Chapter 1 Overview of waste water ( 1 ) 1.1 What is waste water ( 1 ) 1.2 The types of the waste water ( 2 ) 1.2.1 Domestic waste water ( 2 ) 1.2.2 Industrial waste water ( 16 ) 1.. Rural waste water ( 27 ) 1.3 The effects of the waste water ( 40 ) 1.3.1 Chemistry of water impurities ( 40 ) 1.3.2 Metallic corrosion ( 43 ) 1.3.3 Scale formation ( 47 ) 1.3.4 Fouling ( 48 ) 1.4 Waste water treatment processes ( 50 ) 1.4.1 Preliminary an piary treatment ( 50 ) 1.4.2 Secondary (biological) treatment ( 55 ) 1.4.3 Tertiary (advanced) treatment ( 65 ) Chapter 2 Treatment theory of the activated sludge ( 75 ) 2.1 The traditional activated sludge ( 75 ) 2.1.1 The basic conception and the process ( 75 ) 2.1.2 The forms and component of the activated sludge ( 76 ) 2.1.3 The microorganism in the activated sludge and its function ( 77 ) 2.1.4 The cariction process by the activated sludge ( 78 )