Air & Water

Mercer’s Responsible Management of Air and Water Resources

Resource management is guided by a core set of principles that drive ethical and responsible practices. At Mercer, we wholeheartedly embrace these principles to ensure the responsible and ethical management of our air and water resources.

Sustainability: Our primary commitment is to ensure that our resource management practices are sustainable, preserving these valuable assets for future generations.

Efficiency: We use our resources diligently, minimizing waste and maximizing their utility to achieve optimal results.

Environmental Responsibility: Mercer places the utmost importance on minimizing the environmental impact of our resource management, striving to minimize harm.

Stewardship: We recognize our role as stewards, safeguarding and preserving these resources as a collective responsibility.

Data–Driven Decision–Making: Our resource management decisions are grounded in data, enabling us to make well-informed choices that maximize benefits and minimize risks.

Compliance: Mercer strictly adheres to all relevant laws and regulations, upholding the highest ethical and legal standards in resource management.

Adaptability: We remain flexible and adaptable, ready to adjust our resource management strategies to accommodate changing environmental and market conditions.

Community Engagement: We actively involve local communities and stakeholders, ensuring their voices and needs are considered in our resource management decisions.

Innovation: Embracing innovative technologies and practices, we continually seek ways to enhance the efficiency and sustainability of our resource management efforts.

Transparency: Mercer maintains open communication about our resource management practices and outcomes, building trust and accountability.

These principles guide our actions as we strive to manage our air and water resources responsibly, reflecting Mercer’s dedication to environmental protection and ethical resources.

Air Quality Management

Our mills are modern and incorporate leading air emission abatement equipment and technology. We focus on continuous improvement of our processes to minimize or eliminate production upsets which may impact our emission levels. Our strategies include combustion control, precipitators, scrubbers, and the incineration of gasses related to our recovery boilers, power boilers, lime kilns, and smelt dissolving tanks all with a view to minimizing SO2, TRS, NOX, and particulate matter.

Mercer Air – SO2

Mercer Air – Particulate Matter

Mercer Air – NOX

We use modern electrostatic precipitators to effectively remove particulate from flue gases. The material collected in the recovery boiler and lime kiln precipitators contains valuable minerals, which are recycled back into the process and reused. As well, there are various scrubber systems located in our mills. From bleach plant scrubbers designed to clean the gas emissions from the bleach plant, while also being designed to allow us to return and reuse the scrubbing solutions; to the CLO2 plant scrubbers that minimize the gaseous emissions of chlorine and CLO2 from the R8 generators (which produces the CLO2 solution used in the bleaching process). The efficiencies realized from our scrubbers are yet another way we are working towards lowering our emissions and working in an environmentally friendly manner.

Controlling Odour Emissions

Kraft mills are often associated with distinct smells and odours. The source of odours is non-condensable gases (NCGs) which contain reduced sulphur compounds, commonly called total reduced sulphur (TRS) compounds. Our mills control and manage our odours by employing three NCG collection systems:
- Steam Stripping System (takes foul condensates, which are wastewaters saturated with odorous compounds, and strips them of these compounds using a counter-current flow of high-pressure steam)
- LVHC System (low-volume high concentration; collects non-condensable gases that are relatively small in volume, but high in sulphur content)
- HVLC System (high-volume low concentration; collects non-condensable gases that are low in sulphur content).
The stripped NCGs collected in these three systems are directed to an incineration source (lime kiln, power, or recovery boilers) where they are destroyed, thereby eliminating the odour.

We understand that odours do impact our neighbours, from time to time, as an irritant due to smell. We take odour issues very seriously and work to notify our neighbours proactively if an odorous release occurs; however, we do encourage members of our communities to contact us directly if there is an odour issue, allowing us to respond, monitor, and improve our processes. We can then work towards achieving zero odour reports, as our goal is to continuously improve.

Sustainable Water Use

Responsible water use is an increasingly important global topic. We understand and fully agree that limiting water use and protecting water quality is an extremely important aspect of sustainably managed operations.

Mercer’s global water strategies include the goals of water conservancy and water efficiency. Together they contribute to ecosystem stability and allow us to be better prepared in times of water shortage and support best management practices.

We use water for carrying fibre throughout the pulping process: for cooling and to generate electricity. Most of the water we utilize comes from large waterways such as the Columbia and Peace Rivers in Canada and the Elbe and Saale Rivers in Germany. We also utilize backup supplies of water from wells, when necessary, and we clean the water before using it. In fact, we operate the largest industrial-use reverse osmosis water treatment plant in Germany at our Stendal mill. Our cleaning process removes sediment and chemicals such as phosphorus that are present in the water from agricultural runoff.

While pulping processes require water, we seek always to limit unnecessary water usage and we ensure that the water is treated and returned to its source at the appropriate temperature.

Mercer Water Usage

Cooling Water Process

The majority of the water we use is returned to the same waterway from which we drew it. Most of the water we draw is used for the sole purpose of cooling; other than the cleaning the water receives when it is drawn, our water is not treated in any way. The primary focus of this water is to limit losses to the air through steam and to keep the water as close as possible to the temperature of its source when it is returned. We have strict limits on water temperature as regulated by government agencies and we are in compliance with these permits.

Treatment of Wastewater

Over time, we have achieved substantial advancements in the treatment of our process and wastewaters, enabling us to limit the use and improve the quality of our effluent discharge to receiving waters. The control of our effluent discharge is essential for maintaining the aquatic health of ecosystems, ensuring safe, secure drinking water supplies, and reliable water supplies for a sustainable economy.

As part of our kraft process, Mercer uses water as a carrying medium for the fibre and chemicals we use to produce our pulp. To satisfy this requirement and meet strict wastewater technology-based standards and environmental quality objectives, our mills utilize the appropriate abatement and control technologies so that substance releases to receiving waters are minimized through advanced effluent treatment systems. The AOX per tonne of pulp has decreased by 6% over the past three years. The Celgar mill was able to reduce their AOX by over 10% during this period due to increased focus on process optimization and return to a 4-stage bleaching process.

It is in our bio-basins where we see the treatment of water really ‘come alive.’ Our effluent treatment systems are a series of vessels and basins which incorporate anaerobic consumption of organic materials to limit oxygen depletion in receiving waters. The most important element of the system is a carefully managed population of microbiotic organisms (affectionately referred to as “bugs”). These bugs gorge themselves on any remaining organic elements. To enhance the treatment, Mercer pulp facilities utilize an anaerobic system by adding air through submerged jet aeration systems and nutrients (i.e. nitrogen) which are supplied to maintain the population of organisms at a high level.

After the organics are consumed, the short-lived bugs expire and are removed from the system where they are burned in an electricity-generating power boiler. Modern effluent treatment systems can remove chemical, organic, and suspended solids to a high level. This is another example of how we work towards environmentally sustainable processes.

Mercer Water Use – Treated Effluent

Mercer Effluent – TSS

Mercer Effluent – BOD

Mercer Effluent – COD

Mercer Effluent – AOX