Reverse Osmosis Dishwasher Rinse System for Zero Wastewater
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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 increased water usage, despite efforts to minimize waste through recycling and multiple membranes in series.
Innovation Solution
A method and system that split the water stream into a concentrate rinse stream and a permeate rinse stream, with the concentrate used for the first part of the rinse cycle and the permeate for the second part, allowing for zero wastewater production by using the reverse osmosis system at a self-regulating rate, and including a control system to manage the flow of these streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reverse osmosis membrane is periodically flushed with water to prevent fouling, then the membrane remains functional, but wastewater is generated and water efficiency decreases
Solution Approach 1:
The patent converts the harmful wastewater stream into a useful resource by using it for the initial rinsing of dishware. The concentrate stream, which would normally be discarded, is redirected to rinse dishes before the permeate stream, thereby eliminating waste while maintaining membrane functionality through continued periodic flushing.
Solution Approach 2:
Instead of discarding the concentrate stream as waste, the system recovers it for useful application in the dishwashing process. The concentrate is used to perform the initial rinsing function, recovering value from what would otherwise be a waste stream and achieving zero wastewater discharge.
2Manufacturing precision
If 100% of water is forced through the membrane, then complete purification is achieved, but membrane life is reduced and production is severely reduced
Solution Approach 1:
The system applies partial action by using only a portion of the permeate stream (not 100% of water through the membrane) for the final rinsing step. This allows the membrane to operate at optimal flow rates while still achieving sufficient purification for the application, maintaining both productivity and adequate purification.
Solution Approach 2:
The rinsing process is segmented into two distinct stages: initial rinsing with concentrate and final rinsing with permeate. This segmentation allows each stream to be used optimally for its specific purpose, with the permeate reserved for the final spot-free rinse where purification quality is most critical.
3Adaptability or versatility
If a 50% permeate to 50% concentrate ratio is used, then a balance is achieved for operating in various water conditions, but wastewater is still generated
Solution Approach 1:
The system achieves multi-functionality by using both the concentrate stream and permeate stream for useful purposes in the dishwashing process. The concentrate performs initial rinsing and the permeate performs final rinsing, making the entire water processing output productive and eliminating wastewater while maintaining the adaptable 50:50 ratio for various water conditions.
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 achieves zero wastewater production and reduces energy consumption by using the same amount of water as a conventional system, while maintaining effective warewashing results, and downsizes the reverse osmosis system footprint by half.
Implementation Method 1
Reverse osmosis is an effective mechanism for removing dissolved solids from water in areas that have high levels of dissolved solids in the water.
Implementation Method 2
a heater for heating the permeate stream to a predetermined temperature
Data Source
Figure 1
AI summary
A system for regulating a reverse osmosis system to obtain zero wastewater includes a fresh water supply, a reverse osmosis apparatus, a concentrate storage tank and a permeate storage tank, a concentrate solenoid valve and a permeate solenoid valve, a permeate heater, an institutional dishmachine and a control system. The reverse osmosis apparatus filters water from the fresh water supply into a concentrate rinse stream and a permeate rinse stream. The concentrate storage tank and the permeate storage tank are downstream of the reverse osmosis apparatus and receiving the concentrate rinse stream and the permeate rinse stream, respectively. The concentrate solenoid valve and the permeate solenoid valve control the flow of the concentrate rinse stream and the permeate rinse stream, respectively, from their respective storage tank. The permeate heater heats the permeate rinse stream to a predetermined temperature. The institutional dishmachine successively receives the concentrate rinse stream and the permeate rinse stream during a rinse cycle of the institutional dishmachine. The 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.