Evaluation of Fenton's Reagent and Activated Persulfate for Treatment of a Pharmaceutical Waste Mixture in Groundwater

Groundwater beneath the Kærgård Plantage megasite in Denmark are contaminated with a complex mixtu of pharmaceutical wastes, including sulfonamides, barbiturates, aniline, pyridine chlorinated solvents, mercury, and cyanide.  Regulatory agencies in Denmark are now in the process of evaluating remedial alternatives for source area remediation at the site.  As there is no precedent for treating this type of mixture, the feasibility of a variety of in situ remediation technologies are being evaluated in bench tests, including biological, chemical, and thermal techniques.  This paper describes on-going bench tests evaluating treatment of site groundwater and soil using modified Fenton's reagent and activated persulfate.

These tests are investigating oxidant stability, oxidation efficiency, metals mobilization and, for the persulfate, different activating agents, including NaOH, chelated iron, and modified Fenton's reagent. The stability of the oxidants will be determined under simulated aquifer conditions, with and without catalyst or activating agents. Once an optimal activation technique has been determined, oxidation efficiency towards the complex mix of contaminants will be measured in terms of contaminant loss. The treatment efficiency will also be evaluated on the basis of pre- and post-treatment toxicity tests. Due to the presence of significant quantities of mercury and cyanide in the target treatment zone (up to 1500 kg and 2500 kg, respectively), a key of objective of these tests is to identify the fate of mercury and cyanide consequent to the application of Fenton's reagent and activated persulfate.  Batch and continuous-flow column reactors will be used to measure mobilization of the mercury, cyanide and other metals both within the aqueous and vapor phases.   The collective chemical oxidation experiments will be completed by December 2009, and the results presented at the Battelle conference in May 2010.