Valorization of sorghum distillery residue to produce bioethanol for pollution mitigation and circular economy
Document Type
Article
Publication Date
9-15-2021
Abstract
This research aims to study the wet torrefaction (WT) and saccharification of sorghum distillery residue (SDR) towards hydrochar and bioethanol production. The experiments are designed by Box-Behnken design from response surface methodology where the operating conditions include sulfuric acid concentration (0, 0.01, and 0.02 M), amyloglucosidase concentration (36, 51, and 66 IU), and saccharification time (120, 180, and 240 min). Compared to conventional dry torrefaction, the hydrochar yield is between 13.24 and 14.73%, which is much lower than dry torrefaction biochar (yield >50%). The calorific value of the raw SDR is 17.15 MJ/kg, which is significantly enhanced to 22.36-23.37 MJ/kg after WT. When the sulfuric acid concentration increases from 0 to 0.02 M, the glucose concentration in the product increases from 5.59 g/L to 13.05 g/L. The prediction of analysis of variance suggests that the best combination to maximum glucose production is 0.02 M H2SO4, 66 IU enzyme concentration, and 120 min saccharification time, and the glucose concentration is 30.85 g/L. The maximum bioethanol concentration of 19.21 g/L is obtained, which is higher than those from wheat straw (18.1 g/L) and sweet sorghum residue (16.2 g/L). A large amount of SDR is generated in the kaoliang liquor production process, which may cause environmental problems if it is not appropriately treated. This study fulfills SDR valorization for hydrochar and bioenergy to lower environmental pollution and even achieve a circular economy. (C) 2021 Elsevier Ltd. All rights reserved.
Keywords
Waste valorization, Bioethanol and hydrochar, Wet torrefaction (WT), Sorghum distillery residue (SDR), Response surface methodology (RSM), Optimization
Divisions
InstituteofBiologicalSciences
Funders
Ministry of Science and Technology, Taiwan [Grant No: MOST 106-2923-E-006-002-MY3 & MOST 109-2221-E-006-040-MY3 & MOST 109-3116-F-006-016-CC1],Higher Education Sprout Project, Ministry of Education to the Headquarters of University Advancement at National Chen Kung University (NCKU)
Publication Title
Environmental Pollution
Volume
285
Publisher
Elsevier Science Ltd
Publisher Location
THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND