Utilization of brewery residues to produces granular activated carbon and bio-oil

• Published in: Journal of cleaner production 2017-12, Vol.168, p.908-916
• Main Authors: Gonçalves, Gilberto da C., Nakamura, Patrick K., Furtado, Damaris F., Veit, Marcia T.
• Format: Article
• Language: English
• Subjects: Activated carbon; Bio-oil; Brewer's spent grains; Pyrolysis; Yeast
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2017.09.089

Brewer's spend grain (BSG) and brewer's surplus yeast (BSY) are the main by-products from the brewery industry. The substantial production of these by-products contributes to economic losses in the production process, and may contribute to environmental problems if their proper disposal is not given. In this research, BSG and BSY were used as a novel precursor for the production of bio-oil and a low-cost granular activated carbon (GAC) via pyrolysis and CO2 activation in one-step and two-step. The effects of the production variables, such as BSG:BSY mass ratio and activation time on yield and the some textural properties were investigated. Pyrolysis of briquettes yielded 19%, 56% and 25% charcoal, liquid and gas, respectively. The liquid product showed two phases: aqueous and organic (bio-oil). The bio-oil was similar to other biomass-derived bio-oils, but with a pH of 7.45 and a calorific value of 31.26 kJ g−1. Surface area and pore volume of GAC increased as activation time increased. Six hours of activation produced GAC with a specific surface area of 617.4 m2 g−1, a total pore volume of 0.2316 cm3 g−1 and good adsorption of iodine and methylene blue. The GAC and bio-oil produced by one-step and two-step processes were similar. Thus, the reuse of BSG and BSY can provide an important advantages and benefits as the generation of value-added products (GAC and bio-oil), more jobs and solutions to pollution problems. [Display omitted] •Breweries by-products were successfully tested for bio-oil and GAC production.•Pyrolysis and CO2 activation were evaluated by using single and two-stage process.•Bio-oil yield of 56% was achieved while GAC and gas yield were 19% and 25%.•The GAC demonstrated excellent adsorption performance of iodine and methylene blue.