Journal article
Anaerobic digestion of waste activated sludge—comparison of thermal pretreatments with thermal inter-stage treatments
Bioenergy and Biomass, Biosystems Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark1
Biosystems Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark2
Risø National Laboratory for Sustainable Energy, Technical University of Denmark3
BACKGROUND: Treatment methods for improved anaerobic digestion (AD) of waste activated sludge were evaluated. Pretreatments at moderate thermal (water bath at 80 °C), high thermal (loop autoclave at 130–170 °C) and thermo-chemical (170 °C/pH 10) conditions prior to AD in batch vials (40 days/37 °C) were compared with inter-stage treatments under the same conditions carried out between two separate steps of AD (19–21 days/37 °C).
Combined treatment at 80 °C with CO2/ NH3-stripping was also evaluated. RESULTS: Pretreatment at 80 °C had no effect on methane yield while inter-stage treatment gave a 20% increase, compared with controls. Combining inter-stage treatment with CO2/ NH3-stripping gave an increase in pH (7.1 to 9.3), a drop in ammonia-N concentration (910 mg-N to 510 mg-N) and a methane yield improvement of 31%.
Pretreatment at 130 °C, 170 °C and 170 °C/pH 10 considerably increased the methane production within the first 4 days but the improvement following 40 days of digestion was only 13%, 9% and 2%, respectively. In comparison, inter-stage treatment led to improvements of 9% (130 °C), 29% (170 °C) and 28% (170 °C/pH 10).
All treatment processes increased sludge solubilization. CONCLUSION: Thermal treatment of waste activated sludge for improved anaerobic digestion seems more effective when applied as an inter-stage treatment rather than a pretreatment. Copyright © 2010 Society of Chemical Industry
Language: | English |
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Publisher: | John Wiley & Sons, Ltd. |
Year: | 2011 |
Pages: | 238-245 |
ISSN: | 02682575 , 10974660 and 03681084 |
Types: | Journal article |
DOI: | 10.1002/jctb.2509 |
ORCIDs: | Thygesen, Anders |
anaerobic digestion inter‐stage treatment pretreatment sludge thermal