title: Biological groundwater treatment for chromium removal at low hexavalent chromium concentrations.
abstract: The objective of this work is to develop and evaluate biological groundwater treatment systems that will achieve hexavalent chromium reduction and total chromium removal from groundwater at hexavalent chromium (Cr(VI)) groundwater concentrations in the 0-200 μg/L range. Three lab-scale units operated, as sequencing batch reactors (SBR) under aerobic, anaerobic and anaerobic-aerobic conditions. All systems received groundwater with a Cr(VI) content of 200 μg/L. In order to support biological growth, groundwater was supplemented with milk, liquid cheese whey or a mixture of sugar and milk to achieve a COD concentration of 200 mg/L. The results demonstrate that a fully anaerobic system or an anaerobic-aerobic system dosed with simple or complex external organic carbon sources can lead to practically complete Cr(VI) reduction to Cr(III). The temperature dependency of maximum Cr(VI) removal rates can be described by the Arrhenius relationship. Total chromium removal in the biological treatment systems was not complete because a significant portion of Cr(III) remained in solution. An integrated system comprising of an anaerobic SBR followed by a sand filter achieved more than 95% total chromium removal thus resulting in average effluent total and dissolved chromium concentrations of 7 μg/L and 3 μg/L, respectively.
authors.affiliation: Sanitary Engineering Laboratory, Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, Iroon Polytechniou 5, Zografou 157 80, Athens, Greece. Electronic address: mamais@central.ntua.gr.
authors.forename: Daniel
authors.initials: D
authors.lastname: Mamais
authors.affiliation: Sanitary Engineering Laboratory, Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, Iroon Polytechniou 5, Zografou 157 80, Athens, Greece.
authors.forename: Constantinos
authors.initials: C
authors.lastname: Noutsopoulos
authors.affiliation: Sanitary Engineering Laboratory, Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, Iroon Polytechniou 5, Zografou 157 80, Athens, Greece.
authors.forename: Ioanna
authors.initials: I
authors.lastname: Kavallari
authors.affiliation: Sanitary Engineering Laboratory, Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, Iroon Polytechniou 5, Zografou 157 80, Athens, Greece.
authors.forename: Eleni
authors.initials: E
authors.lastname: Nyktari
authors.affiliation: Sanitary Engineering Laboratory, Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, Iroon Polytechniou 5, Zografou 157 80, Athens, Greece.
authors.forename: Apostolos
authors.initials: A
authors.lastname: Kaldis
authors.affiliation: Sanitary Engineering Laboratory, Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, Iroon Polytechniou 5, Zografou 157 80, Athens, Greece.
authors.forename: Eleni
authors.initials: E
authors.lastname: Panousi
authors.affiliation: Sanitary Engineering Laboratory, Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, Iroon Polytechniou 5, Zografou 157 80, Athens, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Nikitopoulos
authors.affiliation: Sanitary Engineering Laboratory, Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, Iroon Polytechniou 5, Zografou 157 80, Athens, Greece.
authors.forename: Kornilia
authors.initials: K
authors.lastname: Antoniou
authors.affiliation: Sanitary Engineering Laboratory, Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, Iroon Polytechniou 5, Zografou 157 80, Athens, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Nasioka
mesh_terms: D000693:Anaerobiosis; D001105:Archaea / Q000302:isolation & purification; D001673:Biodegradation, Environmental; D002857:Chromium / Q000032:analysis*; D020564:Deltaproteobacteria / Q000302:isolation & purification; D005374:Filtration; D020563:Gammaproteobacteria / Q000302:isolation & purification; D060587:Groundwater / Q000737:chemistry* / Q000382:microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion
keywords: Anaerobic treatment; Groundwater; Hexavalent chromium removal; Microbial reduction; Substrate; Temperature effect