Page 1
Page 2
Page 3
Page 4
Page 5
Page 6
Page 7
Page 8
Page 9
Page 10
Page 11
Page 12
Page 13
Page 14
Page 15
Page 16
Page 17
Page 18
Page 19
Page 20
Page 21
Page 22
Page 23
Page 24
Page 25
Page 26
Page 27
Page 28
Page 29
Page 30
Page 31
Page 32
Page 33
Page 34
Page 35
Page 36
Page 37
Page 38
Page 39
Page 40
Page 41
Page 42
Page 43
Page 44
Page 45
Page 46
Page 47
Page 48
Page 49
Page 50
Page 51
Page 52
Page 53
Page 54
Page 55
Page 56
Page 57
Page 58
Page 59
Page 60
Page 61
Page 62
Page 63
Page 64
Page 65
Page 66
Page 67
Page 68
Page 69
Page 70
Page 71
Page 72
Page 73
Page 74
Page 75
Page 76
Page 77
Page 78
Page 79
Page 80
Page 81
Page 82
Page 83
Page 84
Page 85
Page 86
Page 87
Page 88
Page 89
Page 90
Page 91
Page 92
Page 93
Page 94
Page 95
Page 96
Page 97
Page 98
Page 99
Page 100
Waste Water treatment world pulppaper 81 intrODuCtiOn Water is an essential raw material for manufacturing pulp and paper and effluent treatment is a critical part of this process. To meet tough regulatory standards for discharge of wastewater many modern mills rely on Kemira for cost effective chemical treatment methods and support. Because effluent characteristics can differ greatly from one mill to another so do the treatment procedures. It is clear that advanced treatment is becoming a prerequisite to cost- effectively meet tougher regulatory standards for wastewater and as the interest in specialised effluent treatment methods is growing mills will likely have to monitor their emissions in much more detail in the future. This article describes the major wastewater treatment sub-processes and some measures that can be taken to improve them. Primary treatment can be optimised with chemical coagulation or flocculation for removal of particulate organic matter including surface active toxic compounds. Biological treatment so called secondary treatment is improved with micronutrients and flocculants to secure stable and optimal biomass activity. The treatment is further supported with ATP adenosine triphosphate and biological activity test methods. Tertiary treatment is enhanced with chemicalphysical methods to meet the final regulatory standard for discharge of wastewater. By ulla Gytel Application Specialist EMEA Chen Hongwei Application Specialist APAC edouard Papin Application Specialist NAFTA and Gran Bckman Business Development Kemira Tougher effluent regulation calls for cost effective chemical treatment Sludge treatment is assisted by new types of cost efficient dewatering chemicals capable of handling various types of sludge in demanding conditions. BaCKGrOunD Environmental protection and water management have been in focus for many years especially in areas where clean water is scarce. Numerous guidelines are in force worldwide China has a discharge standard of water pollutants in the pulp and paper industry1 in Europe the IPPC Integrated Pollution Prevention and Control and BAT Best Available Technique2 is guiding mills on effluent limits and in North America federal regulations for the environment are published by the EPA Environmental Protection Agency3. However a comparison between effluent standard limits Table 1 reveals that legislation focuses on different types of emissions in different parts of the world. In China organic pollutants are in focus whereas nutrients and suspended solids are more strictly regulated in the EU. A comparison of regional discharge limits is shown in the table below. This article describes several typical challenges that mills face with wastewater treatment procedures and treatment results that can be achieved using cost effective chemical treatment methods. The most important unit processes discussed are shown in the brief flow sheet overleaf Figure 1. many modern pulp and paper mills are using cost effective chemical treatment methods from Kemira to meet tougher regulatory standards for discharge of wastewater table 1. A comparison between effluent standard limits reveals that legislation focuses on different types of emissions in different parts of the world type of mill regulation Parameter kgadt ss BOD5 COD ntot Ptot Pulp mill China 0.6-1.5 0.3-0.6 2.4-3 0.3-0.45 0.015- 0.024 BAT 0.3-1.5 2.5-20 0.05- 0.25 0.01- 0.03 EPA 3-9.5 1.8-5.5 integrated mill China 0.25-0.75 0.25- 0.5 1.5-2.25 0.25-0.3 0.0125- 0.02 BAT 0.06-0.45 0.9-4.5 0.03-0.1 0.001- 0.01 EPA 3.8 2.5 Paper mill China 0.1-0.3 0.1-0.3 0.1-0.2 0.1-0.12 0.005- 0.008 BAT 0.02-0.35 0.15-1.5 0.01-0.1 0.003- 0.012 EPA 2.3 1.9