Reverse osmosis membranes fail predictably when feed water arrives without adequate pre-treatment. Suspended solids, colloidal organics, and biological matter foul membrane surfaces, compress silt density indices beyond operational tolerance, and shorten replacement cycles that represent one of the largest recurring cost items in desalination plant budgets. Polyaluminium chloride (PAC) sits at the front of the chemical sequence that prevents this outcome, and as global seawater reverse osmosis (SWRO) capacity accelerates through 2026 and beyond, PAC demand tied specifically to desalination pre-treatment is growing at a rate that is structurally faster than the broader water treatment market.

 

Why Reverse Osmosis Expansion Directly Drives PAC Consumption

Global desalination capacity exceeded 150 million cubic metres per day by 2025, with reverse osmosis accounting for over 70% of that installed base. The desalination technologies market was valued at USD 27.8 billion in 2025 and is projected to reach USD 59.3 billion by 2034, growing at a CAGR of 8.85%. RO's dominance over thermal alternatives has solidified due to its energy efficiency advantage large-scale RO systems consume 3–5 kWh per cubic metre of seawater treated, compared to roughly 83–84 kWh per cubic metre for multi-stage flash distillation. As new capacity comes online, and as older thermal plants in the Middle East are progressively retrofitted or replaced with membrane-based systems, the volume of feed water requiring chemical pre-treatment scales proportionally.

The pre-treatment requirement for SWRO is non-negotiable. Almost all SWRO desalination plants require pre-treatment, with the specific approach determined by the fouling potential of the raw seawater intake. Coagulation using PAC is standard in conventional pre-treatment trains, typically deployed ahead of dual media filtration and, in higher-turbidity environments, ahead of dissolved air flotation and membrane filtration stages. PAC's mechanism in this context is twofold: charge neutralisation destabilises negatively charged colloidal particles including suspended silt, clay, and organic matter; adsorption bridging then aggregates those particles into settleable flocs at rates 1.3–3.0 times faster than conventional inorganic coagulants such as aluminium sulfate. In controlled pre-treatment studies, PAC at a dosage of 50 mg/L reduced silt density index values to within SWRO feed water tolerance thresholds, enabling downstream membranes to operate within recommended turbidity limits below 0.1 NTU.

The commercial consequence is direct: each new SWRO plant that enters service creates a recurring chemical procurement requirement for the operational life of the facility, typically 20–25 years.

 

The Middle East: Where Desalination Scale Meets PAC Demand Concentration

The Gulf Cooperation Council states collectively represent over 45% of global desalination capacity, with Saudi Arabia alone contributing approximately 20% of the world total. The Middle East desalination plants market was valued at USD 8.27 billion in 2023 and is projected to reach USD 15.5 billion by 2030, growing at a CAGR of 10.0%. Installed capacity in the region surpassed 52 million cubic metres per day in 2024, up from 40 million cubic metres per day in 2020, and regional projections target 60 million cubic metres per day by 2027. Membrane and pre-treatment systems account for approximately 18% of total CAPEX in Middle East SWRO projects, a share that reflects both the capital intensity of coagulation infrastructure and the region's accelerating transition from thermal to membrane technologies.

Saudi Arabia's SWPC-led megaproject pipeline, including infrastructure associated with NEOM and associated urban water security programs, is generating sustained PAC procurement demand across project lifecycles. The UAE's Shuweihat 4 reverse osmosis independent water project, contracted in 2023 and producing up to 318,225 cubic metres per day, is representative of the scale at which GCC pre-treatment chemical volumes operate. Industrial desalination and oil and gas water treatment together contribute nearly 28% of regional PAC demand, alongside the dominant 66% share tied to drinking water clarification.

For PAC producers and traders, the Middle East is the highest-concentration demand pool for desalination-linked coagulant volume. It is also the region where procurement is most project-driven: chemical supply is tied to plant commissioning and operational contracts rather than spot purchasing, which means supply positioning ahead of project award timelines is commercially material.

