Related Experiment Video
Updated: May 5, 2026

A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities
Published on: December 25, 2015
Cycle length and COD/N ratio determine properties of aerobic granules treating high-nitrogen wastewater
Agnieszka Cydzik-Kwiatkowska1, Katarzyna Bernat, Magdalena Zielińska
1Department of Environmental Biotechnology, University of Warmia and Mazury in Olsztyn, Słoneczna Str. 45G, 10-709, Olsztyn, Poland.
Abstract:
Aerobic granule characteristic in sequencing batch reactors treating high-nitrogen digester supernatant was investigated at cycle lengths (t) of 6, 8 and 12 h with the COD/N ratios in the influent of 4.5 and 2.3. The biomass production (Y obs) correlated with the extracellular polymeric substances (EPS) in grams per COD removed. Denitrification efficiency significantly decreased as the amount of EPS in biomass increased, suggesting that organic assimilation in EPS hampers nitrogen removal. Granule hydrophobicity was highest at t of 8 h; the t has to be long enough to remove pollutants, but not so long that excessive biomass starvation causes extracellular protein consumption that decreases hydrophobicity. At a given t, reducing the COD/N ratio improved hydrophobicity that stimulates cell aggregation. At t of 6 h and the COD/N ratio of 2.3, the dominance of 0.5-1.0 mm granules favored simultaneous nitrification and denitrification and resulted in the highest nitrogen removal.
More Related Videos
Related Concept Videos
The Nitrogen Cycle
Inorganic Nitrogen Assimilation
Comparative Excretory Systems
Overview of Nitrogen Metabolism
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this...
2° Amines to N-Nitrosamines: Reaction with NaNO2

