Sewage Sludge Stabilization and Biomass Enhancement via Indigenous Microalgae: Pilot-Scale Validation, Nutrient Dynamics, EPS Evolution, and Impacts on Sludge Properties
Ben Hamed, Hajer; Saadli, Rana; Parra Angarita, Sergio Luiset al.
[en] This study evaluates the performance of an indigenous microalgae-assisted aerobic digestion process for sewage sludge stabilization in a pilot-scale photobioreactor (20 L) operated over 20 days without external aeration. The system achieved 53% volatile solids reduction, exceeding the 38–40% threshold required by European stabilization guidelines, alongside 34% total nitrogen and 75% total phosphorus removal. Indigenous microalgal biomass increased substantially from 1.6% to 17% of total biomass, with photosynthetically generated oxygen serving as the primary driver of aerobic bacterial activity and organic matter mineralization. Sludge settleability improved markedly (SVI from 154 to 54 mL/g), accompanied by significant floc size reduction (220 to 33 µm); however, this was accompanied by a clear deterioration in dewaterability, with CST increasing from 16 to 27 s and SRF rising approximately 4-fold, representing a practical trade-off that must be addressed for full-scale application. Extracellular polymeric substances (EPS) analysis showed a clear shift from tightly bound to soluble and loosely bound fractions during treatment, and Pearson correlations indicated that soluble EPS was linked to poorer settling and dewatering, while tightly bound EPS was associated with larger flocs and better sludge structure, confirming EPS restructuring as a key mechanism behind the observed changes in sludge properties. These findings highlight both the strong stabilization potential of this process and the need for targeted dewatering mitigation strategies to support its scale-up.
Disciplines :
Chemical engineering
Author, co-author :
Ben Hamed, Hajer ; Université de Liège - ULiège > Chemical engineering
Saadli, Rana ; Université de Liège - ULiège > Chemical engineering
Léonard, Angélique ; Université de Liège - ULiège > Department of Chemical Engineering > PEPs - Products, Environment, and Processes
Toye, Dominique ; Université de Liège - ULiège > Department of Chemical Engineering > PEPs - Products, Environment, and Processes
Language :
English
Title :
Sewage Sludge Stabilization and Biomass Enhancement via Indigenous Microalgae: Pilot-Scale Validation, Nutrient Dynamics, EPS Evolution, and Impacts on Sludge Properties
FRIA - Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture F.R.S.-FNRS - Belgian National Fund for Scientific Research WBI - Wallonia-Brussels International
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