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Effects of anaerobic pre-treatment on the degradation of dewatered-sewage sludge

Ivo Achu, Nges LU and Liu, Jing LU (2009) In Renewable Energy 34(7). p.1795-1800
Abstract
Effects of anaerobic pre-treatment were evaluated on the dewatered-sewage sludge from a municipal wastewater treatment plant in order to improve its biodegradability through anaerobic digestion. The pre-treatment was conducted in laboratory scale at 25, 50 and 70 degrees C for an incubation time of two days. As a reference, sludge sample was also autoclaved at 121 degrees C for 20 min to determine the thermal effect to the subsequent sludge digestion. Characteristics of dewatered-sludge such as viscosity, pH and soluble chemical oxygen demand (SCOD) were affected by the pre-treatment. A higher SCOD after the pretreatment did not necessarily imply an increase in methane yield, although initial biodegradability rate was improved. In fact, a... (More)
Effects of anaerobic pre-treatment were evaluated on the dewatered-sewage sludge from a municipal wastewater treatment plant in order to improve its biodegradability through anaerobic digestion. The pre-treatment was conducted in laboratory scale at 25, 50 and 70 degrees C for an incubation time of two days. As a reference, sludge sample was also autoclaved at 121 degrees C for 20 min to determine the thermal effect to the subsequent sludge digestion. Characteristics of dewatered-sludge such as viscosity, pH and soluble chemical oxygen demand (SCOD) were affected by the pre-treatment. A higher SCOD after the pretreatment did not necessarily imply an increase in methane yield, although initial biodegradability rate was improved. In fact, a 'great' improvement in SCOD concentration (up to 27%) was translated in only 8% increase in the methane yield (298 +/- 9 and 276 +/- 6 Nml CH4 gVS(added)(-1) for pre-treated and untreated samples, respectively). Increasing the anaerobic pre-treatment time from 12 h to 2 days at 50 degrees C led to an 11% improvement in methane yield. Methane content in biogas increased from an average of 65-69% for the pre-treated and untreated substrates, respectively. Volatile solids (VS) reduction increased from 42% to 51%. The overall digestion time was not affected by the pre-treatment but 90% of methane was produced in the first 12 days of incubation for 50 degrees C pre-treated samples whereas it took 2-5 days more for 25, 70 degrees C pre-treated and untreated sludge samples. In this study, thermophilic digestion was also found to be a better option in terms of faster digestion and higher VS-reduction, but it showed lower methane yield as compared to mesophilic digestion, i.e. 9% and 11% increment in methane yields for thermophilic and mesophilic digestions, respectively. (C) 2008 Elsevier Ltd. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Thermophilic, Pre-treatment, Methane yield, Anaerobic digestion, Mesophilic, VS-reduction
in
Renewable Energy
volume
34
issue
7
pages
1795 - 1800
publisher
Elsevier
external identifiers
  • wos:000264739200017
  • scopus:60949098908
ISSN
0960-1481
DOI
10.1016/j.renene.2008.12.001
language
English
LU publication?
yes
id
24031791-5f02-43af-95a0-3d010214be86 (old id 1400877)
date added to LUP
2009-06-12 10:01:02
date last changed
2018-01-14 03:23:04
@article{24031791-5f02-43af-95a0-3d010214be86,
  abstract     = {Effects of anaerobic pre-treatment were evaluated on the dewatered-sewage sludge from a municipal wastewater treatment plant in order to improve its biodegradability through anaerobic digestion. The pre-treatment was conducted in laboratory scale at 25, 50 and 70 degrees C for an incubation time of two days. As a reference, sludge sample was also autoclaved at 121 degrees C for 20 min to determine the thermal effect to the subsequent sludge digestion. Characteristics of dewatered-sludge such as viscosity, pH and soluble chemical oxygen demand (SCOD) were affected by the pre-treatment. A higher SCOD after the pretreatment did not necessarily imply an increase in methane yield, although initial biodegradability rate was improved. In fact, a 'great' improvement in SCOD concentration (up to 27%) was translated in only 8% increase in the methane yield (298 +/- 9 and 276 +/- 6 Nml CH4 gVS(added)(-1) for pre-treated and untreated samples, respectively). Increasing the anaerobic pre-treatment time from 12 h to 2 days at 50 degrees C led to an 11% improvement in methane yield. Methane content in biogas increased from an average of 65-69% for the pre-treated and untreated substrates, respectively. Volatile solids (VS) reduction increased from 42% to 51%. The overall digestion time was not affected by the pre-treatment but 90% of methane was produced in the first 12 days of incubation for 50 degrees C pre-treated samples whereas it took 2-5 days more for 25, 70 degrees C pre-treated and untreated sludge samples. In this study, thermophilic digestion was also found to be a better option in terms of faster digestion and higher VS-reduction, but it showed lower methane yield as compared to mesophilic digestion, i.e. 9% and 11% increment in methane yields for thermophilic and mesophilic digestions, respectively. (C) 2008 Elsevier Ltd. All rights reserved.},
  author       = {Ivo Achu, Nges and Liu, Jing},
  issn         = {0960-1481},
  keyword      = {Thermophilic,Pre-treatment,Methane yield,Anaerobic digestion,Mesophilic,VS-reduction},
  language     = {eng},
  number       = {7},
  pages        = {1795--1800},
  publisher    = {Elsevier},
  series       = {Renewable Energy},
  title        = {Effects of anaerobic pre-treatment on the degradation of dewatered-sewage sludge},
  url          = {http://dx.doi.org/10.1016/j.renene.2008.12.001},
  volume       = {34},
  year         = {2009},
}