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RE: Biodiesel wastewater

Dedalus — Thu, 20 Mar 2008 17:24:47 GMT

I, also, am very interested in anaerobic digestion processes applied to bio-diesel residuals. More specifically, the glycerol bearing water phase.

People seem to think that a use will be found for this by product. My own view is: it's a low value material that's going to be even lower in value once the bio-diesel train starts really rolling; an inevitable consequence of skyrocketing oil prices.

My notion is that the best thing to do with it is to use it on site as a feedstock for bio-gas generation. There are problems with this. Glycerol seems to work well as a supplement to traditional bio-gas feedstocks, like manure, but there's limits to how much can be used. Too much appears to suppress methane production.

http://www.dedalusenviro.com

RE: Biodiesel wastewater

kfonda — Thu, 21 Feb 2008 11:30:52 GMT

I am looking for technologies and users of equipment to concentrate fats, oils and grease from restaraunts to be used as a feed stock for anaerobic digestion. Is this something that may be applicable.

RE: Biodiesel wastewater

idan tendler — Sun, 03 Feb 2008 10:57:22 GMT

I would be happy to have more details about it,

Idan

RE: Biodiesel wastewater

Tjandra Setiadi — Mon, 26 Nov 2007 09:28:46 GMT

We have a paper on treating biodiesel wastewater, please visit http://proceedings.itb.ac.id/indeks.php?li=article_detail_id&id=242 although it is written in Bahasa Indonesia. You may guess the wastewater characteristics from the Tabel 1. BOD = 65 689 ppm with COD = 152 079 ppm and high TDS = 24 454 mg/L.

Regards,

Tjandra Setiadi, Ph.D (Mr.)

RE: Biodiesel wastewater

MoscowLabAnalyst — Mon, 30 Jul 2007 16:26:48 GMT

I am impressed by the breadth and depth of collective knowledge attracted to this forum.

I do not know the process used to produce the biodiesel here (although it is a university project, so I'm sure with some digging I could probably source it.) The operators have been calling the bio-diesel by-product "glycerol".

Our WWTP is located in a university town (30% of our winter population is made up of students). When the university goes on vacation, (i.e. spring break) the operators drip feed the glycerol into the plant to keep the food:microorganism ratio up. So when the students return (30% increase in loading over a 48 hour period) the microbes are up to the task. It's possible that feeding this "junk food" to the plant over a long period of time could contribute to increased nocardia and all it's inherent foaming problems. But in the short term, the microbes seem to enjoy junk food.

I look forward to learning more on the treatment of this waste. I have deep reservations whether the continued production of smog and subsequent load on our food resources is going to be a good thing for our environment as a whole. But that's another thread.

RE: Biodiesel wastewater

Dedalus — Wed, 25 Jul 2007 11:49:35 GMT

MoscowLabAnalyst (7/17/2007)

Biodiesel by-product BOD = 678,000 to 723,000 mg/L (March 2005)

I don't know exactly what the biodiesel process was/is, or at what point they pulled this by-product, but for what it's worth, this is the BOD we have measured on the by-product.

First off, if you are interested in what's involved in bio-diesel production, take a look at:

http://biodiesel.infopop.cc/eve/forums

It's rare that I've seen such a heartening display of shade tree ingenuity than is demonstrated on this board.

Briefly: there are two processes. Alkaline catalyzed transesterification, and acid catalyzed transesterification/direct esterification.

In the first, that I briefly described above, the sodium hydroxide serves two purposes. It catalyzes the glyceride ---> methyl ester transesterification reaction, and it ties up free fatty acids (FFA's) as soap. A two fold molar excess of MeOH is used.

The second uses, generally, sulfuric acid as a catalyst. Because of "product inhibition" (water is a by product of direct esterification) a 5 - 10 fold molar excess of MeOH is used. This process is far more tolerant of poor quality feedstocks than the first described.

It was not clear to me, in the post quoted above, whether methanol recovery was carried out. I did not do it on the sample from my (whited out) BOD test. This is customary in both processes. When this operation is performed, the BOD should decline, sharply.

Wastes from the acid process will contain less glycerol, depending on the FFA concentration of the feedstock. However, there will be lots of sulfates, which it's my understanding, you municipal people don't like.

