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Extraction of Structural Extracellular Polymeric Substances from Aerobic Granular Sludge
Published on: September 26, 2016
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Polyethylene microplastics increase extracellular polymeric substances production in aerobic granular sludge
Piotr Jachimowicz1, Young-Jae Jo1, Agnieszka Cydzik-Kwiatkowska1
1University of Warmia and Mazury in Olsztyn, Faculty of Geoengineering, Department of Environmental Biotechnology, 10-709 Olsztyn, Poland.
The Science of the Total Environment
|August 26, 2022
Summary
Polyethylene microplastics (MPs) in wastewater did not harm biological treatment efficiency but increased extracellular polymeric substances (EPS) and alginate production. However, MPs altered sludge morphology, worsening settling and causing biomass washout.
Area of Science:
- Environmental Science
- Environmental Engineering
- Biotechnology
Background:
- Wastewater treatment plants (WWTPs) are significant sinks for microplastics (MPs).
- The impact of MPs on biological wastewater treatment processes, particularly on biomass and treatment efficiency, remains poorly understood.
- Secondary MP pollution from WWTPs is a growing environmental concern.
Purpose of the Study:
- To investigate the effects of polyethylene (PE) MPs on biological conversions in aerobic granular sludge (AGS).
- To assess the influence of PE MPs on extracellular polymeric substances (EPS) production, including alginate, within AGS.
- To evaluate the impact of PE MPs on the overall efficiency and biomass characteristics of biological wastewater treatment.
Main Methods:
- Aerobic granular sludge (AGS) reactors were exposed to varying concentrations of polyethylene (PE) microplastics (MPs) (1, 10, 50 mg/L).
- Biological conversions, EPS production (specifically alginate), and biomass settling properties were monitored.
- Changes in AGS morphology and biomass concentration in the effluent were analyzed.
Main Results:
- PE MPs did not negatively affect the efficiency of biological wastewater treatment.
- Significant stimulation of EPS and alginate production was observed in AGS with increasing PE MP concentrations.
- Alginate content in AGS increased substantially, from 238.7 ± 4.4 mg/g MLSS in controls to 441.6 ± 13.8 mg/g MLSS at the highest PE MP load.
- MP presence altered AGS morphology and impaired biomass settling properties.
- Biomass washout occurred, with effluent biomass concentration increasing over 2.8 times at the highest PE MP load compared to the control.
Conclusions:
- Polyethylene microplastics do not impede biological wastewater treatment efficiency but enhance EPS and alginate production in aerobic granular sludge.
- Despite no impact on treatment efficiency, microplastics significantly degrade sludge settling characteristics, leading to biomass loss.
- Further research is needed to mitigate the negative effects of microplastics on sludge properties in wastewater treatment plants.
