| As the limitations of site remedial technologies become more apparent and greater experience in their field implementation and effectiveness is gained, increased emphasis is placed on development of a structured technology selection process. Ideally, this selection process should yield the most cost-effective technology, which will accomplish cleanup goals in the shortest time frame. Although laboratory treatability studies comprise an essential component of this process, very little has been written about the methodology of designing, executing, and assessing the value of their results. This article presents practical considerations for environmental professionals who use treatability results in technology selection or others who execute such studies. As more and more site remediation technology are developed and implemented at different application scales, a large body of performance data is becoming available. An important conclusion can be drawn that technology performance data, for the most part, are not transferable from one site to another. Each site has its own unique characteristics that make direct transfer of technology performance data from other sites risky and thus undesirable. Such characteristics are numerous and sometime their effect is not so obvious. They include soil type; mineralogical, physical, and chemical properties: prevailing geohydrology; extent and degree of heterogeneity; groundwater chemistry; type of contaminants and their concentration: age of the spill or discharge: and climatic conditions. Due to the inadvisability of directly transferring technologies from one site to another, the need arises for a structured approach to the selection of the most appropriate technology for each individual site. Laboratory treatability studies are a major component of such an approach, especially when dealing with sites contaminated with complex wastes, such as mixtures of organics and heavy metals. In general, the objectives of a treatability study are to screen various treatment techniques, investigate the physicochemical and/or biological mechanisms responsible for treatment, perform a sensitivity analysis of the technique, assess its feasibility and applicability, and derive design parameters for scale-up. In order to meet these objectives, the study`s design and execution should follow a well-devised protocol. This not only provides quality control but also helps users of the study make useful interpretations of the results. The cost of conducting treatability studies is usually a very small portion of the total cost to clean up a site. However, the intonation obtained from such studies can result in substantial overall project cost savings and may drastically decrease the likelihood for failure. Although the cost savings component of treatability studies had often been overlooked in the past, treatability studies are now gaining widespread recognition for their ability to recuce overall project expenses. |
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