Sustainabilitylive! 2012 Seminar Programme - Experience with Enhanced Bioremediation: Observed Half Lives and Their Variation in Time and Space

A priori assessment of the potential effectiveness of amendments for enhanced bioremediation of chlorinated hydrocarbons is complicated by the varying geologic settings, groundwater flow rates, and background geochemistry encountered. Amendments employing a combination of carbon, nutrients, and micro-scale zero-valent iron result in multiple biotic and abiotic treatment mechanisms at various length and timescales which makes direct prediction of effectiveness difficult. The purpose of this paper is to empirically summarize experience across a range of sites and chemical compounds for the purpose of providing effective half lives suited to approximate prediction of cleanup effectiveness and duration. Using well-documented sites where in situ chemical reduction (ISCR) technologies have been applied over the last 8 years, an analysis of decay rates as a function of time, compound treated, and application rate has been prepared. Data from field sites and column tests are compared, and data for similar compounds in treated and untreated settings are discussed. The variation of effective half lives with distance and time from the point and time of injection are illustrated. Modeling analyses of the use of effective half lives to predict remediation effectiveness are presented. Who should attend: Contaminated land specialists in consulting, regulatory agencies, and universities. What will delegates learn: In situ bioremediation R&D, experience across a range of sites and chemical compounds, database of half lives suited to prediction of cleanup effectiveness and duration.