ABSTRACT
The reactive gas barriers and zones (RGBZ) technology has demonstrated a high efficiency in stimulating the intended transformation and exchange processes, while at the same time showing a low sensitivity to temporal changing geohydraulic and geobiochemical conditions. The RGBZ technology has been approved by German Environmental authorities and additional applications in regard to enhanced natural attenuation are anticipated. RGBZ are ideally applied in horizontal multiple-layered sediment formations of nonuniform fine- to coarse-grained sands and fine gravels. The most common RGBZ application uses atmospheric air and pure oxygen gas or its mixture to supply electron acceptors for aerobic biodegradation. A standalone RGBZ is unable to provide vital nutrients where they may be deficient. A gas injection-based method to support the natural buffering capability of a subsurface domain against high proton production is still needed. RGBZ require specialized gas injection and monitoring methods and devices; techniques to efficiently control gas dynamics and their impact on in situ transformation processes are also required.
