Co-composting of sewage sludge : fats mixtures and characteristics of the lipases involved
Gea Leiva, Teresa (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)
Ferrer, Pau (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)
Álvaro, Gregorio (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)
Valero Barranco, Francisco (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)
Artola Casacuberta, Adriana (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)
Sanchez, Antoni (Universitat Autònoma de Barcelona. Departament d'Enginyeria Química, Biològica i Ambiental)

Date:	2007
Abstract:	Co-composting of sewage sludge and animal fat mixtures was studied in order to determine the possibility of using this technology to recycle fat-enriched wastes. A maximum fat content of 30% in fat:sludge mixtures is recommended to achieve the international sanitation requirements on compost quality and to avoid an excessive thermophilic composting time. Under these conditions a fat content reduction of 85% was achieved. Biological activity was highly dependent on the moisture content as shown by the respiratory quotient values. Moisture content is a critical control factor because of the hydrophobic nature of fats and should be maintained above 40% in the composting of fats. Biological indices of the compost obtained after 69 days of process (maturity grade: IV; respiration index: 1. 1 mg O₂ g OM⁻¹ h⁻¹) indicated a high stability and maturity degree of the material. Lipases responsible for fat hydrolysis were monitored during the composting process and a sample from the thermophilic period was characterized in terms of stability in front of pH and temperature. Optimal conditions for lipase stability were found at 38. 3 °C and pH 7. 97, however, the maximum lipolytic activity was observed at thermophilic temperatures. Lipases from the thermophilic period were purified by anion exchange chromatography and visualised by SDS-PAGE. Two major bands were observed at molecular weights of 29 and 62 kDa. These bands could not be identified precisely by N-terminal sequence analysis.
Grants:	Ministerio de Ciencia y Tecnología REN2003-00823
Rights:	Aquest material està protegit per drets d'autor i/o drets afins. Podeu utilitzar aquest material en funció del que permet la legislació de drets d'autor i drets afins d'aplicació al vostre cas. Per a d'altres usos heu d'obtenir permís del(s) titular(s) de drets.
Language:	Anglès
Document:	Article ; recerca ; Versió sotmesa a revisió
Subject:	Aerobic processes ; Biodegradation ; Waste treatment ; Fat ; Lipase ; Respiration index
Published in:	Biochemical engineering journal, Vol. 33, issue 3 (March 2007) , p. 275-283, ISSN 1369-703X

DOI: 10.1016/j.bej.2006.11.007

Pre-print 35 p, 1.3 MB

The record appears in these collections:
Research literature > UAB research groups literature > Research Centres and Groups (research output) > Engineering > Composting Research Group (GICOM)
Articles > Research articles
Articles > Published articles