In situ remediation of petroleum compounds in groundwater aquifer with chlorine dioxide

A comparison was made of the remedial effect on organic contaminants using ozone, chlorine dioxide, potassium permanganate and hydrogen peroxide in laboratory tests. Chlorine dioxide was chosen for use in in situ remediation of a petroleum contaminated aquifer. The laboratory experiments indicated that oxidation capacity of chlorine dioxide was affected by reaction time, gas injection method, and pH of groundwater. A pilot-scale field experiment was conducted through the oxidation treatment involving the injection of chlorine dioxide solution into the aquifer where pollutants included more than 80 organic compounds containing 14 mutagens. The in situ oxidation treatment proved that most of the organic contaminants including 5 mutagenic compounds were decomposed or removed and 19 new by-products were found without mutagenic carcinogens. The results shows that the unsaturated hydrocarbons were easily removed excluding that some of saturated alkane and alkene and polycyclic aromatic hydrocarbons and heterocyclic compounds were not oxidizable. The oil concentration in groundwater reduced by 50–60%. It was evident that desorption of organic contaminants from aquifer media significantly affected the groundwater quality during remediation process. Therefore, groundwater remediation must include aquifer media cleaning.