Electrodialytic Arsenic Removal from Bulk and Pre-treated Soil Ana Rita Ferreira & Nazaré Couto & Alexandra B. Ribeiro & Lisbeth M. Ottosen Received: 13 September 2018 /Accepted: 11 February 2019 # Springer Nature Switzerland AG 2019 Abstract Arsenic (As) is a well-known highly toxic and carcinogenic element. A combination of electrodia- lytic remediation (EDR) after soil washing with floccu- lant addition targeting remediation of a soil polluted with As from wood preservation industry is the focus of this paper. The fine fraction (< 0.063 mm) from the washed soil after dry sieving was also considered. The EDR experiments were carried out in a 2-compartment cell applying 0.01 mA/cm 2 during 14, 7 and 3 days. The suspended soil slurry was placed in cathode compart- ment separated by anion exchange membrane (AEM) of the anolyte where the pH was kept at 10. The soil was highly polluted with As, and the EDR was able to remove between 50 and 80% corresponding to 400– 478 mg As/kg of soil. The major part of the As was removed within the first 3 days (63%), and approx. 10% more of As was released doubling the time of the experiment: 72% in 7 days and 80% in 14 days. The pre-treated soil showed higher As initial concentration, but did not show a clear advantage in terms of removal rate as the original soil (not washed or sieved) showed 80% of As removal comparing with 61% and 50% for washed and fine fraction, respectively (although the absolute removed concentration was similar). The se- quential extraction results confirmed that As was bound into more mobile fractions in original soil, and the higher removal was mainly due to its larger exchange- able and reducible fractions compared to the oxidizable and residual fraction in pre-treated soil. Keywords Arsenic . Soil contamination . Electrodialytic remediation . Soil washing 1 Introduction Arsenic (As) is a metalloid naturally found in the envi- ronment, but it is widely present in soils in problematic concentrations mainly due to human activities (Sauvé and Desrosiers 2014). It is leaked and accumulated in the soil during mining, agricultural use of pesticides, and the disposal of industrial wastes (Chen et al. 2016). As- contaminated soil is strongly linked to the wood preser- vation industry, which is considered a worldwide prob- lem over the past several decades (Nico et al. 2004). High total and bioavailable concentrations of As in soils represent a potential risk for surface and ground- water contamination, entering in the food chain (Arco- Lázaro et al. 2016). The adverse health effects and the negative environmental impact explain the increasing interest in As abundance, behaviour and remediation, being As considered a legacy contaminant of emerging concern (Ungureanu et al. 2015) and one of the top 10 of the chemicals of major concern considered by World Health Organization (WHO 2018). Water Air Soil Pollut (2019) 230:78 https://doi.org/10.1007/s11270-019-4116-y A. R. Ferreira (*) : N. Couto : A. B. Ribeiro CENSE, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal e-mail: arl.ferreira@campus.fct.unl.pt L. M. Ottosen Department of Civil Engineering, Technical University of Denmark, 2800 Lyngby, Denmark