Water Science & Technology—WST Vol 57 No 8 pp 1221–1226 © IWA Publishing 2008 doi:10.2166/wst.2008.072
Continuous thermal hydrolysis and energy integration in sludge anaerobic digestion plants
F. Fdz-Polanco, R. Velazquez, S. I. Perez-Elvira, C. Casas, D. del Barrio, F. J. Cantero, M. Fdz-Polanco, P. Rodriguez, L. Panizo, J. Serrat and P. Rouge
Departamento de Ingeniería Química y Tecnología del Medio Ambiente, Universidad de Valladolid, Spain E-mail: ffp@iq.uva.es; rvelaz@iq.uva.es; sarape@iq.uva.es; ccasas@iq.uva.es; dbarrio@iq.uva.es; fjcantero@iq.uva.es; maria@iq.uva.es
SOREA – Aguas de Barcelona, Torre Agbar. Av. Diagonal 211, 080118, Barcelona, Spain E-mail: prodiguez@agbar.net; mlpanizo@agbar.net; jserrat@agbar.net; prouge@agbar.net
ABSTRACT
A thermal hydrolysis pilot plant with direct steam injection heating was designed and constructed. In a first period the equipment was operated in batch to verify the effect of sludge type, pressure and temperature, residence time and solids concentration. Optimal operation conditions were reached for secondary sludge at 170°C, 7 bar and 30 minutes residence time, obtaining a disintegration factor higher than 10, methane production increase by 50% and easy centrifugation In a second period the pilot plant was operated working with continuous feed, testing the efficiency by using two continuous anaerobic digester operating in the mesophilic and thermophilic range. Working at 12 days residence time, biogas production increases by 40–50%. Integrating the energy transfer it is possible to design a self-sufficient system that takes advantage of this methane increase to produce 40% more electric energy.
Keywords: anaerobic digestion; biogas; sludge; thermal hydrolysis
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