Application of the Ozone-Hydrogen Peroxide Combination for the Removal of Toxic Compounds from a Groundwater

Summary

Nitro and chloro-benzenic compounds, which are widely used in dye industries, have been associated recently with groundwater contamination. Because of their potential toxicity and for taste and odor considerations, three main actions were decided to solve the problem. First, to follow the advance of pollution toward the wells, samples were collected automatically and analyzed using GC-MS. Results indicate that o-chloronitrobenzene was the main pollutant in concentrations ranging from 10 to 20,000 μg/1. Second, to monitor the drinking water quality, an on-line spectrophotometer was used to measure the optical density at 254 nm at the inlet and outlet of the plant. Third, the feasibility of using the O₃/H₂O₂. combination was determined at a 450 1/h pilot plant. Reduction of chloronitrobenzenes from 1.9 mg/1 to less than 20 μg/1 could be reached by the application of 8 g O₃/m³ and 3 g H₂O₂/m³ with a 20-minute contact time. To avoid an eventual bacterial regrowtn in the network due to biodegradability of the oxidation by-products, sand and GAC filtration were tested after oxidation. An evaluation of the costs of these different treatments is also presented.