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Structural integrity affects nitrogen removal activity of granules in semi-continuous reactors
Cesar R Mota1, Melanie A Head, Jon C Williams
1Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, NC, 27695, USA, cesar@desa.ufmg.br.
Biodegradation
|September 12, 2014
Summary
Wastewater treatment granules showed higher nitrogen removal than flocs. Maintaining granule structural integrity is crucial for effective nitrification and denitrification activity in biological wastewater treatment.
Area of Science:
- Environmental Microbiology
- Environmental Engineering
- Biotechnology
Background:
- Granular sludge formation in wastewater treatment reactors is a key process for efficient pollutant removal.
- Intermittently aerated reactors with alternating aerobic and anoxic cycles are used for nitrogen removal.
- Understanding the physical and microbial differences between granules and flocs is essential for optimizing treatment performance.
Purpose of the Study:
- To compare the physical characteristics, activity, and microbial community structure of granules and flocs in swine wastewater treatment.
- To investigate the impact of granule structural integrity on nitrogen removal efficiency.
- To identify the dominant microbial populations responsible for nitrification and denitrification in both granules and flocs.
Main Methods:
- Semi-continuous feeding of intermittently aerated reactors with aerobic:anoxic cycles.
- Comparison of physical characteristics, specific nitrification and denitrification rates of granules and flocs.
- Microbial community analysis using 16S rRNA-targeted membrane hybridizations.
Main Results:
- Granules exhibited significantly higher specific nitrification and denitrification rates compared to flocs.
- Disruption of granule structural integrity led to a decrease in activity to floc-like levels.
- Ammonia oxidizing bacteria populations were dominated by Nitrosomonas and Nitrosococcus mobilis in both granules and flocs, with granules favoring Nitrospira.
- Dominant bacterial population diversity was similar between granules and flocs.
Conclusions:
- Granule structural integrity is critical for maintaining high nitrogen removal activity in wastewater treatment.
- Granules offer superior conditions for specific microbial groups involved in nitrification and denitrification.
- Optimizing conditions to preserve granule structure is key for enhancing the efficiency of biological wastewater treatment systems.
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