期刊
JOURNAL OF HAZARDOUS MATERIALS
卷 302, 期 -, 页码 468-474出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jhazmat.2015.10.013
关键词
Coking wastewater; Cyanide; Ferrous sulfate; Complexation; Biodegradability
资金
- National Science Foundation of China [21207040, 51278199]
- Chinese Postdoctoral Science Foundation [2012M521607]
- K.C. Wong Magna Fund in Ningbo University
The effect of ferrous sulfate (FeSO4) treatment on the removal of cyanide compounds and the improvement of biodegradability of coking wastewater were investigated by varying Fe:TCN molar ratios. Results suggested that the reaction between FeSO4 and coking wastewater was a two-step process. At the first step, i.e., 0 <= Fe:TCN <= 1.0, the reaction mechanisms were dominated by the precipitation of FeS, the complexation of CN-, and the coagulation of organic compounds. The COD of coking wastewater decreased from 3748.1 mg/L to 3450.2 mg/L, but BOD5:COD (B/C) was improved from 0.30 to 0.51. At the second step, i.e., 1.0 < Fe:TCN <= 3.2, the immobilization of soluble metal-cyanide compounds by ferrous ions was the dominating mechanism. The COD showed a continuous increase to 3542.2 mg/L (Fe:TCN = 3.2) due to the accumulated ferrous ions in coking wastewater. Moreover, B/C decreased progressively to 0.35, which was attributed to the negative effects of excess ferrous ions on biodegradability. To improve coking wastewater's biodegradability, a minimum ferrous dosage is required to complete the first step reaction. However, the optimum ferrous dosage should be determined to control a safe residual TCN in coking wastewater for the further biological treatment. (C) 2015 Elsevier B.V. All rights reserved.
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