 

Asia-Pacific: Volume Growth Driven by Coastal Urbanisation and New Capacity

Asia-Pacific held approximately 49% of global PAC market revenue in 2025 and is the largest single regional consumption base, driven by municipal water treatment across China and India rather than desalination specifically. Within the desalination sub-segment, however, the region represents the fastest-growing demand pool. The Asia-Pacific desalination market is growing at a CAGR of 8.2%, with new capacity concentrated in coastal India, Southeast Asia, and China's arid northern provinces. Hong Kong's Tseung Kwan O desalination plant, which began operations using RO technology in February 2024, is one indicator of a broader pattern of urban coastal governments commissioning SWRO as a supplementary or primary source rather than relying solely on transfer from inland reservoirs.

India's desalination investment is accelerating under water security mandates. Tamil Nadu, through the State Industries Promotion Corporation, contracted IDE Technologies in December 2025 for coastal desalination supply. The Philippines desalination project pipeline, with several plants projected to come online through 2027, represents a new PAC demand source in Southeast Asia that did not exist at material scale three years prior. China's position is more complex: the country accounts for over 40% of global PAC consumption and is the leading exporter, but domestic desalination growth in provinces like Shandong and Hebei adds a layer of captive demand that reduces the volume available for export, tightening supply positions for regional buyers outside China.

 

PAC Grade Selection in Desalination Pre-Treatment: A Procurement Consideration

Not all PAC grades perform equivalently in SWRO pre-treatment conditions. Desalination feed water particularly open ocean seawater intakes presents variable turbidity, organic loading influenced by seasonal algal bloom cycles, and salinity levels that interact with coagulant chemistry differently than freshwater sources. High-basicity PAC grades exceeding 85% basicity have become the commercial preference for membrane pre-treatment applications because they achieve superior turbidity removal while leaving residual aluminium levels below 0.1 mg/L in treated water. Poorly controlled residual aluminium carries risk of membrane scaling and regulatory non-compliance in drinking water production, making grade specification a technical procurement decision rather than a purely cost-driven one.

Liquid PAC holds approximately 57% of the global market by form and is the preferred delivery format for large SWRO plants due to ease of dosing, uniform dispersion, and compatibility with automated dosing systems. Powder grades are growing at a CAGR of 4.52%, driven by reduced transport costs and shelf stability, an advantage for remote or modular desalination installations where logistics infrastructure limits bulk liquid delivery. GACL's February 2025 dispatch of the first consignment from its new spray-drying facility producing PAC-30 powder signals that producers are investing in powder capacity to serve project types that liquid supply chains do not reach cost-effectively.

 

Regional Supply Structure and Procurement Risk

The global PAC market was valued at approximately USD 2.72 billion in 2025 and is projected to reach USD 5.03 billion by 2035, at a CAGR of 7.07%. China dominates production, accounting for a commanding share of global output between 2022 and 2024, China commissioned 17 new PAC production expansions adding 580,000 metric tonnes of national capacity. Major international producers include Kemira (Finland), which holds approximately 15% global market share, alongside Feralco Group, GEO Specialty Chemicals, USALCO, and India's Grasim Industries and Gujarat Alkalies and Chemicals Limited.

For desalination plant operators and EPC contractors sourcing PAC, the key procurement risk in 2026 is not availability but price stability. Upstream aluminium supply constraints are tightening the PAC cost base, with global aluminium deficits forecast to persist into the near term. This is driving a shift toward long-term supply contracts with index-linked escalation clauses among municipal and industrial buyers, rather than spot purchasing that exposes operators to aluminium price volatility at the moment of chemical procurement. Buyers sourcing from Chinese producers for Middle Eastern or Southeast Asian plants should factor import registration requirements, including Certificate of Origin and processing standard documentation into procurement lead times.

