Investigating the catalytic degradation performance of the actual coking wastewater DOM by iron-containing...

The resource utilization of iron-containing sludge (FeCS) is an urgent problem to be solved in Fenton wastewater treatment process. In this work, biochar was prepared by FeCS and peanut shells as catalyst for the degradation of dissolved organic matter (DOM) in the actual coking wastewater. The results indicated that iron-containing sludge-based biochar (FeCSB) prepared at 800 °C was conducive to the reduction from Fe³⁺ to Fe²⁺, and the relative content of Fe²⁺ (64.13 %) was distinctly higher than that of Fe³⁺ (35.87 %). The removal rate of phenol, a characteristic pollutant in coking wastewater, is more than 99 %. The removal rates of chemical oxygen demand (COD) and total organic carbon (TOC) in coking wastewater reached 84.9 % and 64.1 %, respectively, under the conditions of a biochar dosage of 1.0 g/L, initial pH of 3.0, H₂O₂ dosage of 16 mM, and a reaction time of 210 min. Fluorescent DOM can be rapidly degraded within 10 min, and the removal rate is in the range of 83.6 %-97.0 %. Two-dimensional correlation spectroscopy (2D-COS) was used to reveal the catalytic degradation characteristics of DOM, the results showed that protein-like components (280, 300, and 305 nm) can be changed preferentially, followed by humic-like (580 nm), fulvic-like (355, 365, 325, 330, and 375 nm), humic-like (420, 500, 490, 520, 465, and 540 nm) substances. Protein-like and fulvic-like substances contributed the most to TOC mineralization. Radical quenching experiments indicated that the •OH free radical played a crucial role in the catalytic degradation process. This work provides valuable insights into the application of spectral technologies in the degradation process of organic matter in wastewater and the resource utilization of FeCS and waste biomass.