IN SITU MICROCOSM ARRAY (ISMA): A NOVEL DEVICE FOR CONDUCTING TREATABILITY STUDIES

Site-specific feasibility studies of in situ remediation technologies conducted in the laboratory (a.k.a. lab treatability studies) are common practice in the environmental restoration industry. The uniqueness of each hazardous waste site demands customized cleanup solutions, yet accurately replicating field conditions in the laboratory is difficult. Many experts agree that the primary value of lab treatability studies is restricted to quantitative rather than qualitative information. Further, artifacts in treatability studies can translate into suboptimal remedial design and thus into cost and performance issues during full-scale in situ remediation. As a result, the remediation industry is caught up in an innovation paradox, in which novel technologies cannot easily transition from the lab to the field-scale because in situ performance data are lacking.

To address these critical challenges we have developed a novel tool for conducting treatability studies in situ. The technology, called the In Situ Microcosm Array (ISMA), is a field-deployable device that fits down any standard 4 inch monitoring well. The ISMA is designed to perform flow-through microcosm studies in the subsurface under in situ conditions without releasing any chemicals into the environment. The self-contained device consists of a stainless steel pipe featuring an array of sediment columns (microcosms) and is equipped with multi-channel peristaltic pumps and electronics enabling groundwater to be drawn directly from the subsurface formation and to be fed as influent to multiple microcosms. During the course of the deployment, effluent from each column is captured in separate effluent collection vessels, which is then transported back to the lab for analysis after in situ incubation. The ISMA allows for the comparison of up to three different in situ remediation approaches in triplicate, at the same time in the same well.

By generating in situ performance snapshots of different technologies simultaneously, the ISMA enables remediation engineers to directly compare and evaluate candidate remedial technologies without the penalty of deployment well contamination. This results in an innovative remedial design tool that addresses the above challenges and may pave the way for more sustainable and effective environmental restoration.