Preconditioning of model biocarriers by soluble pollutants: a QCM-D study

Area of Science:

• Environmental Science
• Biotechnology
• Surface Chemistry

Background:

• Biofilm formation in attached-growth bioreactors relies on biocarrier surface preconditioning.
• Quantification and control of this crucial initial step remain underexplored.
• Understanding solute deposition is vital for optimizing bioreactor performance.

Purpose of the Study:

• To investigate the deposition of soluble pollutants on polystyrene (PS) and polyamide (PA) biocarriers.
• To elucidate the influence of wastewater characteristics and biocarrier properties on surface preconditioning.
• To establish control strategies for biocarrier preconditioning in bioreactors.

Main Methods:

• Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) was used to quantify solute deposition.
• Model biocarriers (PS and PA) were exposed to real and synthetic wastewaters.
• Wastewater composition varied in macromolecules (bovine serum albumin, sodium alginate) and ionic strength (Na+, Ca2+).

Main Results:

• High organic content in real wastewater significantly increased solute deposition on both PS and PA.
• Calcium ions (Ca2+) influenced adlayer properties on PS, transforming rigid layers to viscoelastic ones under low organic conditions.
• Elevated organic material strengthened viscoelastic adlayers on PA, while high ionic strength weakened Ca2+ effects.

Conclusions:

• Solute deposition is highly dependent on both biocarrier properties (hydrophilicity/hydrophobicity) and wastewater quality.
• Specific control strategies for biocarrier preconditioning can be developed based on water conditions.
• Findings provide critical insights for optimizing the start-up phase of attached-growth bioreactors.