Dual-Stage Membrane Distillation for One-Step Separation, Concentration of Volatile Fatty Acids, and Simultaneous...

Area of Science:

• Environmental Engineering
• Chemical Engineering
• Separation Science

Background:

• Anaerobic digestate from municipal sludge is rich in volatile fatty acids (VFAs) with high industrial value.
• Conventional VFA recovery methods suffer from low purity, low concentration, and poor selectivity.

Purpose of the Study:

• To develop and evaluate a novel dual-stage membrane distillation (MD) coupled with alkali adsorption for efficient VFA separation and concentration.
• To achieve simultaneous water recovery alongside VFA purification from anaerobic digestion wastewater.

Main Methods:

• A dual-stage membrane distillation (MD) system integrated with alkali adsorption was designed.
• The system was tested using real anaerobic digestion wastewater.
• Performance was evaluated based on VFA recovery, concentration, concentration factor, and water recovery.

Main Results:

• Achieved 86.2% VFA recovery, 103.3 g L-1 VFA concentration, and a 20.3 concentration factor.
• Obtained 62.8% water recovery, outperforming existing technologies in concentration, factor, and purity.
• Demonstrated stable operation for 192 hours with real wastewater.

Conclusions:

• The dual-stage MD system offers a highly effective one-step solution for separating and concentrating VFAs.
• This technology presents a promising approach for recovering valuable volatile components from anaerobic digestion wastewater.
• The system provides superior performance and stability compared to current state-of-the-art recovery methods.