Mixing in anaerobic digesters
Mixing in anaerobic digesters
Mixing in anaerobic sewage digesters has been investigated using two scales of vessel with the overall aim of providing quantified design information in terms of the active volume expected with different gas sparger types and the blend times expected within this active volume.
Due to a greater sludge production and restrictions enforced on disposal routes, many sludge producers want to increase the available sludge digestion capacity using their existing digesters. This can be achieved both by reducing the size of any inactive volume and by digesting thicker sludges. In both cases, successful volume utilisation and digestion are dependent on the detailed design of the mixing systems involved.
An experimental programme was undertaken to study unconfined gas mixing using a sludge stimulant. Measurements of blend time were made using an electrolyte tracer and conductivity probes positioned around the vessels. Video footage was taken to determine the size and location of any inactive volume within the vessel.
It was found that a sequential gas sparger performed best overall, both in terms of active volume produced and also in terms of the active blend time. The choice of sparger layout had a considerable effect on mixer performance. The size and location of inactive volume dependent on the mixer layout, the viscosity of the liquid and the power input. In general, an increase in viscosity resulted in a decrease in active volume and an increase in blend time. Conversely, an increase in power input resulted in an increase in active volume and a decrease in blend time.
University of Southampton
Christodoulides, Jacqueline S
e3c5f354-6d12-4575-a769-b0b521dc4fbe
2001
Christodoulides, Jacqueline S
e3c5f354-6d12-4575-a769-b0b521dc4fbe
Christodoulides, Jacqueline S
(2001)
Mixing in anaerobic digesters.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Mixing in anaerobic sewage digesters has been investigated using two scales of vessel with the overall aim of providing quantified design information in terms of the active volume expected with different gas sparger types and the blend times expected within this active volume.
Due to a greater sludge production and restrictions enforced on disposal routes, many sludge producers want to increase the available sludge digestion capacity using their existing digesters. This can be achieved both by reducing the size of any inactive volume and by digesting thicker sludges. In both cases, successful volume utilisation and digestion are dependent on the detailed design of the mixing systems involved.
An experimental programme was undertaken to study unconfined gas mixing using a sludge stimulant. Measurements of blend time were made using an electrolyte tracer and conductivity probes positioned around the vessels. Video footage was taken to determine the size and location of any inactive volume within the vessel.
It was found that a sequential gas sparger performed best overall, both in terms of active volume produced and also in terms of the active blend time. The choice of sparger layout had a considerable effect on mixer performance. The size and location of inactive volume dependent on the mixer layout, the viscosity of the liquid and the power input. In general, an increase in viscosity resulted in a decrease in active volume and an increase in blend time. Conversely, an increase in power input resulted in an increase in active volume and a decrease in blend time.
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Published date: 2001
Identifiers
Local EPrints ID: 466755
URI: http://eprints.soton.ac.uk/id/eprint/466755
PURE UUID: 00bb8eec-f861-4224-832a-83add1a616f4
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Date deposited: 05 Jul 2022 06:34
Last modified: 16 Mar 2024 20:51
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Author:
Jacqueline S Christodoulides
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