ACH Water Treatment Coagulant | Beta Pramesti Asia

ACH water treatment uses aluminum chlorohydrate, a pre-hydrolyzed coagulant, to destabilize colloids before flocculation, sedimentation, or filtration. ACH is worth testing when alkalinity is limited or pH depression must be controlled, but the final dose must come from jar tests on current raw water and full-scale verification.

PT Beta Pramesti Asia supplies coagulants and application support for drinking water, process water, and industrial wastewater. Selection cannot rely on the coagulant name alone: turbidity, colour, TOC/COD, pH, alkalinity, temperature, residual-aluminum target, sludge production, and cost per m³ all need comparison.

What is Aluminum Chlorohydrate (ACH)?

• Chemical name: Aluminum Chlorohydrate, sometimes written “ACH” or “Aluminum chlorhydrate”.
• General formula: Al₂(OH)₅Cl · 2H₂O for a hydrated representation.
• ACH is a hydrated aluminum compound containing chloride and hydroxide.
• It dissolves in water and forms positively charged species.

ACH belongs to the family of polymerized/pre-hydrolyzed aluminum salts. Commercial specifications vary in Al₂O₃ content, basicity, density, liquid/solid form, impurities, and intended grade. A price-per-kilogram comparison is therefore incomplete; compare the cost at the tested dose and actual treated-water volume.

Supplier document to check	Why it matters
Technical Data Sheet	Defines active content, density, product pH, form, and storage conditions
Batch Certificate of Analysis	Shows the delivered batch against the purchase specification
Safety Data Sheet	Defines PPE, first aid, spill response, and incompatibilities
Grade/regulatory statement	Confirms suitability for the intended drinking, process, or wastewater duty

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Role of ACH in Water Treatment

ACH destabilizes suspended particles, selected organic matter, colloids, and impurities before solids separation. US EPA explains that coagulation neutralizes colloid surface charge and flocculation grows settleable aggregates; EPA recommends jar tests to assess coagulant dose, polymer aids, mixing time, and raw-water response (US EPA, water-treatment effects guidance).

Function / Advantages	Explanation
Coagulant / Flocculant	ACH destabilizes fine particles so downstream mixing can grow flocs that settle or filter more readily.
Potential dose reduction	Its charge and pre-hydrolysis can justify a lower tested dose than another aluminum salt in some waters.
Potentially smaller pH effect	ACH may consume less alkalinity than a lower-basicity aluminum coagulant under comparable conditions.
Operating window	Performance can remain useful across a practical pH window, but the window is water-specific.
Potential sludge reduction	A lower effective product dose may reduce chemical solids, provided raw-water removal and residual targets are met.

Treat every advantage in the table as a hypothesis to test against the site’s PAC/alum baseline. ACH does not automatically dose lower or make less sludge in every raw water. Compare products as delivered and, when active-content data are available, on an Al or Al₂O₃ basis.

ACH vs PAC vs alum decision table

Criterion	ACH	PAC	Alum	How to decide
pH/alkalinity effect	Often tested where buffering is limited	Depends on basicity and grade	Usually needs closer alkalinity review	Measure pH and alkalinity before/after jar tests
Grade flexibility	More specialized specifications	Many liquid/solid grades	Simpler, widely available product	Compare TDS/CoA, not generic names
Dose	Not universal	Not universal	Not universal	Run a dose sweep on the same sample
Sludge	Depends on dose and raw water	Depends on dose and raw water	Depends on dose and raw water	Measure volume and settleability
Residual Al	Must be monitored	Must be monitored	Must be monitored	Test settled/filtered water at operating pH
Cost	Product price may be higher	Varies with grade/logistics	Often lower per kg	Calculate total cost/m³ including alkali, polymer, sludge, handling

Starting-dose calculation for a jar test

Use a known stock concentration and keep dose units consistent as commercial product or active material:

Stock volume (mL) = target dose (mg/L) × jar volume (L) ÷ stock concentration (mg/mL)

Example: a 10,000 mg/L ACH stock equals 10 mg/mL. To test 20 mg/L in a one-litre jar, add 20 × 1 ÷ 10 = 2 mL of stock. Prepare points below and above the baseline dose; 20 mg/L is a calculation example, not an operating recommendation.

Record at least turbidity, pH, alkalinity, colour/UV254 or TOC where relevant, floc size/strength, settling time, residual aluminum, sludge volume, and chemical cost per m³. EPA notes that there is no universal jar-test protocol and that raw-water changes can alter the outcome (US EPA, water-treatment effects guidance).

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Example in Water Treatment Process

In a drinking water treatment system:

1. Raw water is added with ACH solution.
2. Suspended particles, organic matter, and colloids are destabilized and form flocs.
3. The flocs are then filtered or settled, making the water clearer.
4. After that, filtration, disinfection, and final pH adjustment may be performed.

At full scale, injection order and mixing energy must provide rapid dispersion followed by gentler flocculation so flocs grow without excessive breakage. Transfer a jar-test result in stages: run a controlled trial, monitor settled and filtered water, inspect sludge, then establish a dose-control rule tied to raw-water changes.

Plant-trial checklist before changing coagulant

1. Establish the PAC/alum baseline at the same flow, raw-water quality, and finished-water target.
2. Verify ACH TDS, SDS, CoA, density, active content, basicity, grade, and tank/pump compatibility.
3. Run a dose sweep, a pH sweep where relevant, and a blank/control under consistent mixing.
4. Select from water quality, residual aluminum, settleability, sludge, and total cost—not turbidity alone.
5. Calibrate the chemical dosing pump for actual product density and concentration.
6. Run the plant trial during stable conditions and change one primary variable at a time.
7. Set alarms for pH, turbidity, flow-paced dose, tank level, and filtrate quality.
8. Retain batch, dose, raw-water, laboratory, and operator-change records for auditability.

For product comparison, review PAC and ACH for water treatment, Betagard Aluminum Chlorohydrate Series, and coagulants for water and wastewater.

Frequently asked questions about ACH water treatment

When should ACH be tested instead of PAC or alum?

ACH belongs in a jar-test comparison when PAC or alum depresses pH too far, raw-water alkalinity is limited, residual-aluminum targets are difficult to meet, or total treatment cost is unstable. A change still needs side-by-side evidence for finished-water quality, alkali/polymer demand, sludge, and cost per m³.

Is the ACH dose always lower than the PAC dose?

No. Product basicity and active content vary, while raw-water pH, alkalinity, temperature, turbidity, and organic matter affect the response. Compare commercial-product doses and, when the CoA provides the required data, normalize the comparison to Al or Al₂O₃ through a consistent dose sweep.

Which documents should a buyer request before purchasing ACH?

Request the Technical Data Sheet, Safety Data Sheet, batch Certificate of Analysis, grade statement, active content, density, product form, packaging, and storage requirements. These details are needed to check tank compatibility, calibrate the dosing pump, and compare commercial offers on the same basis.

Data needed for ACH selection

Send normal/peak flow, source water, turbidity, colour, pH, alkalinity, temperature, TOC/COD, TSS, current coagulant and dose, finished-water target, tank space, dosing-line material, and sludge data to the Beta Pramesti team. The team can structure a jar-test and trial program; the operating dose still comes from site data.