A Study on Optimal Operating Conditions for In-Situ Treatment of TCE and 4-CP Contaminated Soils by Electrokinetics-Fenton Process

• Main Authors: Liu Chyi-Yech, 劉奇岳
• Other Authors: Gordon C. C. Yang
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/28259693647956276582

碩士 === 國立中山大學 === 環境工程研究所 === 87 === This research was to determine the optimal operating conditions for in-situ treatment of trichloroethylene and 4-chlorophenol contaminated soils by electrokinetics-Fenton process. An electric gradient of 1 V/cm, deionized water in the cathode reservoir, and a reaction time of ten days were employed in all experiments. Soil types (No. 1 and No. 2), contaminant kinds (trichloroethylene and 4-chlorophenol), catalyst types (iron powder and FeSO4), catalyst dosage and position (one layer of 1.5 g iron powder placed in the soil column at a distance of 5 cm from the anode reservoir and two layer of iron powder placed in the soil column one at a distance of 5 cm from the anode reservoir and the other next to the cathode reservoir), and electrode types (graphite and stainless steel) were employed as the experimental factors in this study. In this study, treating the soil with a higher electrical conductivity would consume more H2O2 because H2O2 electrolyzed in the anode reservoir; whereas treating the soil with a higher organic content would lower the treatment efficiency because of the adsorption of contaminants and the consumption of hydroxyl radicals by the organic matter of soil. The directions of all electroosmotic flows were found to be from anode toward cathode in this investigation. Experimental results showed that the type of catalyst and its dosage affected the reaction mechanisms (i.e., "destruction" and "removal") and the treatment efficiency. For iron powder of a smaller size, the overall destruction and removal efficiency (DRE) was lower, but the percent of destruction was higher. For iron powder of a higher dosage, the DRE was lower, but the percent of destruction was higher. When trichloro-ethylene was the target pollutant, the highest destruction and removal efficiency (i.e., 88.91%) for Soil No. 1 was obtained by adding 1.5g of UPF-030 iron powder; whereas the highest destruction efficiency (i.e., 59.41%) was obtained by adding two layers of 1.5g scrap iron powder. However the highest removal efficiency (i.e., 63.64%) was obtained for Soil No. 1 by using 0.0196 M FeSO4 as the catalyst. When 4-Chlorophenol was the target pollutant, adding 1.5g of UPF-030 iron powder would yield the highest destruction and removal efficiency (i.e., 88.91%) and the highest removal efficiency (i.e., 49.84%) for Soil No. 1. But the highest destruction efficiency (i.e., 64.47%) for Soil No. 1 was obtained by adding two layers of 1.5g UPF-030 iron powder as the catalyst. For Soil No. 2 contaminated by trichloroethylene or 4-chlorophenol, a greater DRE and removal efficiency were obtained by adding one layer of 1.5 g UPF-030 iron powder. However, to obtain greater destruction efficiencies for Soil No. 2 contaminated by trichloroethylene and 4-Chlorophenol, adding one layer of scrap and UPF-150 iron powder, respectively are necessary.