Table 1. Sludge characterisation, and expected amount of methane gas from the digestion of sludge.

Type of sludge

1º

1º hydrol

2º

2º hydrol

mixed

mixed hydrol

 g COD/g VS

1,8

1,8

1,4

1,4

1,6

1,6

 % SV/ST

70%

70%

67%

67%

68%

68%

 % VS degradation

50%

60%

40%

64%

44%

62%

 L CH4/kg VSfeed

315

378

196

314

240

341

1º: primary sludge.
1º hydrol.: primary sludge after thermal hydrolysis.
2º: secondary sludge.
2º hydrol.: secondary sludge after thermal hydrolysis.
mixed: mixed sludge (40% VS from primary, 60% VS from secondary).
mixed hydrol.: secondary sludge after thermal hydrolysis.

Supported by UNESCO / MIRCEN network