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Published on: June 15, 2014
Domestic wastewater treatment using immobilized sludge fluidized-bed reactors
1Department of Chemical and Biological Engineering, University of British Columbia, 2357 Main Mall, Vancouver, BC, V6T 1Z4 Canada.
Summary
This study optimized wastewater treatment using immobilized activated sludge in fluidized-bed reactors. An intermittent aeration pattern of 1 hour on, 3 hours off achieved 74.4% total nitrogen removal with stable performance.
Area of Science:
- Environmental Engineering
- Wastewater Treatment Technologies
- Bioreactor Design
Background:
- Domestic wastewater treatment requires efficient methods for removing organic matter and nutrients.
- Immobilized activated sludge processes offer potential advantages in bioreactor stability and performance.
- Optimizing operational parameters like aeration is crucial for enhancing nutrient removal, particularly total nitrogen (TN).
Purpose of the Study:
- To investigate the effectiveness of immobilized activated sludge in fluidized-bed reactors for domestic wastewater treatment.
- To determine the optimal intermittent aeration pattern for maximizing total nitrogen (TN) removal.
- To evaluate the impact of different influent feed patterns on treatment efficiency and sludge stability.
Main Methods:
- Utilized bench-scale fluidized-bed reactors with immobilized activated sludge.
- Investigated various intermittent aeration cycles (e.g., 1 hour aeration/3 hours non-aeration).
- Assessed removal efficiencies for biochemical oxygen demand (BOD), ammonium (NH4(+)-N), total Kjeldahl nitrogen (TKN), and total suspended solids (TSS).
- Examined the influence of continuous versus intermittent influent feed patterns.
Main Results:
- Achieved a maximum TN removal efficiency of 74.4% at a hydraulic retention time (HRT) of 6 hours and an aeration pattern of 1:3 (aeration:non-aeration).
- Maintained high removal efficiencies (>90%) for organic carbon, NH4(+)-N, TKN, and TSS, unaffected by the optimized aeration pattern.
- Demonstrated simultaneous removal of organic carbon and nitrogen in a single reactor.
- Identified a continuous feed pattern as optimal for robust TN removal without compromising other pollutant removal.
- Confirmed the mechanical stability of immobilized sludge beads over a 180-day experimental period.
Conclusions:
- Intermittent aeration, specifically a 1:3 cycle, significantly enhances total nitrogen removal in immobilized activated sludge fluidized-bed reactors.
- The immobilized activated sludge process is effective for simultaneous organic carbon and nitrogen removal from domestic wastewater.
- Continuous feeding is recommended for stable and efficient treatment performance.
- The immobilized sludge exhibits excellent mechanical stability, making it suitable for long-term wastewater treatment applications.
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