Filtering Suspended particles from water

We have a Supertreat onsite sewerage management system. The basis of this system is a pair of tanks, one of which is the septic tank and the second is the effluent treatment tank. The water that ultimately comes out of the system is not drinking quality but is OK for spraying on the garden, which is what we have been doing with it.

When we plumbed the house, we put in separate lines to the toilets, the ultimate aim being to use the treated effluent to flush the loos. We have set this up and it works fine. The only issue, and it is a minor one, is that the water is quite yellow. Our daughter flushed it three times last night before coming to Mum and saying "I've tried to flush it but the wee wont go away". Kids :o

The treatment removes all of the toxic stuff but it is quite heavy in various elements which are good for the garden but look a bit unsightly in the loo. What we would like to do is to filter it.

Over a few ales last night, the old man and I pondered the problem and I wondered if a sand filter from a swimming pool might not be the go. It can be backwashed to flush out the sediment and, in theory, should not need to be replenished like a cartridge filter would.

I suppose we could buy one, or maybe pick one up from the tip. However, on the off chance that someone here might know, can anyone suggest how one could be made from scratch? The main problem that I can see is how to stop the sand coming out of the vessel when you pump water through. There must be some trick, so if anyone has ever pulled one apart, how do they work, eh?

Why go to the trouble & expense of a filter? If the problem is only the colour, just get one of those hangy-thingies that go in the cistern and turn the water blue.

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Why go to the trouble & expense of a filter

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Because it's fun!!

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just get one of those hangy-thingies that go in the cistern and turn the water blue

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No offence, but that is a woman's solution to the problem ;) My wife's to be specific.

Now, do you know how they work or doncha?

Maybe a bit of alum will settle the sediments in the holding tank
It will turn muddy damwater clear

Its not rocket science (nor expensive) to make a solar evaporator which theoretically would give you clear potable water. Should be examples on the web as they are used in many 3rd world countries.

Dunno how your system works but the big town systems use a 'flocculant' in the other end of the treatment systems, before it goes throught the sand filters. This causes the small particles to 'floculate' - have a group hug - and fall to the bottom. You might be able to dose the tank once a week. I think it's a lime product.

Sand filters have a series of graded sized layers on the base, coarse to fine, with a base peppered with holes underneath. When the filter 'blocks up' the pump is reversed and the wastwater from this dumped. The local wawter treatment operator would be proud to show off his equipment (!) as these guys are a breed apart - esp. wastwater plant operators!

The'res no reason why a sand filter wouldn't work, but it will always be a maintence thing. Would a large-volume settling tank be viable? Could be emergency fire storage too.

Go a googling.

D

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a solar evaporator

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I have thought of doing that. All you need is an old window, a bath tub, a bit of gutter and a pump. Will definately mess about with something along those lines one of these days. Will I be game to drink it? Hell yes!!

I have also been experimenting with distilling. I took a funnel and a bit of rubber hose on a coastal walk I did last year. The funnel goes over a billy full of seawater and the hose comes off the top and you coil it up inside a big mound of wet sand. The idea is that the sand absorbs the heat causing the steam to condense. It works OK but takes a lot of seawater and a lot of boiling to get a cup full because it's not very efficient. What comes out is pure water though. Next trip I'm going to try something enclosed with a lip around the inside of the funnel. You fill the top with cold water to help the steam condense and it runs down the sides of the funnel into the lip. You have a little spout out the side where the water runs out.

The filter would have a much faster turnaround. With a still, I would need enough storage capacity to keep the loos flushing while water is being distilled, which could take days to do a few litres at this time of the year.

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The local wawter treatment operator would be proud to show off his equipment

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Good idea. I ride past the local treatment plant every day. Might drop in one day and take a squizz.

SilentC,

I would use alum, as suggested by echidna. I used to use it in the bush in Tanzania, when the only water I could access was muddy. The alum is very effective in flocculating the particulate matter in water and clearing it. At the time, I was not aware that alum in drinking water is suspected of causing Alzheimer's. This could account for difficulty I sometimes have in remembering what it was that I had gone to the other end of my shed to fetch. But if you are simply using the water for flushing toilets, it should be no problem.

It seems to me that using a sand filter to do the job would be using a sledgehammer to crack a nut.

Rocker

You need to know what is causing the colour for the best results. You will need to get the water properly tested to determine this (I am sure we all have a fair idea, but you need to know chemically). Once you know what the colourant actually is, you can use the best flocculant for it to give filtration the best chance to remove the colour.

Some organic compounds breakdown in sunlight and all you need to do to remove the colour is store it in an open top tank in full sun. Fill a clear bottle with the water and leave it in the sun and see what happens.

Personally, I would just replace the pan with one the same colour as the water, might not fit with the bathroom theme but would solve your problem. I wish I had not replaced our pale yellowy mustardy apricoty pan with a white one, you need to clean it 5 times as often.....

Cheers
Ben

OK. Alum: I have that problem Rocker and, to the best of my knowledge, I have never been in contact with alum. Maybe they use alum to filter beer?

So what happens to the flocculated particles (can I say that here?). When I was a pool owner, there was a chemical you put in to remove particles and the clumps that formed would fall to the floor of the pool and had to be vacuumed up.

Ben, thanks. I'll try the water in a clear bottle idea and see what happens. My old man insists that the particles are not fecal. There's no odour, maybe a very faint urine smell. Our septic tank is only new and hasn't formed a decent crust (I trust you've all finished your lunch) and it is his opinion that things will clear up in due course.

All our pans are brand new and white. It would not be a popular decision to rip them all out now, seeing as we only moved in 2 weeks ago.

I have always found sledgehammers do an admirable job of cracking nuts, if that's all you want to do. Eating them afterwards is not always an option.

SilentC,

The flocculated particles sink to the bottom, as in your pool. In fact I believe the pool flocculant chemical is alum, although I may be wrong.

Rocker

Ah yes - alum. What were we talking about again?

Question - have you spoken to the installers/designers of the system? They surely would've come up against the question before, maybe it will stop this in time.

The installer was my old man. To the best of our knowledge, no-one has ever tried to recycle the treated effluent this way. You're supposed to spray it on an area of medium density vegetation over an area of approximately 100 sq. metres and hang signs everywhere warning people not to come into contact with it. If the council knew we were doing this, they'd probably write us a harsh letter telling us to stop it at once.

The manufacturers of the system claim that it is perfectly safe, it's just not approved for anything other than irrigation of non-vegetable plants.

The local supplier has suggested a couple of ideas but that doesn't stop me from looking around for others. He reckons exposing it to sunlight will do the trick. It's a problem to solve, that's all. Gives me something to think about when I stand and/or lean.

i believe that fullers earth can be bought from a swimming pool supply shop and is a (one of many) flocculant (I really wanted to be the first to say flocculant, and missed out :( )

I'm sure you have Wik'd flocculant - maybe you should try putting some of your water in a drum with some fullers earth and see what happens.

Have a look at hydroponic farms that recycle their water, a fairly commonplace activity. They use flocculants and filters.

I think you are putting your familys health at risk by recycleing the water back through the dunny.

http://en.wikipedia.org/wiki/Pathogen.

Al :eek: