fulltext.study @t Gmail

Impacts of hydrodynamic conditions on sludge digestion in internal circulation anaerobic digester

Paper ID Volume ID Publish Year Pages File Format Full-Text
34770 45047 2012 6 PDF Available
Title
Impacts of hydrodynamic conditions on sludge digestion in internal circulation anaerobic digester
Abstract

An investigation of hydrodynamic conditions and their impacts on sludge digestion in internal circulation anaerobic digester (ICAD) was conducted. This novel sludge digester employing upflow reactor concept was composed of reaction zone, riser and downcomer, etc. Part of the generated biogas was injected to the reaction zone to intensify the circulation in ICAD in order to enhance the mass transfer. The advanced particle image velocimetry was used to explore the hydrodynamic conditions at micro scale. The results revealed that the average shear rate in the reaction zone and downcomer was linearly correlated with the Reynolds number; the shear rates in ICAD revealed an order as riser > downcomer > reaction zone. Thermophilic digestion of waste activated sludge in a pilot ICAD for 5.25 d combined with thermal pretreatment at 60 °C for 1 d was conducted under various hydrodynamic conditions. The survey at global level demonstrated that both the longer sludge retention time than the hydraulic retention time and the satisfactory mass transfer could be realized and as consequences, the maximal biogas production rate and VSS removal were obtained when the Reynolds number of the reaction zone was approximately 0.53. This digester under the optimal hydrodynamic conditions demonstrated good degradation capacity and buffer capability to resist various shock loadings.

Keywords
Hydrodynamic conditions; Internal circulation anaerobic digester; Thermophilic digestion; Upflow reactor; Waste activated sludge
First Page Preview
Impacts of hydrodynamic conditions on sludge digestion in internal circulation anaerobic digester
Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 47, Issue 11, November 2012, Pages 1627–1632
Authors
, , , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering