Thread: UV & greywater

I haven't used UV for grey water, but I do use it for treating rain water (we are not on mains water).

What level of treatment are you after?

One thing to be aware of is that UV relies on the transmission of UV into and through the water to be treated. As grey water is generally not very clear, you would have to provide a longer exposure time to allow for a more thorough treatment.

Spot on Vernon. UV would have little effect on grey water.
UV only kills bugs it won't remove any of the chemicals or suspended solids in grey water.

Yeah, and as NCArcher mentioned, it won't remove solids or chemicals.

We run out tank water through the UV and then through 2 parallelled 5um (micron) polyester cartridge filters and we get very clean and clear water - although we sometimes get some tannin staining of the water from one particular tank, which can't be removed (with our setup).

We replace the filters every 3 to 4 months and they are filled with gunk, so I would image that a similar systems to remove solids from grey water would have to be replaced much more often.

As for chemicals I think you can use activated carbon filters, but you'd need to check on that.

Again ... the bottom line is what you want to do with the water.

I would like to be able to store greywater for use on my garden & eventually set it up so I can use it for flushing toilets & washing clothes. I just don't want to have a breeding ground for chripto, ghiardia & E.coli sitting in my backyard though! I actually use a UV filter with a bio filter for my fishpond (13 6" goldfish in @ 1000L) the water is always sparkling clean!

I use a big fish pond type of unit for my tank water, but it runs online instead of circulating (i.e. the water only flows through it once - on the way into the house).

I think that you could get the system functional if you used an overspec'ed UV unit (overspec'ed because of the opacity of the water) and cycled the water through it multiple times (similar to the way it works on your fish pond).

I've got treated effluent from my sewerage system running through a sand filter for use in toilets and on the garden.

The filter is a 'slow sand filter'. The water passes through it quite slowly and the sand develops a layer of scum that bacteria from the water collect in and feed on each other.

I've done a trial with it and it cleans the water up a bit but it is still cloudy. About to set it up permanently this weekend. It consists of a reservoir into which you pump the raw water. This trickle feeds into a pre filter (a wheelie bin half full of gravel and river sand). Then the water flows into the sand filter proper, then out into a storage tank.

They use them in 3rd world countries for filtering drinking water.

Some pics

The house I'm currently renting uses a BioCycle grey water processing tank - it basically takes the place of a septic tank and leach drain.

It takes all the house wastewater and pumps it out onto the garden after adding chlorine. The water itself seems pretty clear enough, although the system comes with ample warnings that the water isn't safe to drink.

Some plants don't like the chlorine it adds, but it hasn't missed a beat in 10 years my family has been in the house. It gets serviced every two or three months, and apart from changing the air pump once, its been good as gold.

SilentC: You got a permit for that?

Rick: We've had a similar unit for over 10 years, but it has become a maintenance nightmare in the last year or so. We're thinking of ditching it and moving up a level...

There's a new mob (there is always a new mob...) using membrane technology in a wastewater treatment system (that's the new name for a septic system these days) It was developed in conjunction with 3 Qld Universities, and once you get past the advertising blurb, it does look good, but it is also pretty new (2006). The Company name is Econova, unit is here:

http://www.econova.com.au/detail.php?ID=73

It's a poly single tank system incorporating several sections.

Anyway, they are claiming A/A+ quality water out of the unit, and there are people who have drunk it without dying, although they do stress that the water is definitely not approved for human consumption.

Apart from the chlorine in a normal unit, you also have to watch Nitrates, Phosphates and Sodium which all can cause issues in the garden and damage your soil. Some of this you can control by eliminating laundry powders (that knocks out most of the salt, and a lot of the phosphates) but the interesting thing for me with this new system is that it seems to remove a lot of the phosphates and Nitrates, even though they make no claims in this area. It doesn't use chlorine, and depending on which state it is installed in, it may have a uv steriliser.

It's also the only unit I could find that has a no-smell claim on above-ground irrigation of the effluent. Most of the current units claim no-smell, but that is based on subsoil irrigation: they still smell, but they are pumping the effluent where you can't smell it...

If we decide to get it, I'll post more info.

woodbe.

You got a permit for that?

Haven't you read my signature line?

Originally Posted by RedRaven

The house I'm currently renting uses a BioCycle grey water processing tank - it basically takes the place of a septic tank and leach drain.

It takes all the house wastewater and pumps it out onto the garden after adding chlorine. The water itself seems pretty clear enough, although the system comes with ample warnings that the water isn't safe to drink.

Some plants don't like the chlorine it adds, but it hasn't missed a beat in 10 years my family has been in the house. It gets serviced every two or three months, and apart from changing the air pump once, its been good as gold.

Gday Rick, We have just had one of those installed six months ago.Do you grow any vegies using the water from the system, i'm thinking of growing tomatos as they will be above the spray pattern and root vegetables because the soil will act as a filter as well. ( i hope )

I think you'll find that growing food crops is frowned upon, not because the plants can't cope and filter out the nasties, but because the food may get overspray and/or the users may pickup some bug or other entering the area and tending/picking the crop.

Drippers are the go I think, especially that hose with an inbuilt dripper every foot or so.

woodbe.

Originally Posted by woodbe

I think you'll find that growing food crops is frowned upon, not because the plants can't cope and filter out the nasties, but because the food may get overspray and/or the users may pickup some bug or other entering the area and tending/picking the crop.

Drippers are the go I think, especially that hose with an inbuilt dripper every foot or so.

woodbe.

With the Biocycle you cant use drippers because the pump cuts in when the water reaches a certain level, we had micro sprays on at first and the Biocycle people said we needed larger holes because the smaller holes put more strain on the pump and block up too easily.

Yea, they told me that too. I put a pressure reducing filter gizmo on the line (from the irrigation section at bunnings) and it seems to work ok with the cheap drip irrigation line. It's not clogging up anyway, and the irrigation pump hasn't blown up yet. (all the other pumps have, so it won't be long) Ours is currently about half sprays and half dripper line, but it's going to get a big redesign and go 100% drip with the Netafim lines if I can get approval to replace the system.

woodbe.