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Sludge stabilisation
An overview of sludge stabilisation − alkaline stabilisation, lime and solids dosing, plus anaerobic and aerobic digestion
Anaerobic digestion
Anaerobic digestion (AD) is the most extensively employed sludge stabilisation process. AD stabilises the sludge biologically in the absence of air. In doing so, it reduces the amount of volatile solids by their conversion to a biogas (methane CH4, carbon dioxide CO2 and water H2O). The biogas then demands further processing for recovery and reuse of its methane content.
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About sludge stabilisation
Stabilisation processes reduce the odour and putrescence of sludge, and level of pathogenic organisms
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Anaerobic digestion
An overview of anaerobic digestion − an introduction to sludge processing AD theory
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Sludge treatment - the anaerobic digestion process
Anaerobic digestion (AD) is the most extensively employed sludge stabilisation process, and generates a methane gas product
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Sludge treatment − how does anaerobic digestion work?
Anaerobic digestion is a multi-step biochemical process comprising hydrolysis, acidogenesis, acetogenesis and methanogenesis
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Designing anaerobic digestion systems for sludge treatment
Anaerobic digestion can be a single or multiple tank process, and employ different conditions of stirring and temperature
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Sludge pretreatment for anaerobic digestion
Pretreating sludge upstream of the anaerobic digestion is sometimes carried out to improve the sludge biological treatability
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Operating an anaerobic digester for sludge treatment
Anaerobic digestion can be conducted at moderate (mesophilic) or elevated (thermophilic) temperature conditions
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Challenges to anaerobic digestion in sludge treatment
Two widely recognised operational challenges to anaerobic digestion operation are foaming and over-acidification
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Managing anaerobic digestion biogas in sludge treatment
Anaerobic digestion generates a biogas containing 50-60% methane which can be used to generate heat and electrical power
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Managing anaerobic digestion digestate in sludge treatment
The digestate is the residual slurry, containing up to 20% solids, generated from the anaerobic digestion process
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Managing anaerobic digestion supernatant in sludge treatment
The supernatant is the liquid stream generated from anaerobic digestion process and has a high nutrient content
Anaerobic digestion related videos
Anaerobic digestion − an introduction
Anaerobic digestion (AD) is the most extensively employed sludge stabilisation process and, as with most sludge and wastewater unit processes, the design and performance of AD depends on the feed characteristics. Professor Simon Judd explains.
Anaerobic digestion 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 Anaerobic digestion topics…
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Alkaline stabilisation
Alkaline stabilisation reduces the sludge odour, putrescence and pathogenic organism content by raising its pH using lime
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Anaerobic digestion
AD stabilises the sludge biologically in the absence of air, producing a useful biogas while biodegrading the organic solids
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Aerobic digestion
Aerobic digestion is the degradation of the organic sludge solids to carbon dioxide in the presence of oxygen
More process and operation topics…
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Thickening, dewatering & drying
Thickening, dewatering and drying extract water from sludge to reduce the sludge volume
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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