Nutrient Removal and Phosphate Recovery Using Agricultural Residue Media in Denitrifying Bioreactors
Abdoul Kouanda1, Siavash Ebrahimzadeh1, Peng Dai1
1Department of Civil and Environmental Engineering, South Dakota State University, Brookings, South Dakota, USA.
Summary
Corn cobs effectively removed both nitrate and phosphate in denitrifying bioreactors over 390 days, outperforming woodchips and other residues. This agricultural residue offers a sustainable solution for water remediation.
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
- Bioremediation
Background:
- Agricultural residues are explored as sustainable alternatives to woodchips in denitrifying bioreactors for nitrate removal.
- The phosphate removal capacity of agricultural residues remains largely unevaluated.
Purpose of the Study:
- To assess the long-term nitrate and phosphate removal capabilities of various agricultural residues in bioreactors.
- To evaluate the phosphate desorption potential of these residues post-treatment.
Main Methods:
- Laboratory-scale denitrifying bioreactors were established using corn cobs, corn stalks, barley straw, and woodchips.
- Bioreactors were operated for 390 days to measure nitrate and phosphate load reduction rates.
- Phosphate desorption was analyzed after the experimental period.
Main Results:
- Corn cobs demonstrated the highest average nitrate (57.1 g N/m³/day) and phosphate (0.35 g P/m³/day) removal rates.
- Barley straw showed a rapid decline in removal capacity over time.
- Corn cobs exhibited the most stable performance and lowest phosphate desorption potential among the tested residues.
Conclusions:
- Corn cobs are a highly effective medium for simultaneous nitrate and phosphate removal in denitrifying bioreactors.
- Agricultural residues, particularly corn cobs, present a viable option for water remediation, offering nutrient removal and potential phosphate recovery.
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