Key Considerations When Implementing Chlorine Dioxide in Water Pre-Treatment Applications

Chlorine dioxide (ClO2) is a widely used, environmentally friendly microbicide that is popular in the brewing industry for water disinfection, equipment sanitization, surface sanitization, and CIP processes. Chlorine dioxide has many advantages compared to other common oxidants such as chlorine or ozone:

• Broad-Spectrum Efficacy: Effective against bacteria, viruses, molds, yeast, and fungi. ClO2 also disrupts biofilms, preventing bacterial regrowth.
• pH Range Stability: ClO2 remains stable within a pH range of 3-10, covering practical operating conditions for most water treatments.
• Low Corrosivity: ClO2 is less aggressive toward metals due to its low dose concentrations and lower reduction potential.
• Selective Oxidizer: ClO2 selectively reacts with certain oxidizable materials without affecting ammonia, carbohydrates, and hydrocarbons.
• No Toxic Byproducts: Unlike chlorine, ClO2 doesn’t form harmful byproducts like THMs or HAAs. It also doesn’t chlorinate phenols, preventing a “medicinal” taste in beer.

While chlorine dioxide offers numerous benefits, effective applications in water treatment require careful consideration of generation, measurement, and safety protocols. Key considerations for each are present when implementing a chlorine dioxide program in your brewery.

Generation of Chlorine Dioxide

Chlorine dioxide can be generated using an electrochemical method or by mixing chemical precursors, most commonly leveraging sodium chlorite as a precursor. Onsite production involves a generator that mixes the precursors and feeds the ClO2 solution directly to the water.

When selecting a generator, it is crucial to ensure that the chemicals and equipment used meet specific safety and health standards:

• NSF 60 Certification: Ensures that the precursors used in the ClO2 generation process meet the health and safety standards for chemicals used to treat drinking water.
• NSF 61 Certification: Ensures that the equipment used in the ClO2 generation process is safe for use in potable water applications, minimizing any potential contaminants, such as lead or mercury, that could leach into the water.

Proper sizing of the generator to meet peak demands is also crucial to ensure sufficient ClO2 production without overloading the system. Generators are rated by the mass of product per unit of time (e.g., 15 pounds/day). Since application demands vary with time (biocidal demand, production schedules, etc) you must consider the appropriate generate rate as well as the amount generated per day. The precursors used to generate ClO2 may also influence the rate of generation as well. For example, Ecolab’s Envirox™ Chlorine Dioxide Generation System only utilizes sodium chlorite as a precursor but carries a lower generation rate than the AccuPro On-site Generator which utilizes both sodium chlorite and a mixed acid. Each of these use precursors that carry the NSF 60 certification while each generator is also rated for the NSF 61 certification. 

Measurement of Chlorine Dioxide

Effective measurement of ClO2 concentration in water is essential to ensure proper disinfection and to prevent overdosage. If your ClO2 concentration is too low it can lead to microbiological outbreaks while overdosing can lead to corrosive conditions. Common methods for direct measurement include:

• Colorimetric (DPD): Uses reagents for periodic measurements. This method requires reagent monitoring and waste disposal.
• Membrane Sensors: Provides continuous monitoring through amperometric techniques. Membranes may foul over time, requiring periodic replacement.
• Bare Sensors: Monitors continuously through amperometric techniques but the sensor is in direct contact with the water source. These sensors can be manually or automatically cleaned to maintain reliability and increase their lifespan relative to membrane sensors.

When choosing a measurement method it is important to consider total costs, maintenance, and reliability for each type of sensor.

Safety Considerations

Due to the hazardous nature of ClO2 production involving precursors like sodium chlorite, bleach, and hydrochloric acid, strict safety measures must be in place. Key considerations include:

• Ensure proper mixing and storage to prevent adverse reactions.
• Wear proper PPE when handling precursors
• Store precursors in a well-lit, dry environment with secondary containment.
• Implement proper clean-up protocols to prevent sodium chlorite combustion.
• Install sensors and alarms to monitor ClO2 gas accumulation.
• Maintain equipment properly to avoid malfunctioning or incorrect ClO2 dispensing.

Opting for a supplier who provides regular maintenance for their ClO2 generators can help ensure the system is functioning correctly and safely.

READ MORE: Quality Control Methods

In summary, implementing chlorine dioxide can provide substantial benefits across brewery operations. However, careful consideration of generation methods, measurement techniques, and safety protocols is necessary to maximize advantages while mitigating risks. By addressing these key points, breweries and other industries can leverage ClO2’s strengths effectively.

*Biocide and food and beverage applications are regulated at the state and local levels. It is a violation of federal law to apply biocides outside of the stipulations stated on the USEPA Pesticide Label.

About Ecolab: Ecolab specialists can help streamline your brewery, enhancing product quality and productivity while helping your brewery achieve their sustainability goals. Ecolab is a global sustainability leader offering water, hygiene, and infection prevention solutions and services that protect people and the resources vital to life. Building on a century of innovation, we deliver comprehensive science-based solutions, data-driven insights and world-class service to advance food safety, maintain clean and safe environments, optimize water and energy use, and improve operational efficiencies for brewers around the world.

Talk with an Ecolab expert about aligning your brewing goals – from quality and efficiency to hygiene and water management. Learn more about Ecolab’s brewing solutions.