Comprehensive desalination solutions featuring advanced pre-treatment, DAF technology, precision dosing systems, and high-efficiency reverse osmosis.
RO membrane protection and fouling control for SWRO desalination.
Specialised treatment systems for refinery desalter effluent containing high salinity, oil, solids, and dissolved metals from.
Illustrative scenario: Open seawater intake for 5,000 m3/day SWRO desalination plant.
Brine management and environmental compliance for desalination plants.
From raw seawater to compliant potable water through integrated membrane desalination
Seawater reverse osmosis plants convert saline feedwater into fresh permeate through a tightly orchestrated sequence of physical, chemical, and membrane separation processes. Each stage is engineered to protect downstream equipment and progressively refine water quality to meet stringent potable and industrial standards.
Open or subsurface intakes withdraw raw seawater and route it through coarse bar screens and fine band screens to remove debris, jellyfish, and marine organisms. Velocity caps limit impingement while chlorination or copper-nickel alloy surfaces control biofouling at the intake structure. Seawater intake & screening →
Dissolved air flotation removes algae, suspended solids, and transparent exopolymer particles, followed by dual-media filtration or ultrafiltration to achieve silt density index below 3. Cartridge filters provide a final barrier before the high-pressure feed pump.
High-pressure multi-stage SWRO arrays operating at 55–65 bar separate dissolved salts from permeate. Thin-film composite membranes achieve nominal salt rejection of 99.6–99.85%, producing permeate with total dissolved solids below 500 mg/L in a single pass.
Permeate is remineralised through calcite contactors or lime dosing to raise alkalinity and calcium hardness, then disinfected with chlorine or chloramines. Boron polishing via second-pass RO may be required depending on intake salinity and regulatory limits.
Concentrated brine at 65–80 g/L salinity is discharged through multi-port diffusers designed to maximise dilution and prevent benthic habitat disruption. Discharge modelling ensures compliance with marine environmental quality standards.
Not sure which technology fits your application? Our process engineers will review your water quality data, flow rate, and treatment targets — then recommend the optimal solution.
Contact UsScreening, coagulation, flotation, and filtration configured for marine water chemistry
Bar screens with 20–50 mm gaps remove macro debris, while drum or band screens with 1–6 mm apertures exclude fish larvae and juvenile organisms. Low through-screen velocities reduce impingement and entrainment rates.
Learn moreFerric chloride at 3–10 mg/L as Fe destabilises negatively charged colloids and algae cells through sweep flocculation. Dissolved air flotation at 500–600 kPa saturator pressure produces micro-bubbles that lift flocs to the surface for skimming, achieving greater than 95% algae removal and 60–80% transparent exopolymer particle rejection.
Explore DAF systemsAnthracite over silica sand with optional garnet support layers filters flocculated particles at 8–15 m/h hydraulic loading. Backwashing with air scour and filtered water maintains bed cleanliness and ensures consistent effluent turbidity below 0.5 NTU.
Explore multimedia filtersAbsolute-rated polypropylene cartridges at 5 µm provide the final particulate barrier immediately upstream of the RO feed pump. This guard filter protects membrane elements from debris that could bypass upstream units during upset conditions.
Learn morePre-treatment performance target: A well-designed train reduces raw water SDI15 from above 10 to below 3, and modified fouling index-0.45 below 2 L/hr². These indices are the strongest predictors of long-term RO membrane fouling rates and cleaning frequency.
Staging, recovery, and flux distribution for seawater thin-film composite membranes
A conventional single-pass array uses 6–8 elements per pressure vessel arranged in two stages, typically 2:1 or 3:2 stage ratios. Feed pressure of 55–65 bar overcomes osmotic pressure and drives permeate flux at 12–17 LMH while concentrating brine to 65–80 g/L TDS.
When boron compliance below 1.0 mg/L is required, first-pass permeate feeds a second brackish-water RO pass operating at 8–15 bar with high-rejection membranes. This configuration also reduces chloride and sodium to levels suitable for sensitive agricultural or industrial applications.
Seawater recovery is thermodynamically limited to 40–50% for open intakes. At 50% recovery, the brine concentration factor reaches 2.0×, pushing calcium sulphate, barium sulphate, and silica toward saturation limits that dictate antiscalant selection and dose.
Concentration polarisation at the membrane wall raises local TDS by a factor of 1.1–1.3, increasing effective osmotic pressure and reducing net driving pressure. Cross-flow velocity and feed spacer geometry are optimised to keep the polarisation index below 1.2 and minimise fouling potential.
