May be useful to look at this web:

http://www.h2o2.com/industrial/fentons-reagent.aspx?pid=143&name=General-Chemistry-of-Fenton-s-Reagent

The optimum dosage of ferrous sulfate and hydrogen peroxide were 560 mg L−1 and 1020 mg L−1 respectively. The reduction in COD will be about 56℅.

For wastewater with COD above 10000 mg/L, this ratio reached 23.16 g/L of Fe+2 and 200.52 g/L H2O2. The reductions in COD will be 86℅.

Stepwise addition of Fenton’s reagent was more effective than

adding the entire volume in a single step.

For good results, temperature should be above 10C.

Now questions arise, what type of water you have and what is the temperature? You should tune your dose accordingly.

For further details, see the following paper.

https://www.google.com.pk/url?sa=t&source=web&rct=j&url=https://www.researchgate.net/publication/282148450_A_Review_on_the_Fenton_Process_for_Wastewater_Treatment&ved=2ahUKEwjbleyk2LDeAhUDtRoKHcy4A6MQFjABegQIBhAB&usg=AOvVaw2sz6SI_dQmLir6LE3YJZfe&cshid=1540990581581

Atun Roychoudhury : Because the composition of wastewater to be treated is not known, hardly to say what the best ratio ferrous iron : hydrogen peroxide is. I recommend (as Augustine above) to perform laboratory testing. Without such tests you cannot determine the optimum ratio for your case.

Best regards

Vit

I suggest to start with the theoretical amount needed for oxidizing all COD, i.e. H2O2 (in mg/L) = 2.13 x COD (in mg/L). Fe:H2O2 = 1:5-10. pH should be 3-4.

this is a good question