PURIFICATION fuel product specialist with Schroeder Industries, says Schroeder does not recommend any type of wet-wash process, “as this adds more variables into the chemical reaction process,” he says. “We feel that the dry-wash process is the simplest, most effective and most economical way to produce biodiesel, regardless of the feedstock being used.” Eco2Pure is a unique, cellulose-based, natural and sustainable composition of adsorbent technologies, Santelli says, specifically formulated for biodiesel purification from any feedstock. “Eco2Pure is designed to be a filter-free wash process with no consumables in the wash stage,” he says. “Each kilogram of Eco2Pure is
capable of purifying between 80 and 190 gallons of biodiesel, making it the lowest cost drywash biodiesel purification method in existence today.” Santelli says per-gallon treat costs using Eco2Pure is as low as 1.5 cents. “Eco2Pure outperforms existing ion exchange resin technologies in terms of fuel quality, purification speed as well as price,” he says. While water-washing requires proper handling and discharge of wastewater, silicates require operation of a filter press and disposal of spent filter cake. “There is also a process loss of approximately 1:1 for silicates use,” Barnes says. “In general, there is greater mass of silicates that would have to be disposed of as opposed to res-
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in. One of the cons to silicates is the flammability of the biodiesel-containing spent cake.” On the other hand, ion exchange resin lasts longer, according to Barnes, “assuming the upstream soap content is not excessive.” In addition, he adds upkeep of a manually cleaned filter press requires more operator effort than resins. Yawn says dry-wash resins were used to purify 200 million gallons of U.S. biodiesel in 2013, a small percentage of the more than 1.5 billion gallons of biodiesel produced. Kate Mansker, a fuel additives technical manager for MidContinental Chemical Co., which distributes Dow Water & Process Solutions’ Amberlite BD10Dry resins, says silicates are viewed as a workhorse approach to dry-washing, whereas resins perform as the racehorse. “There’s an inherent preference for a simplified technology, which I think the dry wash resins offer, but much of it has to do with what the facility is starting with,” she says. “A lot of facilities are acquisitions, so it’s kind of like an inherited process. Many of the recent calls we’ve gotten are from those who are restarting plants that have been acquired.” Mansker says if an acquired plant had a filter press and used magnesium silicate powders for dry-washing, then that’s what they’re comfortable with. “Not only is it a process change, but it’s an operational mindset change too,” she says about switching from silicates to resins, what she refers to as a “quantum leap.” There are also capital costs to consider in installing resin vessels. “You get some folks who are open to it,” she says, “others have very tight constraints on expenditures and it’s hard for them to justify the changeover, even if it has a short return on investment.” Mansker says treat costs of BD10Dry is about 4 to 5 cents per gallon. Yawn says the advantages resins hold over silicates include cost, safety and manpower. “The use cost for resins ranges from 2 to 5 cents per gallon,” he says. “Use cost for silicates ranges from 10 to 15 cents per gallon.” Yawn says resins are safer to handle than silicates, which carry warnings of worker exposure to silicate dust. “Also, auto-combustion of silicate sludge is also a safety concern,” he says. Finally, Yawn says labor costs for resin dry-wash are significantly lower than silicates. “For silicates, mixing, feeding, operating the filter, and filter-cake handling all require manpower.” He adds, however, that silicates do provide some color removal, a benefit resins do not offer. Resins are very easy to handle, Mansker says, and they can be pumped out of their vessels in a slurry. “As far as adding them into a vessel,” she says, “it’s a dry resin so there can be static electricity buildup. As a precaution, you