Troubleshooting Biodiesel Batches – Tips & Tricks

When making Biodiesel, one of the things that can creep up & get you is the strange things that can happen to batches of Biodiesel from one batch to the other. Everything can be going fine and then out of no where something really strange happens. We hear about it all the time and figured we’d share some of the tricks we use to help people troubleshoot a trouble-some batch of the good stuff.

How To Troubleshoot A Batch
1) Write Down Everything You Know About The Batch
Record on a piece of paper everything you can about the batch.
Things we recommend include:
– Where did the oil come from?
– What did it titrate at?
– What was the water content? (or, was it wet?)
– Was it dewatered?
– How much catalyst was used?
– How much methanol was used?
– How hot was the oil before catalyst was added?
– How long was the oil mixed with catalyst & methanol for?
– How long did it settle?
– Did it pass?
Biodiesel Conversion 27/3 Test?
– If washed, did it pass a Shake-Em Up test or a Soap Titration Test?

Also, ALWAYS keep a sample of the oil you’re reacting in a small jar until the batch is successful. You’ll never know when you may run into something strange and having access to the original oil to run some tests on will be absolutely vital.

2) Look At The Variables & Look For Possible Issues
Once you’ve recorded what you know about the batch, it’s time to go back & systematically rule things out. I always start from the very start of the process and work forward until I can pinpoint what it might be. If I get a few idea’s, I start testing to prove that theory.

Here’s an example of how I approach it.
Waste Vegetable Oil
– If the oil came from the same source, was there something different about how it was collected? Did it look different? If so, what was it that was different?
– If you suspect something strange about the oil, test the sample you put in reserve. Retitrate it. Test it for water content. Make a mini batch out of it. If everything checks out, then you can move to the next step.

Water In The Oil
– Water content should be no higher than 1500 PPM (0.15%) before using it to make Biodiesel.
– You can still make high quality Biodiesel if the oil is wet, but it will require a little more work
– If your oil is wet and it was reacted into Biodiesel, there’s a good chance that it can fail the Biodiesel Conversion 27/3 Test
– If you fail this test, reprocess your Biodiesel. I recommend using reprocessing with 30% of the original catalyst & methanol initially used
– Be aware that water will also tend to make a lot of soap so when water washing batches of Biodiesel that were re-processed, go easy on the first couple mist washes otherwise an emulsion can occur

Old Or Contaminated Catalyst (NaOH or KOH) 
– Check your catalyst for large clumps (they indicate it’s absorbing moisture or water has leaked in)
– Check the strength of your catalyst
– Use this cool method for making sure it’s still potent
– If your catalyst is over a year old and it’s been opened before, there’s also a chance it could be going bad
– If it’s bad, dispose of it and get new catalyst
– Contaminated or weak catalyst tends to cause poor reactions (Fail 27/3 tests) and also contributes to more soap production.
– Poor conversion with lots of soap made can again mean emulsions during washing

– Anecdote: About a year ago we were struggling with emulsions in our Biodiesel. The oil was good, titration solution was good, everything was working right, but we kept getting soap (even though we’d pass a 3/27 test). Finally, we bought new catalyst & the problem went away. We determined that even though there weren’t any clumps in the catalyst, it had somehow gone bad. It was well over a year old and had always been sealed, but somehow it had still gone bad. So, moral of the story, if there’s clumps or if it’s over a year old, get new catalyst.

Titration Solution 
– Check your titration solution to ensure it’s not expired.
– Titration solution should be changed every 90 days, if not sooner.
– If the lid has been left open or it’s been left in the sun, change it even sooner than that
– As titration solution goes bad, it will take more to turn the oil pink and can make it look like the oil is worse than it really is.
– After making new titration solution, retitrate the oil sample and see if the titration goes down
– If this occurs, and you had made a batch based off the higher titration number, it means you may have added too much catalyst. All that extra catalyst can end up making lots of extra soap, which can also lead to emulsions during washing
– Like above, go easy on the first few mist washes to keep the emulsion from occurring

Titration Method
– Is your titration method outdated?
– 5.5 is the base for NaOH, 7.0 is the base for KOH
– Adjust either one for the purity of your chemical
– ie. 5.5/chemical purity (say 90%) makes new base 6.1
– Learn the basics of how to properly titrate here
– Also, be sure to use clean vials, syringes, and solution

