Effects of chromium (VI) addition on the activated sludge process

Stasinakis, AS; Thomaidis, NS; Mamais, D; Papanikolaou, EC; Tsakon, A; Lekkas, TD

dc.contributor.author	Stasinakis, AS	en
dc.contributor.author	Thomaidis, NS	en
dc.contributor.author	Mamais, D	en
dc.contributor.author	Papanikolaou, EC	en
dc.contributor.author	Tsakon, A	en
dc.contributor.author	Lekkas, TD	en
dc.date.accessioned	2014-03-01T01:18:55Z
dc.date.available	2014-03-01T01:18:55Z
dc.date.issued	2003	en
dc.identifier.issn	0043-1354	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/15263
dc.subject	COD removal	en
dc.subject	Nitrification	en
dc.subject	Sludge settling	en
dc.subject	Toxicity	en
dc.subject	Wastewater	en
dc.subject.classification	Engineering, Environmental	en
dc.subject.classification	Environmental Sciences	en
dc.subject.classification	Water Resources	en
dc.subject.other	Chemicals removal (water treatment)	en
dc.subject.other	Chromium	en
dc.subject.other	Microorganisms	en
dc.subject.other	Nitrification	en
dc.subject.other	Reduction	en
dc.subject.other	Rotifers	en
dc.subject.other	Activated sludge process	en
dc.subject.other	chromium	en
dc.subject.other	activated sludge	en
dc.subject.other	chromium	en
dc.subject.other	nitrification	en
dc.subject.other	wastewater treatment	en
dc.subject.other	activated sludge	en
dc.subject.other	article	en
dc.subject.other	bacterium contamination	en
dc.subject.other	chemical composition	en
dc.subject.other	concentration response	en
dc.subject.other	effluent	en
dc.subject.other	nitrification	en
dc.subject.other	priority journal	en
dc.subject.other	protozoon	en
dc.subject.other	Rotifera	en
dc.subject.other	sludge settling	en
dc.subject.other	waste water treatment plant	en
dc.subject.other	Bacteria	en
dc.subject.other	Bioreactors	en
dc.subject.other	Carcinogens, Environmental	en
dc.subject.other	Chromium	en
dc.subject.other	Flocculation	en
dc.subject.other	Nitrogen	en
dc.subject.other	Population Dynamics	en
dc.subject.other	Sewage	en
dc.subject.other	Waste Disposal, Fluid	en
dc.subject.other	Protozoa	en
dc.subject.other	Rotifera	en
dc.title	Effects of chromium (VI) addition on the activated sludge process	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/S0043-1354(02)00623-1	en
heal.identifier.secondary	http://dx.doi.org/10.1016/S0043-1354(02)00623-1	en
heal.language	English	en
heal.publicationDate	2003	en
heal.abstract	The effect of hexavalent chromium, Cr(VI), addition on various operating parameters of activated sludge process was evaluated. To accomplish this, two parallel lab-scale continuous-flow activated sludge plants were operated. One was used as a control plant, while the other received Cr(VI) concentrations equal to 0.5, 1, 3 and 5mg1(-1). Cr(VI) concentrations of 0.5 mg 1(-1) caused significant inhibition of the nitrification process (up to 74% decrease in ammonia removal efficiency). On the contrary, the effect of Cr(VI) on organic substrate removal was minor for concentrations up to 5mg1(-1), indicating that heterotrophic microorganisms are less sensitive to Cr(VI) than nitrifiers. Activated sludge floc size and structure characterization showed that Cr(VI) concentrations higher than 1 mg 1(-1) reduced the filaments abundance, causing the appearance of pin-point flocs and free-dispersed bacteria. Additionally, the variability of protozoa and rotifers was reduced. As a result of disperse growth, effluent quality deteriorated, since significant amounts of suspended solids escaped with the effluent. Termination of Cr(VI) addition led to a partial recovery of the nitrification process (up to 57% recovery). Similar recovery signs were not observed for activated sludge floc size and structure. Finally, shock loading to the control plant with 5 mg 1(-1) Cr(VI) for 2 days resulted in a significant inhibition of the nitrification process and a reduction in filamentous microorganisms abundance. (C) 2002 Elsevier Science Ltd. All rights reserved.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	Water Research	en
dc.identifier.doi	10.1016/S0043-1354(02)00623-1	en
dc.identifier.isi	ISI:000182421600019	en
dc.identifier.volume	37	en
dc.identifier.issue	9	en
dc.identifier.spage	2140	en
dc.identifier.epage	2148	en