How to Precisely and Effectively Reduce RO System Operating Costs? Are You Aware of These “Hidden Tricks”?

How to Precisely and Effectively Reduce RO System Operating Costs? Are You Aware of These “Hidden Tricks”?

Reverse osmosis technology operates by applying pressure exceeding the solution's osmotic pressure, separating substances from water through a semi-permeable membrane that blocks other materials. The membrane's extremely small pore size effectively removes dissolved salts, colloids, microorganisms, and organic compounds from water.

RO systems involve high-pressure pumps and require specialized scale inhibitors, resulting in relatively high operating costs. So how can we reduce these costs?

As a core process in modern water treatment, the operating costs of reverse osmosis (RO) systems remain a key concern for operators. Many water plants often focus only on superficial factors when trying to reduce RO operating costs, overlooking some critical details. This article will delve into how to precisely and effectively reduce the operating costs of RO systems, revealing those often-overlooked “hidden techniques.”

01- Selecting Ultra-Low Pressure RO Membranes

Conventional RO membranes operate at pressures of 1.3–1.5 MPa, while ultra-low pressure membranes run at approximately 0.8 MPa or lower (closely tied to water temperature), achieving over 30% electricity savings. For large-scale RO systems, this can offset over 70% of annual membrane depreciation costs, yielding even more significant savings.

02-Equip High-Pressure Pumps with Variable Frequency Drives (VFDs)

VFDs on high-pressure pumps not only mitigate water hammer impacts during startup but also reduce valve throttling energy losses by setting optimal operating pressures. This yields annual energy savings of at least 15% on a quarterly basis.

03-Optimized Scale Inhibitor Dosage Calculation

By analyzing water quality data and optimizing chemical dosing, chemical costs can typically be reduced by 20% or more.

04-Appropriate Increase in Membrane Quantity to Reduce Operating Pressure

Increasing membrane surface area appropriately can lower operating pressure to some extent, thereby reducing power consumption.

05-Environmental Considerations

Water temperatures exceeding 45°C shorten membrane lifespan. Generally, water temperatures should be maintained below 40°C, with cooling measures implemented when necessary. For RO systems, wastewater containing strong oxidizing agents or easily precipitating substances can reduce membrane service life. During system design, incorporating safety margins in pretreatment and installing protective shutdown mechanisms can prevent such issues from occurring.

06-Utilizing Anti-Fouling Reverse Osmosis Membranes

Anti-fouling membranes are reverse osmosis membrane elements developed specifically for Chinese water conditions. They feature high salt rejection, high water production, high chemical durability, high fouling resistance, and ultra-low pressure operation. Under identical water conditions, they can reduce energy consumption by 30%-40% and are easier to clean. While effectively addressing increasingly severe water source contamination issues, they also significantly lower operating costs, delivering greater value to customers. Typically, reverse osmosis membranes have a service life of approximately 2-3 years, which is normal. However, improper operation can shorten membrane lifespan, consequently reducing the operational lifespan of the direct drinking water equipment.
 

Next, we reveal those often overlooked “hidden tricks.”

PART 01

I. Precisely Optimize Operating Parameters to Avoid “Over-Operation”

1. Scientific Setting of Recovery Rate

Recovery rate is one of the key factors affecting RO operating costs. Too high accelerates membrane fouling, while too low wastes water resources.

Precision Control Recommendations:

- Dynamically adjust recovery rate based on feedwater quality instead of maintaining a fixed value

- Establish a TDS-recovery rate correlation table for real-time optimization

- Implement segmented recovery rate design with distinct recovery rates for different zones

2. Precise Control of Operating Pressure

Operating pressure directly impacts energy consumption and membrane lifespan, requiring meticulous regulation.

Optimization Approach:

- Employ the lowest feasible pressure while meeting production requirements

- Develop a temperature-pressure compensation model for automatic adjustments based on temperature fluctuations

- Regularly calibrate pressure gauges to ensure accurate readings

PART 02

II. Intelligent Chemical Cleaning to Extend Membrane Lifespan

1. Data-Driven Predictive Cleaning

Traditional time-based or differential pressure-triggered cleaning often falls short.

Innovative Approach:

- Develop standardized flux decline rate models to predict optimal cleaning timing

- Integrate multi-parameter analysis including pre/post-membrane pressure, water production, and salt rejection rate

- Employ machine learning algorithms to optimize cleaning strategies based on historical data

2. Precision Cleaning Formulation Design

Generic cleaning agents offer limited effectiveness; customized formulations are paramount.

Expert Recommendations:

- Conduct regular membrane element dissection analysis to understand fouling characteristics

- Customize cleaning formulations based on contaminant composition to avoid one-size-fits-all approaches

- Establish a cleaning effectiveness evaluation system for continuous optimization

PART 03

III. Energy Recovery Technology Upgrades to Unlock Energy-Saving Potential

1. Application of High-Efficiency Energy Recovery Devices

For brackish water and seawater desalination, energy recovery is key to reducing energy consumption.

Technology Selection:

- Choose positive displacement or centrifugal energy recovery units based on system scale

- Regularly evaluate energy recovery efficiency and promptly replace outdated equipment

- Optimize coordinated control between energy recovery systems and high-pressure pumps

2. Utilizing System Residual Heat

Many RO systems overlook the impact of feedwater temperature on energy consumption.

Innovative Approaches:

- Utilize process residual heat to moderately increase feedwater temperature and reduce operating pressure

- Conduct economic feasibility analysis for feedwater heating in cold regions

- Develop temperature-energy consumption correlation models to optimize temperature control strategies

PART 04

IV. Preventive Maintenance to Reduce Unplanned Downtime

1. Condition-Based Preventive Maintenance

Traditional scheduled maintenance is costly and limited in effectiveness.

Precision Maintenance Strategy:

- Implement online monitoring and early warning systems for real-time equipment status tracking

- Establish life prediction models for critical equipment to plan replacements proactively

- Develop spare parts inventory optimization models balancing stock costs and downtime losses

2. Intelligent Fault Diagnosis

Detect and address issues early to prevent minor problems from escalating into major failures.

Implementation Plan:

- Develop RO system fault knowledge base and diagnostic algorithms

- Utilize digital twin technology to simulate system operating conditions

- Establish remote diagnostic platform for expert resource sharing

PART 05

V. Full Lifecycle Cost Optimization

1. Membrane Element Replacement Strategy Optimization

Delaying membrane replacement isn't always optimal; performance and maintenance costs require comprehensive consideration.

Economic Analysis:

- Develop a model correlating membrane performance degradation with economic viability

- Determine optimal replacement cycles for different operational scenarios

- Evaluate cost comparisons between batch replacement and full-set replacement

2. Precision Chemical Dosage

Excessive chemical dosing increases costs and may cause membrane damage.

Precision Chemical Dosage Plan: - Dynamically adjust scale inhibitor dosage based on real-time water quality monitoring - Establish a chemical efficiency evaluation system to select cost-effective products - Optimize dosing point locations and mixing efficiency to enhance chemical utilization