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Electrochemically and Bioelectrochemically Induced Ammonium Recovery
Published on: January 22, 2015
Nitrification in fixed-bed reactors treating saline wastewater
Utomo Sudarno1, Stephan Bathe, Josef Winter
1Department of Environmental Engineering, University of Diponegoro (UNDIP), Semarang, Indonesia.
Applied Microbiology and Biotechnology
|November 17, 2009
Summary
Marine bacteria capable of nitrification were enriched and studied in lab reactors. Fixed-bed reactors showed higher ammonia oxidation rates than batch cultures, with one reactor type excelling in overall nitrification efficiency.
Area of Science:
- Marine microbiology
- Environmental biotechnology
- Biogeochemical cycles
Background:
- Halophilic nitrifying bacteria, including Nitrosomonas and Nitrospira, are crucial for nitrogen cycling in marine environments.
- Understanding their efficiency in different reactor configurations is vital for wastewater treatment and aquaculture.
Purpose of the Study:
- To enrich and characterize halophilic nitrifiers from North Sea samples.
- To compare the performance of two fixed-bed reactors (FBRs) for continuous nitrification under varying conditions.
- To investigate the impact of operational parameters on ammonia oxidation rates and microbial community shifts.
Main Methods:
- Enrichment of halophilic nitrifiers from seawater and marine sediments.
- Operation of two fixed-bed reactors (FBR A: polyethylene/claysinter lamellas; FBR B: porous ceramic rings) under different ammonia concentrations, loading rates, and pH conditions.
- Measurement of ammonia oxidation rates (AOR) and nitrite oxidation rates.
- Analysis of microbial community shifts within Nitrosomonas and Nitrospira populations.
Main Results:
- Maximal AOR in batch enrichments reached 15.1 mg N L(-1) day(-1) with intermediate nitrite accumulation.
- Fixed-bed reactors demonstrated significantly higher AORs (at least tenfold) compared to suspended cultures.
- FBR A showed higher AOR (6 mg N L(-1) h(-1)) and nitrite oxidation rates (7 mg N L(-1) h(-1)) than FBR B (5 and 5.9 mg N L(-1) h(-1), respectively).
- FBR B achieved better overall nitrification without nitrite accumulation.
- A shift in the Nitrosomonas subspecies occurred in FBR B under increasing ammonia loading rate and decreasing pH, while Nitrospira remained stable.
Conclusions:
- Fixed-bed reactors are highly effective for marine nitrification, outperforming batch cultures.
- Reactor design (FBR A vs. FBR B) influences nitrification efficiency and microbial community dynamics.
- Operational parameters like ammonia loading rate and pH can induce shifts in ammonia-oxidizing bacteria populations.
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