Minimising specific energy consumption through advanced hydraulic energy transfer
Rotor-based isobaric devices transfer hydraulic energy from the concentrated brine stream directly to the feed stream with 95–98% efficiency. This technology reduces high-pressure pump duty and is the dominant energy recovery approach in modern large-scale SWRO plants.
DWEER systems use reciprocating pistons to achieve comparable efficiency to rotary pressure exchangers while offering simpler maintenance access and fewer wearing parts. Both isobaric architectures eliminate the thermodynamic losses inherent in Pelton wheel turbines.
The thermodynamic minimum for seawater desalination at 50% recovery is approximately 1.06 kWh/m³. Real plants equipped with isobaric energy recovery devices achieve 2.5–3.5 kWh/m³, while plants without energy recovery operate at 4.5–6.0 kWh/m³ due to irrecoverable brine pressure loss.
Photovoltaic arrays coupled with DC-coupled RO skids and battery storage enable autonomous off-grid desalination for remote communities and islands. Direct solar-to-RO drive architectures eliminate inverter losses and match variable solar generation to flexible membrane throughput.
Plant-level energy balance: In a typical 10,000 m³/day SWRO facility, roughly 70–75% of electrical demand is consumed by high-pressure feed pumps, 10–12% by intake and pre-treatment pumping, 8–10% by post-treatment and distribution, and the remainder by instrumentation and auxiliary systems. A 1 bar reduction in feed pressure through improved pre-treatment lowers specific energy by approximately 0.045 kWh/m³.
WHO, EPA, and regional standards governing potable desalinated water
WHO guidelines specify a palatability threshold of 1,000 mg/L TDS for potable water, with a provisional boron limit of 2.4 mg/L based on reproductive toxicity studies. EPA National Primary Drinking Water Regulations set enforceable maximum contaminant levels for heavy metals, disinfectants, and disinfection by-products.
Seawater contains 4–5 mg/L boron as boric acid, which passes poorly rejected through standard polyamide membranes at neutral pH. Single-pass permeate often contains 1.5–2.5 mg/L, necessitating either high-pH first-pass operation, dedicated second-pass boron polishing, or blending with low-boron sources.
RO permeate TDS typically ranges from 100–400 mg/L depending on feed salinity, membrane rejection, and recovery. Partial blending with filtered seawater or deliberate remineralisation adjusts final TDS to 300–600 mg/L, improving taste and reducing corrosivity in distribution networks.
Aggressive RO permeate with LSI below −2.0 dissolves calcium carbonate from cement-lined pipes and copper from domestic plumbing. Post-treatment targets LSI slightly above zero and calcium carbonate precipitation potential of 4–10 mg/L to form a thin protective scale layer without bulk precipitation.
| Parameter | RO Permeate (Typical) | WHO Guideline | Post-treatment Action |
|---|---|---|---|
| pH | 5.5–6.5 | 6.5–8.5 | Caustic soda or lime dosing |
| TDS | 100–400 mg/L | <1,000 mg/L (aesthetic) | Remineralisation or blending |
| Boron | 0.5–2.5 mg/L | 2.4 mg/L (provisional) | Second-pass RO or pH adjustment |
| Chlorine Residual | 0 mg/L | >0.2 mg/L | Chlorination or chloramination |
| LSI | −3.0 to −2.0 | Slightly positive | Calcite contactor or lime + CO₂ |
In-depth guides for specific desalination challenges and processes
Complete seawater DAF design guide. Saturator pressure compensation for salinity (500–600 kPa), FeCl₃ coagulation chemistry, bubble dynamics in saline water, TEP/AOM removal, DAF-DMF vs. DAF-UF configurations, and seasonal adaptation for HAB response.
View GuideHarmful algal bloom response protocols. 2008–2009 Gulf shutdown context, HAB species identification, TEP/AOM characterisation via LC-OCD, chlorination strategy, emergency protocols, and DAF performance during severe HAB events.
View GuideFouling taxonomy, SDI vs. MFI metrics, biofouling potential (ATP, BGP, AOC), DAF's role in BGP reduction, membrane CIP strategies, and lifecycle optimisation. Direct correlation between pretreatment quality and membrane replacement frequency.
View GuideERD technology comparison (PX, DWEER, turbochargers, Pelton wheels), SEC targets, two-pass RO for boron removal, high-recovery configurations, and renewable integration. Engineering trade-offs between efficiency, reliability, and maintenance requirements for each ERD type.
