Emulsified Fatty Acid Esters
ABC-Olé is an emulsified fatty acid ester product for anaerobic bioremediation sites where emulsified vegetable oil (EVO) products are being considered. ABC-Olé is a modified blend of ABC® which contains emulsified fatty acid esters up to 60 percent. ABC-Olé also contains a quickly metabolized carbon substrate at up to 5 weight percent to initiate the bioremediation process. Just like ABC, ABC-Olé contains a phosphate buffer to maintain the pH in the optimal range for complete biodegradation.
ABC® was always designed uniquely for each site. Greater amounts of buffer are added for low pH or high solvent sites. For high flowing aquifer systems, we typically added greater amounts of fatty acids because the fatty acids are more likely to sorb to the soil and not be washed out. Ultimately, the goal is to bring the oxidation-reduction potential of the aquifer to around sulfate reducing conditions (ORP of -175 mV). If the carbon substrate is not fermented at a rate sufficient to overcome the flow of oxygen (and other electron acceptors) into the system, the ORP may never become sufficiently reducing. That is one instance where insufficient short-lived substrate can be a problem, and a sign of this problem is cis-DCE stall. On the other hand, a substrate mix with too much short-lived material maybe expended (or washed out) prior to the subsurface being completely remediated and a sign of this can be cis-stall or large amounts of methane formation.
Let’s Talk About Vegetable Oil Hydrolysis
Vegetable oil is an example of a triglyceride. All triglycerides react with water to form glycerin and three long-chain fatty acids. Most oils react with water to produce fatty acids with 18 carbons atoms (thus C18), but other fatty acids such as C14 and C16 can be produced. When emulsified oil is used for bioremediation, it is actually the fatty acids that are the slow-release substrate.
Vegetable Oil + water →slow→ Glycerin + 3 Fatty Acids (typically Oleic)
ABC® is formulated to site-specific conditions and historically has contained 5 to 15% dissolved fatty acids. The fatty acids are typically dissolved into ethyl lactate versus being emulsified. ABC-Olé can contain up to 85% emulsified Oleic Acid (fatty acid). Fatty acid is used rather than oil because the need for the water reaction is eliminated. There are pros and cons associated with using a product that predominantly contains long-chained fatty acids. Redox Tech still feels that there is a balance to be struck between short-lived and long-lived carbon substrates. Our emulsified oil competitors typically add glycerin (or lactate) to their EVO to provide a short-lived component.
ABC-Olé is a mixture of emulsified fatty acid esters, fast-acting organic substrate, and pH buffers, all in one product. In most applications, there is no need to purchase and mix additional amendments.
- Unlike emulsified vegetable oil (EVO), with fatty acid esters there is no waiting for hydrolysis to occur and subsequent conversion to glycerin and fatty acids
- Emulsified fatty acid esters are pH neutral, so less buffering is required to maintain optimal pH conditions
- Unlike fatty acids and EVO, fatty acid esters don’t react with pH buffers and bases to form soaps, which can causing foaming in wells and tanks
- Fatty acid esters have lower viscosity and lower surface tension than vegetable oils, allowing better distribution when injected into the subsurface
- No chase water is required
- Emulsified fatty acid esters are comparable in price to EVO