Development of an integrated fixed-film activated sludge (IFAS) reactor treating landfill leachate for the biological nitrogen removal through nitritation-denitritation
- PUBLICATIONS
- Aug 14, 2024
- 2 min read
Updated: Jun 13
Authors: Evangelia Themeli, Elena Koumaki, Panagiotis Kaperonis, Spiridoula Michalaki, Daniel Mamais, Constantinos Noutsopoulos, Simos Malamis
Journal: Journal of Environmental Management
Year: 2024
Keywords: IFAS, Biofilm, Attached biomass, Biological nitrogen removal, Nitritation-denitritation, Landfill leachate
Highlights
The IFAS-SBR treating landfill leachate could reach high BNR via nitrite efficiency.
BNR was maintained above 90% under an NLR of 0.45 kgN/m3-d.
The cultivation of nitrifiers in the biofilm requires high DO concentration.
The biocarrier filling fraction has a strong effect on mass transfer in the rector.
Extensive stagnant zones may hinder substrate and DO distribution.
Abstract
The current work investigated the performance of an Integrated Fixed-Film Activated Sludge Sequencing Batch Reactor (IFAS-SBR) for Biological Nitrogen Removal (BNR) from mature landfill leachate through the nitritation-denitritation process. During the experimental period two IFAS-SBR configurations were examined using two different biocarrier types with the same filling ratio (50%). The dissolved oxygen (DO) concentration ranged between 2 and 3 mg/L and 4–6 mg/L in the first (baseline-IFAS) and the second (S8-IFAS) setup, respectively. Baseline-IFAS operated for 542 days and demonstrated a high and stable BNR performance maintaining a removal efficiency above 90% under a Nitrogen Loading Rate (NLR) up to 0.45 kg N/m3-d, while S8-IFAS, which operated for 230 days, was characterized by a limited and unstable BNR performance being unable to operate sufficiently under an NLR higher than 0.20 kg N/m3-d. It also experienced a severe inhibition period, when the BNR process was fully deteriorated. Moreover, S8-IFAS suffered from extensive biocarrier stagnant zones and a particularly poor sludge settleability. The attached biomass cultivated in both IFAS configurations had a negligible content of nitrifying bacteria, probably attributed to the insufficient DO diffusion through the biofilm, caused by the low DO concentration in the liquid in the baseline case and the extensive stagnant zones in the S8-IFAS case. As a result of the high biocarrier filling ratio, the S8-IFAS was unstable and low. This was probably attributed to the mass transfer limitations caused by the biocarrier stagnant zones, which hinder substrate and oxygen diffusion, thus reducing the biomass activity and increasing its vulnerability to inhibitory and toxic factors. Hence, the biocarrier filling fraction is a crucial parameter for the efficient operation of the IFAS-SBR and should be carefully selected taking into consideration both the media type and the overall reactor configuration.
Citation: Themeli, E., Koumaki, E., Kaperonis, P., Michalaki, S., Mamais, D., Noutsopoulos, C. and Malamis, S., 2024. Development of an integrated fixed-film activated sludge (IFAS) reactor treating landfill leachate for the biological nitrogen removal through nitritation-denitritation. Journal of Environmental Management, 365, p.121709.
Link to publication: doi.org/10.1016/j.jenvman.2024.121709
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