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Fluidized-bed denitrification for mine waters. Part I: low pH and temperature operation
1Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, 33101, Tampere, Finland, stefano.papirio@tut.fi.
Biodegradation
|October 30, 2013
Summary
This study shows that fluidized-bed reactors can effectively remove nitrate from acidic mining wastewater, even with low temperatures. Iron stimulates this process, while copper inhibits it, identifying key factors for bioremediation.
Area of Science:
- Environmental Microbiology
- Bioremediation Engineering
Background:
- Mining activities frequently contaminate water resources with nitrates and heavy metals.
- Acidic conditions and contaminants pose challenges for effective water treatment.
Purpose of the Study:
- To investigate the denitrification of acidic water using up-flow fluidized-bed reactors (FBRs).
- To assess the impact of temperature, pH, ethanol, iron, and copper on denitrification efficiency.
Main Methods:
- Utilized two up-flow fluidized-bed reactors (FBRs) with bacterial communities enriched on ethanol and nitrate.
- Conducted batch assays to determine the effects of pH, temperature, ethanol/nitrate ratios, iron, and copper.
- Employed polymerase chain reaction-denaturant gradient gel electrophoresis (PCR-DGGE) to identify microbial communities.
Main Results:
- FBRs enabled denitrification at pH 2.5 and 7-8 °C, overcoming inhibition seen at pH 4.8 in batch tests.
- Excess ethanol ensured nitrate removal and pH neutralization.
- Iron (up to 100 mg/L) stimulated denitrification, while copper (0.7 mg/L) caused significant inhibition.
- Identified Dechloromonas denitrificans and Hydrogenophaga caeni as key nitrate-reducing bacteria.
Conclusions:
- Fluidized-bed reactors are effective for treating acidic, nitrate-contaminated water from mining.
- Optimizing ethanol supply and understanding metal ion effects are crucial for bioremediation success.
- Specific bacterial species play a vital role in nitrate removal under challenging conditions.
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