quote:

Originally posted by Green energy:
I have searched the topics about the trap grease. There are still something not very clear.

(1) When the grease trap company clean the traps, they only pump the grease or they need to empty everything in the trap? (The grease is on the top layer while water is in the botom)

As close to everything that's in the trap as possible, not close to everything.

(2) What is the average percentage of the oil(grease) in the total liquid pumped from the traps? 30% or less?

I would think that is close to accurate.

(3) After settling the trap grease, can you just get the grease and let the water flow into the sewer? (Since the function of the grease trap is to collect the grease while let the water flow into the sewer, I suppose after the settling, we can also do this. But just not sure.)

That's what grease trap collectors did in my past experience

(4) I think Acid reaction is what we should start. The problem is how to pretreat the trap grease. There are a lot of contaminations in the grease. How to get rid of them? For example the bad smell?(Sure we can filtered the solids particles etc. But I belive there are also other contaminations that can not be get rid of by filtering) Maybe we can use water washing the trap grease?

I believe convert the FFA to biodiesel is not so complicate, but how to get rid of other contamination(4) is really challenge, any thoughts?

Thanks a lot!

quote:

Originally posted by Double D:

quote:

Originally posted by Green energy:
I have searched the topics about the trap grease. There are still something not very clear.

(1) When the grease trap company clean the traps, they only pump the grease or they need to empty everything in the trap? (The grease is on the top layer while water is in the botom)

As close to everything that's in the trap as possible, not close to everything.

(2) What is the average percentage of the oil(grease) in the total liquid pumped from the traps? 30% or less?

I would think that is close to accurate.

(3) After settling the trap grease, can you just get the grease and let the water flow into the sewer? (Since the function of the grease trap is to collect the grease while let the water flow into the sewer, I suppose after the settling, we can also do this. But just not sure.)

That's what grease trap collectors did in my past experience

(4) I think Acid reaction is what we should start. The problem is how to pretreat the trap grease. There are a lot of contaminations in the grease. How to get rid of them? For example the bad smell?(Sure we can filtered the solids particles etc. But I belive there are also other contaminations that can not be get rid of by filtering) Maybe we can use water washing the trap grease?

I believe convert the FFA to biodiesel is not so complicate, but how to get rid of other contamination(4) is really challenge, any thoughts?

Thanks a lot!

Filter and dewater would be my guess.

quote:

Originally posted by Tim c cook:
I have only seen grease traps cleaned one time, this was behind a large restaurant, they had 5 traps. The folks cleaning these out sure had the right equipment, they had a brand new 40 ft stainless steel semi tanker trailer and pulled a vacuum on the entire tank using a big roots-type blower. They used semi-rigid 5 inch diameter hoses that appeared to simply be dropped to the bottom of the traps to suck everything, they did not make any attempt to control the depth of the hoses to only collect the grease floating on the water.

The trap grease that I have seen has been congealed into something like gray pudding, I would think you would have to heat it until it melts before you could do much of anything to clean it.

I have not treated actual trap grease but I have collected some pretty bad dog vomit vegoil, I water wash this with baking soda in the mix, it takes about a week for the bubbling/oil/water/BS/ soap reaction to stop, another week of settling and I have nice pretty clean oil floating above the crud/soap/water, the cleaned oil has only a little smell but the crap on the bottom is REALLY foul smelling.

Doing this type of BS or lye caustic stripping on trap grease will likely convert far too much of the grease into soap so, yes, acid processing to FFA has always been what I have read as the first step to processing trap grease.

quote:

Originally posted by buckeyebiodiesel:
Grease trap waste is very difficult to process, I know, Ive been doing it. Grease content varies wildly from less than 2% all the way to 25% by volume.

The smell is very strong and is difficult to clean out of the oil. Also everything this oil gets in contact with will hold that smell for weeks.

Very few companies will let you collect grease trap oil aka 'brown grease' without proper licensing, bonding, equipment, and at least a $1,000,000 liabilty insurance policy.

Once you pass these fun milestones you have to deal with some of the highest FFA oil you have ever seen. The best I have ever gotten titrated at about 40T with the worst at 94.5T and an average if about 60T (I expect to break the record tomarrow when I visit the town of Buckeye WWTP)

Once you build a reactor to handle a proper acid esterification to deal with such high FFA oil you move onto base transesterification as usual (but with less methonal since you already converted over a large portion of the oil [FFA's] into biodiesel during esterification)

After that there is still one big obstacle, gelling. Grease trap oil is primarily animal fats and will gel at very high temps. This is a problem I am still working on.

It has taken a very large financial investment for me to collect and process brown grease, Im not saying dont try it, because I think its a good step to take, just be prepared to put in a lot of time, energy, and $$$ to making it happen.