Critical appraisal of respirometric methods for metal inhibition on activated sludge


Cokgor E. , WDEMIR S., KARAHAN Ö. , INSEL G., ORHON D.

JOURNAL OF HAZARDOUS MATERIALS, vol.139, no.2, pp.332-339, 2007 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 139 Issue: 2
  • Publication Date: 2007
  • Doi Number: 10.1016/j.jhazmat.2006.06.038
  • Title of Journal : JOURNAL OF HAZARDOUS MATERIALS
  • Page Numbers: pp.332-339
  • Keywords: activated sludge, heavy metals, inhibition, oxygen uptake rate, respirometry, WASTE-WATER, OXYGEN-UPTAKE, TOXICITY, HYDROLYSIS, MICROTOX(R), SUBSTRATE, STARCH, NICKEL, YIELD

Abstract

This paper evaluates the merit of oxygen uptake rate measurements for the assessment of metal inhibition on activated sludge. For this purpose, experiments are conducted to calculate EC50 levels of nickel and hexavalent chromium using the ISO 8192 procedure, yielding results that are highly variable and difficult to correlate, depending on the type of substrate and the initial food to microorganism ratio. Similar experiments based on continuous respitometric measurements to give the entire oxygen uptake rate profile provide a much better insight on the impact of inhibition on different biochemical processes taking place in the reactor. The results indicate that percent reduction of the amount of dissolved oxygen utilized after an appropriate reaction time is a much better index for the assessment of the inhibitory effects. (c) 2006 Elsevier B.V. All rights reserved.