High-basicity aluminum chlorohydrate (ACH) is a practical coagulant for the water-reuse and recycling schemes that keep drought-prone Australia running. With more than 23% Al2O3 and 82-85% basicity, ACH removes fine solids, colour and organic matter at low dose, producing clear water that is ready for further treatment and reuse, with a negligible effect on pH and low sludge volume. As the Australian Guidelines for Water Recycling and the National Water Initiative push towns, farms and industry toward greater reuse, that performance becomes strategic. This guide explains what ACH is, why high basicity suits recycling schemes, and how to select, dose and monitor it. Whether the goal is municipal recycling, aquifer recharge or industrial reuse, correctly applied ACH improves clarity, protects downstream filters and membranes, and supports regulatory confidence. For councils, growers and industry alike, that clarity is the foundation of a reliable, drought-resistant water supply. In a dry country, that is a strategic advantage.
Aluminum chlorohydrate (ACH) is a highly polymerised, water-soluble aluminium coagulant with the formula Al2(OH)5Cl·2H2O. It offers the highest Al2O3 content (over 23%) and the highest basicity (82-85%) of any commercially available aluminium-based solution, and it ships as a ready-to-use liquid.
Its role in water reuse. Reuse schemes must remove the fine solids, colour and organic matter that would otherwise foul filters, block membranes and pose a health risk. ACH's highly charged, polymerised aluminium species neutralise the charge on these contaminants and gather them into dense flocs that are easily separated, leaving clear water ready for the next treatment step.
| Property | Value |
|---|---|
| Al2O3 content | >23% |
| Basicity | 82-85% |
| Density | 1.30-1.38 g/ml |
| Water insoluble | ≤0.1% |
| Iron (Fe) | ≤100 ppm |
Why pre-polymerised matters. Conventional coagulants consume alkalinity and depress pH, which can destabilise a treatment train. ACH is already neutralised, so it works across a wide pH range, barely changes pH and performs reliably even in the variable water qualities seen in recycling schemes.
Blend flexibility. ACH can be blended with organic polymers such as PolyDADMAC or polyamine, and it pairs naturally with membranes and filtration, protecting them by improving upstream clarification.
Supplied as a ready-to-use liquid, ACH is metered with standard dosing pumps and holds its properties in storage, so the performance validated in trials is repeated on site.
How it compares with conventional coagulants. Alum and similar salts consume alkalinity, depress pH and can perform poorly in variable or cold water, which is exactly the profile of many reuse sources. ACH is already neutralised, so it works across a wide pH range, barely changes pH and performs reliably, forming dense flocs that filters and membranes can readily remove - protecting the very equipment a reuse scheme depends on.
Because it is concentrated and pH-stable, ACH suits the variable, sometimes nutrient-rich water that recycling schemes actually receive.
Australia is the driest inhabited continent, and the way it manages water is defined by scarcity. The National Water Initiative and the Australian Guidelines for Water Recycling (AGWR) set out how towns, farms and industry can safely reuse water, and coagulation is a cornerstone of every robust scheme, because removing solids and organic matter protects everything downstream.
Protects filters and membranes. Fine particles and organic matter are the main causes of membrane fouling and filter blockage. Efficient coagulation with ACH extends run times, cuts cleaning frequency and reduces operating cost in membrane and filtration trains.
Improves treated-water quality. By removing turbidity, colour and much organic matter, ACH helps recycled water meet the quality needed for irrigation, industrial use or aquifer recharge, supporting the risk-based framework of the AGWR.
Low dose, low sludge, pH-stable. ACH's high Al2O3 content means less product per megalitre, its low water-insoluble content produces less sludge, and its negligible pH impact avoids destabilising the process.
The economics are compelling in a dry climate. Every megalitre reused is a megalitre not drawn from stressed rivers, dams or aquifers, and not discharged. For councils, growers and industry, efficient coagulation lowers the cost of producing recycled water while strengthening the reliability of supply through drought.
Public confidence matters as much as performance. Reuse schemes live or die on community trust, so consistent, demonstrable water quality is essential. A dependable coagulant such as ACH that delivers predictable results helps operators meet the monitoring and validation requirements of the AGWR and reassure regulators and the public.
Seasonality adds stress. Droughts concentrate contaminants, while intense storms and floods wash in sediment and organic matter; a stable, pre-polymerised coagulant keeps performance on target through both extremes.
A growing number of Australian applications depend on reliable coagulation, from municipal recycling for parks and ovals, to industrial reuse for cooling and washing, to managed aquifer recharge and agricultural irrigation. In each case the principle is the same: clean the water well at the front end, and the whole scheme performs better and lasts longer.
Logistics suit regional and remote schemes: ACH ships as drums, IBCs or a flexitank, so a single concentrated liquid can serve a scheme far from major centres.
