Use of reclaimed water in industrial cooling systems

Climate change will change the way we use water. With greater unpredictability in weather patterns, it is going to be harder to ensure sufficient water provision, maintain water quality and deliver all the water required for development, biodiversity and human sanitation.

The reuse of reclaimed water could be one part of the solution. By reusing industrial or domestic wastewater, companies may be able to reduce the impact on the environment and help conserve clean water supplies.

A new standard, BS ISO 22449-1:2020 Use of reclaimed water in industrial cooling systems. Technical guidelines sets out a basic framework for how industry can use wastewater in cooling systems. The standard aims to promote systems using reclaimed water and help implement their use.

Industry uses half of all water in Europe and North America

Vast quantities of water are used each year by industry cooling systems. Industry is responsible for 22% of global water use. In advanced economies such as Europe and North America in 2009, industrial water consumption is 50% of total use.

In developing economies, only 4-12% of water is currently consumed by industry. However, this proportion is predicted to rise rapidly in the next few decades, putting pressure on supplies and causing conflict between different user groups.

Countries including the United States, Japan, Israel and Indonesia have been making rapid progress in developing cooling systems that use wastewater for industrial cooling.

How reclaimed water is used in industrial cooling

Industry can utilize industrial wastewater, domestic wastewater or a mix of the two in cooling systems but until this standard was published there was no ISO guidance on using reclaimed water in this way. Designing a cooling system is complex, requiring the careful balancing of cooling requirements, site-specific factors and environmental requirements.

Use of reclaimed water can be associated with corrosion and scaling within a cooling system. Care needs to be taken to address these potential problems as well as finding the most environmentally friendly solution within the constraints of the industrial process.

Common pollutants in wastewater include asbestos, lead, mercury, nitrates, phosphates, sulphur, oils and petrochemicals, all of which can be harmful to human or animal life. Many of these pollutants can be addressed using a chemical treatment (scale or corrosion inhibitor) or a physical treatment (electronic descaling).

The business case for reducing water usage

Using reclaimed water will contribute to a company’s environmental targets and commitment to an industrial circular economy within an environmental management system (EMS). These initiatives often involve more straightforward uses of wastewater or grey water, such as using rainwater collected on roofs for  toilet flushing, irrigation or vehicle washing.

There is the scope to reduce expenditure on water supply and effluent disposal by up to 30%. These costs have been rising in recent years and this increase looks set to continue.

Where companies opt to treat their industrial wastewater to remove some raw material or product prior to using the water in a cooling system, this can have the added benefit of reducing cost for the effluent stream further down the line.

What does the standard cover?

BS ISO 22449-1:2020 provides a basic framework for using reclaimed water in an industrial cooling system. It sets out water quality specifications, water quantity and temperature requirements, wastewater treatment technologies for reuse and the treatment for inhibition of corrosion, scaling and biological fouling.

Annexes to the standard provide guidance on types and characteristics of industrial cooling systems, water quantity requirements, and make-up water quality requirements in a closed-circuit hybrid cooling system. There are diagrams showing the different types of cooling water system, as well as guidance on their characteristics.

The standard is available from the online BSI shop.