Contaminated Methanol
– If your oil, titration & catalyst check out, it might be worth checking your methanol (especially if you’re using recovered methanol)
– Methanol can absorb moisture quite readily, which can make it wet, which can lead to poor Biodiesel reactions and soap production
– If you suspect yours might be contaminated, pick up a methanol test kit & check it for purity with a hydrometer

Poor Mixing & Poor Heat
– Biodiesel should be mixed for about 2-3 hours between 130-140 Deg. F (54.5 – 60 Deg C)
– Don’t mix it long enough, or if the oil isn’t hot enough, it can lead to a poor reaction (flunk a Biodiesel Conversion 27/3 Test)
– Heat the oil past 148.5 Deg. F (64.7 C), and too much methanol can boil off
– If you determine this is the case, just reprocess it with the proper mixing time and at the proper temperature

Emulsions During Washing
– Caused by many of the things above, emulsions can be cured using vinegar, salt water, or glycerin
– I prefer using Salt Water as it’s cheap, effective, and will wash back out fairly easily
– See our article on emulsions for details on breaking them

Cloudy Biodiesel After Washing
– If the fuel hasn’t been dried, this is normal, just dry the fuel
– Normal, wet Biodiesel looks kind of like the color and consistency of orange juice
– If the fuel has been dried and it’s still cloudy perform a soap test on it
– If it flunks a soap test, re-wash it and re-dry the fuel

It’s Something Else….
– While we’ve tried to include many of the common issues we’ve seen, making Biodiesel involves quite a few variables; some of which we can control and others which we can’t
– With a systematic approach, you should be able to pinpoint most issues.
– However, if you can’t, give us a call or shoot us an email and we’d be happy to help you trouble-shoot that strange batch
– You can reach us by phone or via email (see our contact us page)
– We check emails every day of the week except Sunday and our office phone is available Monday, Tuesday, Thursday, & Friday from 9am to 5:30 PM Mountain Time. If we don’t pick up, just leave a message and your phone number. We try to return all calls.

There are also several online resources available as well:
– Our Quality Testing Page
– Our Articles Index Page (every article we’ve written is linked here)
– Infopop Biodiesel Forum (Lots of sections, post away!)
– Yahoo Biodiesel Forum (requires joining the group)
– website (awesome resource!)
– Let Google be your friend! Verify any information found on “the internet” though! There’s a lot of great stuff, but there’s lot of junk too.

Part of the fun of making Biodiesel can be the learning process that goes with it. I’ve heard of just about every crazy thing out there that can or will go wrong with a batch (bacteria in the oil, catalyst not dissolving, lightning strike, you name it), so if you’re stumped, give us a call. There’s a chance we’ve probably ran across the problem, or have a good idea of what might be causing it.

Happy Brewing!

About Utah Biodiesel Supply

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4 comments on “Troubleshooting Biodiesel Batches – Tips & Tricks

  1. Hello,

    I am a chemistry teacher who regularly runs a unit of the making of biodiesel from both new and waste oil. Most of the time, the glycerin layer falls nicely to the bottom. About 10 percent of the time, there are two distinct layers, but the layer on top is about the same size as the typical glycerin layer. Any ideas what might be going on here? Do you think it can be salvaged? I have searched for similar conditions and I have had no success finding anyone else with similar findings. Thanks for any input you can provide.

    Candice Behnke

  2. Hi there ie been making biodiesel for the last year or s0 maybe 150 ltrs a month most times its ok i only use it for my heating system so maybe it doesnt have to be 100% just made a batch yesterday i use sulfuric acid to pre treat my oil always tiretes at 20/21 so i treated it with the acid 150 ltrs of oil 675 mls of acid and i put 15 lts of methanol straight after that it got late so i left the remaining 15 ltrs for today brought it back up to temp lte 12 ltrs in kept mixing for 90 mins i took a sample before i drainded 20 ltrs of gly off and then let the remaining 3 ltrs in but when i took the sample a pint in a glass it usually starts to seperate near enough straight away this tim it didnt when i looked into the glass after a few mins it was / is still active and slightly smoking thought it was steam oil moving around in the glass so a bit stumped as to what happened or what to do any suggestions thanks mick

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