For some GCSE Biology exams, you may have to know about two types of recycling - water (sewage) and paper (trees).
Any water, including drunk water, excreted in urine, can be treated so it is able to be reused. It is treated in sewage plants where harmful organisms are destroyed. However, it needs more treatment until the water is pure enough to drink.
In order to reduce the number of trees cut down, paper, newspapers and magazines can all be recycled. In a recycling plant, the print is first removed with chemicals. Next the paper is mixed with water to create a slurry, then rolled into sheets. This paper may not be white enough for paper, so it is used for paper bags and packaging; its texture can also sometimes be less fine.
However, in many places in the world trees are grown specially for making paper. Here the growth is sustainable since when a tree is cut down, new trees are planted. However, in mature forests, such as rain forests, cutting trees down is damaging the environment.