Performance of a hybrid persulfate−electrokinetic system for the removal of odor pollutant mixtures from soil

Abstract

There is an urgent need for fast and cost-effective in-situ remediation of sites contaminated with odor pollutants. The focus of this study was to develop an effective and environmentally sustainable pollutant control system based on a persulfate (PS)−coupled electrokinetic (EK) strategy. The system was evaluated by comparing the removal efficiencies of odor pollutant mixtures, degree of soil disturbance, and economic costs. A novel EK device was established based on the characteristic volatility of odor pollutants and the need for the in-situ collection of soil solutions. Several common activators, i.e., sodium hydroxide (0.25 mol L⁻¹), citric acid chelated iron (II) (CA-Fe (II), PS/ citric acid/ Fe²⁺ molar ratio of 4:1:1), and bamboo derived biochar (BC) (2 %, w/w) pyrolyzed at 700°C, were used to enhance the PS−EK strategy when remediating freshly prepared composite soil contaminated with an odor pollutant mixture. After the six-day experiment, the removal efficiencies of typical odor substances (dimethyl disulfide (DMDS)/trichloroethylene (TCE)/benzene) using the three activators referred to above were 57.4−89.0 %, 52.0−81.7 %, and 44.7−69.9 %, respectively. Chemical probe technology and quenching experiments indicated that singlet oxygen played the dominant role in the degradation of DMDS, while hydroxyl radicals were the main participants in the degradation of TCE and benzene. From the perspective of green remediation, the activation system including BC had positive effects on soil stability and reusability.