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Published on: December 25, 2015
Total nitrogen removal in a hybrid, membrane-aerated activated sludge process
Leon S Downing1, Robert Nerenberg
1Department of Civil Engineering and Geological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
Water Research
|August 19, 2008
Summary
The hybrid membrane biofilm process (HMBP) effectively removes total nitrogen from wastewater by combining suspended and attached growth. This novel method achieves high nitrogen removal rates, even under varying loads, by promoting denitrification in the suspended phase.
Area of Science:
- Environmental Engineering
- Wastewater Treatment Technologies
- Microbial Ecology
Background:
- Conventional wastewater treatment struggles with efficient total nitrogen removal.
- Membrane-aerated biofilm processes offer potential but face challenges with process control and efficiency.
- The hybrid (suspended and attached growth) membrane biofilm process (HMBP) presents a novel approach to enhance nitrogen removal.
Purpose of the Study:
- To investigate the performance of the HMBP for total nitrogen removal under various BOD and ammonium loadings.
- To identify the dominant nitrogen removal mechanisms within the HMBP.
- To assess the impact of operational parameters on nitrification and denitrification efficiency.
Main Methods:
- Implementation of air-filled hollow-fiber membranes in an activated sludge tank.
- Controlled variation of BOD and ammonium loadings to simulate different wastewater conditions.
- Microsensor measurements to analyze nitrogen species and oxygen gradients.
- Fluorescence in situ hybridization (FISH) to identify microbial populations within the biofilm.
Main Results:
- Nitrification rates remained stable at 1gNm(-2)day(-1) across a wide range of BOD loadings (4-17gBODm(-2)day(-1)).
- Shortcut nitrogen removal was confirmed, with nitrite being the dominant oxidized nitrogen form.
- Denitrification primarily occurred in the suspended phase, reducing biofouling potential.
- Total nitrogen removal approached 100% with sufficiently high influent BOD concentrations.
Conclusions:
- The HMBP is a robust and effective method for simultaneous BOD and total nitrogen removal in activated sludge systems.
- The hybrid nature, promoting suspended denitrification, is key to the process's efficiency and reduced biofouling.
- The process demonstrates resilience to varying loads, making it suitable for diverse wastewater treatment applications.
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