Concentrations of TCE, cis-DCE and VC were measured using 8610GC instrument with purge-trap system (SRI, USA), photoionization detector and MXT-VOL stationary column. The purge-trap autosampler was equipped with carbon-sieve trap and Tenax™ trap, allowing the detection of highly volatile VC. 50 μL of water sample was injected in 5 mL deionized water in glass tubes, and loaded into the 10-port autosampler. The GC was programmed at 40°C for 6 minutes, then ramped to 60°C in 2 minutes, held at 60°C for 10 minutes. Hydrocarbon gases (methane, ethene, ethane and acetylene) in headspace of electrolytic cell were analyzed through a Model 310 GC (SRI, USA) with flame ionization detector and Haysep-T column. 100 μL of headspace gas was sampled and injected from an on-column port. The temperature program applied was: heat column from 40 to 140°C at a rate of 15°C min−1, hold 140°C for 1 minute, and cool to 40°C at a rate of 20°C min−1. Chloride ion concentration was analyzed by Dionex DX-120 ion chromatograph. After each experiment, an aliquot 0.2 to 0.5 ml of supernatant was transferred into 5 mL vials which had been pre-filled with de-ionized water (> 18 M3), then filtered by 0.45μm pore size filter paper prior to final analysis. pH, conductivity and oxidation-reduction potential (ORP) of the electrolyte were measured by pH meter, conductivity meter and ORP meter with corresponding microprobes (Microelectro, USA). The microprobes allow the measurement on these parameters using small amount of liquid (≈0.2 mL).