Clean & Capture - things I've learned

[john@AEC 37]

G'day

I've been watching the progress of waste water capture & filtration systems for a while, plus experimenting with a few things, so, as it's raining today and I've had to postpone todays work, I thought I'd go through my designs & plans and maybe save some-one some hassle and angst.

What I wanted from a system was -

- Simple to operate for one person

- Able to handle very large amounts of sediment without stopping frequently

- No consumables (eg cartridge filters) that needed to be carried

- Waste water cleaned to "trade waste" or "re-use" quality

While I don't claim to have met these criteria... I'll share what I have found out

Stage 1. The pre-filter.

Conical base with tangent inlet to spin out the heavy sediment. The outlet is in the centre of the vortex and about 100mm below the inlet height. The waste outlet is a 50mm pipe fitting and ball valve at the base - this is too small as it it clogs with the huge amount of sediment that is collected, I would like to try a 75mm and a 100mm. I would also consider including a second pre-filter to catch as much sediment as possible before the vacuum.

On one large job (10 hours) I collected over 20 litres of solids just from this basic pre-filter (stopping every hour or so), I then collected about 10 litres of solids in the base of the vacuum drum. In the fine print of one system I read where it recommended stopping and cleaning the filters every 10 minutes under these conditions. This would drive me crazy!

Vacuum drum.

I have changed to a horizontal inlet with a 90 degree bend inside to give a spinning action for more filtration. This drum currently has a flat bottom which 1. clogs the pump-out & 2. requires the top to be removed and the sediment to be manually scooped out. I would like to rebuild this with a small conical base to allow easier removal of sediment (after just 1 day I have found 50+mm of fine sediment in the base).

The vacuum is a basic 3 x 1100w @240v wet vac which is barely adequate. Lamb make some much larger & more powerful motors which can give up to 170cfm from 8 amps (at 240v) and my generator can easily run three of these.

Stage 3. Further conical filtration & cooling.

The pump-out in the vac drum sends the still hot water full of oil and fine sediment to another conical based drum. It enters on the side (top right) with a 90 degree bend to make it spin around the outside with sediment collecting in the conical base. The out-let is in the centre and is up-turned so the water and lighter sediment & oil falls into it and then down the outside. The lower outlet with the white tap is for draining the drum of water after the waste has settled.

This drum is also to allow the water/oil to cool, thus allowing the oil to coalesce.

From here the water falls into a collection drum.

Collection drum with inlet at top right and pump-out.

Stage 4. More sediment filtration.

This thing is a cyclone separator (http://www.heattransfer.com.au/pdf/separator brochure.pdf), the water enters on a tangent (top left) and spins down with sediment collecting at the bottom and clean water exiting at the top centre. These are used in many places for water treatment & filtration and are a simple, low maintenance method of removing very fine sediment. This combination of separator and drum has two problems, 1. sealing around the lid, as it must be air-tight to stop pressure loss. Some type of flat face that mates with the lid would be better, and 2. a flat bottom on the collection drum which requires dis-assembly and scooping sediment out. A conical base with drain would make this simpler and more efficient. I would also suggest using the s/steel version.

Stage 5. Oil water separation.

http://www.everythingwater.com/wp-content/uploads/2010/10/Domino-VGS-NG-New-Generation-Separator.pdf

Waste water needs to be collected in a 1000 litre IBC for more settling before being pumped into the Vertical Gravity Separator by a double diaphragm pump (creates less turbulence than a pump with an impeller). These separators have approval for use in trade waste systems and are used by mobile fleet washing contractors. Water is collected in another 1000 litre IBC.

Stage 6. More fine sediment filtration.

20 micron bag filtration and maybe even finer cartridge filters. This probably isn't needed for "trade waste" disposal, but certainly is for "re-use".

Other observations -

I can't find a practical (ie. quick and simple) method for removing cleaning chemicals. Some are called "quick break" and may separate in the settling tanks or VGS, so "re-use" is hot water only.

I have seen mouldy concrete car-parks, driveways and footpaths cleaned with a "re-use" system where the result was "stripes" because no chlorine was used - this would drive me crazy - a more expensive way of giving the customer an inferior (but EPA compliant) result.

Well, I've run out of money and there isn't a lot of work around, so I've stopped at Stage 4. As much as I've enjoyed the technical exercise of researching and designing it's time to sell off my commercial grade equipment and stick with simple, low capital, closer to home, domestic work.

Cheers

John

[Christopher 102]

Great info and pictures John.

PM or email me, I can give you some different ideas that might help you for some parts of your system.

There are different types of flocculant out there that will take chemicals, soaps, etc.... out of the water and are about $5.00 per pound in US dollars but I am sure that flocculant is available all around the world, you just have to find the right one for your purpose.

You can use something as simple as an IBC tote with mixer. You add the flocculant into the tank, mix it for about 10 minutes or so then you can let it settle or start pumping it through filter socks, say 100 to 20 micron then use polishing filters down to 5 micron if you want to run it back through the pressure washing pumps.

There are companies out there that sell complete systems but I can see that you would have no problem making one, the hardest part would be finding the right flocculant. I know of a supplier here that has one that takes the soap out but I would see if you can find it there closer to you as the shipping will be expensive I am sure but if you cannot find it, let me know and I will give you his contact number, just email or pm me.

How much did the blue cyclone separator cost?

Do you have any other pictures of the system?

Keep up the good work.

[splashandash 15]

Great info,you have put a lot of thought into your system. I like the conical barrels I wonder if any makes them commercially.

[Chappy 138]

what a great example of Auso-engineering! Very interesting stuff. My biggest problem and why I havnt tried going after bigger stuff is the silt. The sand trap helps but the fine silt makes it through everything and clogs up my filters to the pump and am constantly having to stop to clean them when on full recycle.

I have some 5 micron bags coming from Jerry that insert in the water tank. Easier to pull out and rinse.

I like the conical drum idea for easy cleanout but obviously needs a bigger outlet.

Gotta read through this one more time to get more details i might have missed.

[810F250 14]

Thanks for sharing John, what gpm are your machines, attempting to figure how much time the wasteewater has in each section.

[Christopher 102]

I have not looked but it would be nice if there was a box or drum that would hold like 8 or more of the filter socks so you open the lid and pull them out to replace/wash and then close it and get back to work.

This way you would have a lot more capacity for fine filtering before shutting down, this would be after the larger particle filtering.

The same thing for smaller micron filters to try to help get rid of the silt in case you wanted to re-use the water, if you could get the soap out by other method than floc.

[tonyshelton 112]

I glanced through your EPA regs John. They look similar to ours. It was interesting to note that they did have a clause that states that only storm water should enter the drains "to the best extent possible" or some other similar wording.

Interestingly it also gives sample ways to filter storm drain inlets with pictures without any advertisements from companies that sell such equipment, and none of them require power equipment.

Your setup looks great. Did you embark on this because of regulation enforcement or of your own accord?