Sequencing Zerovalent Iron Treatment with Carbon Amendments to Remediate Agrichemical-Contaminated Soil

Abstract

Agrichemical spills and discharges to soil can cause point-source contamination of surface and ground waters. When high contaminant concentrations inhibit natural attenuation in soils, chemical treatments can be used to promote degradation and allow application of treated soils to agricultural lands. This approach was used to remediate soil containing >650 mg atrazine, >170 mg metolachlor and >18,000 mg nitrate kg −1 . Results indicated a decrease in metolachlor concentration to <1 mg kg −1 within 95 days of chemical treatment with zerovalent iron (Fe 0 , 5% w/w) and aluminum sulfate (Al 2 (SO 4 ) 3 , 2% w/w) but after one year >150 mg atrazine and >7000 mg nitrate kg −1 remained. Laboratory experiments confirmed that subsequent additions of sucrose (table sugar) to the chemically pretreated soil promoted further reductions in atrazine and nitrate concentrations. Field-scale results showed that adding 5% (w/w) sucrose to windrowed and pretreated soil significantly reduced atrazine (<38 mg kg −1 ) and nitrate (<2,100 mg kg −1 ) concentrations and allowed for land application of the treated soil. These results provide evidence that zerovalent iron in combination with Al 2 (SO 4 ) 3 and sucrose can be used for on-site, field-scale treatment of pesticide-and nitrate-contaminated soil.

A comprehensive overview of elements in bioremediation

“…Also known as passive remediation, in situ bioremediation, intrinsic remediation, bioattenuation, and intrinsic bioremediation, natural attenuation is an in situ treatment method that uses natural processes to contain the spread of contamination from chemical spills and to reduce that concentration and amount of pollutants at contaminated sites (Boparai et al 2008;Khan et al 2004). This means the environmental contaminants are undisturbed while natural attenuation works on them.…”

Comparison of the Effectiveness, Kinetics and Costs of Three Remediation Techniques for Agricultural Soils Historically Contaminated with Dieldrin, Using Laboratory Experiments

“…For ZVI and ZVI + AA treatments, the ratio stay close to 1, showing no significant change in the concentration of 𝑅 𝑡 Dieldrin in the soil, even after 70 d of treatment. Regarding the treatment ZVI + AS, the results show a decrease in Dieldrin concentration with a maximum decline of 40% after 70 d. This decrease can be approximated by a first-order kinetic model which is classically used for the degradation of organic compounds with ZVI in aqueous solution (Boparai et al, 2008;Boussahel et al, 2007;Cao et al, 2013;Satapanajaru et al, 2003;Wang et al, 2011), with a constant k of 9.3×10 -4 h -1 and the model fitted the data at 60.3% according to the ME calculation. Electronic copy available at: https://ssrn.com/abstract=4154291 10 There are still uncertainties about ZVI dechlorination effect on chlorine compounds, with contradictory studies.…”

“…This technique is based on the dechlorination of OCPs, thanks to the reducing capacity of ZVI (Boussahel et al, 2007). In the literature, ZVI amount of 5% (w/w) has been found to be optimal (Boparai et al, 2008;Comfort et al, 2001;Satapanajaru et al, 2003). However, in these studies, the Electronic copy available at: https://ssrn.com/abstract=4154291 5 2.…”

Advanced technologies for the remediation of pesticide-contaminated soils

“…The combination of chemical treatment using nZVI with biodegradation can maximize the remediation of pesticide-polluted soils. Boparai et al (2008) (Sudharshan et al, 2012).…”