Engineered RO Systems for Industrial and High-Purity Water Applications

Reverse osmosis is one of the most effective technologies available for removing dissolved salts from water.

But a reliable RO system is not simply a collection of membrane vessels connected to a high-pressure pump.

Its performance depends on the feedwater chemistry, membrane selection, pretreatment, recovery, flux, operating pressure, instrumentation and control philosophy all being engineered correctly.

At Hydra-Clear, we design and manufacture reverse osmosis systems in-house for industrial, food and beverage, pharmaceutical and high-purity water applications.

From relatively small process-water systems through to multi-stage and duty/standby RO plants, every system is designed around the actual water and the process it serves.

Start With the Water Analysis

An RO system should never be selected on flow rate alone.

Before designing a plant, we need to understand what is actually in the incoming water.

Important parameters can include:

Conductivity
Hardness
Alkalinity
Chloride
Sulphate
Silica
Sodium
Iron
Manganese
Nitrate
Turbidity
pH
Temperature
Organic loading

The relationship between these constituents determines how the system should be designed and, critically, how far the water can be concentrated before scaling or fouling becomes a problem.

That information forms the basis of the membrane design.

Membrane Projection

Where appropriate, Hydra-Clear uses membrane projection software to model the proposed RO system against the actual feedwater analysis.

This allows us to assess predicted:

Permeate quality
Salt rejection
Operating pressure
Permeate flow
Concentrate chemistry
Membrane flux
Stage loading
Recovery
Scaling potential

The objective is to predict how the membrane system will behave before we manufacture it.

A nominally identical RO system can perform very differently on two different water supplies.

The design needs to reflect that.

Recovery Is a Design Decision

RO recovery is the proportion of incoming water converted into permeate.

For example, a system operating at 75% recovery produces approximately 750 litres of permeate from every 1,000 litres of feedwater.

It can therefore be tempting to simply design for the highest possible recovery.

That is not always the correct approach.

As recovery increases, dissolved salts become progressively concentrated within the reject stream and across the later membrane elements.

This can increase the risk of scaling from compounds such as:

Calcium carbonate
Calcium sulphate
Barium sulphate
Strontium sulphate
Silica

Higher recovery also increases osmotic pressure and can affect membrane performance.

We therefore design recovery around the feedwater chemistry and operating requirement rather than treating the highest possible percentage as automatically better.

A sustainable 75% recovery can be far more valuable than an unstable 85% system that continually scales membranes.

Correct Membrane Flux

Membrane flux describes the amount of permeate produced across a given membrane area.

Driving an RO system too aggressively can reduce capital cost because fewer membrane elements are required.

It can also increase membrane fouling and shorten membrane life.

Conversely, excessively conservative design can unnecessarily increase the size and cost of the plant.

The correct flux depends on factors including:

Feedwater source
Pretreatment
Fouling potential
Temperature
Application
Required recovery
Operating hours
Cleaning philosophy

Membrane loading should therefore be engineered rather than assumed.

Pretreatment Protects the RO

The performance of an RO system is heavily influenced by the treatment installed upstream.

Pretreatment may include:

Water softening
Multimedia filtration
Activated carbon
Iron and manganese removal
Ultrafiltration
Cartridge filtration
Antiscalant dosing
pH correction
Dechlorination
Chemical conditioning

The correct arrangement depends entirely on the incoming water.

For example, a mains-water RO may require relatively simple pretreatment, while a borehole supply containing iron, manganese, hardness and silica may require several treatment stages before the water is suitable for the membranes.

Good RO design begins upstream of the RO itself.

Reverse Osmosis Is More Than Salt Rejection

RO membranes reject a high proportion of dissolved ionic material, making them particularly effective for producing low-conductivity water.

Depending on the feedwater and membrane selected, reverse osmosis can significantly reduce:

Calcium
Magnesium
Sodium
Chloride
Sulphate
Nitrate
Silica
Dissolved metals
Alkalinity
Many organic contaminants

The exact rejection varies between individual ions and operating conditions.

For this reason, we design systems against the required treated-water specification rather than assuming a fixed percentage rejection for every contaminant.

Single-Pass Reverse Osmosis

For many industrial applications, a correctly engineered single-pass RO system provides the required product-water quality.

Typical applications include:

Boiler make-up water
Process water
Food and beverage production
Manufacturing rinse water
Cooling-system make-up
Ingredient water
Borehole treatment
General industrial demineralisation

Where the required conductivity or contaminant level cannot reliably be achieved with a single pass, further treatment can be incorporated.

Two-Pass Reverse Osmosis

In a two-pass RO system, permeate from the first RO becomes the feedwater to a second membrane stage.

Because the second pass is treating water that already contains very low concentrations of dissolved salts, considerably lower final conductivity can be achieved.

Two-pass systems can be appropriate for:

Pharmaceutical applications
High-purity process water
Electronics
Laboratory systems
Final polishing applications
Processes requiring consistently low conductivity

Interstage pH adjustment can also be incorporated where required to improve the rejection of specific contaminants, particularly carbon dioxide-derived species.

RO With Final Polishing

Reverse osmosis can also form part of a wider high-purity water treatment system.

Depending on the required water specification, downstream treatment can include:

Electrodeionisation – EDI
Mixed-bed ion exchange
Deionisation
UV treatment
Fine filtration
Sub-micron filtration
Hygienic storage and distribution

This allows the complete treatment train to be engineered around the final process requirement rather than expecting RO alone to achieve every water-quality target.

Industrial RO Systems

Hydra-Clear designs and manufactures reverse osmosis systems for industrial manufacturing and utility applications.

