Use of sodium nitrate injection to prevent H2S in wastewater system 1

[cajunj]

Specifically in a 10-12" force main with 360,000 gallons per day avg. flow in approx 18,000 linear feet force main. Samples reveal over 200 ppm H2S (maxed out my meter) and PH of less than 2.

 

[odle1128]

I don't know what a force main is. So, answers below may not apply.

H2S can be oxidized but kinetics are slow, hours? Something like copper sulfate can be used. H2S will react to precipiate copper as copper sulfide which can been removed by conventional solid/liquid separation. H2S is consumed in the process.

Robert Odle

 

[hacksaw]

Sounds like you are dealing with feed lot or food processing waste. Most localities adopt regulations that require all such sources to pretreat their waste. It would be a mistake to treat in the force main.

 

[jay165]

It has been done in oildfield waterflooding projects. The nitrate is injected into the water injection system. The purpose is to prevent the reservoir from souring by feeding the nitrate reducing bacteria, which then consume the other carbon based nutrients at the expense of sulfate reducing bacteria (which produce the H2S). I'm not sure if this would work in your application or not.

The only refernce source I can give you that might lead to some useful information is a Society of Petroleum Engineers (SPE) paper # SPE 49152, Microbial Water Treatment: An Alternative Treatment to Managing Sulfate Reducing Bacteria Activity, etc by Cassinis, Portwood and Farone.

Good Luck!

 

[cajunj]

The force main in question is a 12" pvc line transporting raw sewage from one drainage basin to another. The topography of the area we live in requires pump stations to assist in the transport of sewage waste to the treatment facility. The downside to this method of transport is the long retention time of the material in the holding wells and the force main while in transit. If the time period is too long the sewage will go septic resulting in an anerobic environment producing H2S. The common threatment of this problem is to inject ferrous sulfate which is no more than a metal cleaning biproduct. It's more of a "sacrificial lamb" than a cure. The H2S attacks the "liquid iron" in the ferrous sulfate neutralizing it but it causes it to fall out and become a precipitate. This obstructs the line reducing pumping capacity. This leads us to my present problem. Can sodium nitrate be used to neutralize H2S without the problems of our previous attempts?