Breakdown of soap and detergents

[JOHN9386]

I am building a greywater harvesting system. I have all of it designed except one aspect. It is a 3 phase system. The first phase breaks down soap and detergents. The second phase filters the water. The third phase pumps water out of system. My question is what is the best way to break down soap and detergents in a timely manner with as little mechanical parts?

 

[moltenmetal]

Timely? Not really. But if you want to keep it from getting stinky (without sulphate reduction), you need to do the degradation aerobically. That calls for air injection and probably some media for the bacterial slime to grow on. And you'll need to ensure that the soaps and detergents are all readily biodegradable ones. Some degrade, but only very slowly.

 

[moltenmetal]

...unless you have the space to build an artificial wetland...

 

[JOHN9386]

I have entertained the idea of wetlands. I honestly want something that will be inside the tank because the tank is buried. I'm thinking about using a sand filter, but i really think there is a better solution than that.

 

[moltenmetal]

A sand filter will just filter insoluble stuff. But without active air injection, the water will go anaerobic and you'll have sulphate reduction and odour. Filtering the raw gray water will reduce the amount of stuff you have to degrade, but you need a place to back-flush the filtered material into periodically or else the filter will plug with solids and biofilm. Presume the absence of this kind of place is the reason for the gray water system in the first place.

A wetland needs to be fairly large to do the job, and you could lose a lot of water due to evaporation and transpiration- better for water treatment and disposal than for water recovery. But an artist in Toronto was commissioned by the Canadian Plastics Association to build some elevated wetland planters as a kind of art installation along a major highway (the Don Valley Parkway).

http://donwatcher.blogspot.ca/2009/09/elevated-wetlands.html

I never saw any data from them as to how much they treated the water from the Don- don't know if any such data was ever collected, as the water was coming from the Don and going back there surely at least someone cleaner than it left so I doubt anyone really cared. They're still there, but look somewhat abandoned.

 

[bimr]

A better understanding of your project would help. Is this a residence, soap plant, or a truck wash? Is it 5 GPM or 5 MGD?

 

[JOHN9386]

It is for residential, car washes, and hotels.

 

[moltenmetal]

Oh: this is commercial? Then I'm done commenting! Sounded like it was a home project...

 

[bimr]

Don't think there are any options that operate in a timely manner with just a few mechanical parts. A system for treatment may consist of the following steps:

- Neutralization
- Filtration
- Flocculation
- Biological treatment
- Disinfection

Note that it is very important to disinfect the recycled water as the water will be a risk to human health when sprayed.

To breakdown the biological components, you will need some type of biological treatment. The simple way is a biological filter, not a tank.

You will need someone to design this, permit it as an industrial wastewater treatment plant, construct it, and operate it under the supervision of a licensed wastewater treatment operator.

Here are some examples:

http://www.washtec.de/Englisch.8891.0.html?&no_cache=1&L=&tx_nfdownloads_pi1[d]=2633

http://www.orenco.com/doclib/documents/ABR-ATX-GREYWATER-1.pdf

Here is a comparison of wastewater technologies:

http://www.waterboards.ca.gov/sandi...ne_country/docs/updates081910/owts_review.pdf