Anaerobic biological treatment of methylparaben in an expanded granular sludge bed (EGSB)

Area of Science:

• Environmental microbiology
• Wastewater treatment engineering
• Bioremediation

Background:

• Methylparaben (MPB) is a common preservative found in consumer products, leading to its presence in wastewater.
• Anaerobic digestion is a promising technology for treating recalcitrant organic pollutants.
• Granular sludge systems offer high efficiency and stability in anaerobic treatment processes.

Purpose of the Study:

• To evaluate the performance of an anaerobic expanded granular sludge bed (EGSB) system for methylparaben (MPB) removal.
• To assess the impact of increasing MPB concentrations on the EGSB system's efficiency and biomass characteristics.
• To investigate the effect of glucose addition on MPB degradation.

Main Methods:

• An anaerobic EGSB system was operated for 268 days with increasing MPB concentrations (300-1000 mg/L).
• Inoculum used was a mixture of anaerobic granular and flocculent active sludge (80% organic content).
• MPB removal efficiency was monitored with and without glucose co-substrate in the influent.

Main Results:

• High MPB removal rates were achieved, ranging from 84% to 98.2% depending on MPB concentration and glucose presence.
• MPB removal was higher in phases without glucose addition (96-98.2%) compared to phases with glucose (84-94%).
• The granular biomass exhibited excellent stability, with no significant changes in physical or biological characteristics despite increasing MPB concentrations.

Conclusions:

• Anaerobic EGSB systems are highly effective for methylparaben removal from wastewater.
• The granular sludge biomass demonstrates robustness and stability when exposed to varying methylparaben concentrations.
• Co-digestion with glucose can influence MPB removal efficiency, suggesting substrate competition or metabolic pathway interactions.