Bjorn - Here are a few crazy ideas to bounce off you. There is a neat thread in the alt fuels section tittled "Crazy idea for filtering used oil",
http://www.steelsoldiers.com/index....topic&t=7397&postdays=0&postorder=asc&start=0.
As I understand the Biodiesel process, two significant problems are adequately filtering the WVO to get a clean oil to start the process, and at the end of the process getting as much as the glycerol as possible out of the finished Biodiesel to assure a quality fuel.
Towards the end of the second page of the "Crazy idea for filtering used oil" thread is a discussion of the Dieselcraft model OC-20 oil centrifuge, which filters .93 GPM/55GPH for $289 delivered ($239 w/o mounting bracket). The manufacturer claims this centrifuge will remove particles down to 0.1 micron, probably at the higher operating RPMs.
Admittedly, this centrifuge requires some additional hardware to make it work - a 40-90 PSI pump (the user mentioned in one of the links used an old power steering pump), a heating element and a bit of plumbing supplies. I would estimate a complete working system could be put together for under $400 with a bit of scrounging for a few used parts.
Thought #1 - This would make a great system for prefiltering WVO. Cleaning the WVO down to 1 micron or less should greatly improve the Biodiesel conversion process. This should also work quite well for cleaning WEO and WATF.
Thought #2 - With a little extra plumbing, you could use this system to post centrifuge the Biodiesel AFTER the the bulk of the glycerol has settled out by gravity. Removing much if not all of the suspended glycerol after settling should greatly improve the quality of the finished Biodiesel.
Really Crazy Idea #3 - After reading many articles on many websites, glycerin fueled heaters are fairly common in many "less developed" countries. A glycerin based air-oil heat exchanger would greatly reduce the cost of producing Biodiesel by reducing the need for supplemental electric/propane heat sources, as well as reduce the byproduct load to dispose of. After all, just how many showers can you take?
My 2 cents. I realize $400 or so is a lot of capitalization, based on your current minimal expense process. Your thoughts?