Topic
Sludge separation − filtration
Filtration theory defines the way in which water flows through the bed, which is formed of the sludge solids (cake)
Belt filter presses
A belt filter press (BFP) combines drainage and mechanical pressure sequentially, ultimately providing sludge dewatering by pressing the sludge between two revolving permeable belts to squeeze out the water from the sludge. This produces a cake (the dewatered product) having a dry solids (DS) content of 30% or more in the case of primary sludge. This is to be distinguished from the lower-energy gravity belt thickener process which achieves a maximum DS content of ~10%.
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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
Belt filter presses related videos
Belt filter press Alfa Laval
Animation to demonstrate the operating process of the Alfa Laval AS-H G3 belt press for sludge dewatering. This belt press can handle high volumes, and is used in both municipal and industrial wastewater treatment.
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Belt filter 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 Belt filter presses topics…
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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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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