The Search for Purity
By Pulp & Paper Canada
By Pulp & Paper Canada
In the past, public opinion often pointed its finger at the pulp and paper industry, judging its environmental impact in an oversimplified manner even though other factors (such as municipal waste incinerators and forest fires) have contributed no…
In the past, public opinion often pointed its finger at the pulp and paper industry, judging its environmental impact in an oversimplified manner even though other factors (such as municipal waste incinerators and forest fires) have contributed notably higher pollution levels. It is time now to acknowledge the significant improvement that has been made in the past 10 to 15 years. Due to growing awareness of its impact on the environment, the pulp and paper industry has become strongly regulated, both by itself and the government. In most of the approximately 150 pulp and paper mills in Canada, different steps have been taken to meet the problem head on, targeting the processes used and taking into account the environment and the local community, as well as federal and provincial regulations.
Some of the issues recognized as crucial to the continued improvement of key problem areas are energy conservation and recovery, water reduction and recycling, lime mud waste reduction and the continued study of alternatives to traditional bleaching methods. Until recently, the most common bleaching method for chemical pulp was based on chlorine, along with chlorine dioxide gas or hypochlorite. The use of chlorine to separate and bleach the fibres resulted in toxic emissions to air, water and landfill. Some chemicals, particularly the dioxins, were a major health concern.
To avoid or limit the use of chlorine compounds, other methods are used when possible. Mechanical pulp is usually bleached with hydrogen peroxide. Some mills use oxygen delignification to remove lignin from the brownstock as a prebleaching step. This reduces the amount of chlorine or other bleaching chemicals required to whiten pulp during bleaching. Extended delignification techniques, such as sodium hydroxide and heat remove even more lignin.
One of the greatest improvements in pollution control came with the introduction of Elemental Chlorine-Free (ECF) process. This method, which uses chlorine dioxide for bleaching, has resulted in reports of improvement in pulp quality, although it does represent an immediate increase to the cost factor as the chemical itself is significantly more expensive and requires replacement or upgrade of washers, bleach tower materials and chlorine dioxide generators. Virtually all of the North American pulp producers have switched to ECF, leaving wastewater virtually free of persistent bioaccumulative toxic substances as ECF bleaching results in organic substances that degrade naturally.
Other alternatives to chlorine bleaching include a combination of oxygen and peroxide to augment sodium hydroxide extraction and enzyme bleaching, such as xylanase, which is related to the chemicals secreted by wood-eating insects and bacteria to break lignin bonds.
“There have been great improvements in the last 10-12 years,” stated Avrim Lazar, president and CEO of the Forest Products Association of Canada (FPAC). “Particulates in the air are down by half, dioxins and furans are almost undetectable and recycling has doubled.” As if this were not enough, Lazar added, “Climate change gases have been reduced by 28%, while at the same time, production is up by 25%.”
The pulp and paper industry, particularly mechanical pulping methods, are classified as energy-intensive, along with refineries, steel, glass, ceramic, minerals and cement industries. However, since 1990, the amount of oil consumption by the industry has been halved and is now the single largest producer and user of biomass fuels.
According to FPAC, there are six magic bullets to slash greenhouse gas emissions by an additional 15% by 2012. They include fuel substitution, cogeneration, recycled fibre substitution, process modernization, afforestation and energy auditing. Some mills are already taking advantage of the available bark biomass to supplement energy reserves through practices that improve overall plant thermal efficiency. A few of the projects jumping on the cogeneration bandwagon now are Weyerhaeuser’s Grande Prairie mill (AB), Kruger’s Corner Brook mill (NF), Domtar’s Windsor (QC) and two mills at Canfor’s Prince George (BC).
Future developments in thermo-mechanical and chemi-thermomechanical pulping focus on further reduction of electric energy consumption through understanding the basic properties of wood and their interactions with thermal, chemical and mechanical actions.
