Nitric Acid for Effluent Neutralization
Nitric Acid for Effluent Neutralization
(OP)
Does anyone have any experience using concentrated nitric acid for pH adjustment of effluent? We routinely use nitric acid for pressure filter acid cleaning and have a good storage tank and control system available. I am looking at a possible method of injecting 5-30 gpm of 65% nitric acid into an 8" underground fiberglass sewer pipe for pH control. 100-150 gpm of water must be added to control the heat of reaction to maintain temperature at or below 125 F at higher acid rates. However, I am considering potential for localized flash boiling and pipe damage from inadequate mixing. I am considering using a 2" Kynar injection pipe for the acid inserted in the direction of water flow that would have multiple perforations to promote good mixing similar to a Resistoflex mixing tee.





RE: Nitric Acid for Effluent Neutralization
Do not inject concentrated nitric into an underground pipe. Too much downside potential when something (pH sensor, pumps, valves, water flow) goes wrong. Risk of excesss nitric siphoning, too. Also, in most places (e.g., US) your local POTW or EPA regulator will not give approval for such a treatment system. They need access for sampling, plus you need recording of your effluent pH. Also, I think you would get pH oscillations beyond your limits (mine are pH 6-10).
Use an aboveground mixing tank for neutralization.
Hope this helps,
Ken
RE: Nitric Acid for Effluent Neutralization
RE: Nitric Acid for Effluent Neutralization
how did you get on with this pH adjustment system? I am looking at doing something very similar except with sulphuric acid
Quentin
RE: Nitric Acid for Effluent Neutralization
Your question should be over on the Waste disposal & treatment Forum.
An inline pH correction system will probably never work. You need mixing and reaction times. See this thread:
pH system - Design criteria
Thread161-110441
RE: Nitric Acid for Effluent Neutralization