Topic
Sludge separation − centrifugation
The theory of centrifugation relates to sedimentation theory as it acts to enhance gravity through the centrifugal force
Dewatering
Dewatering processes mechanically remove a significant proportion of the sludge water content to produce a concentrated sludge product, with a dry solids concentration generally between 15 and 45%. At this concentration the product, referred to as a cake, is not free-flowing and instead forms lumps which can only be transported by a conveyor belt, mechanical earth-moving equipment, or spade.
Topic
Sludge separation − filtration
Filtration theory defines the way in which water flows through the bed, which is formed of the sludge solids (cake)
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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
Belt filter presses for sludge dewatering
These presses dewater sludges to produce a cake with a dry solids content of 30% or more in the case of primary sludge
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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
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Filter presses for sludge dewatering
The filter press forces water from the sludge by applying high pressures to sludge layers held between rectangular plates
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Rotary presses for sludge dewatering
This technology removes water by passing the sludge through a narrow, rotating parallel-flow channel with porous walls
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Centrifugal sludge dewatering
Centrifugation is used for thickening and dewatering sewage sludge − dewatered sludge has a higher dry solids concentration
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Sludge drying beds and lagoons
Drying beds dewater sludge by allowing the liquid to drain and to evaporate. Lagoons provide dewatering through evaporation
Topic
Other sludge dewatering processes
Electro-dewatering technology provides enhanced removal by non-mechanical means through the application of an electric field
Dewatering related videos
Benenv's Wave Separator for sludge and waste thickening and dewatering
Film to demonstrate the Benenv Wave Separator for sludge and waste thickening and dewatering.
The Wave Separator is a self-cleaning, solid−liquid separation machine, with thickening and dewatering functions. The Wave Separator can be used for various applications and industries, including for food waste, biological sludge and paint waste.
Dewatering 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 Dewatering 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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Screw presses
A screw press dewaters sludge by passing it along the inside of an inclined permeable cylinder using an Archimedean screw
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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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Drying
In sludge drying the sludge moisture is removed as water vapour by heating, generating a pelleted or powdered product
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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