Sodium Hypochlorite

Primary uses

• Primary and secondary disinfection of drinking water
• Wastewater effluent disinfection before discharge
• Cooling-tower and process-water microbiological control
• Sanitation and clean-in-place duty in food and beverage plants

Applications

• Municipal water and wastewater plants in Ontario and Quebec
• Food and beverage processing sanitation
• Recreational water and aquatic facilities
• Industrial cooling systems

Advantages

• Avoids storing and handling chlorine gas, which removes an entire class of site risk
• Simple liquid dosing with well-understood residual monitoring
• Available from multiple sources across eastern Canada, which supports second-sourcing

Limitations to consider

• Loses strength in storage, faster when warm or exposed to light, so cost per unit of delivered chlorine drifts
• Raises pH as it is dosed, which affects disinfection efficiency and can require pH correction
• Highly incompatible with acids: mixing them releases chlorine gas, so storage separation is non-negotiable
• Attacks many metals and elastomers, so dosing-line materials must be checked
• Dose is established on your own water by jar test, coupon monitoring or a controlled plant trial. Supplier literature values are starting points for that trial, not a specification.
• Many treatment chemicals are regulated in transport and have specific storage, containment and personal-protection requirements. The SDS for the exact product offered is the governing document, and it should be reviewed before the delivery is scheduled rather than after it arrives.

How to choose the right grade

• Say what you are trying to kill or oxidise, and the standard or permit condition you have to satisfy
• State the system: potable water, wastewater, cooling tower, process water, pool or clean-in-place
• Confirm whether the application is regulated for potable or food-contact service, because that decides the documentation before it decides the chemistry
• Consider how the product is dosed and measured — a solid oxidant and a bulk liquid oxidant need different hardware and different operator routines
• Confirm demand in the water: organics, ammonia, iron and manganese all consume oxidant before any residual is available
• Confirm storage turnover, since oxidant strength falls in storage and a large infrequent delivery can be worse value than a small frequent one
• Oxidants lose strength in storage, and the rate depends on temperature, light and time since manufacture. The value that matters commercially is the strength at the point of use, not the strength on the day it was made, so delivery frequency and turnover should be part of the buying decision.
• Exact specification is confirmed against supplier documentation at quotation.

Typical grades

• Industrial solution grade
• Potable-service grade where the supplier holds the certification for that product
• Solution strength and active content are per-offer values, and they change the dose and the true cost per unit of water treated. Compare quotations on active content delivered, not on price per litre or per kilogram, and read the value from the supplier documentation for the exact product offered.
• Drinking-water and food-contact applications require certification held for the specific product and manufacturing site. Whether the product offered carries it is confirmed against supplier documentation at quotation and is never presented here as a held approval.