Electrically conductive membrane distillation via an alternating current operation for zero liquid discharge

Area of Science:

• Water treatment technologies
• Membrane separation processes
• Electrochemistry

Background:

• Membrane distillation (MD) offers low energy consumption and high water quality for desalination and zero liquid discharge (ZLD).
• Performance degradation from fouling and scaling limits MD's effectiveness, especially under high recovery conditions.
• Controlling both cations and anions is crucial for effective scaling mitigation in MD.

Purpose of the Study:

• To introduce and evaluate alternating current (AC) operation for electrically conductive membrane distillation (ECMD).
• To investigate AC operation's potential for controlling both cations and anions to mitigate scaling.
• To enhance water recovery rates in MD processes for improved desalination and ZLD applications.

Main Methods:

• Systematic experimental investigations of ECMD under AC and direct current (DC) operation.
• Theoretical analysis to understand the mechanisms of ion control and scaling mitigation.
• Comparative performance evaluation focusing on water recovery and fouling/scaling resistance.

Main Results:

• AC operation in ECMD significantly increases water recovery by up to 27% compared to conventional methods.
• ECMD with AC operation demonstrates enhanced control over both cations and anions, reducing scaling potential.
• The study validates the effectiveness of AC operation for improving MD performance.

Conclusions:

• Alternating current operation is a novel and effective modification for electrically conductive membrane distillation (ECMD).
• ECMD with AC operation substantially boosts water recovery, addressing a key challenge in high-salinity treatment.
• This advancement increases the feasibility of using MD for high-recovery desalination and achieving zero liquid discharge (ZLD).