Low-cost, high-water recovery desalination using waste heat and sunlight

Overview

SolMem's Solar Multi-Effect Membrane Distillation (SolarMEMD) technology offers a low-cost, high-recovery desalination solution that operates under ambient conditions using two complementary energy sources: industrial waste heat and concentrated sunlight. Designed for on-site deployment at manufacturing facilities, the system preheats saline feed water using available waste heat and supplements thermal energy through a photothermally active membrane surface combined with a parabolic trough concentrator. This dual-energy approach enables efficient treatment of challenging water sources—including agricultural drainage, oil and gas produced water, reverse osmosis brine, and saline water up to 200 g/L total dissolved solids (TDS)—while significantly reducing energy consumption and operating costs.

The technology addresses growing water scarcity and contamination challenges across residential, municipal, and industrial sectors, particularly in off-grid or resource-limited locations. By converting unconventional water sources into high-quality potable water with minimal chemical and energy inputs, SolarMEMD supports sustainable infrastructure development and offers a compelling alternative to conventional high-pressure or high-temperature desalination systems.

Technical specifications

• Spiral-wound membrane distillation architecture enables internal heat recovery, increasing permeate production rate and overall thermal efficiency.
• Dual energy input system combines an external heat exchanger using manufacturing waste heat to preheat feed water with concentrated solar irradiation to generate additional heat directly on the membrane surface.
• Photothermally modified outer membrane surface captures and converts sunlight into thermal energy, reducing reliance on external power sources.
• High contaminant rejection demonstrated across multiple contaminant types, including sodium, arsenic, selenium, and boron, with TDS removal exceeding 99%.
• High recovery rate with potential to achieve up to 98% water recovery at pilot and commercial scale.
• Estimated operating cost of $3.50 per 1,000 gallons of clean water produced.
• Ambient-condition operation eliminates the need for high temperature or high-pressure infrastructure, simplifying deployment and reducing capital requirements.

Technology readiness level

SolMem has completed lab-scale validation across a broad range of challenging water sources, demonstrating consistent rejection of diverse contaminants and strong performance metrics. The company is currently designing and developing a pilot-scale SolarMEMD module to optimize operating parameters under varying climate and solar irradiance conditions. A planned six-month pilot study will investigate energy input balancing between waste heat and solar sources, including the use of waste heat as the sole energy input during periods of low solar irradiance. Following pilot testing, a technoeconomic analysis will establish commercial feasibility. SolMem has been recognized through a National Science Foundation SBIR grant and participation in the American-Made Challenges: Solar Desalination Prize, supporting ongoing advancement toward commercial deployment.