There is a well-recognized need to clean-up contaminants that exist in ground water, i.e., aquifers and surrounding soil formations. Such aquifers and surrounding soil formations may be contaminated with various constituents including organic compounds such as, volatile hydrocarbons, including chlorinated hydrocarbons such as trichloroethene (TCE), and tetrachloroethene (PCE). Other contaminates that can be present include vinyl chloride, 1,1,1 trichloroethane (TCA), and very soluble gasoline additives such as methyltertiarybutylether (MTBE). Other contaminants may also be encountered.
Ozone sparging is now widely recognized as being one of the more effective oxidation techniques for destroying contaminants that exist in groundwater.
Other types of contaminants are more recalcitrant. For instance, pharmaceuticals are particularly resistant to decomposition from known techniques including ozone sparging. Pharmaceuticals enter the groundwater from various sources. One source is pharmaceutical laboratories and manufacturing plants located in area with septic systems for waste disposal. Other sources are hospitals and nursing homes.
Pharmaceutical residuals are increasingly found in sewage discharges. Stronger selective oxidation techniques are necessary to the discharge of antibiotic-resistant bacteria and pharmaceutical residuals into groundwater and surface waters. Zwiener and Frimmel “Oxidative Treatment Of Pharmaceuticals In Water” Water Research 34(6) 1881-1885 (2000); Andreozzi et al. “Paracetanol Oxidation From Aqueous Solutions By Means Of Ozonation and H2O2 UV System” Water Research 37 993-1004 (2003), and Huber et al. “Oxidation Of Pharmaceuticals During Ozonation And Advanced Oxidation Processes” Environmental Science and Technology (2003) have proposed that oxidation systems need to be improved to address the variety of compounds involved. Korhonen et al. Oxidation of Selected Pharmaceuticals in Drinking Water Treatment, Presented at the ninth International Conference on Advanced Oxidation Technologies for Water and Air Remediation Canada (2003) felt that ozone or a combination of ozone and peroxide may offer effective treatment. The identified pharmaceutical residuals include the lipid regulator bezafibrate, antiepileplic carbamazepine, analgesic/inflammatory diclofenac and ibuprofen, and the antibiotic sulfamethoxazole. Even though Korhonen et al. (2003) obtained 90% removal of bezafibrate with ozone alone, H2O2 (peroxide) additional was necessary to obtain over 90% removal of carbamazepine, ibuprofen, and bezafibrate in clean water samples. However, with sewage, the presence of natural organic material (NOM) inhibits effective reaction.
Another need improved oxidation systems comes from treatment of alkanes and alkenes, common to petroleum products and spills. The bulk of petroleum products are aliphatic long-chain compounds, which are often 75% of the product. In heavier refined products, the carbon chain notation for molecular size, C5 to C30 denotes the dominant molecular fractions from 5-carbon to 30-carbon atoms strung together in a single chain. The higher fractions, particularly when branched, are resistant to bacterial action. Fogel (2001) has found that well-aerated samples of petroleum from a diesel source, even when supplied optimal nutrients, will leave about 25% undigested.