Is anyone treating Grey Water? 2

[ChrisConley]

With LEED we're being pushed to consider reusing grey water in building (all water in the facility not coming from the toilets and urinals) for reusue in irrigation, toilet flushing, cooling tower make-up and other non-potable applications.

I haven't found a clear standard that says: do this, this and that... are there any?

What filtration/treatment would be recommended...in general?

 

[PEDARRIN2]

ASPE has a section in their Data Book about grey water.

We have looked at it. But where we typically do work, water is not a big issue so we get away with using low flow fixtures and stuff like that. Not many owners want the up front expense of the system and the maintenance just to save water.

But, from what I have heard, if you filter it to remove suspended solids and you chlorinate to kill any bugs (bacteria) in it, you can use it.

 

[bimr]

It depends on the government regulations where the project is located.

California has the most comprehensive regulations:

http://www.watereuse.org/ca/usestable.html

 

[BarryEng]

Have a look at: -

http://www.epa.gov/nrmrl/pubs/625r04108/625r04108.pdf

for a 480p "Manual - Guidelines for Water Reuse". (about 12Meg download).
It was published in Sep04 (updated from Sep92).

There are heaps of pubs covering this subject. Try this one & if it does not cover what you want, I'll have a look for others.

 

[ChrisConley]

Thanks all, the second part of my question was.. is anyone doing this? I was hoping for some hands-on experiences.

I'm in an area of the world with pretty cheap water, and the payback on these systems is infinite.

In fact, many people argue that the additional electricity cost to 'repump' the water and treat it negates the water savings.

 

[PEDARRIN2]

I agree.

I would like to do one myself, just to say I did and to have the experience under my belt. However, I work mostly in the midwest and I have been told we live on top of the biggest aquifer in the US. So, grey water and even storm water reuse just is not economically feasible here.

We put in the low flow fixtures and stuff like that. Those do not impact the cost - except for the maintenance on the sanitary because the low flow toilets just do not give the drain line carry that the older toilets did.

 

[jartgo]

I second bimr's suggestion above that it depends on where you're at. Where I'm located, treating grey water isn't an option, it's a requirement. There's a push to use the water after it's been through the treatment plant (before being discharged) but using grey water directly is a no no.

 

[bimr]

There are some requirements like low flow showerheads and toilets that have been applied in all areas of the United States.

There are also specific projects where the project developers have volunteered to do some specific conservation methods in order to speed the approval of a project.

There may also be certain permitting processes where you have to show that you evaluated reuse as part of your project in order to be able to get a permit for your project.

However, I have not run across any mandate to reuse water. Right now, it still doesn't make sense in most of the United States. Water reuse and zero discharge type projects are located in the arid regions of the country like the southwest and in areas prone to seawater intrusion like Florida.

 

[jcook14]

As stated above, it depends on the value placed on water in your particular location.

An Australian perspective...grey water re-use is big news in most Australian cities as there are water shortages caused by drought over the majority of the country.

One option has been to recycle/reuse existing water supplies. These have been investigated and implemented at different scales from the simple house system to Reclaimation plants which provide water for industry by treating secondary output from sewerage treatment plants (eg

http://csrp.com.au/database/au/kwin/kwrp.html)

Grey water systems are generally more expensive than standard systems as you have extra piping to keep it isolated from toilet water, extra pumping and possibly a need for a storage tank. Also there is the cost for chemical treatment. The level of treatment is usually determined by the use of the "grey" water. More likelihood of human contact increases the treatment level of the "grey" water.

Benefits can be a reduced water cost and the associated "green" image of having a grey water system.

 

[jartgo]

I think it's important to point out that grey water and reuse water are two different animals. "Reuse" is essentially reusing treated wastewater, that is after it's been through the WWTP. Grey water has had no treatment, untreated water that basically hasn't been in a toilet (i.e., washing machine water, etc.)

 

[dicksewerrat]

Everybody downstream from a treatment facility is 'reusing' water.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[ch81pc]

Depneding on what you want to do with it, an upflow gravel filter removes a fair ammount of material. and requires little input other than shutting off the flow, opening the drain down and let gravity backwash your filter.
You can then go for further filtration through finer sand or membranes if you wanted to. You could even go for UV sterilasion. There is no point trying to use chlorine as the chemcial usage would be huge and you would end up with vast ammounts of organo chlorines in there which would proably do more harm than good.

I've got a very simple system that I built at home using water from the shower, bath and rainwater. I've got a 45 gallon tank to act as a buffer, then use gravity to push the flow through a gravel filter and into a storage tank. It works fine for irrigation, toilet flushing.

 

[rngrrix]

Like any engineering project, you need to spec out the end use requirements, characterize the water available, then the design is straightforward. There are a lot of good suggestions here but at the end of the day if you do not have a good specification and characterization you will be disappointed with the results. I currently work near the Caspian Sea and we even account for evaporation as water is out-of-sight $$$$$$.