Remediation of trichloroethene (TCE)-contaminated groundwater by persulfate oxidation: a field-scale study

Abstract

This study uses a trichloroethene (TCE)-contaminated site to determine the efficacy of persulfate oxidation for the treatment of TCE-contaminated groundwater.

Remediation Efficiency and Soil Properties of TCE-Contaminated Soil Treated by Thermal Conduction Heating Coupled with Persulfate Oxidation

“…The results showed that PS could significantly improve the TCE removal of the TCH treatment. The TCE removal ratio increased to 44.28~60.02%, 53.94~73.60%, 68.27~87.18%, and 72.99~89.82% after adding 7.0, 10.5, 14, and 17.5 mmol/kg PS, respectively, compared to the TCE removal ratios of 36.27~48.92% with TCH alone under 40 • C for 3 to 6 h. This demonstrated the contributions of TCE removal due to the coupling effects of volatilization and oxidation introduced by the usage of PS [29], generating hydroxyl and sulfate radicals upon activation by heat [6][7][8][9], which can react with TCE as described in Equations ( 1)-( 4). In addition to the effect of PS usage, temperature exerted significant influences on the TCE removal ratio in the TCH + PS treatment.…”

“…Zhao et al [7] demonstrated that the hydroxyl radical was the main species in the thermal activation of PS, followed by some superoxide radicals and sulfate radicals. These radicals were capable of oxidizing many volatile organic compounds (VOCs), especially with "C=C" bonds or with benzene rings bonded to reactive functional groups [8,9], such as Equations ( 1)- (4). Although the energy consumption of thermal activation is higher, the activation efficiency is better [7].…”

From Theory to Practice: Leveraging Chemical Principles To Improve the Performance of Peroxydisulfate-Based In Situ Chemical Oxidation of Organic Contaminants

“…Microorganisms that are sensitive to oxidative treatments, including anaerobic organisms such as organohalide-respiring bacteria (e.g., Dehalococcoides mccartyi , Dehalobacter , Geobacter , and Desulfitobacterium ), will experience a decrease in abundance and activity . In contrast, the population and activity of microbes that are less sensitive to the alteration in redox potential (e.g., facultative anaerobes) might remain unchanged or even exhibit positive responses. − For example, it has been demonstrated that acidification (pH < 3) and an increase in redox potential (>500 mV) associated with S 2 O 8 2– treatment disrupt the microbial community, with full recovery of anaerobic bacteria such as Dehalococcoides mccartyi taking longer than half a year . The recovery is likely due to the recolonization of the previously oxidized area by organisms moving in groundwater from the upgradient direction or the reintroduction of microorganisms into a treated area, potentially originating from blind pockets or low-permeability zones. , Additionally, the observed increase in biomass following the application of S 2 O 8 2– oxidant could be linked to the increased presence of bioavailable oxidation byproducts …”

Activation of Persulfate for Groundwater Remediation: From Bench Studies to Application

“…Sperryet al ( 2002) observed a drop in pH from 5.7 to 5.3 in monitoring wells [124]. Results obtained from Yu-Chen Chang (2018) showed that when the persulfate was injected, the pH was firstly decreased from 7.0 to 6.2, but recovered to 7 in the next few days and the groundwater in each injection well remained at a near-neutral pH (6.70-7.22) [120].…”

“…Due to the diffusion of persulfate in groundwater and the complex contaminants in actual spiked sites, however, the concentration of persulfate used in the laboratory may not be properly matched when applied to site applications. For instance, the concentrations of persulfate used in the laboratory typically ranged from 10 mmol/L to 100 mmol/L and can obtain a promising removal efficiency, whereas the concentrations of persulfate used in field applications need to reach 1000 mmol/L to meet the same removal efficiency [120]. For this reason, bench-scale studies or pilot-scale studies were needed using the site contaminated soils to evaluate the optimal persulfate concentration prior to field-scale site remediation.…”