Investigation of Cr(VI) reduction in continuous-flow activated sludge systems

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

dc.contributor.author	Stasinakis, AS	en
dc.contributor.author	Thomaidis, NS	en
dc.contributor.author	Mamais, D	en
dc.contributor.author	Lekkas, TD	en
dc.date.accessioned	2014-03-01T01:20:40Z
dc.date.available	2014-03-01T01:20:40Z
dc.date.issued	2004	en
dc.identifier.issn	0045-6535	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/16007
dc.subject	Activated sludge	en
dc.subject	Biotransformation	en
dc.subject	Chromium	en
dc.subject	Speciation	en
dc.subject	Wastewater	en
dc.subject.classification	Environmental Sciences	en
dc.subject.other	Activated sludge systems	en
dc.subject.other	Organic substrates	en
dc.subject.other	Biomass	en
dc.subject.other	Chromium	en
dc.subject.other	Reduction	en
dc.subject.other	Toxic materials	en
dc.subject.other	Wastewater	en
dc.subject.other	Sewage sludge	en
dc.subject.other	chromium	en
dc.subject.other	activated sludge	en
dc.subject.other	biodegradation	en
dc.subject.other	chromium	en
dc.subject.other	reduction	en
dc.subject.other	wastewater treatment	en
dc.subject.other	activated sludge	en
dc.subject.other	anaerobic reactor	en
dc.subject.other	article	en
dc.subject.other	concentration response	en
dc.subject.other	continuous flow reactor	en
dc.subject.other	dissolution	en
dc.subject.other	medical research	en
dc.subject.other	microorganism	en
dc.subject.other	particulate matter	en
dc.subject.other	reduction	en
dc.subject.other	waste water	en
dc.subject.other	Anaerobiosis	en
dc.subject.other	Bioreactors	en
dc.subject.other	Biotransformation	en
dc.subject.other	Chromium	en
dc.subject.other	Oxidation-Reduction	en
dc.subject.other	Sewage	en
dc.subject.other	Spectrophotometry, Atomic	en
dc.subject.other	Time Factors	en
dc.subject.other	Water Pollutants, Chemical	en
dc.subject.other	Water Purification	en
dc.subject.other	Gadus morhua	en
dc.title	Investigation of Cr(VI) reduction in continuous-flow activated sludge systems	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.chemosphere.2004.08.020	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.chemosphere.2004.08.020	en
heal.language	English	en
heal.publicationDate	2004	en
heal.abstract	The aim of this research was to investigate hexavalent chromium, Cr(VI), reduction by activated sludge and to evaluate the use of continuous-flow activated sludge systems for the treatment of Cr(VI)-containing wastewater. Three series of experiments were conducted using two parallel lab-scale activated sludge systems. During the first experiment, one system was used as a control, while the other received Cr(VI) concentrations equal to 0.5, 1, 3 and 5 mg l(-1). For all concentrations added, approximately 40% of the added Cr(VI) was removed during the activated sludge process. Determination of chromium species in the dissolved and particulate phase revealed that the removed Cr(VI) was sorbed by the activated sludge flocs mainly as trivalent chromium, Cr(III), while the residual chromium in the dissolved phase was mainly detected as Cr(VI). Activated sludge ability to reduce Cr(VI) was independent of the acclimatization of biomass to Cr(VI) and it was not affected by the toxic effect of Cr(VI) on autotrophic and heterotrophic microorganisms. During the second experiment, both systems were operated under two different hydraulic residence time (theta equal to 20 and 28 h) and three different initial organic substrate concentration (COD equal to 300, 150 and 0 mg l(-1)). Cr(VI) reduction was favored by an increase of theta, while it was limited by influent COD concentration. Finally, at the last experiment the effect of anoxic and anaerobic reactors on Cr(VI) reduction was investigated. It was observed that the use of an anoxic zone or an anaerobic anoxic zone ahead of the aerobic reactor favored Cr(VI) reduction, increasing mean percentage Cr(VI) reduction to almost 80%. (C) 2004 Elsevier Ltd. All rights reserved.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	Chemosphere	en
dc.identifier.doi	10.1016/j.chemosphere.2004.08.020	en
dc.identifier.isi	ISI:000225053200004	en
dc.identifier.volume	57	en
dc.identifier.issue	9	en
dc.identifier.spage	1069	en
dc.identifier.epage	1077	en