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Full-scale simultaneous partial nitrification, anammox, and denitrification process for treating swine wastewater
Chikako Ishimoto1, Tsukasa Sugiyama1, Toshimi Matsumoto2
1Shizuoka Prefectural Research Institute of Animal Industry, Swine and Poultry Research Center, 2780 Nishikata, Kikugawa, Shizuoka 439-0037, Japan.
Summary
Maintaining low dissolved oxygen (DO) levels in swine wastewater treatment plants enhances nitrogen removal through simultaneous nitrification, anammox, and denitrification (SNAD). This microaerobic approach optimizes treatment efficiency despite fluctuating influent loads.
Area of Science:
- Environmental Microbiology
- Wastewater Treatment Engineering
- Biogeochemical Cycles
Background:
- Swine wastewater presents significant treatment challenges due to high organic load and nitrogen content.
- Anammox bacteria, particularly Planctomycetes like Candidatus Jettenia and Candidatus Brocadia, are crucial for nitrogen removal in activated sludge systems.
- Fluctuating influent characteristics in full-scale plants can impact treatment efficiency.
Purpose of the Study:
- To investigate the performance of a full-scale swine wastewater activated sludge plant enriched with anammox biofilms over two years.
- To determine the impact of operational parameters, especially dissolved oxygen (DO) levels, on nitrogen removal efficiency.
- To evaluate the feasibility of simultaneous nitrification, anammox, and denitrification (SNAD) under microaerobic conditions.
Main Methods:
- Long-term (2-year) monitoring of a full-scale swine wastewater treatment plant.
- Analysis of influent characteristics, including biochemical oxygen demand (BOD) and total nitrogen (TN).
- Measurement of dissolved oxygen (DO) concentrations and assessment of their correlation with nitrogen removal rates.
Main Results:
- Stable BOD removal efficiency (95 ± 4%) was achieved despite influent variability.
- Total nitrogen (TN) removal fluctuated (75 ± 14%), significantly influenced by DO concentrations.
- Lower DO levels (<0.3 mg/L) consistently resulted in higher total inorganic nitrogen removal, particularly at mesophilic temperatures (20-30 °C).
- Evidence suggests nitrogen removal primarily occurred via SNAD under microaerobic conditions.
Conclusions:
- Microaerobic conditions, maintained by low DO concentrations, are critical for optimizing nitrogen removal via SNAD in swine wastewater treatment.
- Controlling DO levels offers a simple and effective strategy to improve nitrogen removal efficiency in systems treating fluctuating swine wastewater.
- The presence of abundant anammox bacteria supports the viability of SNAD processes in full-scale applications.
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