Theoretically, mechanical dehydration can be realized, but the unmodified sludge is a hurdle when the water content is 80%, and then the energy consumption rises sharply to an unacceptable level.
Therefore, there are usually three methods of deep dehydration at present.
1, sludge modification.
By heating, adding acid and alkali, adding electrolyte, etc. Sludge cells are destroyed and modified, releasing capillary water, adsorbed water and internal water.
2, increase the mechanical dehydration pressure
High pressure plate and frame filter press, steel belt filter press, etc. It is used to apply a mechanical force much larger than the conventional mechanical dewatering force to achieve further dewatering effect.
3, heating evaporation
In the process of dehydration, some heating and heat tracing devices are assisted to further reduce moisture.
Deep dehydration can generally reach the water content of 30% ~ 60%, and if it needs to be reduced again, it must be achieved by heating and drying.