Removal of MTBE in Biological Activated Carbon Adsorbers

摘要

Methyl tert-butyl ether (MTBE) is a common gasoline additive; it has become a groundwater pollutant in many countries. Granular activated carbon (GAC) adsorption treatment is not cost-effective for removing MTBE because it is not well adsorbed. Acclimated MTBE degraders actively growing in the GAC adsorber will make it a biological activated carbon (BAC) system capable of long-term MTBE removal without periodic GAC replacement. The conventional inoculation method of circulating a seeding solution of the MTBE degraders present in the spent GAC sample from a BAC system of a southern California MTBE remediation site failed to initiate the BAC function in treating a high MTBE influent (30 mg/L, simulating a newly contaminated ground-water); the effluent samples of inoculated coal and coconut GAC columns were nearly the same as those of the non-inoculated columns. After a start-up period of less than two months, the small GAC columns filled with new coconut GAC on top of the MTBE degrader containing spent GAC became effective BAC systems accomplishing more than 40% of MTBE removal from the high concentration (30 mg/L) influent and more than 80% of removal from the low concentration (1 mg/L) influent. When MTBE concentration of the influent declined steadily, the BAC capability prevented the sudden rise of MTBE in the effluent. A small dose of hydrogen peroxide provided the essential dissolved oxygen to sustain aerobic degradation of MTBE in the BAC; adding peroxide to the influents of two serial adsorbers is more efficient in treating newly contaminated groundwater.