Sewage sludge dewatering process
AssigneeBechtel Group, Inc.
InventorsFrank J. Cain, Lawrence J. Gasper
Life of this patent
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Abstract
Solid organic substrates, such as sewage sludge, peat, and biomass, are dewatered in a three-stage process comprising mechanical dewatering of the substrate, followed by combination of the dewatered substrate with an organic solvent, followed by removal of the water-solvent mixture. The dried product is a granular, free-flowing substance suitable for incineration in relatively low-cost equipment. Conveniently, solvent will be recovered from the water-solvent mixture by conventional means, such as distillation, and recycled to the solvent mixing stage.
Claims19
A method for dewatering an organic substrate, said method comprising providing a substantially dry, free-flowing product having properties which enable it to be conveniently incinerated in conventional furnaces other than only fluidized bad combustors and multiple hearth furnaces, by:
- mechanically reducing the moisture content of the organic substrate to below about 90% by weight;
- mixing the organic substrate having reduced moisture content with a low molecular weight organic solvent where the weight ratio of solvent to organic substrate is in the range from about 1:1 to 5:1;
- and
- mechanically removing the water-solvent mixture from the organic substrate.
A method for dewatering an organic substrate, said method comprising providing a substantially dry, free-flowing product having properties which enable it to be conveniently incinerated in conventional furnaces other than only fluidized bed combustors and multiple hearth furnaces, by:
- mechanically reducing the moisture content of the organic substrate to below about 90% by weight;
- mixing the organic substrate having reduced moisture content with a low molecular weight organic solvent where the weight ratio of solvent to organic substrate is in the range from about 1:1 to 5:1;
- and
- mechanically removing the water-solvent mixture from the organic substrate.
Dependencies are inferred from the claim text.