title: Impact of electrochemical treatment of soil washing solution on PAH degradation efficiency and soil respirometry.
abstract: The remediation of a genuinely PAH-contaminated soil was performed, for the first time, through a new and complete investigation, including PAH extraction followed by advanced oxidation treatment of the washing solution and its recirculation, and an analysis of the impact of the PAH extraction on soil respirometry. The study has been performed on the remediation of genuine PAH-contaminated soil, in the following three steps: (i) PAH extraction with soil washing (SW) techniques, (ii) PAH degradation with an electro-Fenton (EF) process, and (iii) recirculation of the partially oxidized effluent for another SW cycle. The following criteria were monitored during the successive washing cycles: PAH extraction efficiency, PAH oxidation rates and yields, extracting agent recovery, soil microbial activity, and pH of soil. Two representative extracting agents were compared: hydroxypropyl-beta-cyclodextrin (HPCD) and a non-ionic surfactant, Tween(®) 80. Six PAH with different numbers of rings were monitored: acenaphthene (ACE), phenanthrene (PHE), fluoranthene (FLA), pyrene (PYR), benzo(a)pyrene (BaP), and benzo(g,h,i)perylene (BghiP). Tween(®) 80 showed much better PAH extraction efficiency (after several SW cycles) than HPCD, regardless of the number of washing cycles. Based on successive SW experiments, a new mathematical relation taking into account the soil/water partition coefficient (Kd*) was established, and could predict the amount of each PAH extracted by the surfactant with a good correlation with experimental results (R(2) > 0.975). More HPCD was recovered (89%) than Tween(®) 80 (79%), while the monitored pollutants were completely degraded (>99%) after 4 h and 8 h, respectively. Even after being washed with partially oxidized solutions, the Tween(®) 80 solutions extracted significantly more PAH than HPCD and promoted better soil microbial activity, with higher oxygen consumption rates. Moreover, neither the oxidation by-products nor the acidic media (pH approximately 3) of the partially oxidized solution inhibited the general soil microbial activity during the washing cycle.
authors.affiliation: Université Paris-Est, Laboratoire Géomatériaux et Environnement (LGE), EA 4508, UPEM, 5 bd Descartes, 77454 Marne-la-Vallée Cedex 2, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Mousset
authors.affiliation: Université Paris-Est, Laboratoire Géomatériaux et Environnement (LGE), EA 4508, UPEM, 5 bd Descartes, 77454 Marne-la-Vallée Cedex 2, France.
authors.forename: David
authors.initials: D
authors.lastname: Huguenot
authors.affiliation: Université Paris-Est, Laboratoire Géomatériaux et Environnement (LGE), EA 4508, UPEM, 5 bd Descartes, 77454 Marne-la-Vallée Cedex 2, France.
authors.forename: Eric D
authors.initials: ED
authors.lastname: van Hullebusch
authors.affiliation: Université Paris-Est, Laboratoire Géomatériaux et Environnement (LGE), EA 4508, UPEM, 5 bd Descartes, 77454 Marne-la-Vallée Cedex 2, France.
authors.forename: Nihal
authors.initials: N
authors.lastname: Oturan
authors.affiliation: Université de Limoges, Groupement de Recherche Eau Sol Environnement - EA 4330, 123 Avenue A. Thomas, 87060 Limoges Cedex, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Guibaud
authors.affiliation: University of Cassino and the Southern Lazio, Department of Civil and Mechanical Engineering, Via Di Biasio, 43 - 03043 Cassino (FR), Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Esposito
authors.affiliation: Université Paris-Est, Laboratoire Géomatériaux et Environnement (LGE), EA 4508, UPEM, 5 bd Descartes, 77454 Marne-la-Vallée Cedex 2, France. Electronic address: mehmet.oturan@univ-paris-est.fr.
authors.forename: Mehmet A
authors.initials: MA
authors.lastname: Oturan
mesh_terms: D000073738:2-Hydroxypropyl-beta-cyclodextrin; D001564:Benzo(a)pyrene / Q000032:analysis; D004787:Environmental Pollution / Q000032:analysis; D052918:Environmental Restoration and Remediation / Q000379:methods*; D010616:Phenanthrenes; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000737:chemistry; D011136:Polysorbates; D011721:Pyrenes; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D012996:Solutions; D013501:Surface-Active Agents / Q000032:analysis; D047392:beta-Cyclodextrins
chemical_list: D010616:Phenanthrenes; D011084:Polycyclic Aromatic Hydrocarbons; D011136:Polysorbates; D011721:Pyrenes; D012987:Soil; D012989:Soil Pollutants; D012996:Solutions; D013501:Surface-Active Agents; D047392:beta-Cyclodextrins; D000073738:2-Hydroxypropyl-beta-cyclodextrin; D001564:Benzo(a)pyrene; C031181:phenanthrene; C030984:pyrene
keywords: Electro-Fenton; Recirculation; Soil microbial activity; Successive washing; Tween(®) 80