Forward Osmosis Subsurface Irrigation System
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Solution Overview
Problem
Current desalination technologies for saline wastewater are energy-intensive and costly, with forward osmosis processes requiring additional energy-intensive steps to separate water from diluted draw solutions, limiting their widespread acceptance for wastewater recovery.
Innovation Solution
A forward osmosis system integrated with a subsurface irrigation system using tubular membranes that utilize soil conditions and solar energy to separate water from a diluted osmotic draw solution, minimizing energy input and efficiently re-concentrating the draw solution for reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If forward osmosis membrane separation is used to remove water from wastewater, then desalinated water is produced, but additional energy-intensive separation step is required to remove water from the draw solution
Solution Approach 1:
The patent combines the forward osmosis membrane separation process with a subsurface irrigation system into a single integrated process. The draw solution is circulated through subsurface irrigation tubes embedded in soil, where water naturally transfers to the soil through the tube walls via osmotic and vapor pressure gradients, eliminating the need for separate energy-intensive water recovery equipment.
Solution Approach 2:
The system uses the soil environment itself to perform the water separation function. Natural osmotic gradients between the draw solution in the tubes and the soil moisture, combined with vapor pressure differences and soil matric potential, drive water transfer without requiring external energy input or complex separation equipment.
2Use of energy by moving object
If conventional desalination technologies are used, then water is removed from saline wastewater, but high energy input and extensive infrastructure are required
Solution Approach 1:
The patent replaces high-energy mechanical desalination systems (reverse osmosis, distillation) with a passive system that utilizes natural osmotic gradients and vapor pressure differences. The subsurface irrigation tubes with permeable walls allow water to transfer naturally from the draw solution to the soil without requiring high-pressure pumps or thermal energy input.
Solution Approach 2:
The subsurface irrigation system serves multiple functions: it acts as the draw solution circulation system, the water separation membrane, and the irrigation delivery system simultaneously. This multi-functionality eliminates the need for separate infrastructure components required by conventional desalination plants.
3Reliability
If water is separated from draw solution using reverse osmosis or distillation, then pure water is recovered, but considerable energy input is required
Solution Approach 1:
The patent changes the operating parameters from high-energy mechanical/thermal processes to low-energy passive processes by utilizing natural osmotic potential gradients and vapor pressure differences. The system operates at ambient temperature and pressure, using the soil's natural moisture potential to drive water transfer while maintaining high purity through selective permeability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides low-energy desalination of saline wastewater, efficiently distributing pure water to soil for irrigation while re-concentrating the draw solution, reducing overall energy consumption and operational costs.
Implementation Method 1
Forward osmosis is the transport of a solvent (e.g., water) across a water permeable membrane from a region of lower osmotic potential to a region of higher osmotic potential
Implementation Method 2
a feedwater solution (e.g., waste water) on one side of the membrane has a lower osmotic potential than the osmotic potential of a draw solution (e.g., osmotic agent) on an opposing side of the membrane
Implementation Method 3
The tubular membranes allow the water to be drawn from the interior of the tubular membrane across the membrane and into the soil due to the differences in the energy gradient that exists between the diluted osmotic agent and the surrounding soil. This energy gradient induces mass transfer across the membrane due to the following mechanisms, the magnitude of all of which may vary with soil moisture and/or soil composition: vapor pressure, hydraulic pressure, osmotic potential, and the soil matric potential.
Implementation Method 4
This energy gradient induces mass transfer across the membrane due to the following mechanisms, the magnitude of all of which may vary with soil moisture and/or soil composition: vapor pressure, hydraulic pressure, osmotic potential, and the soil matric potential.
Implementation Method 5
This energy gradient induces mass transfer across the membrane due to the following mechanisms, the magnitude of all of which may vary with soil moisture and/or soil composition: vapor pressure, hydraulic pressure, osmotic potential, and the soil matric potential.
Data Source
AI summary
The present disclosure is directed to a forward osmosis system/process utilized primarily in conjunction with a subsurface irrigation system/process. Saline wastewater or naturally saline water is treated using forward osmosis membranes that draw at least partially purified water from the wastewater into an osmotic draw solution (draw solution). The resulting diluted osmotic draw solution is then circulated through the subsurface irrigation system including one or more tubular membranes that reject the draw solution while permitting water in the diluted draw solution to pass through.