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Updated: Jul 3, 2026

A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities

A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities

Published on: December 25, 2015

Nitrifying genera in activated sludge may influence nitrification rates.

M A Dytczak¹, K L Londry, J A Oleszkiewicz

¹Environmental Engineering, Department of Civil Engineering, University of Manitoba, Winnipeg, Canada.

Water Environment Research : a Research Publication of the Water Environment Federation

|July 9, 2008

Summary

Alternating anoxic/aerobic conditions enhance nitrification rates by selecting for specific bacterial populations. This treatment strategy optimizes wastewater treatment efficiency through superior microbial community adaptation.

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Published on: October 7, 2020

Area of Science:

Environmental microbiology
Wastewater treatment engineering
Bioreactor technology

Background:

Nitrification is a key process in wastewater treatment, crucial for removing ammonia.
Sequencing batch reactors (SBRs) are widely used for biological wastewater treatment.
Optimizing nitrification rates in SBRs is essential for efficient ammonia removal.

Purpose of the Study:

To investigate the reasons for higher nitrification rates observed in alternating anoxic/aerobic reactors compared to aerobic reactors.
To compare environmental conditions and kinetic parameters between the two reactor types.
To determine the influence of microbial community composition on nitrification performance.

Main Methods:

Acclimation of sequencing batch reactors under aerobic and alternating anoxic/aerobic conditions.
Monitoring of key environmental parameters including pH, alkalinity, oxygen, and nitrite levels.
Kinetic studies and batch tests using biomass from both reactor types.
Theoretical analysis of nitrifying genera's kinetics and environmental sensitivities.

Main Results:

Alternating reactors exhibited higher nitrification rates, with elevated pH, alkalinity, oxygen, and nitrite at the onset of aerobic nitrification.
Environmental conditions and kinetic studies alone could not fully explain the observed differences in nitrification rates.
Theoretical analysis suggested that genera like Nitrosomonas and Nitrobacter, with higher nitrite tolerance, could dominate under alternating conditions, leading to faster nitrification.

Conclusions:

The superior nitrification rates in alternating anoxic/aerobic reactors are attributed to the selection of specific nitrifying bacteria with inherently faster nitrification kinetics.
Alternating treatment conditions favor microbial communities adapted to fluctuating environments and higher substrate availability.
This approach offers a promising strategy for enhancing biological nutrient removal in wastewater treatment.