Treatment chemicals make most water and wastewater processes work: coagulants clarify water, antiscalants protect membranes and boilers, biocides control microbial growth and pH chemicals keep every step in range.
Chemicals are bought continuously, so small differences in price per kilogram add up. But price per kilogram of product is rarely the right comparison. What matters is the cost of achieving the required result at the required dose.
What falls under this category
- Coagulants and flocculants
- Aluminium sulphate, polyaluminium chloride, ferric chloride and organic polymers (polyelectrolytes) for clarification and sludge dewatering.
- Antiscalants and dispersants
- Formulated for RO membranes, boilers or cooling systems to keep scale-forming salts in solution.
- Biocides
- Oxidising types such as sodium hypochlorite and chlorine dioxide, and non-oxidising types such as isothiazolinones, DBNPA and glutaraldehyde.
- pH adjustment
- Sulphuric and hydrochloric acid, caustic soda and lime.
- Dechlorination and oxygen scavengers
- Sodium metabisulphite ahead of RO membranes; oxygen scavengers for boiler water.
- Membrane cleaners and regenerants
- Acid and alkaline membrane cleaning formulations, and salt, acid and caustic for ion-exchange regeneration.
Specifications to compare
- Active content
- The concentration of the active ingredient and how it is measured. Compare cost per kilogram of active, not per kilogram of product.
- Recommended dose
- The dose and how it was calculated for your system. For RO antiscalants, reputable suppliers run dosing software against your water analysis and share the result.
- Compatibility
- With your membranes, other chemicals and materials. For example, cationic polymers carried over from pretreatment can foul negatively charged RO membranes, so coagulant and antiscalant choices should be checked together.
- Approvals
- Certification for use in drinking-water treatment (for example NSF/ANSI/CAN 60) where the treated water is potable.
- Documentation
- Current safety data sheet, certificate of analysis for each batch, shelf life and storage temperature limits.
- Packaging and logistics
- Drums, IBCs or bulk delivery, and lead times to your site.
Information to send suppliers with your enquiry
- System type (RO, boiler, cooling tower, clarifier, ETP) and a recent water analysis.
- Current product, dose and monthly consumption, if you are replacing an existing programme.
- Preferred packaging and delivery frequency.
- Documents you require with each delivery.
Common sourcing mistakes
- Comparing prices without comparing active content.
- Switching product mid-programme without a compatibility check against other chemicals in the system.
- Storing incompatible chemicals together. Acids and sodium hypochlorite, for example, release chlorine gas if mixed.
- Accepting deliveries without a batch certificate of analysis.
Test before you commit
For coagulants and flocculants, a jar test on your own water is the most reliable way to compare products and doses before a trial on the full plant. Many suppliers will run one, or supply samples for your laboratory to test.