Study on the treatment of coking wastewater biochemical effluent by Fenton-like system based on natural pyrite

Abstract

After biochemical treatment，coking wastewater still has a large number of refractory components，and direct discharge will lead to natural water pollution. The classical Fenton reaction has problems such as the generation of iron-containing sludge and the narrow pH application range，which is limited in practical applications. Natural pyrite was used as a heterogeneous Fenton reaction catalyst to treat the biochemical effluent of coking wastewater，and phenol in the wastewater was used as a model pollutant to explore its oxidation mechanism. The results indicated that the process could effectively remove COD from wastewater under relatively broad initial pH conditions. The removal rate of COD in wastewater was proportional to the amount of pyrite added，and the removal rate of COD increased slightly under the condition of high concentration of H2O2，but the increase rate slowed down. There were two catalytic conditions in the system，homogeneous and heterogeneous. After adding ·OH scavenger，the degradation efficiency of the system significantly decreased，indicating that the main free radical in the system was ·OH. Phenol was the main organic pollutant in coking wastewater，and the intermediate products of phenol degradation by Fenton-like using pyrite were detected，and phenol was first oxidized to p-phenol，then quickly converted to p-benzoquinone，and finally oxidized to small molecule acids.

Keywords

• pyrite
• biochemical effluent of coking wastewater
• fenton reaction catalyst
• hydroxyl radicals