Self-sustaining direct contact membrane distillation for nutrient removal

Overview

This solution leverages Direct Contact Membrane Distillation (DCMD) to simultaneously remove dissolved nutrients such as nitrogen and phosphorus salts from storm water while producing reclaimed water suitable for non-potable reuse. By using a hydrophobic porous membrane that only permits water vapor to pass, the system achieves near-complete rejection of non-volatile constituents. The process is driven by a thermal gradient created through solar heating rather than mechanical pumping, enabling energy savings of up to 90% compared to conventional pressure-driven membrane technologies.

The technology addresses two critical needs in water management: nutrient pollution reduction and water reclamation. Recovered water can be used for agricultural irrigation, botanical irrigation, or toilet flushing, while separated nutrients can be directed to municipal wastewater treatment or onsite recovery processes. The modular and scalable design allows deployment with a small footprint, making it adaptable to diverse site conditions.

Technical specifications

Key features:

• Hydrophobic porous membrane that selectively allows water vapor passage while rejecting non-volatile nutrients, achieving near 100% rejection of nitrogen, phosphorus, COD, and dissolved metals
• Solar-driven thermal gradient eliminates the need for high-pressure pumping, reducing energy consumption by up to 90%
• High water flux demonstrated at over 24 liters per square meter per hour (LMH) with low ammonia transfer rates
• Strong antifouling performance due to low operating pressures and cross-flow operation
• Modular and scalable architecture with small footprint requirements suitable for distributed deployment
• Compatibility with low-grade and renewable heat sources, enabling off-grid operation
• Plate-and-frame module configuration for initial deployment, with potential for spiral wound or hollow fiber modules to increase treatment capacity

Technology readiness level

The DCMD technology has been validated in prior research for ammonia recovery from urine and manure wastewater, with demonstrated nutrient removal approaching 100%. A heat pipe solar membrane-based DCMD system has been tested and shown effective for wastewater treatment applications. The NJIT research team has established experimental platforms supported by federal grants, enabling immediate testing with synthetic rainwater. Planned validation includes examining water flux and nutrient rejection across various nutrient concentrations, exploring alternative module geometries for enhanced capacity, and assessing membrane fouling behavior in the presence of suspended solids and organic matter to develop operational maintenance protocols.