Impact of Iron Salts on Activated Sludge and Interaction with Nitrite or Nitrate

Philips, Sarah, Rabaey, Korneel and Verstraete, Willy (2003) Impact of Iron Salts on Activated Sludge and Interaction with Nitrite or Nitrate. Bioresource Technology, 88 3: 229-239. doi:10.1016/S0960-8524(02)00314-0

Author Philips, Sarah
Rabaey, Korneel
Verstraete, Willy
Title Impact of Iron Salts on Activated Sludge and Interaction with Nitrite or Nitrate
Journal name Bioresource Technology   Check publisher's open access policy
ISSN 0960-8524
Publication date 2003-07
Sub-type Article (original research)
DOI 10.1016/S0960-8524(02)00314-0
Volume 88
Issue 3
Start page 229
End page 239
Total pages 11
Place of publication Barking, England
Publisher Elsevier Science
Language eng
Subject 090409 Wastewater Treatment Processes
Abstract Iron salts are often used in activated sludge treatment plants as coagulants or to improve reactor performance. Previous studies have indicated that iron itself has an impact on the activated sludge process. However, the interaction of iron with nitrite or nitrate present in the sludge has received little attention. In this research, the influence of addition of Fe(II) or Fe(III), alone or together with NO2− or NO3− on bench-scale activated sludge reactors was examined. Large differences were established between the distinct treatments, regarding reactor performance, sludge characteristics as well as microbial community. Ferric iron was more detrimental than ferrous iron. In some cases, nitrite was found to enhance inhibitory effects of the added iron, whereas nitrate had more a neutralizing effect. It was found that precipitation of phosphate by the iron was not responsible for the observed inhibition. Decrease in pH upon formation of iron hydroxides and the impairment of the floc structure could partially explain the toxicity of the iron dosages. The formation of toxic nitrogen oxides, such as nitric oxide, can also be of importance. The observed positive effect of nitrate on the floc activity is of interest and warrants further elucidation.
Keyword Agricultural biotechnology
Energy crops
Agricultural wastes
Ferric iron
Ferrous iron
Activated sludge
biological oxygen demand
chemical oxygen demand
capillary suction time
dissolved oxygen
mixed liquor
nephelometric turbidity units
oxygen uptake rate
oxygen uptake rate for nitrification
total oxygen uptake rate
semi-continuous activated sludge
Total oxidized nitrogen (=NO−2–N+NO3−–N)
total ammoniacal nitrogen (=NH3–N+NH4+–N)
volatile suspended solids
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
Advanced Water Management Centre Publications
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Citation counts: TR Web of Science Citation Count  Cited 25 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 29 times in Scopus Article | Citations
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Created: Fri, 13 Feb 2009, 13:19:55 EST by Ms Karen Naughton on behalf of Advanced Water Management Centre