Competitive removal of VOCs with GAC and BAC following advanced oxidation processes

Abstract

Studies have been conducted to remove trichloroethylene (TCE), tetrachloroethylene (PCE) and 1,1,1-trichloroethane (1,1,1-TCA, TCA) as volatile organic compounds (VOCs) using the combination of chemical oxidation, adsorption by granular activated carbon (GAC) and biological activated carbon (BAC) with a selected microbial consortium (SMC). The purposes of this research were to investigate the competitive removal of VOCs and to develop the most optimal process by using a pilot plant composed of three GAC columns and three BAC columns. Simulated groundwater systems were used not only to examine the competitive adsorption availability for VOCs on GAC and BAC but also to examine the oxidation efficiency using O3 alone and H2O2/O3. The microbial species isolated from the soil contaminated by VOCs were Gram-negative, rod-shaped bacteria, identified as Pseudomonas aeruginosa, Pseudomonas maltophilia, Acinobacter calcoaceticus and Bacillus sphacricus. The results revealed that systems pre-treated by H2O2/O3 were more effective at removing VOCs than systems treated by ozone alone and non-pre-treated systems. The mixture of VOCs was removed in the order of PCE, TCE and TCA in GAC and BAC systems. Biological treatment alone was not effective at removing VOCs. However, pre-treatment of these chemicals by H2O2/O3 showed high removals. PCE and TCA were less effective than TCE at being oxidized by chemical oxidation and biodegradation.