Grease Trap. Don't read this before meal times.

[ToughButterCup]

If you don't want to know the result, look away now. Don't read this until well after tea time .

 

I need a grease trap. For my digester. Anyone got any experience of them?

 Can't find out much about them. (that isn't Yankeee)

[Jeremy Harris]

54 minutes ago, recoveringacademic said:

If you don't want to know the result, look away now. Don't read this until well after tea time .

 

I need a grease trap. For my digester. Anyone got any experience of them?

 Can't find out much about them. (that isn't Yankeee)

 

We built a great one at Penwyllt, as the septic tank kept getting blocked up with "fat bergs " (a consequence of a few dozen cavers having fry ups for breakfast every weekend).  In essence it was a deep brick built chamber (only built of bricks as it was right next to the old Penwyllt brickworks, so there were thousands just lying around) that had an inlet pipe around half way up it's depth and an outlet right at the very bottom, that led to the septic tank.

 

Midway across the chamber was a weir, designed to deflect the incoming flow upwards.  Above this was a suspended galvanised steel milk crate, resting on ledges just above the top of the weir.  The low level outlet pipe went via an inverted U bend, made from 110mm waste pipe fittings, so that it worked as an auto-syphon.

 

The way it worked was pretty simple.  The chamber would fill with the kitchen waste water run off (the toilets and showers went directly to the septic tank) and the fat would float up to the top, and clog in the milk crate.  The relatively fat free effluent would flow over the weir and when the level on the outlet side exceeded the auto-syphon height it would drain away to the septic tank.

 

Part of the Duty Officer's job each weekend was to lift the lid and check the fat trap.  We kept spare milk crates, so if it was looking clogged with a fat berg, it would be lifted out and put on the bonfire to burn off, and a fresh crate dropped in.

 

Before adding this system we used to have to dig the septic tank out at least once a year, as the fat made it impossible for the truck to suck out the sludge.  The indication that this was needed was from complaints from those camping in the field in front of the club house (below the septic tank) as it used to over flow across the campsite.  Digging the tank out was a thoroughly miserable job.  It was a long, rectangular, tank, with the lid made up from a lot of concrete railway sleepers.  All these had to be lifted off, the digging party had to don wetsuits, boots and goggles, and climb in to break up the contents, whilst keeping the tank flooded with water so that the tanker could suck up the stuff that was liquid enough.

 

As an aside, shortly after I got my explosives permit, I was Duty Officer one weekend when the tank had to be dug out.  I definitely did not want to climb into it, so I made up a handful of small charges (around an ounce of plastic blasting gel in a small screw top aluminium pill can) poked an electric det into each one, wrapped them in electrical tape and pushed them deep into the solid mass at intervals, using a long stick.  All the wires were connected up to the exploder, we all stood back, and the handle was wound and the button was pressed.  All the charges went off, but they blew the contents of the tank immediately above them vertically, for a considerable height, smattering all the cars in the car park with some of the contents.  We were hoping that we'd have fractured the solid mass (the inspiration was the "hot rocks" project in Cornwall), allowing it to be liquefied with water and sucked up.  Sadly we had to climb in and dig it out as usual, and then clean up the mess in the car park.........

Edited November 20, 2017 by JSHarris

[ToughButterCup]

Well, we can't complain about the lack of entertainment  now can we? 

 

I mean,  how many people do we know who willingly go around dynamiting balls of watery fat and in the process deluge a car parks-worth of cars? H+S rules were invented to put a stop to this sort of hooliganism.

 

No, thought not.......

[ProDave]

Do you WANT one, or has someone told you you must have one?

 

Personally Wen we cook anything with fat, I pour the resulting fat into the wheely bin (only when there is enough rubbish already in there to soak it up) then wipe out the pan with a couple of sheets of kirchen towel ans put that in the bin as well. Virtually no fat goes down my drain.

 

No doubt someone will tell me this is a bad idea.

[ToughButterCup]

1 hour ago, ProDave said:

Do you WANT one, or has someone told you you must have one?  [....]

 

I'm trying to protect our digester and our local water courses. 

Every little helps.

[Onoff]

Could you add the fat to a big tank of old engine oil and burn in a waste oil burner. Every time I open a tin of mackrel, sardines etc I wonder if it'd burn...

Edited November 20, 2017 by Onoff

[Jeremy Harris]

Seriously, a basket in the top of a chamber works very well.  The keys are:

 

1.  Only direct water with fats in to the trap - the slower the flow the better it will work.

 

2.  Make the trap deep and big, so the flow rate is slow and there is time for the fat to rise to the top.

 

3.  Fit some sort of grid in the top to hold and secure the fat for removal.

 

4.  Always draw the clear effluent off from the bottom, where it will be fat-free.

[Bitpipe]

We had an Italian au-pair last year.

