Advances in Water Treatment and Enviromental Management

28 WATER TREATMENT• further improvement of water quality for all uses;• prevention of septic conditions in some river reaches;• better self-purification characteristics of the stream;• full protection of aquatic life;• possibility of using the river for recreation.Third Degree of ProtectionBenefits of the applied third degree of protection are:– all positive effects of both previous degrees of protection are included plus thefollowing benefits:• return of the stream in its class as prescribed by the Regulations;• guaranteed possibility of using river for water supply of towns and industrywith usual treatment only;• better organoleptic characteristics of water;• reduction of water quality deterioration in the distribution network.Fourth Degree of ProtectionBenefits of the applied fourth degree of protection are:Table 6. Necessary Degree of Treatment and Costs of Protection for the 1990*1 DIN=0.08 US$