Complete and simultaneous removal of ammonium and m-cresol in a nitrifying sequencing batch reactor
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The kinetic behavior, oxidizing ability and tolerance to m-cresol of a nitrifying sludge exposed to different initial concentrations of m-cresol (0–150 mg C L−1) were evaluated in a sequencing batch reactor fed with 50 mg NH4 +-N L−1 and operated during 4 months. Complete removal of ammonium and m-cresol was achieved independently of the initial concentration of aromatic compound in all the assays. Up to 25 mg m-cresol-C L−1 (C/N ratio of 0.5), the nitrifying yield (Y-NO3 −) was 0.86 ± 0.05, indicating that the nitrate was the main product of the process; no biomass growth was detected. From 50 to 150 mg m-cresol-C L−1 (1.0 ≤ C/N ≤ 3.0), simultaneous microbial growth and partial ammonium-to-nitrate conversion were obtained, reaching a maximum microbial total protein concentration of 0.763 g L−1 (247 % of its initial value) and the lowest Y-NO3 − 0.53 ± 0.01 at 150 mg m-cresol-C L−1. m-Cresol induced a significant decrease in the values of both specific rates of ammonium and nitrite oxidation, being the ammonium oxidation pathway the mainly inhibited. The nitrifying sludge was able to completely oxidize up to 150 mg m-cresol-C L−1 by SBR cycle, reaching a maximum specific removal rate of 6.45 g m-cresol g−1 microbial protein-N h−1. The number of SBR cycles allowed a metabolic adaptation of the nitrifying consortium since nitrification inhibition decreased and faster oxidation of m-cresol took place throughout the cycles.
KeywordsNitrification Inhibition Oxidation m-Cresol Sequencing batch reactor
This work was supported by CONACYT (169563) and PROMEP (103.5/07/2554; 103.5/10/5329).
- APHA (1998) Standard methods for the examination of water and wastewater, 20th edn. American Public Health Association, WashingtonGoogle Scholar
- Verhagen FJM, Duys H, Laanbrock HJ (1992) Competition for ammonium between nitrifying and heterotrophic bacteria in continuously percolated soil columns. Appl Environ Microb 58:3303–3311Google Scholar