Among many other Earth-threatening factors, deforestation in order to produce paper products is one of the most serious issues. From disposable paper cups to facial tissues, we ‘consume’ 30 million acres of forest yearly. To solve the problem of sustainable paper production, we need to look for non-wood alternatives. The fibrous, perennial energy crop, Arundo donax (or giant reed) is one of the best choices to replace wood and contribute to the making of sustainable paper.
Sustainable paper: the situation in our world
Paper can be produced from wood or non-wood pulp. For wood pulp 2-2.5 tonnes of hardwood and softwood are required, and from this much feedstock 1 tonne of pulp is made. The rising demand for paper resulted in widespread planting of trees for pulpwood production. Even though it is less publicised, in some countries (for example in Brazil) this brought about the conversion of areas where food crops were grown to pulpwood production.
Prices of woodchips used to range from 25 to 50 $/tonne, in recent days, however, prices of up to 70–75 $/tonne have been quoted. It is clearly predictable that the future world demand for pulp cannot be satisfied by wood chips alone and that non-wood pulp production and sustainable paper production must be increased.
Reed-based pulp is not new: it has been produced for centuries in China and India. The country of China produces 10 million tonnes of non-wood pulp yearly, and non-wood pulp amounts to 25 % of the total pulp production in India (Powlson, 2011).
The traditional technology for the production of non-wood pulp was deemed polluting, however, new non-polluting technologies for non-wood pulp production have been developed over recent decades. Examples are the Free Fiber technology (Metso GMBH), the Conox technology (Conox Ltd) and the Chempolis technology (Chempolis Ltd). For all of these technologies to produce sustainable paper it is claimed that pollution from non-wood pulping processes is within modern and acceptable norms (Croon & de Man, 2007).
Why is Arundo donax suitable for sustainable paper production?
The qualities of giant reed as a feedstock for pulp and sustainable paper are not in doubt. Arundo donax was tested and from the results it is known that
It cooks more rapidly than wood and its cellulose yields are rather high, varying from 33% to 53%.
Another great advantage of using giant reed for paper production is that its bleach response is good, which means it requires less chemical, making the process eco-friendly.
The strength properties of Arundo donax were proven superior to hardwood. The comparison of giant reed with hardwoods in particular is driven by the similarity in fibre length and length to diameter ratio of the fibres. Estimates indicate that giant reed has the potential to produce 500% more air dry pulp per hectare per year compared to blue gum (Eucalyptus globulus) hardwood trees. Viscosity and, especially, tearing strength of pulps from Arundo donax are higher than those from Eucalyptus globulus.
Bamboo is also often seen as a sustainable paper raw material for pulp production and so even large-scale pulp mills based on bamboo have been built, for example by the Guizhou Chitianhua Paper Industrial Company Ltd., China. Sadly, this is not without controversy since large-scale harvesting may threaten the many ecosystems where bamboo grows.
Giant reed, on the other hand, does not require good quality soil nor fresh water to grow. With its ability to adapt to marginal lands, contaminated and water-scarce regions, there is no need to sacrifice good soil in which otherwise food crops could be grown. Moreover, no ecosystems would be threatened by Arundo donax plantations. Therefore, cultivating giant reed for sustainable paper production is both environmentally friendly and financially beneficial.
Sustainable paper: pulp production from Arundo donax
There are botanically two distinct parts of the stem of giant reed: nodes and internodes. The two parts showed some differences in chemical and anatomical composition and a different access to pulping. It seems that under equal cooking conditions of a conventional kraft process, pulps with higher yield and lower content of residual lignin were produced from internodes. The strength properties as well as brightness and viscosity were also higher for pulps from internodes, compared to nodes.
Pulp beating developed much more actively the strength properties of kraft pulps from internodes, but created some dewatering problems. Therefore, the nodes of the plant stem can be reckoned as an undesirable component for pulp manufacturing, so it is advised using suitable screening techniques to eliminate nodes from the crushed stems before pulping. Once it is done, giant reed will provide good quality pulp, suitable for sustainable paper production.
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