Advanced Oxidation Pretreatment for Biological Treatment of Reclaimer Wastewater Containing High Concentration N-methyldiethanolamine

A wastewater treatment configuration consisting of advanced oxidation pretreatment and biological wastewater treatment process (BWTP) was investigated to treat a reclaimer wastewater generated in a steel-making industry, which contained high concentration MDEA (N-methyldiethanolamine) of up to 20,548 mg/L and other pollutants such as formate, phenol, and thiocyanate. The Fenton, ozone, and peroxone methods were tested as candidates, and the peroxone method was chosen because it could selectively decompose MDEA resulting in the final MDEA and chemical oxygen demand (COD) removal efficiencies of 92.87% and 27.16%, respectively. Through the respirometer tests using the sludge of the BWTP, it was identified that the microbial toxicity of the peroxone-pretreated wastewater was negligible and the short-term biochemical oxygen demand (BOD) to COD ratio, indicating that the biodegradability of wastewater significantly increased from 0.103 to 0.147 by the peroxone pretreatment. Analysis of the oxygen uptake rate profiles also revealed that the microbial degradation rate of the pollutants present in the reclaimer wastewater was in the order of phenol > formate > thiocyanate > MDEA, which could be changed depending on the microbial community structure of the BWTP.

Automated summary

This study investigated a wastewater treatment configuration consisting of advanced oxidation pretreatment and biological wastewater treatment process for treating reclaimer wastewater generated in a steel-making industry. The peroxone method was found to be effective in decomposing MDEA and achieving high removal efficiencies of MDEA and COD. Additionally, the peroxone pretreatment greatly improved the biodegradability of the wastewater, and the oxygen uptake rate profiles showed the microbial degradation rates of different pollutants.