In addition, reducing waste water usage has a significant impact on energy reduction since most of the water used in mills is heated — the less water used, the less energy expended.
Pulp mills require a significant amount of water in all parts of the process, such as pulp washing, digestion and bleaching, as well as deinking and washing in recycling mills.
The website for Reach for Unbleached! quotes a government report from 1991, stating that the pulp and paper industry is the largest single commercial user of water in Canada.
At that time, the total mill effluent discharged from Canadian bleached pulp mills averaged 137 cubic metres per tonne which is roughly equal to the flow of the St. Lawrence River at Cornwall, ON, or to that of the Columbia River, BC.
At present, there is still no way to avoid pulp washing since it is a necessary step in removing black liquor, fines, lignin and bleach by-products after each processing step. However, since the early 1990s, the industry has been fiercely implementing water-reduction strategies such as using different types of washers. Examples include vacuum drum, pressure washing, diffusion washing and belt washing, all offering high degrees of cleaning.
White water, typically clean but containing some contaminants such as fibre, lignin compounds and various organics, is usually recycled back to bleaching or pulping operations. Where bleaching does not exist, white water from the paper machines can be reused or partially reused directly in pulp washing or in the wet end of the paper machine after clarification has settled the sludge.
Prior to discharge, the wastewater is treated to reduce biological oxygen demand (BOD), chemical oxygen demand (COD) and total suspended solids (TSS). After passing through clarifiers and aeration ponds, nutrients in the form of ammonium nitrate or ammonia are often added to encourage microbe activity to neutralize effluent, before being discharged.
Newer mills tend to have better pollution controls, since they use secondary wastewater treatment electrostatic precipitators and scrubbers.
Within the scope of water management, the industry has also focused on containment separation and chemical recovery, as well as secondary waste water treatment systems.
“We’ve dramatically improved our water quality,” said Lazar, pointing to studies that show there has been a 32% reduction in water consumption and a 90% reduction in the presence of organichlorines.
Canada still has more than 91% of its original forest area and the raw material used by the industry represents one quarter of one percent annually. Comprehensive tree-planting programs work towards reseeding all harvested areas successfully to satisfy the sustainable forestry initiative.
Careful design and mechanical improvement has reduced log yard waste due to the bark and woodchips that are mixed with soil, over-sized logs and logs that have been damaged through embedded metal or exposure to mould. Further down the line, improved screening and rechipping of oversized chips has already led to improved delignification in standard or modified cooking processes.
Canada has legislated allowable effluent concentrations, sewage treatment plant discharges, sludge wasting and disposal and compliance with federal pulp and paper effluent regulations.
Sampling and flow measurement procedures must be in place, regular maintenance work scheduled, outfall posted and any process modification reported, among other level surveillance methods. Levels are set for foam, colour and nutrient level of the water, among other parameters. As well, an emergency resp
onse plan must be prepared and submitted to describe the procedures used by each mill in the case of an abnormal event occurring that would affect the environment or community.
The Kyoto Protocol is an international agreement that, once ratified, commits industrialized countries to reduce emissions of greenhouse gases, such as carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulphur dioxide. Each of these gases has distinct properties, and the overall emissions reduction targets for the six gases are weighted by the relative heat-trapping effect of each gas. It is an important interim step in the overall goal of sustainable development.
As of the 15th of April, 2004, 84 countries have signed and 122 countries have ratified or acceded to the Kyoto Protocol, Canada being one of them. However, according to FPAC, absolute emissions in 2002 were already at 28% below the levels measured in 1990 — exceeding the targets set by Kyoto.
Improving energy efficiency from biomass and reducing the energy demand in the biomass conversion to products and eventually also carbon dioxide capture are important for compensating the effects of fossil fuel usage. Key processes in these areas are biomass gasification, energy reduction in mechanical pulping and carbon dioxide capture from fuel or flue gas originating from biomass.
