TOXICITY OF COPPER IN THE PRESENCE OF ORGANIC-SUBSTANCES IN SEWAGE-SLUDGE

The toxicity of Cu to Photobacterium phosphoreum was studied in the pr esence of both model substances and organic substances that have been identified as sludge components. Copper toxicity increased in the pres ence of LAS, caffeine, myristic acid, palmitic acid, nonylphenol, ethy l xanthogenate and oxine, with a steep toxicity gradient for the latte r two compounds. Other substances, including complexing agents, amelio rated Cu toxicity. Synergistic/antagonistic effects of organics and Cu in sludge were tested through comparison of the toxicity of Cu added to three sludge types with the concentration of electrochemically avai lable Cu at different sludge/Cu proportions. The toxicity of Cu in raw and digested sludge was much higher than could be explained by the co ncentration of electrochemically available Cu alone and was attributed to synergism and potentially the formation of lipid-soluble Cu comple xes.