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
page 101
page 102
page 103
page 104
page 105
page 106
page 107
page 108
page 109
page 110
page 111
page 112
page 113
page 114
page 115
page 116
page 117
page 118
page 119
page 120
page 121
page 122
page 123
page 124
page 125
page 126
page 127
page 128
page 129
page 130
page 131
page 132
page 133
page 134
page 135
page 136
page 137
page 138
page 139
page 140
page 141
page 142
page 143
page 144
page 145
page 146
page 147
page 148
page 149
page 150
page 151
page 152
page 153
page 154
page 155
page 156
page 157
page 158
page 159
page 160
page 161
page 162
page 163
page 164
page 165
page 166
page 167
page 168
page 169
page 170
page 171
page 172
page 173
page 174
page 175
page 176
page 177
page 178
page 179
page 180

in Svenljunga together with municipal wastewater from Svenljunga. This situation was a barrier for the tannery to increase the leather production, and furthermore the environmental authorities in Sweden were pressing the tannery to reduce the nitrogen pollution. The reduction of the nitrogen discharge to rivers and lakes has been a very high priority in Sweden for several years. The tannery started planning for the construction of a new treatment plant in 2002, with a clear goal that the amount of nitrogen removed should be high ( more than 80%) and stable. The nitrogen removal should not be affected by changes in the composition of the wastewater, nor by the harsh winter conditions in Svenljunga where temperatures of - 20 ° C are not uncommon. Selection of technology The project started with an extensive survey of results from other wastewater treatment plants. The study showed that the nitrification and denitrification of tannery wastewater to reduce the nitrogen content in the wastewater has gradually been discussed as an option in countries with strict nitrogen discharge limits. However, due to severe difficulties in controlling the process and odour problems, the process has not been introduced or considered possible for the treatment of tannery wastewater. One of the major suppliers of nitrification/ denitrification systems in Europe performed laboratory trials for a total of eight months on the use of nitrification/ denitrification " The reduction of the nitrogen discharge to rivers and lakes has been a very high priority in Sweden for several years"

technology on tannery wastewater with Elmo Leather. These trials were very successful and the results from the trials were used for upscaling to demonstrate that the technology can be used on wastewater from tanneries. Examples of important factors needed to obtain a stable cleaning process are: the plant has a strict process control ( pH and balance of nutrients is especially important); the plant is a two- step plant ( toxic compounds degraded in the first step) and the plant has the possibility of hydraulic equalization ( in order to avoid fluctuations in, for example, chloride concentration). Technical description An overview of the plant is given below and followed by a description of the plant. The principle of the WWTP ( wastewater treatment plant) is as follows: The wastewater flows from the tannery to the new inlet pumping station through a 2mm screen. The wastewater is then pumped to biological treatment.