3.There are technical limitations to the amount of paper which can be recycled and some paper products cannot be collected for re-use. These include paper in the form of books and permanent records, photographic paper and paper which is badly contaminated. The four most common sources of paper for recycling are factories and retail stores which gather large amounts of packaging material in which goods are delivered, also offices which have unwanted business documents and computer output, paper converters and printers and lastly households which discard newspapers and packaging material. The paper manufacturer pays a price for the paper and may also incur the collection cost.
% S0 f' Z: K4 m 4.Once collected, the paper has to be sorted by hand by people trained to recognize various types of paper. This is necessary because some types of paper can only be made from particular kinds of recycled fibre. The sorted paper then has to be repulped or mixed with water and broken down into its individual fibres. This mixture is called stock and may contain a wide variety of contaminating materials, particularly if it is made from mixed waste paper which has had little sorting. Various machinery is used to remove other materials from the stock. After passing through the repulping process, the fibres from printed waste paper are grey in color because the printing ink has soaked into the individual fibres. This recycled material can only be used in products where the grey color does not matter, such as cardboard boxes, but if the grey color is not acceptable, the fibres must be d-inked. This involves adding chemicals such as caustic soda or other alkalis, soaps and detergents, water-hardening agents such as calcium chloride, frothing agents and bleaching agents. Before the recycled fibres can be made into paper, they must be refined or treated in such a way that they bond together.6 `' u4 S- S1 p& K) u5 ^
5.Most paper products must contain some virgin fibre as well as recycled fibres and unlike glass, paper cannot be recycled indefinitely. Most paper is down-cycled which means that a product made from recycled paper is of an inferior quality to the original paper. Recycling paper is beneficial in that it saves some of the energy, labor and capital that goes into producing virgin pulp. However, recycling requires the use of fossil fuel, a non-renewable energy source, to collect the waste paper from the community and to process it to produce new paper. And the recycling process still creates emissions which require treatment before they can be disposed of safely. Nevertheless, paper recycling is an important economical and environmental practice but one which must be carried out in a rational and viable manner for it to be useful to both industry and the community.
: N; i0 s9 R. @; Z5 ~5 I B Some questions:
1 I# r4 j" W1 M; D* `$ s 1: What can be the best title of this article?" b+ z y" M$ Q8 M3 ?! i
--Paper recycling
- {; [) n# {! m" J+ b 2: What’s the main idea of the 1st paragraph?, s& \% q, K* d% d
--the background and significance of paper recycling.% h9 T) s" s+ ^: w v. N
3: What’s the main idea of the 2nd paragraph?; B* S6 x$ V! H! v
--Advances in technology and the role the community can play in promoting paper recycling.
6 _% M/ V+ o& b7 { 4: What’s the main idea of the 3rd paragraph?
* m3 B5 `& ]2 s. | --limitations in paper recycling and the four major sources of waste paper
1 I* \8 s) l2 u r 5: What’s the main idea of the 4th paragraph?
' q2 U( N/ S% j --troubles with paper recycling process
" D% Q/ _% ?* Y& e$ f 6: What’s the main idea of the 5th paragraph?5 w3 _8 m& x4 T! S! B, ~
--the troubles and significance of paper recycling |
发表于 2012-8-14 11:29:10
