Method for dewatering sludge-type material

A process for continuous dewatering of sludge-type material containing solid particles comprising the steps of:

• receiving, from an outside process stream, material to be dewatered;
• adding the material to be dewatered into a mixing means,
• adding flocculant into said mixing means,
• mixing the material to be dewatered with said flocculant in said mixing means;
• passing the thus flocculated material through a reactor-thickener means in which water is separated therefrom through a filter surface of the reactor-thickener means while dewatered flocculated material remains on said filter surface,
• collecting the water separated from the flocculated material in the reactor-thickener means,
• axially advancing said dewatered flocculated material along said filter surface to an outlet end of said reactor-thickener means for discharge thereat, the flocculated material being progressively dewatered as it travels axially along said filter surface towards said outlet end,
• subjecting the thus dewatered flocculated material received from said reactor-thickener means as a solids mass to the action of a filtering means to extract filtrate from the material thereby causing solids from the material to form a sludge cake;
• discharging the cake;
• washing the filtering means with wash water obtained from the water collected from the reactor-thickener means to wash solids inclusive of flocculated solids from the filtering means;
• said wash water now containing said solids;
• returning at least part of said wash water with the flocculated solids contained therein after passage through the filtering means to the material to be dewatered for passage through the reactor-thickener means with the flocculated material received from the mixing means;
• the wash water and said flocculated material in said reactor-thickener means undergoing reaction on said filter surface for causing free water to be separated from the solids in the flocculated material and causing solids in the wash water to be captured by reaction with the flocculated solids in the flocculated material;
• and
• discharging clean free water from the reactor-thickener means as a discharged product from the process.