Glycerin 101- Lessons Learned While Pilot Testing Glycerin to Enhance Denitrification

The demand for external carbon sources to achieve enhanced nitrogen removal is expected to grow significantly in the Chesapeake Bay watershed area. Although methanol remains the least cost and most frequently applied alternative, the price of methanol has increased substantially in recent years, methanol is flammable (burns without a visible flame) and toxic, and cold weather denitrification kinetics using methanol are problematic. Biodiesel fuel is an alternative to conventional petroleum diesel. It is produced by combining virgin or waste vegetable oil, or animal fat, with 10–20% methanol and sodium or potassium hydroxide. The reaction results in a product that is 80–90% biodiesel fuel and 10–20% waste glycerin by volume. Glycerin is fully miscible in water, biodegradable by ordinary heterotrophic organisms, nonflammable and nontoxic. Biodiesel waste glycerin is typically contaminated with