Reverse Osmosis Rinse Sequencing for Zero-Waste Dishwashing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Reverse osmosis systems used in institutional dishmachines generate wastewater due to the need to flush the membrane with water to prevent fouling, leading to inefficiencies and unsightly mineral deposits on dishware, especially when water contains high levels of dissolved solids.
Innovation Solution
A method and system that split the water stream into a permeate rinse stream and a concentrate rinse stream, using the concentrate stream for the first part of the rinse cycle and the permeate stream for the second part, with a ratio of concentrate to permeate of 3:2 or less, allowing for zero wastewater production by reusing the concentrate water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If reverse osmosis is used to remove dissolved solids from water, then water quality for rinsing is improved, but wastewater is generated due to membrane flushing requirements
Solution Approach 1:
The patent recovers the concentrate stream that would normally be discarded as wastewater and reuses it for the initial rinsing of dishware. This transforms a waste product into a useful resource, eliminating wastewater generation while maintaining effective warewashing through the subsequent permeate rinse.
Solution Approach 2:
The patent converts the harmful effect of high dissolved solids in the concentrate stream into a benefit by using it for rinsing dishware. The concentrate, which contains minerals that would normally cause spotting, is applied to dishware before the final permeate rinse, and the brief contact time prevents significant mineral deposition while still providing effective rinsing.
2Reliability
If concentrate water is wasted to maintain membrane function, then membrane performance is preserved, but water efficiency deteriorates
Solution Approach 1:
The system makes the concentrate stream serve itself by automatically routing it to the dishware rinsing function. The control system detects when the permeate tank needs refilling and automatically opens the concentrate valve to transfer water, eliminating the need for manual intervention and ensuring continuous operation.
Solution Approach 2:
The concentrate stream serves multiple functions: it rinses dishware effectively and simultaneously refills the permeate storage tank by displacement. This multi-functionality maximizes the utility of the concentrate water while maintaining membrane performance.
3Manufacturing precision
If permeate water is used for the entire rinse cycle, then spot-free dishware is achieved, but system size and complexity increase
Solution Approach 1:
The patent segments the rinse cycle into two distinct phases: an initial concentrate rinse phase for removing food soils and detergent, followed by a final permeate rinse phase for achieving spot-free results. This segmentation allows each stream to be optimized for its specific function, reducing the need for excessive permeate production capacity.
Solution Approach 2:
The patent applies partial action by using the concentrate stream for only the initial portion of the rinse cycle rather than the entire cycle. This limited exposure time prevents significant mineral deposition on dishware while still providing effective rinsing, allowing smaller system components to suffice.
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
This approach eliminates wastewater production, maintains effective warewashing results, reduces energy consumption, and downsizes the reverse osmosis system by half, achieving the same water usage and cycle times as a conventional system without a reverse osmosis system.
Implementation Method 1
Reverse osmosis is an effective mechanism for removing dissolved solids from water
Implementation Method 2
Reverse osmosis apparatus for splitting water from the fresh water supply into a concentrate stream and a permeate stream
Data Source
AI summary
A system for regulating a reverse osmosis system to obtain zero wastewater. A reverse osmosis apparatus filters water from the fresh water supply into a concentrate rinse stream and a permeate rinse stream. A concentrate storage tank and a permeate storage tank are downstream of the reverse osmosis apparatus and receive the concentrate rinse stream and the permeate rinse stream, respectively. A concentrate solenoid valve and a permeate solenoid valve control the flow of the concentrate rinse stream and the permeate rinse stream from their respective storage tank. An institutional dishmachine receives the concentrate rinse stream and the permeate rinse stream during a rinse cycle of the institutional dishmachine. A control system is operatively connected to the concentrate solenoid valve and the permeate solenoid valve and control flow of the rinse streams into the institutional dishmachine.