 

As a treat for the kids I made some home made chips (only really do this a few times a year) - used a fresh bottle of sunflower oil in a pan. I'd left it to cool with the plan to decant the next morning and store back in the bottle for future use.

 

Anyway, I come down and she's doing the washing up - cheerfully washing the big pan that was used for chips.

 

I asked where the oil was and she'd just poured it down the sink - about 2l. Cue me emptying a bottle of fairy liquid down after it and then running the hot tap to try and disperse it.

 

55 minutes ago, Onoff said:

Could you add the fat to a big tank of old engine oil and burn in a waste oil burner. Every time I open a tin of mackrel, sardines etc I wonder if it'd burn...

 

When we had the old house on site it had an open fire that was often lit as it was freezing. One evening I'd just finished the last of a plastic tub of supermarket deli anchovies, the ones in vinegary oil. I tossed the empty pot onto the fire and nearly cr@pped myself as it exploded in a fireball. So yes, it will burn....

[PeterW]

1 hour ago, Onoff said:

Could you add the fat to a big tank of old engine oil and burn in a waste oil burner. Every time I open a tin of mackrel, sardines etc I wonder if it'd burn...

 

Yep....

 

 

[PeterW]

We had one - I insisted - on a commercial activity centre build that fed an 18,000 litre Klargester Biodisc unit. Its the Hepworth clay one, and as @JSHarris says, they work pretty simply.

 

http://hepworthclay.wavin.com/web/solutions/foul-water/clean/grease-trap.htm

 

The Hepworth ones seem barking mad prices - no way I paid £1300 (!!!!) but I did find this online for £230. Search for grease interceptor instead...

 

https://www.greasetrapsales.co.uk/buy-online/grease-traps---underground/gt-100-litre-underground-grease-trap

[dpmiller]

these guys do small underground *and* freestanding units

 

 

https://www.ebay.co.uk/itm/HYDRA-ST3-70L-Grease-Trap-Low-Commercial-Use-470mm-L-x-470mm-B-x-475m-H-/272715158658

[Jeremy Harris]

The only comment I'd add about the two cheaper models, is that they don't have an easy way of getting the fat berg out.  We added the old galvanised milk crate in the top simply to allow the block of fat to be lifted out in one lump.  Before that, the trap had to be dug out at the top, which was a lot more faffing around. 

 

Anything that will stick into the fat and has a handle, or handles, to lift it out will do, so it should be easy enough to fabricate something from stout steel mesh to fit one of the cheaper ones.  Make it of steel, as that way you can just stick it in a small fire to clean it off.

Edited November 21, 2017 by JSHarris

[Cpd]

I have a fat interceptor..... i have not built the cage yet so its still a PITA of a job to clean.

So living in a very isolated and rural setting its really expensive and very hard to get the Septic tank emptied so i do what i can to prolong the need.

i built a very basic trap out of various bits and bobs but in essence the water from the sink and dishwasher run into it vie the top, its about 400x400x400.

there is an outlet half way down with a ubend in it that then runs on into the septic pipe line. 

We are very carful not to put fat down the drains and do wipe out any excess fat with paper towel

from my observation the warm water from the dishwasher or sink hits the cold water in the “catchment tank” and any fat solidifies and sticks to the sides, heavy particles sink to the bottom  and the rest of the waste water makes its way to the septic tank. This sytem works really well and i have to clean it out about 4 times a year. Its a nasty job, the fat is the easy part, its the sludge at the bottom if the tank that is the stomach turner.....

i have a cottage that i am one day wanting to rent out and i have to assume that even with sighns and a bit of education on guests arrival there will be much more fat going down the drains.... 

so i will be building a new fat trap but with the advanced ideas put forward by JSH   

So also following this thread for any great easy fix ideas. 

 

 

 

[TerryE]

I've got a smaller one on our kitchen outlet. The good news is that this saves a lot of fat going into the sewer. The bad news is that no matter how careful we are at avoiding pouring fat down the sink, I still need to clean it out every year or so.  A nasty smelly job which yields a gob of fat about the size of 4 blocks of lard, but a lot smellier!  Nasty job!!

[TheMitchells]

18 hours ago, ProDave said:

Personally Wen we cook anything with fat, I pour the resulting fat into the wheely bin (only when there is enough rubbish already in there to soak it up) then wipe out the pan with a couple of sheets of kirchen towel ans put that in the bin as well. Virtually no fat goes down my drain.

thats what I do so hopefully its okay.

[ProDave]

6 hours ago, Cpd said:

So living in a very isolated and rural setting its really expensive and very hard to get the Septic tank emptied so i do what i can to prolong the need.

