Nutrient removal efficiency in a rice-straw denitrifying bioreactor.
Xinqiang Liang1, Limin Lin2, Yushi Ye2
1College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Key Laboratory for Water Pollution Control and Environmental Safety, Zhejiang Province, Hangzhou 310058, China.
Bioresource Technology
|October 11, 2015
Summary
Rice straw effectively removes agricultural nutrients in denitrifying bioreactors. This study shows rice straw outperforms woodchip as a carbon source for nutrient removal, especially under medium loading and long hydraulic retention times.
Area of Science:
- Environmental Science
- Agricultural Engineering
- Water Treatment
Background:
- Agricultural drainage often contains high levels of nutrients like nitrogen and phosphorus.
- Effective nutrient removal is crucial to prevent eutrophication and water pollution.
- Bioreactors utilizing carbon sources are a promising method for nutrient remediation.
Purpose of the Study:
- To evaluate the efficiency of rice straw as a carbon source in a denitrifying bioreactor for nutrient removal from agricultural drainage.
- To compare the performance of rice straw with woodchip as a carbon source.
- To investigate the impact of nutrient loading rates and hydraulic retention time on nutrient removal.
Main Methods:
- A denitrifying bioreactor was operated using rice straw as the primary carbon source.
- Nutrient removal efficiencies were assessed under varying nutrient loading rates (low, medium, high) and hydraulic retention times (HRT).
- Performance was compared against a bioreactor using woodchip as the carbon source.
Main Results:
- Rice straw bioreactors achieved significant reductions in nitrate nitrogen (53%), ammonia nitrogen (25%), total nitrogen (40%), and orthophosphate phosphorus (35%) at medium nutrient loading and 24h HRT.
- The denitrification rate (DR) was 0.40 mg N L(-1)h(-1) under these conditions.
- Rice straw demonstrated significantly higher nutrient removal efficiency (p<0.05) compared to woodchip under identical medium loading and 24h HRT conditions.
Conclusions:
- Rice straw is a highly effective and superior carbon source for nutrient removal in denitrifying bioreactors treating agricultural drainage.
- Optimized conditions, including medium nutrient loading and long HRT, maximize the efficiency of rice straw-based bioreactors.
- The findings support the use of agricultural byproducts like rice straw for sustainable water quality management.
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