The Kyoto Protocol encourages the use of more green energy production with either tax exemptions or subsidies and less use of fossil fuels through higher taxation. Biomass from plants falls into the category of renewable energy sources because a similar amount of carbon dioxide, which is emitted during combustion, is used in the photosynthesis process as long as growth and harvest of the biomass are in balance. Therefore, energy production from biomass is considered to be carbon dioxide neutral. There is also a unique potential for actually reducing carbon dioxide content in the atmosphere by carbon dioxide capture and sequestration.
Looking beyond the typical boundary limits, the paper industry feeds a continuous flow of biogen fuel in the form of paper into the marketplace. This type of biogen “waste” will be increasingly used for energy production. In most European countries, the land-filling of organic material will be prohibited from 2005 onwards so therefore all this product will need to be re-routed. According to The Kyoto Protocol and Greenhouse Gas Emissions – Implications for Mechanical Pulping, the energy value of waste paper, which is not recycled, exceeds the energy value of all the fossil fuels used by the paper industry.
The paper continues to state that the pulp and paper industry may have other opportunities to capitalize on its position as the largest single producer and user of biomass fuels. Recent developments in technology are introducing methods to prevent carbon dioxide from combustion from entering the atmosphere. If these capture and sequestration technologies are successful and can be applied to recovery / biomass boilers, carbon dioxide will actually be removed from the atmosphere.
The stigma of high energy consumption and the high pollution levels in the past created popular misconceptions about the pulp and paper industry. The industry is now fiercely improving the situation, through mandated impact studies and follow-up research. Overall, there have been eight billion dollars invested in environmental improvements since 1990. Although limited by cutbacks due to a slowly-recovering economic outlook, existing mills have vastly improved their impact on the environment through retrofitting and improved efficiency.
This tremendous effort should be known and acknowledged by the general population, since it shows the level of commitment of the pulp and paper industry in Canada. For marketing purposes, Lazar believes that the government has a role to play in communicating this fact. “The government,” he insists, “should be more aggressive in promoting the environmental record of the industry both overseas and within North America.”
As far as the mills are concerned, the work continues.
1. Greenbaum, P.J. Making progress in water reduction. Pulp & Paper Canada 103:2 (2002).
2. Pryke, Douglas. ECF is on a roll! Pulp & Paper International. August 2003.
3. Muenster, H., Sabourin, M. and Fisera, P. The Kyoto Protocol and Greenhouse Gas Emissions – Implications for Mechanical Pulping. Presented at the 2003 International Mechanical Pulping Conference. Quebec City, QC. Presented in June 2003. To be published in Pulp & Paper Canada soon.
4. Canadian Environmental Protection Act Priority Substances List Assessment, Report No.2, Effluents from Pulp Mills Using Bleaching, 1991
5. Ministry of Water, Land, and Air Protection of British Columbia, Permit PE-01149.
6. The Kyoto Protocol to the United Nations Framework Convention on Climate Change 7. EU Directive 1999/31/E6
8. Environment Canada: a national assessment of pulp and paper environmental effects monitoring data – Excerpts from the NWRI Scientific Assessment Report series No.2
9. Howe Sound Pulp & Paper Mill website: www.howesoundpp.com
10. Reach for Unbleached! website: www.rfu.org
11. Forest Products Association of Canada website: www.fpac.ca
ENVIRONMENT CANADA: A NATIONAL ASSESSMENT
The Pulp and Paper Effluent Regulations (PPER) require Canada’s pulp and paper mills to conduct Environmental Effects Monitoring (EEM) Program studies on their receiving environments in order to assess and monitor the potential effects of their effluents on fish, fish habitat and the use of fisheries resources. An EEM study includes the following components:
A fish population survey to assess the health of fish;
A benthic invertebrate community survey to assess fish habitat;
A study of dioxins and furans in edible fish tissue and a tainting study as assessments of the usability of fisheries resources;
A sublethal toxicity testing to assess effluent quality; and
Supporting water and sediment quality variable to aid in the interpretation of biological data.
