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Purwadi, Ronny
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Publications (3 of 3) Show all publications
Purwadi, R. & Taherzadeh, M. J. (2008). The performance of serial bioreactors in rapid continuous production of ethanol from dilute-acid hydrolyzates using immobilized cells. Bioresource Technology, 99(7), 2226-2233
Open this publication in new window or tab >>The performance of serial bioreactors in rapid continuous production of ethanol from dilute-acid hydrolyzates using immobilized cells
2008 (English)In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 99, no 7, p. 2226-2233Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Elsevier BV, 2008
Keywords
Energi och material
National Category
Other Industrial Biotechnology
Identifiers
urn:nbn:se:hb:diva-2403 (URN)10.1016/j.biortech.2007.05.021 (DOI)2320/3550 (Local ID)2320/3550 (Archive number)2320/3550 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-01Bibliographically approved
Purwadi, R., Brandberg, T. & Taherzadeh, M. (2007). A Possible Industrial Solution to Ferment Lignocellulosic Hydrolyzate to Ethanol: Continuous Cultivation with Flocculating Yeast. International Journal of Molecular Sciences, 8(9), 920-932
Open this publication in new window or tab >>A Possible Industrial Solution to Ferment Lignocellulosic Hydrolyzate to Ethanol: Continuous Cultivation with Flocculating Yeast
2007 (English)In: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 8, no 9, p. 920-932Article in journal (Refereed)
Abstract [en]

Cultivation of toxic lignocellulosic hydrolyzates has been a research topic in recent decades. Although several methods have been proposed, there has been doubt about their industrial applications. The current work deals with a solution to this problem which has a good potential application in industrial scale. A toxic dilute-acid hydrolyzate was continuously cultivated using a high-cell-density flocculating yeast in a single and serial bioreactor which was equipped with a settler to recycle the cells back to the bioreactors. No prior detoxification was necessary to cultivate the hydrolyzates, as the flocks were able to detoxify it in situ. The experiments were successfully carried out at dilution rates up to 0.52 h-1. The cell concentration inside the bioreactors was between 23 and 35 g-DW/L, while this concentration in the effluent of the settlers was 0.320.05 g-DW/L. The ethanol yield of 0.42-0.46 g/g-consumed sugar was achieved, and the residual sugar concentration was less than 6% of the initial fermentable sugar (glucose, galactose and mannose) of 35.2 g/L.

Place, publisher, year, edition, pages
Molecular Diversity Preservation International (MDPI) AG., 2007
Keywords
dilute-acid lignocellulosic hydrolysate, scharomyces cerevisiae, flocculting yeast, ethanol, HMF, furfural, continuous cultivation, Energi och material
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:hb:diva-2294 (URN)10.3390/i8090920 (DOI)2320/2957 (Local ID)2320/2957 (Archive number)2320/2957 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-01
Purwadi, R. (2006). Continuous ethanol production from dilute-acid hydrolyzates: detoxification and fermentation strategy. (Doctoral dissertation). Göteborg : Chalmers tekniska högskola
Open this publication in new window or tab >>Continuous ethanol production from dilute-acid hydrolyzates: detoxification and fermentation strategy
2006 (English)Doctoral thesis, monograph (Other academic)
Abstract [en]

The production of fuel ethanol from cellulosic biomass is of growing interest around the world. Lignocellulosic residuals can be used to produce transportation fuel, with the overall process having little net production of greenhouse gases. Lignocellulosic materials are available as a by-product of many industrial processes and agricultural materials, or can potentially be produced from dedicated energy crops. The production of ethanol from lignocellulosic materials includes hydrolysis which breaks the cellulose and hemicellulose polymers to fermentable sugars, followed by cultivation which converts the sugars into ethanol, and finally a separation process where ethanol purification is carried out to produce fuel ethanol. However, some byproducts such as furan compounds are released during chemical hydrolysis and inhibit the yeast during cultivation. This work contributes a solution to overcome these problems especially for a continuous process which is economically superior. Hydrolyzate detoxification using lime (â overlimingâ ) in concert with the capability of yeast to carry out in-situ detoxification is focused upon in the work. The kinetics of the overliming process were studied, where both sugars and furan compounds are degraded through a formation of complex ion. The sudden addition of lime in a batch process shows severe degradation of sugars together with furan compounds. This knowledge leads to development of a continuous detoxification process where gradual addition of lime can save 25% of the initial sugar with similar detoxification effects under certain conditions. Cell immobilization and cell flocculation have been studied to develop a high cell density system. High cell density is effective in carrying out in-situ detoxification. This study shows a good combination of continuous detoxification and cell immobilization where continuous ethanol production of 5.14 g/L·h can be carried out at a high feeding rate of 0.648 h-1. In addition, the application of a serial bioreactor has been found to increase the utilization of substrates. A gain in substrate assimilation of 11.6% has been achieved when using a serial bioreactor at residence time of 2.32 h. Furthermore, a cell flocculating system has been studied and developed. In a steady-state condition, the cell flocculation system could cultivate fresh hydrolyzates at a high feeding rate of 0.52 h-1 without any additional chemical detoxification, while sugar assimilation and ethanol productivity were 96% and 7.4 g/L·h respectively. In conclusion, this study proposes a concept of rapid continuous production of ethanol where inhibitory obstacles can be overcome by chemical detoxification and/or in-situ detoxification by yeast.

Place, publisher, year, edition, pages
Göteborg : Chalmers tekniska högskola, 2006
Series
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie, ISSN 0346-718X ; 2520
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:hb:diva-3388 (URN)2320/1649 (Local ID)91-7291-838-1 (ISBN)2320/1649 (Archive number)2320/1649 (OAI)
Note

I. Kinetic study of detoxification of dilute-acid hydrolyzates by Ca(OH)2

Ronny Purwadi, Claes Niklasson, Mohammad J. Taherzadeh (2004), Journal of

Biotechnology, Vol. 114, page 187-198. Reprinted with permission from

Elsevier.

II. Performance of continuous detoxification of dilute-acid hydrolyzates by

Ca(OH)2

Ronny Purwadi, Mohammad J. Taherzadeh

Submitted for publication.

III. The performance of serial bioreactor in rapid continuous production of

ethanol from dilute-acid hydrolyzates using immobilized cells

Ronny Purwadi, Mohammad J. Taherzadeh

Submitted for publication.

IV. A possible industrial solution to ferment lignocellulosic hydrolyzates to

ethanol: continuous cultivation with flocculating yeast

Ronny Purwadi, Mohammad J. Taherzadeh

Submitted for publication.

Available from: 2015-12-04 Created: 2015-12-04 Last updated: 2016-05-11
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