Particle filter before or after the grease trap

[GILow]

Originally Posted by Mr B

My Marina in Vic is in a national park and a very high conservation area,
On the gate is two signs, No dogs or discharging toilets overboard while in the Marina,
There is nothing on the sinks being discharged overboard that I have seen,,

In my RV, I can discharge my grey tanks any where,
But the Black tank must be into a Regulated discharge point, Which most towns now have, Dump Point,

I haven’t found the Victorian regs yet, but I should get onto it.

I will be passing through in late April and I would like to be clear on the compliance issues. Particularly as I’d like to spend a week or two at The Prom.

Also, I must check the regs for the Gippsland Lakes in particular as I’d like to spend some time there too.

[GILow]

Originally Posted by thinwater

Thanks for posting that! A few thoughts that I'm pretty sure of, based on experience.

• The particle filter goes before the grease trap. Just a chunk catcher. If this is just for your saticfaction, a screen in the sink will work well. Otherwise, something in-line, easy to clean, no smaller than 3/16" holes (or it will clog constantly).
• The inlet should go below the water surface ~ 2 inches and end in a Tee. This prevents the falling water from entraining the grease back into the water. VERY IMPORTANT and a common mistake.
• The exit should not be on the bottom (about 1/2 way or 2/3 down). There will be sludge. But maybe not much.
• Floating the oil off is clever. I like that. But you will also need a way to remove sludge periodically. Perhaps a small valve in the bottom to drain, and then a way to remove it.
• Remember that you need a P-trap to keep gasses out of the sink. This will smell.
• Without a vent (the P-trap will block that) this becomes like a holding tank. Gasses that generate will find a place to go. They will either push into the sink or push water and grease out the discharge.
• Typically you need at least 20 minutes settling time for separation. It depends how good a job you want to do. Constant flow through, not as good, but the Tee at the inlet will help. Remember that the grease bubbles must rise faster than the water down flow rate or they can't buck the tide.

Good luck! It's nice to see people that try.

Excellent, I am very grateful for your advice.

New version attached... addresses all points except sludge drain.

Questions on that... is it poor form to allow sludge to leave the system via an overly low pickup on the logic that at least it is grease free and the larger particles have been filtered out?

If so, I think I’d favour a small hand pump to collect sludge instead of a drain tap as I wouldn’t trust the drain tap not to weep a bit. Also access would be a bit of a PITA.

My galley sink is TINY so I think I’ll meet the need for settlement time by accident rather than design.

Thank you for the advice on the P or S trap from the sink. I would have ended up stinking out the boat for sure. As it is, fitting one or at least shaping the drain hose appropriately will actually make installation easier, so it’s win/win.

As for the particle filter, you get the casting vote. If you say before the trap then before it shall be.

[GILow]

Originally Posted by gamayun

If it were me, I'd filter particles first and then capture grease, which is also easier to control on the front end so cleaning should be less frequent. You're likely to have easier access to the inline filter trap if you put it first. But that's just the way I'd thought process it. I have no direct experience so take that for what it's worth.

Sounds like your instincts are good. [emoji846]

[Wotname]

Matt, you are probably on top of this but do remember to allow for heeling and use under way.

Your diagrams haven't given any idea of the distance between the hull outlet and the waterline (heeled or otherwise).

[Mr B]

Originally Posted by GILow

I haven’t found the Victorian regs yet, but I should get onto it.

I will be passing through in late April and I would like to be clear on the compliance issues. Particularly as I’d like to spend a week or two at The Prom.

Also, I must check the regs for the Gippsland Lakes in particular as I’d like to spend some time there too.

Try Corner inlet behind the Prom, Its a great protected bay to sail or park in,

Not sure of the actual name for them,
But the Port Authority at Paynesville will give you all the details regarding sailing on the gippy lakes,
Paynesville has a very large boating community,

[GILow]

Originally Posted by Wotname

Matt, you are probably on top of this but do remember to allow for heeling and use under way.

Your diagrams haven't given any idea of the distance between the hull outlet and the waterline (heeled or otherwise).

Thanks mate, will do.

Actually, I’m looking forward to this thing shutting up the sink which gurgles and glugs when on a starboard tank.

[GILow]

Originally Posted by Mr B

Try Corner inlet behind the Prom, Its a great protected bay to sail or park in,



Not sure of the actual name for them,

But the Port Authority at Paynesville will give you all the details regarding sailing on the gippy lakes,

Paynesville has a very large boating community,

Refuge Cove for me. No phone coverage... perfect!

But yeah, there are lots of beautiful places to choose from.

[David B]

Originally Posted by GILow

Hi all,

I’m stuck in a logical stalemate. I can construct a logic for putting the particle filter either before or after the grease trap on my galley sink.

Regulations here require that I have both devices, so which order would you put them in, and why?

