The Acute Toxicity of Binary Heavy Metal Mixtures Evaluated by the Microtox® Assay

• Main Authors: Jian-Long Chen, 陳建龍
• Other Authors: Shun-Cheng Wang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/88178355012243219841

碩士 === 朝陽科技大學 === 環境工程與管理系碩士班 === 99 === This study used Microtox testing method to test the toxicity of a single heavy metal, and binary heavy metal to seek cotoxicity coefficient of binary heavy metal to determine mutual relationships between heavy metals, such as the synergistic effect, additive effect or the antagonistic effect. Meanwhile, this study also tested the acute toxicity of wastewater from two electroplating factories in the Changhua Industrial Park, and discussed the relevance between EC50 value and the COD of the water quality monitoring project. The results suggested that, the single heavy metal toxicity base on the EC50 was in the descending order of Hg>Cu>Zn>Pb>Cd>Ni>Cr. The toxicity of Hg was the highest with EC50 at 0.13 mg/L; and the toxicity of Cr was lowest with EC50 at 59.33 mg/L. Among the binary heavy metals, the cotoxicity coefficient of Cr + Ni and Zn + Pb was above 110, indicating asynergism effect. The cotoxicity coefficient of Cr + Cu and Ni + Pb was 85-95, indicating an addition effect. Other heavy metal compositions had the antagonism. The EC50 value of the treated wastewater from electroplating factory A dropped from 8.59 to 56.54 at the medium biotoxicity level, demonstrating an apparent reduction in toxicity. The EC50 value of the treated wastewater from electroplating factory B dropped from 0.73 to 9.56 at highly toxic level. Its Cu content was 1.07 mg/L, making the water highly toxic. Hence, the wastewater treatment procedure should be strengthened. The EC50 value of Factory A had a low correlation with COD of the water quality project (R2=0.50); The EC50 value of Factory B had a low correlation with COD of the water quality project (R2=0.06), suggesting that the EC50 value of the wastewater of the electroplating factories are not correlated with COD, however, the results can be the basis for toxicity early warning and rapid screening of water toxicity.