An improved hybrid strategy for online dosage of hydrogen peroxide in photo-Fenton processes

Abstract

This work addresses the challenge of designing H2O2 dosage strategies for improving photo-Fenton applications, as well as for further understanding the effect of the dosage. The developed strategy focuses on the limitations of the current solution schemes by adopting a hybrid methodology between open and closed loop approaches and it is based on three different stages: (i) one-shot initial H2O2 addition (ii) continuous H2O2 dosage until reaching a specific dissolved oxygen (DO) level and (iii) on-off control of H2O2 dosage using DO slope as control variable. The proposed strategy is validated in the remediation of a Paracetamol solution (100 mg L-1) and the results are assessed using H2O2 consumption and mineralization rate and level as performance criteria. The final tuning of the proposed strategy consists of: (i) only 40% of the stoichiometric H2O2 concentration, (ii) continuous feeding of H2O2 until a 4 mg L-1 DO concentration is attained, and (iii) on-off control dosage selecting DO slope set-points in 0.1 and 0.2 mg L-1 min-1. These scheme and settings show an improvement of the process performance by ~ 15% with respect to the same H2O2 amount in a single-addition. This work contributes to improving photo-Fenton operations and designing more efficient processes.