Feasible process development and techno-economic evaluation of paper sludge to bioethanol conversion: South African paper mills scenario

Charles L.L. Robus, Lalitha Devi Gottumukkala, Eugéne van Rensburg and Johann F. Görgens

Renewable Energy, 2016, vol. 92, issue C, 333-345

Abstract: Paper sludge samples collected from recycling mills exhibited high ash content in the range of 54.59%–65.50% and glucose concentrations between 21.97% and 31.11%. Washing the sludge reduced the total ash content to between 10.7% and 19.31% and increased the concentration of glucose, xylose and lignin. Samples were screened for ethanol production and fed-batch simultaneous saccharification and fermentation (SSF) was optimised for the washed samples that resulted in highest and lowest ethanol concentrations. Maximum ethanol concentrations of 57.31 g/L and 47.72 g/L (94.07% and 85.34% of the maximum theoretical yield, respectively) was predicted for high and low fermentative potential samples, respectively, and was experimentally achieved with 1% deviation. A generic set of process conditions were established for the conversion of high ash-containing paper sludge to ethanol. Techno-economic analysis based on three different revenue scenarios, together with Monte Carlo analysis revealed 95% probability of achieving IRR values in excess of 25% at a paper sludge feed rate of 15 t/d. Feed rates of 30 t/d and 50 t/d exhibited a cumulative probability of 100%. This study presents the technical feasibility and economic viability of paper mills expansion towards bioethanol production from paper sludge.

Keywords: Paper sludge; Bioethanol; Simultaneous saccharification and fermentation (SSF); Fed-batch; Techno-economic analysis; Monte carlo analysis (search for similar items in EconPapers)
Date: 2016
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Citations: View citations in EconPapers (5)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:92:y:2016:i:c:p:333-345

DOI: 10.1016/j.renene.2016.02.017

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