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Enhancing denitrification in constructed wetland with algae addition.
Shuiping Cheng1,2, Jing Huai3, Fei Zhong4
1College of Environmental Science and Engineering, Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, 1239 Siping Road, Shanghai, 200092, People's Republic of China. shpcheng@tongji.edu.cn.
Environmental Science and Pollution Research International
|August 7, 2021
Summary
Adding algae to constructed wetlands (CWs) boosts nitrogen removal efficiency by providing a carbon source. Optimal results were achieved with specific algae dosage, enhancing denitrification in wastewater treatment.
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
- Microbial Ecology
Background:
- Constructed wetlands (CWs) are effective for tertiary wastewater treatment.
- Denitrification in CWs is often limited by insufficient carbon sources.
- Algae can serve as an external carbon source to enhance CW performance.
Purpose of the Study:
- To investigate the impact of algae addition on nitrogen removal in CWs.
- To determine the optimal algae dosage for maximizing denitrification efficiency.
- To analyze the underlying mechanisms of algae-mediated denitrification.
Main Methods:
- Experimentation with varying algae dosages in CW influent.
- Monitoring of nitrogen and organic matter concentrations.
- Analysis of nitrogen functional gene ratios (nirS, nirK, narG) relative to 16S rRNA.
- Assessment of anoxic conditions and volatile fatty acid levels.
Main Results:
- Nitrogen removal efficiency was highly dependent on algae dosage, with an optimal removal of 80.5% at 81.1 mg·L-1 dry weight algae.
- The chemical oxygen demand/nitrogen (COD/N) ratio of 5.3 was identified as optimal.
- Algae addition enhanced anoxic environments, increased volatile fatty acids, and improved key denitrification gene ratios.
Conclusions:
- Algae addition is a viable strategy to overcome carbon source limitations in CWs.
- Optimized algae dosage can significantly enhance nitrogen removal efficiency.
- Algae facilitate denitrification by improving microbial conditions and gene expression.
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