Wastes from the alkaline process will have negligible sulfates, but more soaps; salts of fatty acids. My understanding is that you municipal people don't like those too much, either. How much you get depends on the quality of the feedstock.

I'm doing some experiments to see if the FFA's can be separated from substandard feedstock so that it may be processed via the alkaline catalyzed method; later, recovered FFA's could be transformed via the acid process. Perhaps, HCl could be used instead of H2SO4.

In the works: tests to determine whether glycerol could be used on-site to generate bio-gas. Studies I've seen indicate that acetogenic fermentation must precede methanogenic fermentation. And, that this process works best if there is a lot of more conventional feed, like manure, and the glycerol is spiked in at moderate concentrations.

In short, I'm still learning. This technology is going to experience explosive growth in the next ten years, as petroleum supplies dwindle. The people on top of these waste handling problems will be the winners, and I aim to be one of them.

RE: Biodiesel wastewater

danygraig — Wed, 25 Jul 2007 10:29:00 GMT

does anyone have any experience of the impact of biodiesel production plant wastewater on a municipal treatment works ?

RE: Biodiesel wastewater

Dedalus — Tue, 17 Jul 2007 15:11:56 GMT

Waste vegetable oil is combined with methanol and sodium hydroxide. The mixture is stirred, with a bit of heat. At the end of the reaction, the aqueous layer settles to the bottom. It contains water, glycerol, residual methanol (generally, a two fold molar excess is used) and some soap.

RE: Biodiesel wastewater

MoscowLabAnalyst — Tue, 17 Jul 2007 11:50:11 GMT

Biodiesel by-product BOD = 678,000 to 723,000 mg/L (March 2005)

I don't know exactly what the biodiesel process was/is, or at what point they pulled this by-product, but for what it's worth, this is the BOD we have measured on the by-product.

RE: Biodiesel wastewater

Dedalus — Wed, 27 Jun 2007 15:59:28 GMT

Thanks very much for the information, it's extremely helpful.

Dedalus Environmental Homepage

RE: Biodiesel wastewater

Eduardo Torres — Tue, 26 Jun 2007 10:22:41 GMT

In BD production we have to deal with residues, spills, dry weather
contaminated drainages, storm weather contaminated drainages and
sludges linked to:

1-vegetal oil (spills/contamination)
2-methanol/ethanol (spills/contamination)
3-biodiesel (spills/contamination)
4-glycerine (spills/contamination - besides the by-product itself)
5-alcaline solution of high pH (NaOH as catalyst)
6-acid solution of low pH (H2SO4 or HCl as neutralizers)
7-salty solution (product of neutralization)
8-organic catalysts (sodium methylate, e.g.)
9-soaps (formed by saponification of vegetal oil by NaOH)
10-coagulants/floculants (aluminium sulphate and other chemicals)
11-filtering adjuvants (diatomaceous earth and similar materials)
12-filtering backwashing (high suspended solid content streams)
13-filtering/decantation/dewatering cakes
14-sludges from anaerobic/aerobic biological treatment of effluents
15-other sludges and wastewaters

RE: Biodiesel wastewater

WasteWater07 — Mon, 21 May 2007 18:24:36 GMT

Although this is not a response to your question, if you would like to discuss waste water management and evaporation processes, please feel free to contact me directly. There is new technology ready to hit the market that is more efficient and economically sound than any other current process. It has great potential to reduce polluted water entering our systems, continuously recover water, and increase the bottom line.

RE: Biodiesel wastewater

Dedalus — Thu, 17 May 2007 20:16:49 GMT

It's going a bit more slowly than I'd hoped.

But, I ran a series of BOD's on the settled aqueous layer of a test batch I made. The highest dilution - 5 microliters in a 300 ml bottle, -"whited out."

That corresponds to a BOD of at least 480,000 mg/l O2.

I've never seen a value that high.

RE: Biodiesel wastewater

Dedalus — Fri, 27 Apr 2007 17:33:22 GMT

The composition of the waste depends a lot on the feedstock used.

I'm embarking on a series of jar tests to find out what type of residuals are going to result, when this is varied. I should know more next week.

Biodiesel wastewater

Joe — Fri, 27 Apr 2007 12:34:05 GMT

Trying to locate information on the quantity and quality of biodiesel wastewater discharges expected from a large scale biodiesel production facility (assuming glycerin and methanol recovery).