 

Outlook: Pre-Treatment Demand as a Structural PAC Growth Driver

The desalination-linked PAC demand trajectory through 2026 and beyond is structurally insulated from the demand volatility that affects PAC consumption in discretionary industrial applications such as paper manufacturing or textile wastewater treatment. Desalination plants, once commissioned, operate at consistent throughput and require coagulant dosing regardless of commodity price cycles or industrial output fluctuations. That operational continuity makes desalination pre-treatment one of the most predictable and contract-stable demand sources in the PAC buyer landscape. As the global SWRO installed base continues to expand and as the Middle East's remaining thermal capacity transitions toward membrane systems requiring chemical pre-treatment that thermal evaporation did not. PAC producers with direct project supply relationships and high-basicity grade portfolios will be positioned to capture demand that commodity suppliers without technical differentiation will not.

 

FAQ

What is the role of polyaluminium chloride in desalination pre-treatment? PAC is used as a coagulant in the pre-treatment train ahead of reverse osmosis membranes in seawater desalination plants. It destabilises and aggregates suspended solids, colloidal particles, and organic matter in raw seawater, reducing turbidity and silt density index values to within the tolerance limits required for RO membrane operation. Without effective coagulation pre-treatment, RO membranes experience accelerated fouling, higher cleaning frequency, and shortened operational lifespan.

Why is PAC preferred over conventional coagulants like aluminium sulfate in SWRO applications? PAC offers faster floc formation, lower sludge volumes (typically 30–50% less than aluminium sulfate), and effective performance across a wider pH range. In SWRO pre-treatment specifically, high-basicity PAC grades produce lower residual aluminium levels in treated water below 0.1 mg/L reducing membrane scaling risk and supporting compliance with drinking water quality standards.

How large is the global PAC market and what is the growth forecast? The global PAC market was valued at approximately USD 2.72 billion in 2025 and is projected to reach USD 5.03 billion by 2035, growing at a CAGR of 7.07%. Desalination pre-treatment is among the fastest-growing demand sub-segments, alongside municipal drinking water treatment and industrial wastewater management.

Which regions are driving the fastest growth in PAC demand for desalination? The Middle East and Africa is projected to be the fastest-growing regional PAC market through 2031, at a CAGR of 4.38%, driven by GCC desalination megaprojects and the ongoing transition from thermal to RO-based technologies. Asia-Pacific, which holds nearly 49% of global PAC consumption, is adding new desalination-linked demand from coastal India, Southeast Asia, and China's water-stressed provinces.

What PAC grade specifications are most relevant for SWRO pre-treatment procurement? High-basicity PAC grades exceeding 85% basicity are the commercial preference for SWRO pre-treatment, offering superior turbidity removal and residual aluminium control. Liquid PAC is the dominant form for large-scale continuous operations due to dosing precision and handling efficiency. Powder PAC is growing in relevance for remote or modular plant configurations where logistics favour dry chemical supply over bulk liquid.

How does aluminium supply volatility affect PAC procurement for desalination operators? Aluminium is the primary feedstock for PAC production, and global aluminium supply deficits in 2025–2026 are pushing PAC prices and tightening supply. Desalination plant operators are increasingly moving toward long-term supply contracts with index-linked price escalation clauses to manage cost exposure, rather than relying on spot purchasing arrangements.

Who are the major global PAC producers supplying the desalination sector? Key producers include Kemira (Finland, approximately 15% global market share), Feralco Group (Sweden), GEO Specialty Chemicals and USALCO (United States), Grasim Industries and Gujarat Alkalies and Chemicals Limited (India), and a significant cluster of Chinese producers including Henan Lvyuan Water and Zhejiang Jiaxin Chemicals. China leads global production capacity following major capacity expansions between 2022 and 2024.

What is driving the shift from thermal to membrane-based desalination in the Middle East, and why does it matter for PAC demand? Thermal desalination technologies such as multi-stage flash distillation do not require chemical coagulation pre-treatment in the same way RO systems do. As GCC countries transition aging thermal capacity toward energy-efficient SWRO systems driven by lower operating costs and renewable energy integration targets, the volume of feedwater requiring PAC-based pre-treatment increases proportionally with each unit of new RO capacity commissioned.