England’s water scarcity challenge has intensified profusely. Recent government reports confirm that widespread drought has placed an intense amount of pressure on water supplies, with leakages at 19% and household water consumption surpassing 136 litres per person per day. The statistics paint a bleak picture; by 2055, the UK will need an additional 5 billion litres daily to meet demand, driven primarily by climate change and a growing domestic population.
As such, for the first time, large-scale desalination and water reuse have been discussed heavily in Water Resources Management Plans for 2025 to 2035. These technologies are essential at providing vital additional water sources, and with drought becoming more common than ever, desalination itself has become essential for strategic infrastructure, rather than a contingency plan as it was known for so long.
How Desalination Works
Desalination removes dissolved salts from seawater or brackish water to produce fresh, clean water for human consumption. The most widely adopted method is reverse osmosis, which uses semi-permeable membranes to separate salt from water under high pressure.
The process begins with seawater intake, which then goes through a pre-treatment stage to remove suspended solids, microorganisms and organic matter that could damage downstream equipment. Pre-treated water is then pressurised and forced through thin-film polyamide membranes, producing two streams:
- Permeate (fresh water)
- Concentrate (brine).
The permeate undergoes post-treatment to adjust its pH and mineral content before distribution, whilst the concentrate supply requires careful environmental management.
Modern membranes are engineered to resist fouling and chlorine degradation, extending their operational lifespan. Pre-treatment membranes (such as ultrafiltration and microfiltration) are increasingly integrated to improve overall system reliability.
Why Flow Monitoring Matters
When a desalination system flow rate deviates from its design parameters, everything downstream is adversely affected. Intake, pre-treatment, reverse osmosis and post-treatment all suffer; insufficient flow reduces output and starves membranes, while excessive flow adds more pressure to equipment (increasing its wear) and requires more energy.
Real-time flow monitoring directly influences and affects efficiency, reliability and operating costs. It protects membranes’ stability, optimises production, and allows more control over energy usage and consumption. Given that membrane replacement is a high operational cost, accurate flow control delivers tremendous financial benefits.
Vital Flow Measurement Points
Flow measurement serves distinct needs at multiple points throughout a desalination facility. Flow monitoring:
- Prevents overloading of pre-treatment systems at seawater intake stage
- Ensures optimal performance of filtration during pre-treatment
- Protects the investment in membranes and ensures sufficient fresh water delivery
- Supports recovery calculations for both permeate and concentrate streams
- Controls feed flow to membranes
- Ensures consistent quality during post-treatment before distribution
- Provides essential environmental compliance data
Flow Measurement Technologies
Electromagnetic flow meters excel in seawater applications, accurately measuring conductive fluids from raw intake through to brine discharge. With no moving parts, they offer reliable performance and long service life in demanding marine environments.
Oval gear flow meters deliver exceptional accuracy for chemical dosing systems and auxiliary processes, maintaining precision regardless of temperature or viscosity changes.
Pressure switches protect pumps and membranes from operating outside safe parameters. Pressure monitoring is correlational with flow control, as incorrect flow rates often manifest as pressure variations.
Level switches ensure proper operation throughout the process, from chemical storage tanks to product water reservoirs, preventing overflows and protecting equipment from dry running.
Performance, Protection and Compliance
Effective flow monitoring prevents membrane damage from insufficient or excessive, either of which can significantly reduce the lifespan of a membrane. Flow monitoring also detects membrane fouling in the early stages, allowing cleaning cycles to be implemented before this fouling becomes severe. This avoids costly downtime and keeps systems running efficiently.
Energy efficiency is critical. Desalination is an inherently energy-intensive process, with pumping costs making up a significant portion of operating expenditure. Real-time flow monitoring enables operators to optimise pump performance, balancing flow against pressure and energy consumption whilst maintaining production targets (and reducing overall power costs).
Contemporary desalination facilities integrate flow sensors with control systems for automated adjustments and consistent, 24/7 monitoring. With the integration of IoT (Internet of Things) technology, data can be collected and analysed continuously, with alarms being triggered when flow rates deviate from expected or acceptable ranges.
In turn, this integration supports modern facilities’ predictive maintenance strategies. Analysing flow trends over time can give operators more oversight to escalating problems such as partial blockages or pump inefficiencies, reducing unplanned downtime and extending equipment life.
Brine discharge requires careful management from an environmental perspective. Flow monitoring ensures compliance with environmental permits and regulations, while helping operators manage mixing zones to minimise impact on marine ecosystems.
Desalination’s Imminent and Long-Term Future
The UK Environment Agency has recognised desalination’s potential within a diversified water supply strategy. It emphasises how projects must obtain and comply with environmental permits and preserve ecosystems as the water sector advances towards large-scale implementation.
The importance of reliable instrumentation becomes more apparent, with desalination facilities representing a significant capital investment. Selecting appropriate flow monitoring, pressure control and level sensing equipment at the design and construction stages will ensure multiple decades of reliable operational life.
Flow monitoring, pressure control and level sensing form the instrumentation foundation upon which efficient, reliable desalination facilities are built. Investment in this type of equipment represents a commitment to long-term water security, as well as being good engineering hygiene.
At Applications Engineering, we are proud nationwide suppliers of high-quality, validated pressure control, level sensing and flow monitoring equipment to facilities across the country. We uphold the same commitment to product integrity and quality that helps these types of facilities maintain the high standards that we in the UK have come to expect. Contact us today to find out more about our product range and availability, or discuss integration opportunities for your facility.
