Combination of synchronized oxidation-adsorption with mesopore-rich powdered activated carbon in the deep removal of refractory COD from coking wastewater

• Published in: Journal of water process engineering 2024-11, Vol.67, p.106128, Article 106128
• Main Authors: Sun, Guangxi, Chi, Yongzhi, Wang, Qi, Huang, Xin, Zhang, Yu, Yu, Jianwei, Tian, Zhe, Yang, Min
• Format: Article
• Language: English
• Subjects: Coking wastewater; Mesopore volume; Powdered activated carbon; Refractory COD; Synchronized oxidation-adsorption
• ISSN: 2214-7144; 2214-7144
• DOI: 10.1016/j.jwpe.2024.106128

Removal of refractory organics from the biological effluent of coking wastewater has been a challenge. In this study, synchronized oxidation-adsorption (SOA), which developed previously based on the Fenton reaction, was combined with powdered activated carbon (PAC) to remove the refractory chemical oxygen demand (COD) from a real bio-treated coking wastewater. Mesopore volume was found to be the most important factor affecting COD loading, and SOA (Fe2+ dose: 4 mM, H2O2 dose: 2 mM) + mesopore-rich PAC W1 (wood-based) could remove 57.2 %–79.3 % of COD with 100–1000 mg/L of PAC dosage, leading to the reduction of 90 % PAC addition comparing with PAC adsorption alone. Analysis revealed that SOA pretreatment could prevent pore blockage of PAC by removing the high molecular weight organics, including biopolymers and humics. The SOA + mesopore-rich PAC adsorption was applied in a full-scale coking wastewater treatment plant to stably decrease the COD from 222 ± 38 mg/L to 60 ± 10 mg/L over six months, and the treatment cost was reduced from over 3.1 US dollar/m3 to 1.1–1.2 US dollar/m3. This study demonstrated that SOA + mesopore-rich PAC is a promising approach for the deep removal of refractory COD from coking wastewater. •Mesopore-rich PAC is favorable for the removal of refractory COD.•High molecular weight substances in wastewater blocked the pores of PAC.•Synchronized oxidation-adsorption effectively removed pore blocking substances.•Synchronized oxidation-adsorption + PAC succeeded in full-scale application.