Pre-Rinse Tank with Timed Release to Reduce FOG Emulsions
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Solution Overview
Problem
The formation of emulsions in kitchen effluent, particularly at the convergence of pre-rinse sink and dishwasher discharges, leads to difficulties in separating fats, oils, and greases (FOG) due to the creation of FOG/detergent emulsions, resulting in inaccurate EPA 1664 Revision B test results and non-compliance issues, as existing separators struggle to differentiate between free-floating and emulsified FOG.
Innovation Solution
A pre-rinse holding tank is positioned below the pre-rinse sink to accumulate effluent from the pre-rinse operation, with a valve system that prevents discharge during dishwasher soap-laden effluent discharge, allowing stratification of FOG and subsequent release when the dishwasher is not active, thereby reducing emulsion formation and improving separator efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pre-rinse sink and dishwasher drains converge directly to the separator, then the system is simple and operational efficiency is maintained, but FOG/detergent emulsions are formed that are difficult to separate and cause compliance issues
Solution Approach 1:
The patent segments the effluent flow by introducing a separate pre-rinse sink holding tank that is isolated from the direct convergence path of the dishwasher drain. This segmentation prevents the mixing of FOG-rich pre-rinse effluent with detergent-rich dishwasher effluent, thereby avoiding emulsion formation while maintaining operational efficiency. The tank acts as a separate collection and controlled release mechanism for pre-rinse waters.
Solution Approach 2:
The pre-rinse sink holding tank serves as an intermediary device between the pre-rinse sink and the separator system. It mediates the flow of FOG-rich effluent by holding it temporarily and controlling its release timing, preventing direct contact with detergent-laden dishwasher effluent. This intermediary approach eliminates emulsion formation while preserving the simplicity and efficiency of the overall system.
2Reliability
If a holding tank with valve control is introduced to prevent emulsion formation, then separation effectiveness is improved, but device complexity increases
Solution Approach 1:
The system performs preliminary action by collecting and holding FOG-rich effluent from the pre-rinse sink in a dedicated tank before it reaches the separator. The effluent is held in a controlled state, and its release is timed to prevent convergence with dishwasher effluent. This preliminary holding action simplifies the overall system design compared to complex real-time control mechanisms, as it relies on straightforward temporal separation rather than sophisticated coordination systems.
Solution Approach 2:
The holding tank system is designed to operate autonomously based on the natural flow patterns of the kitchen fixtures. The tank passively collects effluent when the pre-rinse sink is in use and automatically holds it until the dishwasher completes its cycle, at which point the effluent is released. This self-regulating behavior eliminates the need for complex control systems, sensors, or automated valve mechanisms, thereby minimizing device complexity while maintaining high separation effectiveness.
3Productivity
If FOG-rich effluent is discharged simultaneously with detergent-rich effluent, then operational efficiency is maintained, but emulsions are formed that short-circuit the grease interceptor and flow through without depositing FOG
Solution Approach 1:
The patent applies preliminary action by collecting FOG-rich effluent from the pre-rinse sink in a holding tank before it is discharged to the separator. The effluent is held in the tank during dishwasher operation and only released when the dishwasher completes its cycle, ensuring that FOG-rich and detergent-rich effluents do not converge simultaneously. This preliminary holding prevents emulsion formation and ensures effective FOG capture in the grease interceptor, eliminating substance loss.
Solution Approach 2:
The holding tank system maintains continuous useful action by ensuring that FOG-rich effluent is always available for capture in the grease interceptor at the appropriate time. By holding the effluent and releasing it when the dishwasher is not discharging, the system ensures continuous effective FOG separation without interruption to kitchen operations. The tank continuously accumulates pre-rinse effluent and releases it in a controlled manner, maintaining uninterrupted FOG capture efficiency.
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 solution significantly reduces the average FOG readings in effluent by 27% as shown by EPA 1664 Revision B test results, enhancing the performance of grease interceptors and ensuring compliance with sewage authorities' regulations by minimizing emulsion-related errors.
Implementation Method 1
allowing stratification of FOG and subsequent release when the dishwasher is not active
Implementation Method 2
a valve system that prevents discharge during dishwasher soap-laden effluent discharge, allowing stratification of FOG and subsequent release when the dishwasher is not active
Data Source
AI summary
An apparatus for reducing emulsions in kitchen effluent discharging to a FOG removal apparatus includes a pre-rinse sink, a tank positioned below the pre-rinse sink to receive effluent from the pre-rinse sink, an outlet from the tank and leading to a pipe, a valve in the outlet having an open position and a closed position, a dishwasher having a drain connected to the pipe, and a control for the valve to be in its closed position when the dishwasher is discharging to the pipe.