In general, pulp and paper mills are not impacting the ability of Canadians to use fish. In the two cases studied, pulp mill effluent was confirmed in one and suspect in the other to contribute to fish tainting. There are isolated cases where mills may be contributing to elevated levels of dioxins and furans in fish tissue. Environment Canada will continue to work with these mills on a site-specific basis.
– Excerpts from the NWRI Scientific Assessment Report series No.2
CLEAR EXAMPLE: HOWE SOUND PULP AND PAPER
Besides delivering quality pulp and paper products, Howe Sound Pulp and Paper, near Port Mellon, BC, has an excellent record in environmental protection.
The mill maintains an ambient air monitoring station 10 km south of the mill to measure the amount of nitrogen oxides, sulphur dioxides, particulate matter (smaller than 10 microns in size) and total reduced sulphur — TRS (the odorous gases created in the pulp process) in the local atmosphere. One of the ways TRS odour level was lowered at the mill was when Howe Sound P&P invested in a state of-the-art power boiler that collected and burned the odour-producing gases. This helped bring about a 90% drop in the odour levels at the mill since 1990. Despite the fact that the human sense of smell is extremely sensitive to the odour produced during pulping and can detect this smell at levels as low as one part in a billion, the pulp mill odour is now not usually detectable by local residents, outside of scheduled power boiler maintenance shutdowns.
The mill posts all of its updated (2003) environmental reports, permits and summaries on its website.
Howe Sound Pulp & Paper Mill has virtually eliminated dioxin/furan levels since 1989; effluent is non-toxic since 1990 and the mill has achieved a 22% reduction in greenhouse gas emissions since 1990.
While there is no nati
onal structure for facility pollution prevention programs, Howe Sound P&P mill in BC recognized the importance of its people by forming a Joint Environment Committee. The purpose of the JEC is explained in the mill’s quarterly environment newsletter (envirosound, March 2004):
To receive information, review problem areas and make appropriate suggestions regarding compliance
To inform/educate employees of environmental policies and issues
To listen to concerns
To make recommendations to the Management Environment Committee or appropriate operation groups on issues brought to the JEC
“Our people are the important elements in the structure of Howe Sound’s “in-house” Joint Environment Committee (JEC),” explained Al Strang, manager, Environment and External Relations. “They are a key component in contributing to the success of Howe Sound’s environmental goals and achievements. With their participation in the JEC, we have achieved a greater level of communication and education for environmental awareness throughout our entire workforce.”
PROJECT ZERO: MILLAR WESTERN’S MEADOW LAKE
As a recent addition to the family of Canadian pulp and paper mills, the Meadow Lake BCTMP mill in Saskatchewan was able to take advantage of new developments in technology in order to become the world’s first zero-liquid-effluent-discharge mill.
No one is more enthusiastic about this status than Bob Leslie who was the project’s operation manager during the design and start-up phase in 1992 and later the mill manager before moving to Whitecourt, AB, and taking over as mill manager there.
Leslie explained that during project design, it was recognized that any effluent from the mill would need to reach a high level of purity before joining the pristine waters of the nearby Church River. Why not recycle the water instead of piping it away?
“Since the design called for low water usage to start with,” explained Leslie, “the decision was made right up front to reuse the water within the mill.” He admitted there were difficult choices in the beginning to pinpoint the technology that would create a zero-effluent mill but it was decided to evaporate effluent and burn the organic and inorganic sludge concentrate in the recovery boilers and use the heat for energy.
“A lot of people from all over the world come to see the mill,” said Leslie, proud of the design and the team who helped achieve the project, both on Millar Western’s side and the engineering offices of NLK (now Jaakko Pyry NLK) in Vancouver. The mill now has an international reputation for advancements in the production of totally-chlorine-free, 100% aspen BCTMP sold in international markets.
“It was a big risk but it proved to be extremely successful,” said Leslie. “It was innovation — and it was doing something that was required.”