Purpose
A major operating cost for water purification is the sludge disposal cost. The lower the dry matter content of this sludge, the more one is paying for the disposal of water. To significantly lower the costs for sludge disposal dewatering is often recommended. Sludge dewatering means that the free water between the solid materials is removed so that a semi-solid mass is obtained.
Concentration of solids, sludge dewatering
Separation of manure and digestate into a thick fraction and fine fraction
Dewatering biological or physicochemical sludge
Dewatering mineral slurries
Principle
More advanced sludge dewatering techniques make use of a filter cloth. Conditioning of the sludge with a polyelectrolyte is often necessary to achieve optimum results.
Possibilities of application
Sludge dewatering Container: The sludge is placed in a container with on the inside a perforated double wall over which a filter cloth is placed. The water seeps through the screen cloth and can be recycled to the water treatment. Once the filter cloth is saturated the canvas with silt is removed and the cloth replaced.
Dewatering Table: Conditioned sludge is thickened on a belt that rotates. The cloth is cleansed with sprinklers.
Dewatering Drum: Sludge is moving forward through a drum provided with a sieve cloth. The cloth is cleansed with sprinklers.
Example of realisation
Sludge dewatering container
Approach Trevi
Trevi aims to initially minimize the sludge production by means of process oriented interventions. For this we look both to a reduction of the pollution load from the production as well as optimization of the water treatment plant (load, chemical use). We then investigate in function of the amount and type of sludge if there's an economic advantage to be gained via sludge thickening, sludge dewatering and sludge drying, and if so by what technique.With the degree of sludge dewatering the cost of dewatering increases. The balance between intensity of dewatering and sludge disposal costs has to be found.