Granulation and stability of microalgal–bacterial granular sludge under single and combined exposure to polycaprolactone microplastics and sulfamethoxazole
- 1Institute of Animal Science and Wildlife Management, Faculty of Agriculture, University of Szeged, Hódmezővásárhely, Hungary; Department of Applied and Environmental Chemistry, University of Szeged, Szeged, Hungary. Electronic address: [email protected]
- 2Department of Applied and Environmental Chemistry, University of Szeged, Szeged, Hungary
- 3Department of Applied and Environmental Chemistry, University of Szeged, Szeged, Hungary; HUN-REN-SZTE Reaction Kinetics and Surface Chemistry Research Group, Szeged, Hungary
Abstract
The increasing occurrence of microplastics and antibiotics in wastewater poses emerging challenges for biological treatment processes. Microalgal-bacterial granular sludge (MBGS) has emerged as an efficient algae-based biotechnology for wastewater treatment; however, its response to simultaneous exposure to these contaminants remains largely unexplored. Here, the effects of degradable polycaprolactone microplastics (PCL MPs) and sulfamethoxazole (SMX) were evaluated at 1 mg/L during granulation and long-term operation. PCL alone caused only minor changes, whereas SMX impaired granule stability and reactor performance. Under combined PCL + SMX exposure, the strongest deterioration was observed, including a 5.2% decrease in ammonium nitrogen (NH 4 + -N) removal and a 48.9% decrease in phosphate removal relative to the control. Effluent nitrite nitrogen (NO 2 − -N) and nitrate nitrogen (NO 3 − -N) concentrations increased to 8.9 and 31.6 mg/L, respectively, under combined stress. These changes were accompanied by lower microbial activities, with the specific nitrate reduction rate (SNRR) and specific phosphorus uptake rate (SPUR) decreasing to 31.6 mg N/g mixed liquor volatile suspended solids (MLVSS) and 10.3 mg P/g MLVSS, respectively. Extracellular polymeric substances (EPS) analysis further showed depletion of tightly bound proteins. Microbial analysis revealed community restructuring under SMX-containing conditions (R3 and R4), including enrichment of Nakamurella (up to 36.5% in R3) and Micropruina (up to 18.9%), alongside a decline in polyphosphate-accumulating genera such as Microlunatus . Overall, MBGS showed resilience to PCL alone, whereas SMX (especially in combination with PCL) induced significant structural and functional instability.
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BibTeX
@article{kedves2026granulation,
title = {{Granulation and stability of microalgal–bacterial granular sludge under single and combined exposure to polycaprolactone microplastics and sulfamethoxazole}},
author = {Alfonz Kedves and Máté Balogh and Jamsheed Abbas Dar and Ilia Mehrizi and Zoltán Kónya},
journal = {Bioresource Technology},
year = {2026},
month = may,
doi = {10.1016/j.biortech.2026.134820},
url = {https://doi.org/10.1016/j.biortech.2026.134820},
note = {CC BY},
}
RIS
TY - JOUR
TI - Granulation and stability of microalgal–bacterial granular sludge under single and combined exposure to polycaprolactone microplastics and sulfamethoxazole
AU - Alfonz Kedves
AU - Máté Balogh
AU - Jamsheed Abbas Dar
AU - Ilia Mehrizi
AU - Zoltán Kónya
PY - 2026
DA - 2026/05/09
JO - Bioresource Technology
DO - 10.1016/j.biortech.2026.134820
UR - https://doi.org/10.1016/j.biortech.2026.134820
AB - The increasing occurrence of microplastics and antibiotics in wastewater poses emerging challenges for biological treatment processes. Microalgal-bacterial granular sludge (MBGS) has emerged as an efficient algae-based biotechnology for wastewater treatment; however, its response to simultaneous exposure to these contaminants remains largely unexplored. Here, the effects of degradable polycaprolactone microplastics (PCL MPs) and sulfamethoxazole (SMX) were evaluated at 1 mg/L during granulation and long-term operation. PCL alone caused only minor changes, whereas SMX impaired granule stability and reactor performance. Under combined PCL + SMX exposure, the strongest deterioration was observed, including a 5.2% decrease in ammonium nitrogen (NH 4 + -N) removal and a 48.9% decrease in phosphate removal relative to the control. Effluent nitrite nitrogen (NO 2 − -N) and nitrate nitrogen (NO 3 − -N) concentrations increased to 8.9 and 31.6 mg/L, respectively, under combined stress. These changes were accompanied by lower microbial activities, with the specific nitrate reduction rate (SNRR) and specific phosphorus uptake rate (SPUR) decreasing to 31.6 mg N/g mixed liquor volatile suspended solids (MLVSS) and 10.3 mg P/g MLVSS, respectively. Extracellular polymeric substances (EPS) analysis further showed depletion of tightly bound proteins. Microbial analysis revealed community restructuring under SMX-containing conditions (R3 and R4), including enrichment of Nakamurella (up to 36.5% in R3) and Micropruina (up to 18.9%), alongside a decline in polyphosphate-accumulating genera such as Microlunatus . Overall, MBGS showed resilience to PCL alone, whereas SMX (especially in combination with PCL) induced significant structural and functional instability.
SN - 0960-8524
SN - 1873-2976
ER -