Wastewaters from ethylenediamine production and assessment of their toxicity by bioindicator testing

This article discusses the occurrence of toxic wastewater from the production of ethylenediamine by aminating 1, 2-dichloroethane with ammonia. It is shown that wastewater from ethylenediamine production is formed at the stages of evaporation of ethylenediamine dihydrochloride and rectification of a mixture of amines obtained as a result of evaporation. In the first case, the wastewater contains a saturated NaCl solution with a content of 1÷2% of polyethylene polyamines, and in the second case, the wastewater is a solution containing about 1% of ethylenediamine and about 2% of ammonia. To study the toxicity of these wastewaters, watercress (Lepidium sativium) varieties Zabava and Krupnolistovoy were used. The assessment of toxic properties of wastewater was carried out according to such indicators as seed germination, the average length of seedlings and the dry weight of seedlings. It is revealed that the studied wastewaters have an acute toxic effect on the watercress of both varieties. It is shown that the regression equations obtained for the dry weight of seedlings and seed germination, in contrast to the length of the seedlings, do not adequately describe the experimental results and cannot be used to determine the safe dilution ratio. The safe dilution ratio, calculated using the average length of seedlings, ranges from 489.1 to 892.9 for various runoffs and watercress varieties. It is shown that the most toxic is the runoff containing a saturated NaCl solution with a content of 1÷2% polyethylene polyamines. Zabava is the most sensitive to the degree of effluent toxicity.