Treatment posibilities of groundwater contamined with organohalogenated solvents

Abstract

Chlorinated ethenes such as 1,2-dichloroethylene (1,2DCE), trichloroethylene (TCE), tetrachloroethylene (PCE) were identified in some groundwater sources used for potable purpose. Contamination of groundwater can occur from many sources, the most important of which being leachates from waste disposal sites. Analysis of contaminated groundwater has shown high concentration level of halogenated volatile organics (1,2DCE = 14-18 mg/L, TCE = 80-130 mg/L, PCE = 198-258 µg/L), over the current limits imposed by enforced legislation (L 458(r1)/2011: MACTCE + PCE = 10 µg/L). The main treatment technique used by individual water consumers is based on GAC adsorption in one or two steps (ηTCE = 99.4%, ηPCE = 99.8%, ηDCE = 46%), which can’t assure the required quality for drinking water, the residual concentrations being higher than MAC value (1,2DCE ≤ 10 mg/L; TCE ≤ 500 µg/L; PCE ≤ 0,5 µg/L). The applied treatment processes for advanced degradation of chlorinated ethenes are based on oxidation using photolysis or ozonation in different systems: UV alone, UV/H2O2, UV/O3, O3 alone, O3/ H2O2. Also, air stripping can be used for pollutants removal. The paper presents the experimental results obtained for the advanced removal of halogenated compounds by coupling air stripping with chemical oxidation, which can provide drinking water quality in compliance with legislation requirements.