Reductive/oxidative degradation of tetrachloroethene and its transformation products using combination of permeable ZVI column and UV/Fe/peroxydisulfate system: RSM design and synergy effect study

Abstract Chlorinated aliphatic hydrocarbons (CAHs) are amongst concerning contaminants with high detection in aquifers and soils. This work is focused on removal of tetrachloroethylene and its degradation products through a two-step process including a permeable ZVI column followed by UV/Fe/PDS process. The permeable ZVI column experiments were designed using response surface method with central composite design. Optimum condition of the permeable ZVI column was initial solution pH = 5, 2 mL/min flow and 26 cm column height which brought about 96% dechlorination efficiency. Total iron leach in the column effluent was 0.34 mg/L. The concentrations of CAHs in permeable ZVI column’s effluent were as follows: PCE ≤ 0.08 mg/L, TCE = 0.23 mg/L, cis-1,2-DCE = 0.36 mg/L, VC = 0.34 mg/L. Thus, further treatment step was required to comply with the corresponded standards. Regarding iron leach, a PDS-based advanced oxidation process was applied on the ZVI column’s effluent with focus on cumulative removal of CAHs. Complete removal of CAHs and 79.2% TOC removal were obtained at pH = 6 using 0.75 mM PDS, 6 W UV at 15 min reaction time. In UV/Fe/PDS process, synergy effect of 67% was observed.