Partial nitrification in MBBRs for mainstream deammonification with thin biofilms and alternating feed supply

Area of Science:

• Environmental Engineering
• Microbiology
• Wastewater Treatment

Background:

• Conventional nitrogen removal processes are energy-intensive.
• Developing efficient and cost-effective nitrogen removal technologies is crucial for environmental protection.
• Nitritation-anammox offers a promising alternative for mainstream nitrogen removal.

Purpose of the Study:

• To investigate a new principle for mainstream nitrogen removal using nitritation followed by anammox.
• To optimize a two-stage moving bed biofilm reactor (MBBR) for this process.
• To evaluate the efficiency of ammonia and nitrogen removal under specific operational conditions.

Main Methods:

• Utilized a two-stage moving bed biofilm reactor (MBBR) configuration.
• Optimized the first stage for nitritation using thin biofilms (<200 μm) and alternating feed conditions (wastewater at 15°C, reject water at 30°C).
• Optimized the second stage for anammox using the effluent from the nitritation stage.

Main Results:

• Achieved successful nitritation with a nitrite accumulation ratio consistently above 75%.
• Observed significant ammonia removal rates ranging from 0.25 to 0.50 g NH4-N/L·d.
• Attained nitrogen removal rates exceeding 0.20 g TN/L·d in the anoxic second stage.

Conclusions:

• The two-stage MBBR configuration effectively facilitates mainstream nitrogen removal via nitritation and anammox.
• Alternating feed conditions and controlled biofilm thickness are key to optimizing nitritation.
• The studied process demonstrates high efficiency for both ammonia and overall nitrogen removal.