Hybrid RO/NF Filtration for Scale Control at High Water Recovery

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Solution Overview

Problem

Existing water filtration systems face challenges in achieving high recovery rates without the drawbacks of wear and tear on system components, high power consumption, and the necessity of antiscalant use, particularly in continuous and batch RO operations.

Innovation Solution

A hybrid filtration system that integrates elements of continuous and batch RO systems, utilizing high-pressure filter membranes and variable pressure pumps to achieve extended induction periods with antiscalant injection, allowing for higher water recovery and fouling management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If continuous flow RO systems operate at low recovery rates to avoid scaling, then scale formation is prevented, but water recovery efficiency is limited to 50-75%

Engineering Contradiction:

Improvescale preventionVSAvoidwater recovery rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system alternates between continuous flow operation and batch operation cycles. During continuous flow mode, it operates at low recovery rates to prevent scaling. When scaling conditions are detected, it transitions to batch mode with periodic high-pressure flushing to remove scale deposits, enabling sustained high recovery rates without permanent scale formation

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically changes operating parameters including recovery rate, pressure, and flow mode between continuous and batch operations. By adjusting these parameters based on real-time monitoring of scaling conditions, the system can operate above traditional scaling limits while preventing actual scale deposition through parameter optimization

Inventive Principle:

Principle #35Parameter changes

2Productivity

If batch RO systems operate at high recovery rates, then water recovery efficiency is improved, but periodic flushing is required to maintain permeate flux

Engineering Contradiction:

Improvewater recovery rateVSAvoidflushing time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The system performs rapid high-pressure flushing cycles that quickly remove scale deposits without requiring extended downtime. The batch operation mode enables fast recovery of permeate flux by applying high pressure for short durations to dislodge and remove scale, minimizing the time lost to flushing while maintaining high overall recovery rates

Inventive Principle:

Principle #21Skipping (Rushing through)

3Reliability

If antiscalants are used to enable high recovery rates, then scaling is inhibited, but membrane fouling and environmental concerns increase

Engineering Contradiction:

Improvescale inhibitionVSAvoidmembrane fouling and environmental impact

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system uses physical mechanisms (pressure cycling, batch flushing) to prevent and remove scale rather than relying on chemical antiscalants. The alternating continuous-flow and batch operation modes create self-cleaning effects that prevent scale adhesion and facilitate its removal, reducing dependence on chemical additives and their associated environmental and fouling issues

Inventive Principle:

Principle #25Self-service

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 a balance between recovery rate, power consumption, and operational costs by extending induction periods, reducing wear and tear, and minimizing antiscalant use, while maintaining system stability and efficiency.

Implementation Method 1

at least one pump to generate a pressure to displace the feed water from the at least one feed stream into the at least one filter membrane

Methodology Applied

Scientific EffectPressure: Pressure Increase

Implementation Method 2

reverse osmosis (RO) operation/cycle and a pump that displaces feed through one or more filter membranes

Methodology Applied

Scientific EffectReverse osmosis: Reverse Osmosis

Implementation Method 3

a pump varies pressure over time to overcome the osmotic pressure of one or more filter membrane(s)

Methodology Applied

Scientific EffectOsmotic pressure: Osmotic Pressure

Data Source

PatentUS12623921B2Techniques for managing scale formation in reverse osmosis (RO) and nanofiltration (NF) systems and a hybrid filtration architecture implementing the same

Publication Date: 2026.05.12 CLEAN H2O TECH LLC

AI summary

The present disclosure is directed to filtering technologies that combine elements of continuous and batch NF/RO based on the constraints of the end-user facility to achieve a target balance between, for instance, recovery and power consumption, and to reduce long term operating cost of a plant. A method for extending batch operation into a second induction period with antiscalant injection is also disclosed herein, with the second induction period allowing for yet higher water recovery.