Sodium Lactate (C3H5NaO3)

The anaerobic bioremediation process uses microorganisms to degrade chlorinated solvents such as tetrachloroethene (PCE) and trichloroethene (TCE). An organic substrate is added to the groundwater to generate reducing conditions and provide the necessary carbon and hydrogen to support biodegradation of the chlorinated solvents.

In anaerobic conditions, microorganisms will ultimately metabolize organic contaminants to methane, limited amounts of carbon dioxide, and trace amounts of hydrogen gas. In anaerobic reactions, bacteria gain energy and grow as an atom on a contaminant is replaced with hydrogen. Anaerobic metabolism encompasses many processes including fermentation, methanogenesis, reductive dechlorination, sulfate- and iron-reducing activities, and denitrification. Depending on the contaminant of concern, a subset of these activities may occur. In anaerobic metabolism, nitrate, sulfate, carbon dioxide, oxidized metals, or organic compounds, such as chlorinated hydrocarbons, may replace oxygen as the electron acceptor. Hydrogen used in the reaction typically is supplied indirectly through the fermentation of organic substrates.

Figure 1

In general, anaerobic conditions are used to degrade highly halogenated contaminants, though some petroleum hydrocarbons may also be biodegraded anaerobically. The halogenated compound, typically a chlorinated solvent such as tetrachloroethene (PCE), trichloroethene (TCE), 1,1,1-trichloroethane (TCA), carbon tetrachloride (CT), chloroform (CF), and methylene chloride or their degradation products dichloroethene (DCE), vinyl chloride (VC), dichloroethane (DCA), and chloroethane serves as the electron acceptor while hydrogen serves as the direct electron donor. Chlorinated solvents can exist and migrate in multiple phases depending on how they were released and the site conditions present. These include a vapor phase in unsaturated soils, dissolved phase in groundwater, and non-aqueous phase liquids (NAPL) in the subsurface. Most chlorinated solvents are denser than water and hydrophobic.

During anaerobic biodegradation of chlorinated compounds, sequential removal of chloride ions is generally observed. Figure 1 demonstrates the dechlorination of PCE to TCE to cis-DCE or trans-DCE to VC to the final degradation product, ethene. In this reaction, hydrogen, the electron donor, is oxidized while the chlorinated ethene, the electron acceptor, is reduced. Hydrogen is generally the most important electron donor for anaerobic dechlorination.

The anaerobic reductive dechlorination of the more highly chlorinated (more oxidized) chlorinated hydrocarbons, such as PCE and TCE, occurs more readily than the dechlorination of chlorinated hydrocarbons that already are somewhat reduced (less oxidized), such as DCE and VC.

Hepure is a premier sodium lactate supplier.  Our sodium lactate is distributed as a 60 percent solution in 605 pound drums (55 gallons) and 3025 pound totes (275 gallons).

PRINCIPLES AND PRACTICES OF ENHANCED ANAEROBIC BIOREMEDIATION OF CHLORINATED SOLVENTS,

Sodium Lactate For Remediation Summarized:

1. Stimulation of Anaerobic Biodegradation: Sodium lactate can enhance the biodegradation of various contaminants under anaerobic conditions. It serves as an electron donor, promoting the growth and activity of anaerobic bacteria that can break down a wide range of organic contaminants, such as chlorinated solvents, nitrates, sulfates, and certain heavy metals.
2. Enhancement of Reductive Dechlorination: In the presence of specific bacteria (e.g., Dehalococcoides species), sodium lactate can stimulate reductive dechlorination, a process that can degrade chlorinated hydrocarbons, a common class of soil pollutants. This is particularly important for treating soils contaminated with chlorinated solvents like trichloroethylene (TCE) and perchloroethylene (PCE).
3. Controlled Release: Sodium lactate is a relatively slow-release substrate. This allows for a sustained bioremediation process, limiting the need for frequent application and providing a steady supply of electron donor for the bacteria over time.
4. Safe and Easy to Apply: Sodium lactate is non-toxic and biodegradable, making it an environmentally friendly option. It’s also water-soluble and can be easily applied to the soil through injection or irrigation methods.
5. Cost-Effective: Sodium lactate can be less expensive than other remediation methods, especially for treating large-scale contamination.

Naval Facilities Engineering Service Center Port Hueneme, California, August 2004

Terra System, Terrasystems.net, 2018