Chromium species behaviour in the activated sludge process

Stasinakis, AS; Thomaidis, NS; Mamais, D; Karivali, M; Lekkas, TD

dc.contributor.author	Stasinakis, AS	en
dc.contributor.author	Thomaidis, NS	en
dc.contributor.author	Mamais, D	en
dc.contributor.author	Karivali, M	en
dc.contributor.author	Lekkas, TD	en
dc.date.accessioned	2014-03-01T01:18:45Z
dc.date.available	2014-03-01T01:18:45Z
dc.date.issued	2003	en
dc.identifier.issn	0045-6535	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/15179
dc.subject	Activated sludge	en
dc.subject	Adsorption	en
dc.subject	Chromium	en
dc.subject	Precipitation	en
dc.subject	Reduction	en
dc.subject	Speciation	en
dc.subject.classification	Environmental Sciences	en
dc.subject.other	Oxidation	en
dc.subject.other	Reduction	en
dc.subject.other	Sludge digestion	en
dc.subject.other	Substrates	en
dc.subject.other	Wastewater treatment	en
dc.subject.other	Suspended solids	en
dc.subject.other	Chromium compounds	en
dc.subject.other	chromium	en
dc.subject.other	activated sludge	en
dc.subject.other	adsorption	en
dc.subject.other	chromium	en
dc.subject.other	oxidation	en
dc.subject.other	precipitation	en
dc.subject.other	reduction	en
dc.subject.other	sequencing batch reactor	en
dc.subject.other	wastewater treatment	en
dc.subject.other	acclimatization	en
dc.subject.other	adsorption	en
dc.subject.other	article	en
dc.subject.other	biomass	en
dc.subject.other	comparative study	en
dc.subject.other	isotherm	en
dc.subject.other	molecular model	en
dc.subject.other	nuclear reactor	en
dc.subject.other	oxidation	en
dc.subject.other	oxygen consumption	en
dc.subject.other	pH	en
dc.subject.other	precipitation	en
dc.subject.other	reduction	en
dc.subject.other	sludge	en
dc.subject.other	waste water management	en
dc.subject.other	Adsorption	en
dc.subject.other	Biomass	en
dc.subject.other	Bioreactors	en
dc.subject.other	Biotransformation	en
dc.subject.other	Carcinogens, Environmental	en
dc.subject.other	Chromium	en
dc.subject.other	Kinetics	en
dc.subject.other	Oxidation-Reduction	en
dc.subject.other	Oxygen	en
dc.subject.other	Precipitation	en
dc.subject.other	Sewage	en
dc.subject.other	Waste Disposal, Fluid	en
dc.title	Chromium species behaviour in the activated sludge process	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/S0045-6535(03)00309-6	en
heal.identifier.secondary	http://dx.doi.org/10.1016/S0045-6535(03)00309-6	en
heal.language	English	en
heal.publicationDate	2003	en
heal.abstract	The purpose of this research was to compare trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) removal by activated sludge and to investigate whether Cr(VI) reduction and/or Cr(III) oxidation occurs in a wastewater treatment system. Chromium removal by sludge harvested from sequencing batch reactors, determined by a series of batch experiments, generally followed a Freundlich isotherm model. Almost 90% of Cr(III) was adsorbed on the suspended solids while the rest was precipitated at pH 7.0. On the contrary, removal of Cr(VI) was minor and did not exceed 15% in all experiments under the same conditions. Increase of sludge age reduces Cr(III) removal, possibly because of Cr(III) sorption on slime polymers. Moreover, the decrease of suspended solids concentration and the acclimatization of biomass to Cr(VI) reduced the removal efficiency of Cr(III). Batch experiments showed that Cr(III) cannot be oxidized to Cr(VI) by activated sludge. On the contrary, Cr(VI) reduction is possible and is affected mainly by the initial concentration of organic substrate, which acts as electron donor for Cr(VI) reduction. Initial organic substrate concentration equal to or higher than 1000 mg l(-1) chemical oxygen demand permitted the nearly complete reduction of 5 mg l(-1) Cr(VI) in a 24-h batch experiment. Moreover, higher Cr(VI) reduction rates were obtained with higher Cr(VI) initial concentrations, expressed in mg Cr(VI) g(-1) VSS, while decrease of suspended solids concentration enhanced the specific Cr(VI) reduction rate. (C) 2003 Elsevier Science Ltd. All rights reserved.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	Chemosphere	en
dc.identifier.doi	10.1016/S0045-6535(03)00309-6	en
dc.identifier.isi	ISI:000183788400013	en
dc.identifier.volume	52	en
dc.identifier.issue	6	en
dc.identifier.spage	1059	en
dc.identifier.epage	1067	en