View GuideBrine characterisation, marine discharge plume modelling (CORMIX, VISJET), zero liquid discharge options, regulatory frameworks by region, and emerging brine mining for lithium and magnesium recovery.
View GuideOpen versus subsurface intakes, beach wells and infiltration galleries, through-screen velocity caps for impingement control, band and wedge-wire screening, entrainment mitigation and intake biofouling control.
View GuideConditioning aggressive RO permeate into compliant potable water: Langelier/CCPP stabilisation targets, calcite contactors, lime + CO₂ dosing, second-pass boron polishing and final chloramination.
View GuideDeep technical guides to the organisms that threaten SWRO desalination worldwide
Gulf desalination's worst HAB threat. Very high TEP, ichthyotoxic. Summer–autumn blooms.
View GuideFlorida red tide dinoflagellate. Brevetoxin producer. High TEP, year-round blooms.
View GuideLarge bioluminescent dinoflagellate. Non-toxic but massive biomass. Winter–spring blooms.
View GuideDomoic acid-producing diatom. Moderate TEP. Spring blooms in California and Mediterranean.
View GuideNitrogen-fixing cyanobacterium. No toxins but very high TEP. Summer tropical blooms.
View GuideComprehensive protocols for monitoring, DAF response, intake management, and membrane protection.
View GuideExplore Other Industries We Serve
Desalination plants require specialised process tanks for pre-treatment and post-treatment.
Storage tanks for coagulants, antiscalants and cleaning chemicals.
View Chemical TanksThe stages that protect SWRO membranes and manage concentrate — reliable seawater intake, effective pre-treatment, and responsible brine discharge.
Open and subsurface intake design that delivers low-turbidity feed and protects the downstream membrane train.
Read MoreDissolved air flotation to strip algae, oil and suspended solids ahead of SWRO — critical during algal bloom events.
Read MoreConcentrate dilution, diffuser design and environmental compliance for responsible brine discharge.
Read MorePackaged, containerised, skid-mounted and research-station families engineered for sites with no road, no grid, no operator and no local supply chain.
All five product families plus the engineering choices that span the catalogue — transport envelopes, off-grid power, satellite SCADA, swap-on-failure spares.
Read the HubComplete plants delivered as a single pre-commissioned package — villages, mining camps, expedition bases.
Read More10′, 20′ and 40′ ISO container plants hardened for hurricane, arctic, desert and salt-air environments.
Read MoreModular skids sized to helicopter sling-loads, 4×4 trailers and ATV sleds for sites with no road access.
Read MoreBar racks, inclined/step, band (through/centre/dual-flow), drum, disc, microscreen, wedge-wire and Coanda — types, history and trade-offs
Coarse first stage — logs, weed and large debris.
Read MoreMechanically-lifted inclined and step screens.
Read MoreThe proven workhorse fine travelling screen.
Read MoreCentre-entry, both faces — no debris carryover.
Read MoreDouble-entry, double capacity in narrow channels.
Read MoreHigh capacity, very low head loss, fish-friendly.
Read MoreLarge fine-mesh area in a compact, low-head unit.
Read MoreMicron-scale removal of algae and fine solids.
Read MoreLow-velocity, no moving parts — the 316(b) benchmark.
Read MorePassive, self-cleaning fine screen for small intakes.
Read MoreEntrance-flow vs outside-flow, the 316(b) velocity driver and how to choose
Contact Our Engineers for customised seawater desalination solutions.
Deploying containerised plants in 50 °C ambient, dust-storm zones or solar-powered off-grid sites changes almost every engineering assumption. Our hot-climate technical library covers thermal balance, solar shading, dust ingress, power systems, brackish water chemistry and the full deployment checklist:
Overview of the six engineering domains, design ambient conditions, customer profiles.
ViewHVAC sizing, insulation U-values, derating curves, pump cavitation.
ViewCool-roof coatings, cantilever shade, UV-stable materials.
ViewIP ratings, three-stage HVAC filtration, silica-gel breathers, silicone seals.
ViewPV derating, generator derating, battery cooling, hybrid sizing, fuel logistics.
ViewBrackish bore TDS, scaling species, hot-feed RO, evaporation losses.
ViewSix-step project plan from site assessment to operational hand-over.
ViewOur expertise spans multiple industries with sector-specific water treatment solutions.
Explore closely-related topics, equipment and guides
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