Start-up of a full-scale deammonification SBR-treating effluent from digested sludge dewatering

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies
• Bioreactor Design and Operation

Background:

• Reject water from sludge dewatering poses challenges for wastewater treatment due to high ammonium concentrations.
• Conventional nitrification/denitrification processes can be energy and chemical intensive.
• Developing efficient and cost-effective deammonification methods is crucial for sustainable wastewater management.

Purpose of the Study:

• To evaluate the start-up and long-term operation of a full-scale sequencing batch reactor (SBR) for deammonification.
• To determine optimal operating parameters, particularly aeration strategies, for efficient ammonium removal.
• To assess the economic viability and performance compared to conventional methods.

Main Methods:

• Operation of a 550 m³ sequencing batch reactor (SBR) over 650 days.
• Implementation of discontinuous aeration and monitoring of key performance indicators.
• Utilizing batch tests for microbial activity assessment (aerobic and anaerobic ammonium oxidizing bacteria).
• Calculating oxygen uptake rates from online oxygen measurements to analyze reactor performance.

Main Results:

• Achieved optimal ammonium removal of approximately 85% at a load of 0.17 kg m⁻³ d⁻¹.
• Identified aeration/non-aeration time ranges of 6-9 minutes as optimal for turnover rates and low nitrate production.
• Batch tests and oxygen uptake rate calculations effectively identified operational setbacks.
• Demonstrated significant cost reductions in energy and chemicals compared to parallel nitrification/denitrification SBRs.

Conclusions:

• A full-scale SBR is a viable technology for deammonification of reject water.
• Precise control of the aeration regime is critical for stable and efficient SBR operation.
• Deammonification using SBR offers substantial cost savings over conventional methods, despite slightly increased maintenance costs.