods was investigated based on the effects of disturbance and pH on the stability of the flocs.The results indicated that disturbance and pH had great effects on the stability of the flocs,and the concentrations of Cd^2＋ followed the order of pH 5.0 〉〉pH 〉6.0pH 7.0≈pH 8.0pH 9.0 with the original pH of water.When the original pH of water was 5.0,the concentrations of Cd^2＋ in samples were 19-58 times higher than the national standard limit,and when the original pH of water were 6.0,7.0,8.0 and 9.0,respectively,the concentrations of Cd^2＋ in samples varied from below to 11 times higher than the national standard limit.The release of cadmium from the flocs was higher in the disturbed water,with the concentrations of Cd^2＋ in most samples higher than 5.0 μg·L^-1,and the highest was double of the national standard limit.In contrast,there was little release in the simulated static reservoirs,with the concentrations of Cd^2＋ in all samples below 5.0 μg·L^-1,which was lower than the national standard limit.Therefore,the flocs had good stability in the simulated static reservoirs.But it had poor stability in the simulated acidic floods,with higher release of cadmium,and the concentrations of Cd^2＋ in samples were 14-25 times higher than the national standard limit.Therefore,the monitoring of cadmium concentrations in the floods should be strengthened in the post project analysis for eco-environmental impact of Longjiang River.