听力原文： In the future, water problems will become more and more serious. Our increasing population will greatly increase urban wastes. On the other hand, people's increasing demand for water will decrease the amount of water which can be used for drinking. Rapidly developing industries will produce more liquid wastes. And many of them contain chemicals that will be harmful to people's health. To feed our expanding population, agriculture will have to be developed. Thus larger quantities of agricultural chemicals will be produced in this process. In such an urgent situation, drastic measures must be taken immediately for the pollution problem. The first way is to treat the wastes properly to reduce their danger to society. This involves the processing of solid wastes first, and then comes to the treatment of liquid wastes. A second approach is to recycle or reuse all or part of the wastes. Farm waste water is spread in fields as nutrient supplement. Water waste from recycling plants can be used for irrigation and also as a supplemental source of water. (30)