paper industry

Environmental Concerns in the Paper Making Process


Wood pulp is an important product used in the paper making process. Yet, it wasn't used in the process until around 1850 when a German by the name of Friedrich Gottlob Keller experimented with crushing wood with a wet grindstone in order to obtain wood pulp. This was done largely out of necessity, as the fiber crops that were previously used for the process were experiencing a shortage.

After Keller successfully crushed wood to create pulp, C.B. Tilghman, who was an American chemist, and C.F. Dahl, who was a Swedish inventor, experimented with using chemicals to break the fibers down. The ability to use wood pulp, coupled with the invention of the steam powered printing and paper making machines, made the process of paper making far less expensive. While the greater availability of paper helped improve literacy as more books could be inexpensively produced, the use of wood pulp to create paper has led to a number of environmental concerns.

Forest Reduction

Forest reduction is one of the number one concerns facing the paper and pulp industry. The exact number of trees needed to produce paper depends on the process used to create the pulp. The groundwood process results in more pulp and produces more paper than the Kraft process, but the Kraft process creates paper of a higher quality. By most estimates, it takes approximately twenty-four 40 foot softwood and hardwood trees of six to eight inches in diameter to produce a ton of writing and printing paper when the Kraft process is used. Under the assumption that the groundwood process is twice as efficient, it would take about twelve of these same trees to create a ton of newsprint.

In response to this environmental concern, most paper and pulp factories plant new trees to replace the ones they cut down for their paper making business. Of course, it takes several years for these newly planted trees to reach the same size as the trees they are replacing. Paper recycling has also helped reduce the number of trees needing to be harvested for paper, as a typical piece of paper made from wood pulp can be recycled four to seven times before the fibers become too short to reuse. To maintain the quality of recycled paper, it is usually mixed with virgin pulp wood.

Waste By-Products

The waste by-products created from the paper making process is another concern. Chlorine, for example, has long been used to bleach the pulp in order to create the desired white paper. When this is done, chlorinated byproducts such as furans and dioxins are produced. In British Columbia, some fisheries were forced to close in 1992 as the result of these contaminates. Fortunately, technology has advanced to the point that the use of chlorine in the bleaching process has either been eliminated or substantially reduced.

Wastewater effluent has also caused environmental concerns because it contains high biological oxygen demand, lignins from the trees, and dissolved organic carbon, as well as heavy metals, alcohols, chelating agents, and chlorates. In order to reduce the impact of the wastewater effluent, less detrimental agents are utilized in the pulping process and much of the effluent is recycled.

Another byproduct of papermaking is black liquor, which is created when the Kraft process is used for breaking down the wood chips used to make the paper. Black liquor also contains lignin from the trees. The concentration, however, is weak. Nonetheless, the paper industry has found a way to decrease the environmental impact of this liquid as well as to make the process of paper making more efficient by evaporating the water from the black liquor. After undergoing a boiling process, it is changed into what is know as green liquor and combined with lime to form white liquor. This white liquor is then reused in the pulping process.

Like most industries, there are environmental concerns associated with the paper making process. Fortunately, the paper mills are working hard to find ways to ensure the environment is harmed as little as possible.

 

 

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