 

 

 

It costs us about £150 to have the tank emptied every other year. A local contractor SureClean are the cheapest but Scottish Water will also do it.

 

How remote are you and what do they charge?

[ToughButterCup]

I think I'm getting into the tough on spending and tough on the causes of spending phase of the build. I can see the logic behind installing a grease trap. But boy do I resent paying for one! It's almost as bad as buying socks.

 

And looking at YooChube, people are being very creative about solving the problem. I'm tempted to use Ed's ( @Construction Channel)  mantra:         How hard can it be?  

 

Its a plastic box with mesh  for the hard bits (quite like a pre-pump filter for a water pump) and an arrangement that slows the flow down as much as possible. Add some baffles. Draw the water off at a lower level than the input level. Here's a model

 

Tempted, tempted  I am

[Cpd]

1 hour ago, ProDave said:

It costs us about £150 to have the tank emptied every other year. A local contractor SureClean are the cheapest but Scottish Water will also do it.

 

How remote are you and what do they charge?

Without getting into the logistics and specifics i live on an island without public roads to my house, a ferry that cant carry heavy vehicles and roads that cant carry them anyway, we use a contractor with specialist equipment and due to weather, tides, roads/ access and available ferry's its not a cost efective solution. We are now as a community looking into purchasing all our own equipment and doing the relevant training  so that we can get the cost down for everyone. 

[Jeremy Harris]

1 hour ago, recoveringacademic said:

I think I'm getting into the tough on spending and tough on the causes of spending phase of the build. I can see the logic behind installing a grease trap. But boy do I resent paying for one! It's almost as bad as buying socks.

 

And looking at YooChube, people are being very creative about solving the problem. I'm tempted to use Ed's ( @Construction Channel)  mantra:         How hard can it be?  

 

Its a plastic box with mesh  for the hard bits (quite like a pre-pump filter for a water pump) and an arrangement that slows the flow down as much as possible. Add some baffles. Draw the water off at a lower level than the input level. Here's a model

 

Tempted, tempted  I am

 

It's pretty easy to build one, Ian.  If a bunch of highly disorganised young cavers can build one in a weekend, out of materials that were mainly scavenged from within 100 yds of the clubhouse, and with none of them having a clue as to how to lay bricks, mix mortar etc (I'd say 90% of the club members were either students or science/engineering graduates, with few building skills) and get it to work pretty much first time (the only mod was adding the galvanised steel milk crate) then I'd say anyone can do it.

 

Bear in mind that it helps if you can cool down the trap, so that the water content sinks and the fat and oils float more quickly.  I personally reckon a brick or block built one, or one just made up from fairly cheap concrete rings, would outperform a plastic one, and be tougher and better able to take a bit of abuse if it did get really clogged up.

 

600 x 450 concrete chamber rings are around £20 each if you don't fancy a bit of brickwork.  Making a trap with these would be a doddle, just dig a rectangular hole, pour a concrete slab in the base, drop three or four rings in, drill pipe holes for the inlet and outlet and pour concrete around them to hold them together.  Fit the pipes, make up a catch basket (go scrounging for something that will fit) and top it off with a standard drain cover and the job's done.

[Gone West]

I suppose it's too easy to say, just don't cook with fat, or if you do let it solidify and put it in the bin before washing up. I've never known the vegetable oils we use to clog anything.

[Cpd]

Its all the new rage now @PeterStarck high fat low carb diets, not to get off topic to much but it works for me and what a joy to be able to eat fatty meats without a care. Its obviously not as simle as that but not cooking with fat would be impossible for some. I am still carful but in rented accommodation you have to assume that there will be quite a lot of fat heading down the drains. I will document my building of the new fat trap when the time comes.     

[Onoff]

[ToughButterCup]

21 hours ago, JSHarris said:

(...) 

I'd say anyone can do it.

 

Bear in mind 

600 x 450 concrete chamber rings are around £20 each if you don't fancy a bit of brickwork.  Making a trap with these would be a doddle, just dig a rectangular hole, pour a concrete slab in the base, drop three or four rings in, drill pipe holes for the inlet and outlet and pour concrete around them to hold them together.  Fit the pipes, make up a catch basket (go scrounging for something that will fit) and top it off with a standard drain cover and the job's done.

Right.

I have an old useless coal bunker made from concrete rings. 

Now I know what to do with it. 

I've got a digger, I've learned how to make concrete, I have a load of 393 reinforced mesh left over.

 

What could go wrong? 

[Jeremy Harris]

Sounds like a plan.................

[PeterW]

I think we should have a BH Design Group session on this... I’ll bring the fag packets ..!

 

I’m sure we can (over) engineer this for @recoveringacademic....