Tuesday, February 5, 2013
Contaminated WVO...Lessons Learned!
I have been picking up waste vegetable oil (WVO) from two FiveStar locations, Larry's Midway Market, and Hardscratch Country Store for between 1 and 2 years now; and never have I seen oil that looks, smells, or feels like this! We had just made our first pick up from a new restaurant in town, and they had a very large volume of oil. We assumed that it was because they were just starting out, testing the frequency of oil changes, etc. Well, we had to throw out over half of the oil due to chicken parts and mushrooms and other food scraps in the oil. The rest of the oil looked different but we went ahead and put it in our 300-gallon WVO storage containers anyway. Last week, I taught my sophomore class about the chemistry and processing of biodiesel using waste vegetable oil. (See the slideshow below to see the students at work!) We followed the steps perfectly; came in the next morning....no glycerin fallout! WHAT!! Not wanting to just blow off the project, I talked to the students about some concerns I had based on my experience, but we went ahead and did a 3/27 test and a miscibility test so that they could learn these testing processes. The 3/27 test looked like a "PASS" but the miscibility test showed 3 distinct layers...almost equal in size. So the students started to ask questions that I couldn't answer on the fly, as I had never seen results like this before! We began the think that maybe the lye water (catalyst solution) was expired and therefore gave us a false titration value. Maybe we didn't use enough lye therefore not achieving a full reaction, even though four titrations were completed and yielded very close results...? I took this as an opportunity to talk about the fact that sometimes things don't work out as planned and we must learn from these times. Meanwhile back in the lab, Doug and I began to perform titrations with a fresh batch of lye water (titration solution). The titration values were, in fact, higher than those in the classroom. Please keep in mind that the same WVO was used by both classes and by Doug and I. The next morning (a snow day for school...woo hoo) I texted Doug about the gylcerin fallout. He said, "NO FALL OUT" and it was worse than the classroom batches! We noticed the same "skin" that formed on the top of the fuel in the classroom also formed in the lab. There were free fatty acids and soaps floating around in the fuel. After a quick phone call to our "Biodiesel Help Line"...Mr. Graydon Blair, with Utah Biodiesel Supply, he assured us that we definitely received some contaminated oil. Since we do not actually know where all the oil comes from and what the supplier puts in it, this is not an uncommon problem. The only way to deal with it is to wash, reprocess, wash, wash, and wash! See some pictures below of the "skin" that was formed when the oil was exposed to air. Also notice the jelly like (soap) that was floating on top of the WVO in the barrel.