Different technologies have been used in the prevention of water pollution . For example , when the quality of the water is not bad and there are only some pollutant of suspended solids , we can only use some physical methods , such as grilling , to treat the pollution , which is called the primary treatment. But when the water contains some organic pollutant or some nitrogen and phosphorus pollutants , it should be treated with chemical technology or biotechnology , which is called secondary treatment or advanced treatment .