Effect of temperature and benzalkonium chloride on nitrate reduction
Malek G Hajaya1, Ulas Tezel, Spyros G Pavlostathis
1School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA.
Bioresource Technology
|February 22, 2011
Summary
Low temperatures worsen the inhibitory effect of benzalkonium chloride (BAC) on nitrate reduction by denitrification. BAC inhibits nitrite reduction and adsorbs to biomass, with effects amplified at colder temperatures.
Area of Science:
- Environmental microbiology
- Biochemistry
Background:
- Nitrate reduction is crucial for nitrogen cycling.
- Temperature and chemical inhibitors impact microbial processes.
- Benzalkonium chloride (BAC) is a quaternary ammonium compound with antimicrobial properties.
Purpose of the Study:
- To investigate the combined effects of temperature and BAC on nitrate reduction by a mixed culture.
- To elucidate the mechanism of BAC inhibition on denitrification.
- To understand BAC's fate and interaction with biomass.
Main Methods:
- Batch assays were conducted using a mixed nitrate-reducing microbial culture.
- Nitrate reduction was monitored under varying temperatures (5-22 °C) and BAC concentrations (up to 100 mg/L).
- Kinetic analysis using a competitive inhibition model was applied.
Main Results:
- Complete nitrate reduction to dinitrogen occurred at 5-22 °C in the absence of BAC.
- BAC inhibited denitrification at concentrations ≥50 mg/L, causing nitrite accumulation.
- Nitrite reduction was the most BAC-sensitive step, particularly at low temperatures.
- BAC was not degraded and primarily adsorbed to biomass.
Conclusions:
- Low temperatures significantly exacerbate the inhibitory effects of BAC on denitrification.
- BAC's inhibition is competitive and primarily affects nitrite reduction.
- Biomass adsorption plays a key role in controlling BAC's impact on nitrate-reducing microbial communities.
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