Incubation treatment of sludge for pathogen reduction prior to digestion
AssigneeUnited Utilities PLC
InventorSon Le
Life of this patent
Estimating the term…
Abstract
A method of treating sewage sludge comprises a pathogen reduction stage in which raw sludge is incubated for a predetermined incubation period at a temperature in the mesophilic temperature range. The sludge is incubated in a plurality of sequential vessels (1a,1b,1c) comprising an upstream vessel (1a) which receives the raw sludge to be incubated and a downstream vessel (1c) which discharges the incubated sludge. The sludge is fed from the upstream vessel (1a) to the downstream vessel (1c), via any intermediate vessels (1b), and subsequently discharged after spending a predetermined residence time in each vessel, the total residence time being said predetermined incubation period.
Claims14
A two stage sludge treatment process comprising:
- a first pathogen reduction stage in which raw sludge is incubated for a predetermined incubation period at a temperature in the mesophilic temperature range of about 25° C. to about 46° C.;
- wherein the total chemical oxygen demand (COD) of the raw sludge is greater than about 10,000 mg/l and wherein the raw sludge is incubated in a plurality of sequential vessels comprising an upstream vessel which receives the raw sludge to be incubated and a downstream vessel which discharges the incubated sludge, the sludge being fed from the upstream vessel to the downstream vessel, via any intermediate vessels, to provide a total residence time of between 0.5 and 5 days and subsequently being fed to a suitable reactor for mesophilic anaerobic digestion of the sludge after spending a predetermined residence time in each vessel, the total residence time being said predetermined incubation period.
Dependencies are inferred from the claim text.