The secondary pollution from sludge is reduced as a result of the lower permeability of sludge treated by the S/S(solidification and stabilization) treated. However with the change of the biochemical condition of the environment

the permeability of solidified sludge will change as well. To evaluate the environmental impact

the biochemical condition of solidified sludge was enhanced; and the permeability test with acid and nutritional filtration liquid was performed on the solidified body. The experimental results showed that increasing the solidification level would lower the permeability of sludge

but the permeability will be increased under acid condition. The permeability change of solidified sludge was not only decided by the total infiltration volume of infiltration liquid but also controlled by the strength of acid; and microorganism activity could remarkably decrease the permeability of solidified sludge.