Recycling Water in the Dairy Industry

According to the World Bank, 70% of all freshwater used globally is used for agriculture. In Australia and many other countries around the world, the dairy industry is one of the largest agricultural industries, and accounts for a significant portion of water usage in the agricultural sector. Using recycled water for irrigation on dairy farms and recycling water in diary processing factories can help drought-proof the industry and ensure the sustainability of both our water and milk supply in the future ahead.

Future-proofing water management in the dairy industry

The dairy industry is a water intense industry, with water being used at multiple stages of the milk production process. Water is used to irrigate pastures that feed dairy cows, and in dairy processing facilities for processing milk, cleaning equipment and work surfaces, in cooling processes and steam production, as well as for maintaining staff amenities and irrigating garden landscaping. The pressure on water resources continues to grow as urban areas expand; so too does the competition between urban water demands and that of industrial and agricultural sectors continue to increase. Since the dairy industry is heavily dependent on water, it would benefit from managing water resources more prudently to improve its resilience to drought, and to ensure it can meet future water demands and continue to be productive in a potential future scenario of water scarcity and water restrictions. This can be achieved by reducing its water demand, which can in turn be achieved by reusing and recycling water across all operations.

Sustainable use of water in the dairy industry

Irrigating dairy farms with recycled wastewater

Many dairy farms in Australia are already using recycled sewage wastewater to sustainably irrigate the pastures their cows graze on. Irrigating pastures with recycled water not only helps dairy farmers improve water security and become resilient to droughts, it also frees up freshwater that can serve important ecological functions and/or makes it available to the broader community.

Recycled water in milk-processing operations

The use of recycled water in the dairy industry is not limited to irrigation use only. It can also be used to augment the water supply of milk-processing facilities, thereby ensuring they are able to produce milk even in times when water is scarce. While careful attention must be given to the health risks associated with using recycled water near food items, the technology to safely recycle wastewater back to potable water does exist, making this a viable option for dairy processors to reduce their water intensity and in so doing, future-proof their business operations and improve their environmental sustainability performance.

The main water usage areas in diary processing can be broadly categorised as follows:

•      Process water — water used for cleaning-in-place (CIP), etc.

•      Cooling water — water used to remove heat during the production process.

•      Boiler feed water — water used for steam production.

•      Other water — water used for miscellaneous activities such as crate washing, etc.

According to Dairy Australia, the two largest areas of water use in dairy processing operations are CIP and pasteurisation (which together account for more than 50% of water use during diary processing), followed by cooling towers (16%). These high-water usage areas present an opportunity to implement technologies to reuse and recycle water in an effort to reduce the water demands of these processes, and ultimately the volume of water used in the overall milk production process. Water from non-food product surfaces, for example, can be reused as wash water or as cooling water in cooling towers, with very little to no treatment required.

Reusing condensate

Condensate produced during milk homogenisation, butter churning, cheese production, and milk powder drying is considered clean water and is often reused as process water with very little treatment. Milk powder drying generates a significant amount of condensate water, which can be utilised elsewhere.

Reusing cooling tower water

Cooling water used in cooling towers can potentially be recirculated, thereby extending the length of time it used in the cooling process. However, due to concerns over risks associated with water quality from this source, its use in other areas of dairy processing are limited to cleaning water used to clean surfaces that do not come into contact with food products. There are currently several chemical-free treatment solutions available on the market that are energy-efficient and easy to install.

Recycling wastewater

The final option available to dairy processors to help reduce their water use is to fully recycle wastewater effluent produced during processing. This typically requires installing an advanced biological wastewater treatment system. While the initial cost of installing wastewater treatment technologies capable of treating wastewater to potable quality may seem daunting, this does not necessarily need to be the case. Considering that recycling wastewater to potable standard provides a stream of water that can safely be used throughout diary processing operations, this could mean the difference between make or break during times of water scarcity.

There are a wide range of wastewater treatment technologies available on the market. The key is to choose the most suitable and cost-effective technology according to the application and desired water quality. Implementing an appropriate wastewater treatment and water recycling strategy can provide dairy processors with a viable and sustainable source of water.

Reference: Dairy Australia Report - Opportunities for Reducing the Intensity of Water Consumption in the Australian Dairy Processing Sector.