ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Effect of rapid batch decompression on hydrolysate quality after hydrothermal pretreatment of wheat straw

Lukáš Krátký and Tomáš Jirout

Department of Process Engineering, Faculty of Mechanical Engineering, Czech Technical University in Prague, Technicka 4, 16607 Prague 6, Czech Republic

E-mail: Lukas.Kratky@fs.cvut.cz

Abstract: The subject of this paper was to study the effect of rapid batch decompression on hydrolysate quality and on biogas yield after the hydrothermal pretreatment of wheat straw. An aqueous batch containing 5 mass % total solids of wheat straw was thermally and thermally-expansionary treated in parallel at the process temperature of 170-200°C and the residence time of 0-60 min. An analysis of the thermal and thermal-expansionary hydrolysate provided identical results in the dependences and values of chemical oxygen demand, acidities, and glucose yields of both treatments based on severity factors including the combined effects of temperature and residence time. Increases in the methane content of 33 % for thermally and of 34 % for thermally-expansionary treated wheat straw were reached in comparison to the methane yield from an untreated sample. This means that the polysaccharide cell wall was dissolved because of the high process temperature and residence time. From this it follows that all its nutrients were subsequently washed out of the cell into liquid where they caused changes in its chemical oxygen demand, glucose content, and acidities. There was therefore no rapid decompression effect on the hydrothermally treated wheat straw.

Keywords: batch decompression – biogas yield – lignocelluloses – liquid hot water pretreatment – wheat straw

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2015-0188

Chemical Papers 69 (12) 1563–1572 (2015)