Treatment of Soapy Water for Discharge to Natural Waterway 2

[StructSEZ]

Hi,

I've got a job here to beef up a government agency's 'green rating' on their building.
One of the things that can be improved on is the run-off of soapy water which is created when they wash their cars.
Being a diplomatic/protocol department, they have a fair few fancy cars for use by foreign dignataries etc, which are washed almost daily.

Currently, the run-off is drained into the storm drains which eventually flows into a nearby stream and then to the sea.
I'm trying to find a way of 'cleaning' the soapy water (removing detergent from it) before allowing it into the water way?

My first thought would be some kind of ionic precipitation in a holding tank and then releasing the water, but I'm really not familiar with soapy water treatment.


The following thread;

http://www.eng-tips.com/viewthread.cfm?qid=94876

is not too relevant since I'm on a tropical island with 85% humidity rather than a desert.

Can anyone suggest anything please?

Thanks,

 

[bimr]

Linear alkylbenzenesulfonate is the main ingredient in soap. This is a dissolved organic and difficult to remove from water.
The only process that can remove it is the activated sludge process.

Here are some suggestions:

1. Wash the car under a car port and drain the wastewater into the sanitary sewer system.

2. Concentrate the wastewater with a RO system and transport the RO concentrate off site.

3. Prohibit car washing.

4. Prohibit the use of soap in car washing.

5. Evaporate the wastewater.

 

[Spartan5]

You're working for a government agency on a tropical island? Talk about having it rough!

Assuming your flows are on the order of hundreds of gallons per day and the detergents aren't anything exotic... I would suggest using a small single pass sand filter. Capture the water in a holding tank and use timed dosing and a small 1/2HP pump to apply frequent, small doses to the sand filter. See "Small and Decentralized Wastewater Management Systems" by Crites and Tchobanoglous for design considerations.

See also:

http://www.csuchico.edu/cwtrc/PDFFILES/sytemdesign/SB-Comm83ManualSinglePass.pdf

 

[bimr]

I should have said "biological treatment" will remove soap.

If the only problem that you have is the soap suds, one other option is to use a silicon based defoamer.

http://solutions.3m.com/wps/portal/...2K44_nid=2P6GRCCQGFgsQB2XRP1WS8glBJHHS43N7Bbl

 

[dicksewerrat]

I think you should hire about 200 engineers to visit this site and make recommendations. When do you want us? Please send info to charge our airline tickets. thanks

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[StructSEZ]

Hi guys,

Thanks for all the replies.

Love the way this whole thing became a holiday auction!

Spartan, I don't actually work for the government, just doing some consulting for them. But other than that, yes, Seychelles islands in the tropics (hence the SEZ in StructSEZ)...warm weather, sand, sea...

I'll take a look into the sand filter option. That sounds cheaper. With regards to the biological treatment I'll take a look into that too. Thanks for the links, guys.

 

[bimr]

Actually, the sand filter is biological treatment. There are several firms that make package systems.

http://www.orenco.com/sales/choose_...atment_systems/AdvanTex_treatment_systems.cfm

 

[StructSEZ]

Thanks bimr.