Anaerobic degradation can be accelerated and increased by prior homogenization or disintegration of secondary sludge.

• Homogenization is achieved by mechanical stress and with little energy input. Flocs are broken up, sludge viscosity is reduced and anaerobic degradation accelerated.
• Disintegration is achieved by mechanical, acoustical (ultrasound) or thermal means. With higher energy input cells are broken up and their content is released. Some organic matter is hydrolyzed.

Though there is still need for further scientific investigations, the following results can be stated:

• Disintegration and homogenization can increase power generation from digester gas by 2 to 4 times of power input; this factor decreases with increasing power input. Both processes are most effective where digestion is poor.
• Both processes damage filamentous bacteria and reduce digester foaming.
• While disintegration leads to a smaller average particles size in the digested sludge, thus impairing its dewatering, homogenization does not.