Effect of ORC-inj actions on in-situ BTEX-biodegradation and on the endogenous micro-organisms

摘要

A demonstration pilot-scale study is being conducted at a BTEX-contaminated site to evaluate the use of ORC~(~R) (Regenesis) for enhanced bioremediation. More specifically, the influence of ORC-injections on the chemical composition of the groundwater and on the endogenous micro-organisms at the tested site are being studied. Based on lab scale feasibility tests it was found that a limited oxygen availability reduced the degradation rate, which suggests that an increase of the oxygen concentration may enhance the BTEX-degradation. The ORC has been applied to the site in January 2003 and the evolution of chemical and microbial parameters is being monitored since. Monitoring of the in-situ and some chemical parameters revealed that ORC-injections led to increased dissolved oxygen concentration (up to 45 mg/L) and pH-increases up to pH 10.5. After the ORC-injection a part of the monitoring wells was found to give misleading results. The effect of the ORC-injection on the endogenous microbial population present in the aquifer at the site, is followed by microbial (platings) and molecular techniques (PCR-DGGE) using in-situ mesocosms systems. Analyses of aquifer samples in time indicated the presence and activity of BTEX-degrading micro-organisms at the site.