Charge-Gradient Hydrogels Enable Direct Zero Liquid Discharge for Hypersaline Wastewater Management

Area of Science:

• Materials Science
• Environmental Engineering
• Chemical Engineering

Background:

• Zero liquid discharge (ZLD) is crucial for water scarcity, but requires robust desalination without costly pretreatment.
• Existing membrane technologies struggle with hypersaline wastewater and broad-spectrum foulants, hindering direct ZLD applications.

Purpose of the Study:

• To develop a novel membrane distillation (MD) strategy for direct wastewater recovery.
• To address the limitations of traditional membranes in ZLD by introducing a charge-gradient hydrogel (CGH) membrane.

Main Methods:

• Replaced traditional hydrophobic porous membranes with hydrophilic nonporous charge-gradient hydrogel (CGH) membranes.
• Investigated the performance of CGH-based MD for direct desalination of hypersaline wastewater with high salt and foulant concentrations.

Main Results:

• The CGH membrane demonstrated hypersaline tolerance and fouling/scaling-free properties.
• Achieved high water flux in direct desalination of 130 g L⁻¹ hypersaline wastewater with 500 mg L⁻¹ foulants.
• Maintained performance during 200 hours of continuous operation.

Conclusions:

• The CGH-based MD strategy offers a paradigm shift for wastewater management.
• This technology enables direct zero liquid discharge, maximizing water recovery and minimizing environmental impact.
• Paves a promising way for efficient and cost-effective wastewater treatment.