After commencing an enzyme trial, an upper Midwest ethanol plant discovered elevated sulfate levels as the dosed fermenters were cycled through the plant. Out of spec ethanol cannot be marketed, and plant operations needed to act quickly to fix the product to avoid costly product rejection fees or plant shutdown. The plant was familiar with U.S. Water's ethanol industry experience and the Ethanol Final Filter (EFF) technology, and the two teamed-up for a solution.
Many variables affect final product specifications, a notable one of which is sulfate. Sulfate impacts to manufacturing plants can cost over $1 million/per occurrence if the unit train is rejected. U.S. Water's unique EFF is designed to remove both existent and potential sulfate to improve final ethanol quality.
After a site visit, U.S. Water's Ethanol Process Technology (EPT) team determined the issue that the plant was experiencing was a perfect fit for the EFF technology. Working together with the plant, U.S. Water's EPT and logistics team were able to expedite an EFF system to the site.
Upon receiving the order on Friday afternoon, the skid arrived on-site Sunday morning. U.S. Water's EPT team and plant personal were at the site waiting to commission and startup the equipment promptly after delivery, allowing the plant to remain operational.
Once the EFF was running, the plant was able to immediately begin cleaning up the existing 70 off-spec railcars, filled with 1,270,000 gallons of ethanol. The average sulfates treated through the EFF were 8.8ppm and exiting effluent was .5ppm. After EFF treatment, the sulfates were reduced to met the spec of 4ppm.
After the plant filtered their off-spec rail cars, they entered into a lease agreement to use the EFF as a sulfate risk management tool. The plant has been running at full capacity and is meeting required sulfate COA spec of 4ppm. To maintain the program, plant personnel continue to monitor potential sulfate at the inlet and outlet of the EFF to guarantee they are producing marketable ethanol.