Matt

Would have to be grease trap first. If you have grease in the mechanical (particulate) filter, then that is going to compromise its performance very quickly.

[GILow]

Originally Posted by David B

Would have to be grease trap first. If you have grease in the mechanical (particulate) filter, then that is going to compromise its performance very quickly.

That was one of my thoughts too, but Thinwater does this stuff for a living so they get the casting vote.

I suppose there’s a chance that grease will still be mainly in suspension when it goes down the sink drain so should pass through the filter. That’s my hope.

Meanwhile, a chance conversion with my local EPA water guy turned up the extra info that if a grease trap is not practical then a particle filter on its own is acceptable.

Crazy rules.

But I am still determined to build this thing and try it out. I’ve got 90% of the bits (just getting the T piece next time I go past Bunnings) and they only cost a few $ so I might as well give it a go.

[gamayun]

I don't mean to sound pedantic, but I'm really curious why is there grease going down the sink? Everyone (literally in any kitchen everywhere) should not be washing large amounts of grease down sinks. It coagulates into a gawdawful mess. Just Google "fatbergs." That's why it's easiest to scrape the stuff into a cup, wipe the pan with a paper towel and then wash with HOT soapy water so any remaining grease passes benignly through your large particulate filter. The soap breaks down the cellular matrix and the hot water keeps it in liquid form.

Apologies to the OP for the tone! You're doing the right thing and trying to be mindful of certain requirements. I applaud you. I'm stepping very carefully away from my soapbox now

[GILow]

Originally Posted by gamayun

I don't mean to sound pedantic, but I'm really curious why is there grease going down the sink? Everyone (literally in any kitchen everywhere) should not be washing large amounts of grease down sinks. It coagulates into a gawdawful mess. Just Google "fatbergs." That's why it's easiest to scrape the stuff into a cup, wipe the pan with a paper towel and then wash with HOT soapy water so any remaining grease passes benignly through your large particulate filter. The soap breaks down the cellular matrix and the hot water keeps it in liquid form.

Apologies to the OP for the tone! You're doing the right thing and trying to be mindful of certain requirements. I applaud you. I'm stepping very carefully away from my soapbox now

Fair question, but I put it to you, is it possible to avoid grease going down the sink if you are washing the dishes?

I mean, I’m not the kind of guy who deep fries stuff, but even today’s lunch of a salad and tuna wrap has traces of mayo on the plate and a bit of oil from the tuna.

I suppose I could wipe the plates first with paper towel, but then I’ve got a new waste disposal challenge.

[gamayun]

No, not possible to avoid completely and our overuse of paper towels doesn't really make wiping everything a good alternative. I guess I was more thinking about people who fry a lot (I grew up in the Southern US) and then dump that stuff down the drain. But hey, as I'm thinking this through a bit, you could lick all the plates first!

[GILow]

Originally Posted by gamayun

No, not possible to avoid completely and our overuse of paper towels doesn't really make wiping everything a good alternative. I guess I was more thinking about people who fry a lot (I grew up in the Southern US) and then dump that stuff down the drain. But hey, as I'm thinking this through a bit, you could lick all the plates first!

Yeah, I gotta say, I never could understand the various threads on Cruisers Forum discussing the best deep fryer for a boat.

Being a Melbourne boy, I’ve grown up with a mainly Mediterranean diet, thanks to the large Italian population, with a touch of what you could call “peasant Asian food”, which is very, very different to what many westerners think of when they think of Asian food.

So I cook very little that is fried, and certainly nothing deep fried.

As for licking plates... let’s just say nothing makes me happier as a cook than seeing my guests lick their plates.

[thinwater]

Originally Posted by gamayun

I don't mean to sound pedantic, but I'm really curious why is there grease going down the sink? Everyone (literally in any kitchen everywhere) should not be washing large amounts of grease down sinks. It coagulates into a gawdawful mess. Just Google "fatbergs." That's why it's easiest to scrape the stuff into a cup, wipe the pan with a paper towel and then wash with HOT soapy water so any remaining grease passes benignly through your large particulate filter. The soap breaks down the cellular matrix and the hot water keeps it in liquid form.

Apologies to the OP for the tone! You're doing the right thing and trying to be mindful of certain requirements. I applaud you. I'm stepping very carefully away from my soapbox now

As for the OP, I can't say.


However, the underlying treatment standard includes dissolved and dispersed grease, so adding soap (which reads as grease in the test) only increases the amount of grease.


The preferred treatment tech is DAF, which includes a chemical pre-treatment designed to counter the effects of soap and pop the grease out. He won't be doing that, but this is the intent of the rule for larger boats.



We could argue all day whether dispersing grease with soap is good or bad for the environment, but the regs are all written to punish the use of emulsifying agents. The tests read it just the same, dispersed or not.

[Asmolian]

Never thought that separating fat from particulate could be interesting.