20 Feb 2025 - Peroxide Dosing
Date: 2025 02-February 20
Related: 2025 01-January 27 -USP Technologies Collection Trials
People/Robert Dotson: City of Memphis
People/Sammy Kohl: Contractors/USP Technologies
- Help with hydrogen sulfide in the Nonconnah Interceptor
- There was an uncharacteristic amount summer 2024 in the wet-well at Maxson .
- People/Sammy Kohl: Hydrogen peroxide has been used to control hydrogen sulfide
- Key question: How do we best mitigate sulfide coming into the headworks?
- Systems survey and discussions with Don, Henry, Mike, and Noah.
- Peroxide could be added to reduce hydrogen sulfide to reduce vapor sulfide to reduce corrosion.
- Where do you put dosing equipment? Dose Peroxide downstream of
Sammy: The goal is to neutralize it at the lift station but ultimately through the force main.
A drop in pH that is this significant, so the biofilm must be significant. The goal is to chip away at the biofilm, so that it has less of an impact downstream.
Monitor this discharge point to see day over day what is the pH doing.
Upon shocking the water we would expect the hydrogen sulfide levels to dip down, because we're trying to get the pH levels above 10 in the force main.
Robert: What will this do to the pumps?
Sammy: A rigid application point will feel directly into the water. If there is a concern about the elevated pH and the pumps, we should discuss it before putting it into the lift station.
Robert will check some pump data.
Tasha King-Davis is concerned about high pH in the lift station. Historically, basic (high) pH has been eating away at railing and at pumps.
Sammy: The goal is to get the high pH water through the lift station quickly. Was the former problem acute or long-exposure?
Sammy would like to take a closer look at the study brought up by Tasha King-Davis, to ensure mistakes aren't made.
You would expect to see an immediate pH increase in the flow downstream.
The hypothesis is that you'll see similar or elevated pH for what is going in versus what is going out for a limited number of days, when the shocks are performed.
We should see an immediate jump up in pH, which will degrade a bit as the biofilm grows back. We don't know how long it will take to grow back, until it needs to be shocked again.
Robert: The plants will have to reduce flow to their headworks, which will cause septic conditions. We will need to be operating the plant consistently throughout the test.
Sammy: The extended retention time helps us out, because you want as much exposure as possible. Caustic versus peroxide. The ideal 24 hour diurnal profile. Slug dosing: The dosing will come through a flange from a truck.
Don asked if there are plans to add iron salt at the plant: No.
Sammy: The iron salt program has been paused.
The peroxide feed downstream will oxidize 50% of the liquid hydrogen sulfide coming into the plant. Collection system flow versus plant flow.
There needs to be baseline data taken, to achieve an ideal dose of hydrogen peroxide to achieve a 50% decrease for a positive impact at the headworks.
Liquid samples will be taking at the large chest near headworks. A logger will also be running. Data from logger will be available through USP's FTP site. #ftp
This should help us mitigate our biogas in our influent.
Don: How often does BFD it run at lift station? How often does it take to fill up?
Robert: It is not necessary to add a dome. In wet conditions it has to be in operation, or Solae will be backed up.
Sammy: How quickly it is turning over in dry conditions?
Robert: The lift station runs regularly, day in day out, and the quality is pretty nasty.
SARP10 rebuilt after a corrosion study.
Robert: His station has a polyurea coating. What will happen with the shocking?
Sammy is not sure if the polyurea will be damaged by caustic.
Robert wants to know if they can bypass the whole lift station using pressurized lines.
Sammy says this is a little different that typical hydrogen sulfide control, due to the nature of the slug treatment. The preference is to not tap forced main. "If i can do it in a wet well, I will. If I have to hot-tap a force main, I can, but we would be concerned about getting enough in to be effective."
Robert: How often?
Sammy: Based on EPA guidance, we're hoping every two weeks. More initial shocks may be necessary because the biofilm is entrenched, in this anaerobic environment.
Don says this treatment will comes out of the Stiles budget. It has worked before, and now increasing the scale should work to reduce biofilm coming into the plant, ultimately to reduce corrosion. We are ready to pull the trigger on this right now.
