water problems in the f_500字

　　presently, the world is faced with serious water problems. but these problems witt become more intense and more complex in the future. our increasing population witt tremendously increase urban waters, primarily sewage. on the other hand, increasing demands for water witt decrease substantially the amount of water available for diluting wastes.

　　rapidly expanding industries which involve more and more complex chemical processes will produce large volumes of liquid wastes. many of thesewitt contain chemicals that are poisonous. to feed our rapidly expanding population, agriculture will have to be intensified.

　　this will involve ever increasing quantities of agriculture chemicals. from this, it is apparent that drastic steps must be taken immediately to develop corrective measures for the pollution problems.

　　there are two ways by which these pollution problems can be lessened. the first relates to the treatment of wastes to decrease their pollution hazard. this involves the processing of solid wastes "prior to" disposal and the treatment of liquid wastes to permit the reuse to the water or best reduce pollution upon final disposal.

　　the second approach is to develop an economic use for all or part of the wastes. farm manure is spread in fields as a nutrient. wastes from sewage disposal plants are used in some areas both for irrigation and for the nutrients contained.

　　liquid wastes from other processing plants may also be used as a supplemental source of water. only by doing these promptly now can we expect to solve the serious water problems in the future.