M-real has succeeded in reducing its emissions to air, discharges into waterways and noise from mill operations by applying Best Available Techniques (BAT). For instance, total emissions per average tonne of production have been reduced by about 40 per cent during the past ten years. The amount of landfill waste, alone, has been decreased by about 80 per cent during the past five years.
To maintain these low levels, procedures for environmental risk assessments and controlling and managing potential accidental releases are the main development targets at all M-real mills.
Residuals are minimised by using purification technologies in the mills and by reusing these purified residuals in the production processes. Most of the remaining residuals from the process are reutilised as raw materials for various applications or for their energy content.
Emissions to air
In M-real, air emissions, the main compounds of which being carbon dioxide, nitrogen oxides, sulphur dioxide and particles, mainly originate from the recovery boilers at chemical pulp mills and from power plants at pulp and paper mills. In 2008, M-real’s emissions to air amounted to 1,269,651 tonnes of carbon dioxide and 7,225 tonnes of sulphur dioxide.
Carbon dioxide and nitrogen oxides are formed during combustion processes. Sulphur compounds are released during the recovery processes at chemical pulp mills and from combustion of fuels containing sulphur such as coal and oil. Particle emissions are formed during the combustion of solid fuels. Carbon dioxide is one of the causes for the greenhouse effect, and sulphur compounds and nitrogen oxides cause acidification and eutrophication.
Carbon dioxide and sulphur emissions are reduced mainly by the choice of fuels. Proper combustion conditions reduce nitrogen oxide emissions, and efficient cleaning equipment decreases the emission of particles and sulphur compounds.
Discharges to water
Pulp and paper production requires a lot of water to transport and wash fibres, to act as a cooling and lubricant agent, and to carry energy in the form of steam. Most importantly, water also acts as a bonding agent between the fibres in the formation of sheet of paper.
The discharge of oxygen-demanding substances of wood-origin is the most typical environmental impact of papermaking. Organic compounds in the mill effluent are oxidised either biologically or chemically. The amount of oxygen consumed by the wastewater during the oxidation process is expressed as biological oxygen demand (BOD) and chemical oxygen demand (COD). Oxygen depletion resulting in low oxygen content can harm fishes and bottom animals living in the recipient water. In 2008, M-real’s discharged to water amount to 35,042 tonnes of COD and 210 tonnes of Eutrophication as phosphorus equivalents.
Biologically treated effluents also contain nutrients such as nitrogen and phosphorus. Nutrient enrichment enhances the excessive growth of algae and other green plants and limits the growth of other species.
There are two ways of reducing the impact of paper production on watercourses –reducing water usage in the production process and improving effluent treatment. Both methods are used by M-real. We use water efficiently in the production processes. A full closure of water circulation would compromise M-real’s high standard of product hygiene and may also hamper runnability of board and paper machines. Therefore, minimising water consumption must be in balance with hygiene and runnability objectives.
By-products and wastes
Mill residuals consist of bark, sludge from wastewater treatment plants, lime mud, green liquor dregs and ash. Small amounts of municipal-type waste is also produced, such as scrap metal, packaging and office waste, and some hazardous waste such as waste oil and solvents.
M-real utilises bark, sludge and other organic materials for local energy production at the mill power plants. Sludge is also used in soil construction, as a soil improvement agent and in brick and cement production.
Residual ashes from energy production are used as raw materials for the construction and cement industry. Fly ash is also utilised for forest fertilisation and for various soil construction purposes. Lime mud, green liquor dregs and lime rejects from pulp mills are, for the most part, sent to landfill, although ways of reutilising them are under development. The waste plastics that are removed by the de-inking process are either used in energy production or - when incineration is not possible - sent to landfill.
Hazardous mill waste - oils, solvents, used chemicals, etc. - is treated by companies specialised in handling this type of material. Other industrial waste and office waste is sorted and handled separately and reused by external companies. Packaging and some plastic waste can also be used in energy production. In 2008, landfill waste from M-real’s units amounted to 76,229 tonnes.