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Wastewater reuse can help Canada’s dairy industry

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Rising costs of wastewater treatment and water supplies have made in-house wastewater treatment and water recycling attractive for the dairy industry.

By John Nicholson and Anastazia Jagdeo

The Canadian dairy industry is a major contributor to the nation’s fabric, producing high quality milk, cheese, yogurt, butter and other products. According to the Canadian Dairy Information Centre, there are over 10,000 dairy farms in Canada, employing the full-time equivalent of over 221,000 people. These farms are home to almost 1 million dairy cows.

The industry annually contributes $19.9 billion to Canada’s gross domestic product, with the federal and provincial governments collecting a total of $3.8 billion in tax revenue. Dairy is either the top or second agricultural sector in seven out of the 10 provinces.

In many other jurisdictions around the world, farmers are heavily subsidized by the government. Canadian dairy farmers do not receive direct subsidies, although it can be argued that the industry receives indirect subsidies under Canada’s supply side management regime for dairy products.

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Challenges

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The Canadian dairy industry faces many challenges, especially in the form of trade agreements which subject farmers to increased competition both internally and externally.

The most recent challenge is the renegotiated and yet-to-be ratified United States – Mexico – Canada Agreement (USMCA), also described as the North American Free Trade Agreement (NAFTA) 2.0. If ratified by all three North American countries, the USMCA will further open up the Canadian market to the import of government-subsidized dairy products from the United States and Mexico.

Further pressure on the Canadian dairy industry has been exerted by the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP). The CPTPP is a free trade agreement between Canada and 10 other countries in the Asia-Pacific region. Under the CPTTP, member countries will have more access to the Canadian market.

Finding economic advantages in environmental practices

The new reality of competing for market share with dairy companies from all over the world has created challenges and opportunities for Canadian farmers. Becoming more efficient and productive will allow them to better compete with foreign imports.

One area of opportunity for the Canadian dairy industry to increase competitiveness can be found within its environmental practices, most notably wastewater treatment. If Canadian dairies can lower their wastewater treatment costs, savings can go right to the bottom line. As an added potential benefit, there are a growing number of consumers who “green purchase” and prefer to spend money on goods that are produced in a more environmentally friendly way.

Current wastewater treatment methods

Wastewater generated in the dairy industry comprises 50% – 80% of the total water consumed at a dairy processing facility. Current wastewater management practices vary from jurisdiction to jurisdiction.

The wastewater from a dairy processing plant mainly consists of lost raw materials, intermediate and finished products, and wash water from equipment cleaning. The major pollutants are biochemical oxygen demand (BOD), total suspended solids, phosphorus and ammonia. In addition, dairy wastewater also requires pH adjustment prior to discharge.

The location of the dairy processing facility, urban versus rural, typically dictates the wastewater treatment methods and the extent of treatment required.

In rural areas, where treated wastewater is discharged directly to the environment, stringent requirements of treatment are upheld. For example, it is typical in many jurisdictions that the BOD₅ (five-day biochemical oxygen demand) concentration of wastewater must be below 25 ppm before it is discharged to a river or lake. The BOD₅ of untreated dairy wastewater can be in excess of 500 ppm and requires extensive treatment, especially in rural regions.

In an urban location, wastewater from a dairy processing facility is typically discharged to the sanitary sewer and subsequently treated at a municipal wastewater treatment plant. As such, the limits on the concentration of pollutants are less strict than what is required when there is direct discharge to the environment.

Potential for water recycling

Most dairy operations are situated in rural areas and are in close proximity to their source material – milk. They are increasingly faced with the challenge of sufficient water supply, especially in the case of an increase in production. As such, water recycling and reuse has grown in popularity. Process wastewater is becoming too precious a resource to simply flush down the drain.

Rurally located dairy operations are also faced with the challenge of either treating wastewater on-site prior to disposal, or arranging for off-site treatment. Both options are typically challenging and expensive.

Dairy processors that choose to treat their wastewater on-site realize advantages that include reducing and controlling costs internally, and recycling water for reuse. The challenges of on-site treatment include potential odour issues, spatial restrictions, and the need for specialized training of staff to operate the wastewater treatment system.

The combination of rising costs of wastewater treatment, and challenges with securing water supply has made the appeal of in-house wastewater treatment and water recycling more economical.

CharTech Solutions has developed and implemented both packaged and custom water recycling systems for the food industry. The heart of the system is a compact membrane bioreactor (MBR). Aerobic microorganisms in the MBR remove the organic components (typically measured as BOD5) from the wastewater, and the ultra-filtration system removes any suspended solids. The water is polished, using reverse osmosis and/or ultraviolet disinfection, and can be reused in the facility.

Cost-benefit analysis

CharTech Solutions helped one rural, farm-based operation in Canada develop and commission the first closed loop water treatment and reuse system in North America. The innovative system allowed the farm-based fruit processor to reduce their operating costs by $150,000 per year, and provided a payback of less than three years.

Analysis has shown that there are potential costs savings with wastewater recycling in the dairy industry. Conducting a cost-benefit analysis needs to take into consideration the yearly operating expenses of water intake and wastewater discharge and compare those costs to the capital expense of a new closed loop water system. With the global competition in the dairy industry, it may be worthwhile for many facilities to consider a closed loop wastewater recycle system.

John Nicholson, MSc, P.Eng., and Anastazia Jagdeo, BSc, are with CharTech Solutions. This article appears in ES&E Magazine’s October 2019 issue.

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