Total cost of ownership should guide selection. A highly concentrated, pH-stable ACH that cuts dose and improves clarity lowers chemical, energy and maintenance costs together, an outcome that matters where water is treated every day of the year.
ACH is simple to use, but reuse schemes reward a structured approach. Follow these steps.
State clearly what the recycled water must be fit for - irrigation, industrial use, aquifer recharge or indirect potable supply - and note the water-quality requirements and the AGWR risk controls that apply.
Measure turbidity, colour, organic matter, pH, alkalinity and temperature, and sample across seasons and weather events, because droughts and floods change both the source and the treatment demand.
Test ACH dose against settled turbidity, colour and organic matter removal, and against filterability, since good coagulation shows up as longer filter runs and slower membrane fouling. Start low and bracket upward.
Pair ACH with filtration or membranes, and where needed blend it with an organic polymer for difficult waters, adding ACH first for charge neutralisation. Calibrate pumps, set a control range and monitor treated quality continuously.
Keep ACH sealed in a dry, ventilated place away from rain, heat and sunlight, and never store it with alkaline chemicals such as lime or bleach. Follow the safety data sheet and WHS practice, and use corrosion-resistant dosing equipment.
| Reuse application | Role of ACH |
|---|---|
| Municipal recycling | Clarity for irrigation and non-potable reuse |
| Industrial reuse | Cleaner water for cooling and washing |
| Aquifer recharge | Solids removal to protect recharge wells |
Consider an inland council building a recycling scheme to irrigate parks and sports fields. Secondary effluent is coagulated with ACH ahead of filtration and disinfection. Jar tests set a low dose, given ACH's high concentration, and monitoring confirms settled turbidity and filterability improve, so filter run times lengthen and the scheme meets the quality required for irrigation. Because ACH barely shifts pH, the downstream disinfection step stays stable. The council draws less from its stressed supply, and the confidence that comes from demonstrable water quality helps win community support.
Do not set a fixed dose across the year, because drought concentrates contaminants while storms and floods load the plant with sediment and organic matter; review the dose seasonally. Always jar-test, protect equipment with corrosion-resistant dosing parts, and never store ACH with alkaline chemicals. Where membranes are used, consider filterability or membrane trials, not just jar tests, before committing to a change. Finally, document every trial and monitoring result, because the AGWR framework rewards operators who can demonstrate consistent, validated performance.
Where the recycled water feeds membranes, validate the dose with a silt density index or membrane trial, since good jar-test results do not always guarantee low fouling. Coordinate the coagulation setpoint with the downstream disinfection and reuse requirements, so the whole train is optimised together rather than in isolation. Review the dose after every significant weather event, because a single flood can change source quality for weeks, and keep operators trained on the control response plan.
Yes. ACH is an effective coagulant for water-reuse and recycling schemes, where it removes the fine solids, colour and organic matter that would otherwise foul filters and membranes. Used early in the treatment train, it improves clarity and protects downstream processes, supporting schemes aligned with the Australian Guidelines for Water Recycling.
Reuse water must be clean enough to protect filters, membranes and downstream disinfection, and coagulation is the first and most important step. By removing particles and organic matter, coagulation reduces fouling, improves disinfection and helps recycled water meet the quality required for irrigation, industrial use or aquifer recharge.
Membrane fouling is driven largely by fine particles and organic matter. By coagulating and removing these contaminants upstream, ACH reduces the load reaching the membranes, which extends run times between cleanings, lowers energy and chemical use, and lengthens membrane life.
The dose depends on the source water and the reuse goal, so it must be set by jar testing and, where possible, by filterability or membrane trials. Because ACH is highly concentrated, doses are low. Operators start low and increase until clarity and performance targets are met.
Very little. ACH is already heavily neutralised, with basicity of 82-85%, so it consumes almost no alkalinity and produces a negligible pH change. That stability is valuable in reuse trains, where sudden pH shifts can upset membranes, disinfection and downstream chemistry.
Keep ACH sealed in a dry, ventilated place away from rain, high temperature and sunlight, and well away from alkaline chemicals. It ships as drums, IBCs or a flexitank, which suits regional and remote schemes. Always follow the safety data sheet and local WHS requirements.
In a country defined by drought, water reuse is no longer a niche idea but a necessity, and aluminum chlorohydrate belongs at the front of every well-designed recycling train. Its high Al2O3 content and 82-85% basicity deliver efficient clarification at low dose, with low sludge and negligible pH impact, protecting filters and membranes and helping recycled water meet the standards demanded by the AGWR. Define the end use, characterise the source, jar-test the dose and store the product correctly, and ACH becomes a dependable foundation for confident, cost-effective water reuse across Australia.