Systems can be supplied for duties including:

Boiler and CHP make-up water
Process-water production
Cooling-tower make-up
Wash and rinse applications
Ingredient water
Chemical manufacturing
General manufacturing
Borehole water treatment
Water recovery and reuse

Industrial systems can be engineered for continuous operation, intermittent production or demand-controlled operation depending on the site requirement.

Food & Beverage RO Systems

Food and beverage applications require particular consideration of materials, cleanliness, equipment construction and product-contact requirements.

RO systems can incorporate:

316 stainless steel pipework
Hygienic valves
Hygienic instrumentation
Appropriate elastomers
Food-compatible materials
UV treatment
Hygienic storage
Automated flushing
Controlled chemical dosing
Cleaning and sanitisation provisions

The system is designed around both the required water quality and the production environment.

Pharmaceutical & High-Purity RO

Pharmaceutical and other regulated applications can require significantly greater control over materials, instrumentation, documentation and system operation.

Depending on the project, Hydra-Clear systems can incorporate:

Two-pass RO
Electrodeionisation
Hygienic instrumentation
Pharmaceutical-grade materials
High-purity storage
Recirculating distribution systems
UV treatment
Final filtration
Automated sanitisation
Data logging
User access control
Validation support
FAT and SAT documentation

The design is developed around the User Requirement Specification and applicable project standards.

Siemens PLC & HMI Control

Our RO systems can be supplied with Siemens PLC and HMI control as part of the standard engineering package.

The control system can monitor and manage parameters including:

Feed pressure
Membrane inlet pressure
Concentrate pressure
Differential pressure
Permeate pressure
Feed flow
Permeate flow
Concentrate flow
Recovery
Feed conductivity
Permeate conductivity
Tank level
Chemical dosing
Pump speed
UV status

Automatic sequences can include:

System start-up
Membrane flushing
Tank level control
Permeate diversion
Low-quality water rejection
High-conductivity alarms
Pump protection
Chemical dosing control
Duty/standby changeover
Shutdown flushing

Systems can also be integrated with customer BMS or SCADA platforms where required.

Instrumentation Matters

An RO system should provide enough information to determine whether it is actually performing correctly.

We design instrumentation around the ability to understand the membrane process.

Depending on the system, this may include measurement of:

Pressure
Differential pressure
Flow
Conductivity
Temperature
pH
ORP
Tank level

These parameters allow membrane performance to be trended and deterioration to be identified before it develops into a significant operating problem.

Designing for Maintenance

Eventually, every membrane system needs maintenance.

Membranes require replacement.

Cartridge filters require changing.

Pumps and instruments require servicing.

RO design therefore needs to consider the engineer who will maintain the equipment several years after installation.

Our mechanical designs consider:

Membrane removal clearance
Cartridge filter accessibility
Pump maintenance
Instrument access
Valve positioning
Drain points
Sample points
Chemical dosing access
Isolation arrangements
CIP connections

A compact skid is only useful if it can still be maintained safely.

Cleaning in Place

Membrane fouling is not simply a matter of membrane age.

Performance can deteriorate because of:

Mineral scale
Colloidal fouling
Biological contamination
Organic fouling
Iron
Manganese
Aluminium
Silica

Where appropriate, RO systems can therefore incorporate Clean-in-Place connections or dedicated CIP equipment.

Cleaning chemistry and procedure should be selected around the likely foulant rather than automatically using the same chemical programme for every membrane problem.

Designing for Redundancy

For critical production sites, losing RO water can mean losing manufacturing capacity.

Where continuity is important, systems can be designed with:

Duty/standby RO trains
Duty/assist configurations
Duplex pretreatment
Duty/standby pumps
Automatic changeover
Buffer storage
Redundant instrumentation
Critical spares

The redundancy philosophy is selected according to the consequence of losing treated-water production.

Designed and Manufactured in the UK

Hydra-Clear designs and manufactures its water treatment systems in the UK.

This gives our engineering team direct involvement throughout:

Water Analysis → Process Design → Membrane Projection → Detailed Engineering → Manufacture → FAT → Installation → Commissioning → Service

The people designing the system remain connected to the people manufacturing and commissioning it.

That continuity is particularly valuable when a project is genuinely bespoke.

Standard Where It Makes Sense. Bespoke Where It Matters.

Not every application needs to be reinvented from the ground up.

We use proven engineering arrangements and standardised components where they provide reliability, maintainability and value.

But we do not force every customer into the same machine.

Flow rate, pretreatment, recovery, instrumentation, redundancy, controls, materials and system configuration can all be adapted to suit the application.

Standardisation should improve engineering.

It should not restrict it.

Existing RO System Not Performing?

Hydra-Clear also provides investigation, servicing and optimisation of existing reverse osmosis plants.

If an RO system is experiencing:

Increasing permeate conductivity
Reduced permeate flow
High differential pressure
Frequent membrane fouling
Scaling
Excessive reject-water consumption
Poor membrane life
Repeated cleaning requirements

we can review the operating data, feedwater chemistry, pretreatment and original system design to identify the likely cause.

Replacing membranes without understanding why they failed usually only starts the same problem again.

Talk to an RO Engineer

If you require a new reverse osmosis system, send Hydra-Clear:

Your incoming water analysis
Required treated-water quality
Required flow rate
Daily water demand
Operating hours
Available feed pressure
Details of the downstream process

We can then assess the application and develop the appropriate treatment philosophy.

Don't start with the RO. Start with the water.

Call 0800 999 6770 or contact Hydra-Clear to discuss your reverse osmosis application.

Reverse Osmosis System Design & Manufacture