Dear Hewa,

it is not clear if you are talking about lab experimental conditions (1) or full scale applications (2).

1. In lab scale tests, if you work with an aqueous matrix (such as, deionized water solution, simulated wastewater, real wastewater), which you previously fully characterized in terms of quality parameters (e.g., TOC or COD and other parameters that can affect process efficiency and are of specific interest for your investigation), following your experimental design, you can optimize process conditions in terms of H2O2/Fe ratio (as you know optimum pH is below 3) and subsequently monitor H2O2 and Fe concentrations, respectively, to keep your optimum conditions stable.

2. In full scale applications wastewater characteristics can change, so the conditions established at lab/pilot scale may not be optimal and process efficiency may drastically decay (accordingly process monitoring in terms of TOC or COD, H2O2/Fe ratio, pH, target contaminant/s etc. is increasingly important).

Hopefully my answer can be useful

kind regards

Luigi Rizzo