Sewer Odor Problems 2

[redbridge]

I am working on a project to reduce odor for a sewer system. In the sewer system there are two lift stations with large storage volume and low flows. Have any of you ever filled in a portion of the wetwell with concrete blocks or concrete to get the pumps to cycle more often and keep the sewage moving? There are odor problems at these stations and they pump directly to the sewer plant and they have odor problems there also. The odor problems occur around 9 pm and 7 am. The lift stations were designed for future growth that has not happened. They are set up to chemically treat for odor but I am trying to help optimize the stations so they can reduce the amount of chemicals.

 

[bimr]

Not familiar with that. Have you tried different chemical?

http://www.pncwa.org/assets/documents/2009 PNCWA Odor Control Workshop - Dick Finger.pdf

There is a vortex that can be inserted to reduce odors.

You can also recycle the flow through a venturi to aerate the contents.

http://technicaldesignservice.com/wp-content/uploads/2012/08/3-Lift-Stations.pdf

 

[redbridge]

Thanks bimr. I am getting ready to try some different chemicals. Am I thinking about this correctly. That if I decrease the time the sewage is in the lift stations the less odor there will be. I was wanting to optimize the wet well size before determining the amount of chemicals that would be needed.

 

[bimr]

Most of the time, the lift station wetwells are sized for about 30 minutes to eliminate the problem.

Sometimes, if you are repumping through multiple lift stations, the odor is inevitable.

Odor scrubbers are also available.

 

[cvg]

you may want to optimize the level controls. set the pump to turn on sooner

also, make sure the trunk sewer is not surcharged and anaerobic. a long sewer which is flowing full can also be problematic.

 

[redbridge]

The existing wet well has a several hour hold time instead of 30 minutes. Thanks for the input. I will dig a little more and post back later.

 

[jgailla]

You should be able to adjust the floats to minimize the hold time as cvg says.
If your hold time is several hours, it's going to stink no matter what you do for odor control.

 

[redbridge]

The square footage of the wet well is so large that adjusting the floats wont do much good. That is why I was thinking about installing concrete blocks or pouring concrete in the bottom to reduce square footage so I could get 30 minutes or less hold time. Do you think this would help the situation?

 

[bimr]

It would definitely help with the lift station odor issue. It might be possible to just fillet around the sides. You may still have problems with the force main as the others have pointed out, if the material will be sitting in the pipe for long durations.

The question is when will the lift station capacity be increased and you would need to remove the concrete.

 

[jojopollo7]

just to recap a few others opinions, you will always have odor problems until you reduce the hold time as anaerobic conditions will begin to set in. Have you contemplated installing some diffusers at all if it is absolutely necessary to keep the capacity of the lift stations the same?

 

[dicksewerrat]

They used to have a product for degreasing wet well that smelled like oranges. It floats on top of the liquids and recoats the walls as the level moves. You might try looking for that. Also instead of concrete blocks in the wet well why not use some sealed pipes that are weighted to make them float vertically in the well. Easier to remove.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[dicksewerrat]

One other thing. That is not an odor, that is the aroma of money.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[jamiejones16]

How about doing the chemical scrubbing and using ozone as the oxidant? If the odours were really that terrible and volumes of air are high, scrubbing is the most effective method you can employ. Before that you must first determine the following: type of odour, odour concentration, temperature, specific ozone dose, contact chamber retention time, waste water acceptability criteria and the time of scrubbing system.

Boifilters can also be a good option. The only weak point is the installation, as it requires a vast land site to set it up.