Green issues: behind the paper
Paper has always been one of the necessities of civilization, and it is almost impossible to imagine the continuance of a world without the printed books and publications. In the recent years, the demand for paper consumption has mounted significantly high due to increase in literacy rate resulting in more demand for books and publications, that too with higher paper quality, and use of multicolour printing. Dr Virender Kumar Bharti points out ‘green issues’ linked with paper. In India, the per capita consumption of paper is currently seven kg, whereas, the world’s per capita consumption is 48 kg and the demand is continuously increasing. Paper is made from trees harvested just for that purpose, or from sawmills scraps left over when larger trees are made into timber. The bamboo, hard-wood, bagasse, agri-residues (wheat/rice straw) fibers are mainly used for paper making. It will be amazed to know that a mixture of softwoods and hardwoods 40 feet tall and 6-8 inches in diameter, it would take a rough average of 24 trees to produce one tonne of printing and writing paper. The government is focusing to expend India’s forest cover from the present 21 percent to 33 percent. According to the latest estimates, out of the total 21 percent forest cover area, two percent is good quality and high density forest cover, ten percent is medium density forest cover and the remaining nine percent is degraded forest cover. However, the government’s main thrust is to regenerate the degraded forest area so as to increase the proportion of area under good quality forest cover.
The paper manufacturing process requires large amounts of energy; a portion of it comes from burning wood waste. With the rise in environmental awareness and with increased government regulation there is now a trend towards sustainability in the pulp and paper industry. The production and use of paper has a number of adverse effects on the environment which are known collectively as paper pollution. Pulp mills contribute to air, water and land pollution. Discarded paper is a major component of many landfill sites, accounting for about 35 percent by weight of municipal solid waste (before recycling). Even paper recycling is a source of pollution due to the sludge produced during deinking.
The need for paper is essential but we all need safe and sustainable environment. In the coming years, there will be higher demand for paper so great efforts are needed to ensure that the environment is protected during the production, use and recycling/disposal of this enormous volume of material. Pulp and paper is the third largest industrial polluter to air, water, and land, releasing well over 100 million kg of toxic pollution each year. Worldwide, the pulp and paper industry is the fifth largest consumer of energy, accounting for four percent of the entire world’s energy use. This industry uses more water to produce a tonne of product than any other industry.
Worldwide consumption of paper has risen by 400 percent in the last four decades with 35 percent of harvested trees being used for paper manufacturing. Plantation forest, from where the majority of wood for pulping is obtained, is generally a monoculture and this raises concerns over the ecological effects of the practice. Deforestation is often seen as a problem in developing countries but also occurs in the developed world. Wood chipping to produce paper pulp is a contentious environmental issue worldwide.
Water and energy consumption
The paper industry is said to be water-consuming. Almost all the processing operations in the industry use water suspensions of fibers or chemicals. Paper is formed at very low consistencies. Because of these facts, large quantities of water are involved. Fortunately much of the water used within a mill can be recycled and used more than once. Even so, a very efficient fine paper mill probably requires at least 5,000 gallons of fresh process water per tonne of paper produced. We may assume a mill is producing minimum 300-1,500 tonnes per day; this figure represents a huge quantity of water in a day. The paper industry consumes large amounts of energy in the pulping, bleaching, refining and drying areas. Through a sustained effort, the industry has steadily decreased its reliance on petroleum and natural gas fuels by the increased generation of energy from the burning of wood residuals, wood wastes. Energy is around 18-20 percent of total cost of manufacturing paper. The mills consume, on an average, 1,600 units per tonne of paper. Due to excessive grid power cost, several large paper mills have set up their own power generating units.
Air and water pollution
Nitrogen dioxide (NO2), sulfur dioxide (SO2) and carbon dioxide (CO2) are all emitted during paper manufacturing. Nitrogen dioxide and sulfur dioxide are major contributors of acid rain, whereas CO2 is a greenhouse gas responsible for climate change. Waste water discharges for a pulp and paper mill contains solids, nutrients and dissolved organic matter, and are classified as pollutants. Organic matter dissolved in fresh water, measured by Biological Oxygen Demand (BOD), changes ecological characteristics. The bleaching of chemical pulps causes significant environmental damage, primarily through the release of organic materials into waterways. Pulp mills are located near large bodies of water because they require substantial quantities of water for their processes. Conventional bleaching using elemental chlorine produces and releases into the environment large amounts of chlorinated organic compounds, including chlorinated dioxins. Dioxins are recognized as a persistent environmental pollutant and are highly toxic, apart from affecting on humans involving reproductive, developmental, immune and hormonal problems.
There are three categories of paper that can be used as feed-stocks for making recycled paper: mill broke pre-consumer waste, and post-consumer waste. Mill broke is paper trimmings and other paper scrap from the manufacture of paper, and is recycled internally in a paper mill. Pre-consumer waste is material that was discarded before it was ready for consumer use. Post-consumer waste is material discarded after consumer use such as old magazines, telephone directories, and residential mixed paper. One concern about recycling wood pulp paper is that the fibers are degraded with each and after being recycled four or five times the fibers become too short and weak to be useful in making paper. Recycling paper decreases the demand for virgin pulp and thus reduces the overall amount of air and water pollution associated with paper manufacture. Recycled pulp can be bleached with the same chemicals used to bleach virgin pulp, but hydrogen peroxide and sodium hydrosulfite are the most common bleaching agents. Recycled pulp, or paper made from it, is known as process chlorine free (PCF) if no chlorine-containing compounds were used in the recycling process.