Topic
Sludge separation − filtration
Filtration theory defines the way in which water flows through the bed, which is formed of the sludge solids (cake)
Screw presses
A screw press provides sludge dewatering by passing the sludge along the inside of a permeable cylinder. It uses a slowly-rotating (~5 RPM) Archimedean screw within a cylindrical screen (otherwise termed drum filter/screen or basket). It is normally inclined by ~20° to the horizontal to assist with the draining of water into the sump, and the screen aperture rating is generally below 0.5 mm.
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Sludge dewatering
An overview of sludge dewatering − an introduction to sludge dewatering theory and technologies
Topic
Introduction to sludge dewatering
Dewatering processes provide a concentrated, consolidated product along with a diluted stream which is predominantly water
Topic
Screw presses for sludge dewatering
A screw press is a dewatering technology based on a slowly-rotating (~5 RPM) Archimedean screw within a cylindrical screen
Screw presses related videos
Swingmill sludge dewatering mechanical process
Video to demonstrate the operation of the Swingmill sludge dewatering screw press from Dewlink Sludge Treatment
Screw presses features and blogs
Feature
Co-processing of sewage digestate by hydrothermal carbonisation
Hydrothermal carbonisation (HTC) can be used to co-process anaerobic digestion (AD) digestate and lignocellulosic (or plant-based) feedstocks to improve the the hydrochar product quality. This AD waste co-processing route has been studied at bench scale. Read article
More Screw presses topics…
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Belt filter presses
A belt filter press (BFP) dewaters sludge by pressing it between two revolving permeable belts to squeeze out the water
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Centrifuges
Centrifugal dewatering consolidates sludge by encouraging particles to migrate to the walls of a rapidly rotating cyclinder
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Drying beds
Drying beds dewater sludge by allowing the liquid to both drain from the sludge under gravity and evaporate from its surface
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Filter presses
A filter press dewaters sludge by pressing it between a series of porous plates at high pressure to squeeze out the water
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Lagoons
A lagoon is a large shallow reservoir filled with sludge, which settles and stabilises over an extended time period
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Rotary press
A rotary press dewaters sludge by passing it along a channel formed between two slowly-rotating circular permeable screens
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Conditioning
Conditioning is the pretreatment of sludge upstream of thickening and dewatering to promote solid-liquid separation
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Thickening
Thickening processes concentrate the sludge by removing part of the free water, such that the product can still be pumped
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Dewatering
Dewatering processes mechanically remove a significant proportion of the sludge water to produce a 15-45% cake product
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Drying
In sludge drying the sludge moisture is removed as water vapour by heating, generating a pelleted or powdered product
More process and operation topics…
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Sludge stabilisation
Sludge stabilisation − alkaline stabilisation, lime and solids dosing, plus anaerobic and aerobic digestion
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Thermochemical processes
Thermochemical methods are used to either significantly reduce the sludge solids content or pre-treat sludge upstream of AD
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Sludge quality
Sludge is the main waste stream from the treatment of wastewater