Project

Coupling Chemical Pretreatment and Bioremedioation on Soils Containing Organic Contaminants

Extensive contamination of the subsurface with organic pollutants is widespread. Many remediation technologies exist, however the cost, time, health risk, and intrusion associated with clean-up often impede redevelopment.

Motivation

In situ remediation can overcome many of these challenges by containing remediation within in the subsurface. Through coupling chemical oxidation to rapidly remove high concentrations of contaminants and long term biological breakdown of remaining pollutants, an improved in situ remediation strategy is created that allows rapid redevelopment and extensive contaminant removal.

Technological challenge

During In Situ Chemical Oxidation (ISCO), chemical oxidants are introduced into the subsurface to rapidly degrade contaminants. Alternatively, naturally occurring microorganisms are also able to break down pollutants, albeit slowly. To hasten bioremediation, ideal conditions for microbial degradation are created through the injection of nutrients or adjustment of redox conditions.Through combining these two techniques, redevelopment can occur following chemical oxidation while long term bioremediation ensures removal of residual contaminants. Although ISCO rapidly removes pollutants, chemical oxidants often impede biological activity. Oxidation changes subsurface conditions such as pH which are necessary for microbial growth and can outright kill soil biota. Thus, conditions must be optimized during and following chemical oxidation to allow the bioremediating microbial population to not only survive, but thrive.

Method

ISCO treatments with the least impact on soil biota are determined by adjusting the type and quantity of chemical oxidant used. Similarly, parameters such as pH, nutrient availability, and temperature will be manipulated to create optimized conditions for bioremediation in chemically pretreated soil. To monitor the microbial population and quantify bacterial activity throughout the course of ISCO and bioremediation steps, molecular techniques will be used. 

Geochemical data on soil conditions essential to bioremediation will be combined with molecular data on this microbial population. This theory on bioremediation on chemically pretreated soils provides a new treatment strategy for other contaminated locations.