Biodegradability enhancement of refining effluents from acrylonitrile manufacturing: A batch-scale study

Refining effluents from acrylonitrile manufacturing are hard to degrade. Activated carbon, ion exchange and Fenton oxidation were applied to improve the biodegradability in this study. Granular coal-based activated carbon exhibited better performance than adsorbents produced from granular coal, coconut shell and nut shell. At the optimum conditions (pH=9, 20 °C, 2 h reaction and a dosage of 40 mL adsorbent per liter sample), COD and BOD was reduced by 86.39% and 70.63% respectively, attaining an increase of BOD/COD to 0.369. Ion exchange resins are rated as 001×7 >; 201×7 >; D201 >; D301R >; NKA-9. The optimal COD removal of 43.02% with an increase of BOD/COD to 0.214 was attained at the dosage of 40 mL 001×7 per liter sample, 20 °C, pH=6 for a 3-hour reaction. The most appropriate process for biodegradability enhancement appeared to be Fenton. COD and BOD were finally reduced to 972 mg/L and 404.4 mg/L respectively, attaining a BOD/COD ratio of 0.416. This optimum efficiency was obtained at the c(H₂O₂)/c(Fe²⁺) ratio of 10:1, 40 °C, pH=3 and a oxidation time of 2 h.