Air & Water

Air & Water

Mercer’s Principled Management of Our Resources

We are committed to protecting the environment through our environmental policies and guiding principles. In order to achieve our goals and objectives, we follow the highest standards, practices, laws, and regulations to achieve our certifications and accreditations, and demonstrate an exemplary environmental record.

Our team of biologists, environmental scientists, hydrologists, and water managers monitor, assess, develop, optimize, report, and manage our resources through integrated sustainability strategies. Mercer recognizes the long-term importance of getting sustainability right – and protecting our natural resources is our collective responsibility.

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.

Our Carbon Footprint: Reducing Greenhouse Gas Emissions

While there are numerous forms of greenhouse gases, by far the largest source of human-induced carbon emissions is the burning of fossil fuels. Overall, paper and print products make up 1% or less of our human carbon footprint.  As a comparison, the following numbers are reported for other sectors:

  • Transportation: 15%
  • Land-use change (incl. agriculture and forest loss): 15%[vi]
  • Energy supply (incl. coal mining, fossil fuel extraction, refining and processing): 13%

The largest source of greenhouse gas emissions from our facilities is the acceleration of carbon dioxide released to the atmosphere from the combustion of wood and other organic compounds of wood. This emission is generally distinguished from other sources as an alternative to the natural degradation of organic wood material that would have occurred over time in the forest, if not for the recovery of that wood for use in solid wood products or pulp products. 

Our commitment to sustainable harvesting, as well as implementing global advancements in technologies to reduce our energy use and GHG emissions, will help us ensure our operations are sustainable and appreciated by society. The following are aspects of our commitment to a sustainable future.

  • Lower Carbon Footprint: We strive to improve our carbon footprint by minimizing our fossil fuel consumption.
  • Benchmarking: We continuously benchmark our operations against industry-leading performance to ensure we continue with our strong performance.
  • Our Working Forests: While often misunderstood, old forests are not necessarily healthy forests as they are large carbon emitters susceptible to pests and fire risks. Sustainably managed working forests, on the other hand, contribute to a healthier climate through sequestration of carbon, and the reduction of fire risks. Working forests provide low carbon solutions and play a key role in providing climate change solutions for a better world.

Mercer Greenhouse Gas – Fossil Fuels

 

  • 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.

Mercer Water Usage – Cooling Water

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 – TNb

Mercer Effluent – Ptot

Mercer Effluent – BOD

Mercer Effluent – COD

Mercer Effluent – AOX

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