Flocculation/flotation/ultrafiltration integrated process for the treatment of cork processing wastewaters

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Membrane Science

Background:

• Membrane fouling, particularly by phenolic/tannic colloidal matter, severely limits ultrafiltration (UF) efficiency in treating cork processing wastewaters.
• Reduced permeate flux due to fouling necessitates improved pretreatment methods for effective wastewater management.

Purpose of the Study:

• To develop and evaluate an integrated flocculation/flotation/ultrafiltration (F/F/UF) process for cork processing wastewater treatment.
• To assess the impact of pretreatment on UF performance, specifically permeate flux and pollutant removal.

Main Methods:

• Flocculation studies using chitosan were conducted, monitoring zeta-potential and particle size at varying pH and chitosan concentrations.
• Dissolved air flotation (DAF) was optimized by varying operating pressure and recycle ratio for polyphenol removal.
• Ultrafiltration experiments utilized various membranes (commercial and cellulose acetate) to evaluate permeate flux enhancement post-pretreatment.

Main Results:

• Chitosan addition increased zeta-potential, and decreased pH significantly increased effluent particle size during flocculation.
• Optimal DAF conditions (higher pressure, 0.19 recycle ratio) achieved higher polyphenol removal.
• The F/F/UF pretreatment substantially enhanced UF permeate fluxes, with a 130% increase observed for higher Molecular Weight Cut-Off (MWCO) membranes.

Conclusions:

• The integrated F/F/UF process effectively mitigates membrane fouling in cork wastewater treatment.
• Pretreatment significantly improves UF permeate flux, offering a viable solution for industrial wastewater management.