We studied trichloroethylene (TCE) adsorption from aqueous solutions in equilibrium conditions by activated carbons (AC). They differ in raw materials, porous structure characteristics and chemical state of the surface. TCE adsorption isotherms were found to have a concave shape, which is characteristic of a sorbent—sorbate weak interaction. It can be a result from electrostatic repulsion of organic matter molecule from polar groups on carbon surface and adsorbed water molecules. The basic parameters of adsorption were calculated by the Dubinin–Radushkevich equation. We determined that for AG-OV-1 and SKD-515 in the coordinates of the Dubinin–Radushkevich equation, there are two linear plots suggesting adsorption in pores of different sizes or reorientation of adsorbate molecules on the activated carbon surface. The efficiency of TCE removal by the activated carbons was evaluated. To reduce the TCE to the maximum allowable, the lowest sorbent consumption was observed for AC with the highest values of surface area and micropore volume. However, the high cost and hydrophobicity of these adsorbents make it impractical to use them in adsorption columns with a fixed layer. We offered an adsorbent that reasonably combines extraction efficiency, ease of operation and economic feasibility.

Coconut shell activated carbon (CSAC) was investigated for its ability in the removal of two neutral chlorinated organic compounds, namely trichloroethylene (TCE) and dichloromethane (DCM) from aqueous solution using a packed bed column. The efficiency of the prepared activated carbon was also compared with a commercial activated carbon (CAC). The important design parameters such as flow rate and bed height were studied. In all the cases the lowest flow rate (5 mL/min) and the highest bed height (25 cm) resulted in maximum uptake and per cent removal. The experimental data were analysed using bed depth service time model (BDST) and Thomas model. The regeneration experiments including about five adsorption-desorption cycles were conducted. The suitable elutant selected from batch regeneration experiments (25% isopropyl alcohol) was used to desorb the loaded activated carbon in each cycle.

This study examined the treatment characteristics of hard-to-degrade pollutants such as TCE which are found in organic solvent and cleaning wastewater by nZVI that have excellent oxidation and reduction characteristics. In addition, this study tried to find out the degradation characteristics of TCE by Fenton-like process, in which H2O2 is dosed additionally. In this study, different ratios of nZVI and H2O2, such as 1.0 mM : 0.5 mM, 1.0 mM : 1.0 mM, and 1.0 mM : 2.0 mM were used. When 1.0 mM of nZVI was dosed with 1.0 mM of H2O2, the removal efficiency of TOC was the highest and the first order rate constant was also the highest. When 1mM of nZVI was dosed with 0.5 mM of H2O2, the first order rate constant and removal efficiency were the lowest. The size of first order rate constant and removal efficiency was in the order of nZVI 1.0 mM : H2O2 1.0 mM ＞ nZVI 1.0 mM : H2O2 2.0 mM ＞ nZVI 1.0 mM : H2O2 0.5 mM ＞ H2O2 1.0 mM ＞ nZVI 1.0 mM. It is estimated that when 1.0 mM of nZVI is dosed with 1.0 mM of H2O2, Fe2+ ion generated by nZVI and H2O2 react in the stoichiometric molar ratio of 1:1, thus the first order rate constant and removal efficiency are the highest. And when 1.0 mM of nZVI is dosed with 2.0 mM of H2O2, excessive H2O2 work as a scavenger of OH radicals and excessive H2O2 reduce Fe3+ into Fe2+. As for the removal efficiency of TOC in TCE by simultaneous dose and sequential dose of nZVI and H2O2, sequential dose showed higher first order reaction rate and removal efficiency than simultaneous dose. It is estimated that when nZVI is dosed 30 minutes in advance, pre-treatment occurs and nanoscale Fe0 is oxidized to Fe2+ and TCE is pre-reduced and becomes easier to degrade. When H2O2 is dosed at this time, OH radicals are generated and degrade TCE actively.

Titania-supported chromium oxides with different loadings have been embarked in catalytic oxidation of trichloroethylene (TCE) to inquire association of the formation of crystalline Cr2O3 with catalytic performances. A better activity in the oxidative TCE decomposition at chosen temperatures was represented when chromium oxides (CrOx) had been dispersed on pure anatase-type TiO2 (DT51D) rather than on phase-mixed and sulfur-contained ones such as P25 and DT51. The extent of TCE oxidation at temperatures below 350℃ was a strong function of CrOx content in CrOx/DT51D TiO2, and a noticeable point was that the catalyst has two optimal CrOx loadings in which the lowest T50 and T90 values were measured for the TCE oxidation. This behavior in the activity with respect to CrOx amounts could be associated with the formation of crystalline Cr2O3 on the support surface, that is less active for the oxidation reaction, and an easier mobility of the surface oxygen existing in noncrystalline CrOx species with higher oxidation states, such as Cr2O8 and CrO3.

Pseudomonas sp. EL-04J was previously isolated from phenol-acclimated activated sludge. This bacterium was capable of degrading phenol and cometabolizing trichloroethylene (TCE). After precultivation in the mineral salts medium containing phenol as a sole carbon source, Pseudomonas EL-04J degraded 90% of TCE 25μM within 20 hours. Thus, phenol-induced Pseudomonas sp. EL-04J cells can degrade TCE. Following a transient lag period, Pseudomonas sp. EL-04J cells degraded TCE at concentrations of at least 250μM with no apparent retardation in rate, but the transformation capacity of such cells was limited and depended on the cell concentration. The degradation rate of TCE followed the Michaelis-Menten kinetic model. The maximum degradation rate (Vmax) and saturation constant (Km) were 7nmo ℓ/min·㎎ cell protein and 11μM, respectively. Cometabolism of TCE by phenol fed experiment was evaluated in 50·mℓ serum, vial that contained 10 ㎖ of meneral sals medium supplemented with 10μM TCE. TCE degradation was inhibited in the initial period of 1 mM phenol addition, but after that time Pseudomonas sp. EL-04J cells degraded TCE and showed cell growth.

Several microorganisms which degrade phenol and trichloroethylene (TCE) were isolated from the activated sludge of a wastewater treatment plant. Among them, one isolate EL-04J showed the highest degradability and was identified as a Pseudomonas species according to morphological, cultural and biochemical properties. The phenol-induced cells of Pseudomonas EL-04J, which were preincubated in the mineral salts medium containing phenol as a sole carbon source, degraded 90% of 25μM TCE within 20 h. This strain could also utilize some of methylated phenol derivatives (o-cresol, m-cresol and p-cresol) as the sole source of carbon and energy. Cresol-induced cells of Pseudomonas EL-04J also cometabolized TCE.

Microorganisms capable of degrading trichloroethylene(TCE) using phenol as a induction substrate were isolated from industrial effluents and soil. The strain MS-64K which had the highest biodegradability was identified as the genus Micrococcus. The optimal conditions of medium for the growth and biodegradation of trichloroethylene were observed as follows; the initial pH 7.0, trichloroethylene 1,000ppm as the carbon source, 0.2% (NH_4)_2SO_4 as the nitrogen source, respectively. Lag period and degradation time on optimal medium were shorter than those on isolation medium. Growth on the optimal medium was increased. Addition of 0.1% Triton X-100 increased the growth rate of Micrococcus sp. MS-64K, but degradation was equal to optimal medium. Trichloroethylene degradation by Micrococcus sp. MS-64K was shown to fit logarithmic model when the compound was added at initial concentration of 1,000ppm.