A scientific article simply printed by 4 Brazilian and two American scientists studies positive aspects in electrical and thermal energy obtained when brewer’s spent grain (barley bagasse), an considerable waste produced by the beer industry, is handled with ultrasound earlier than present process anaerobic digestion, a microbiological course of involving consumption of natural matter and manufacturing of methane.
Pre-treatment generated biogas with 56% methane, 27% greater than the proportion obtained with out use of ultrasound. After purification in methane, the biogas can be utilized as automobile gasoline with a really low carbon footprint in comparison with standard fossil fuels. Moreover, in cogenerators, the methane might be burned off by the brewery to provide electrical energy and warmth. The ultimate waste can be utilized as biofertilizer as an alternative of mineral fertilizer. The methodology is described intimately in the article, which is printed in the Journal of Cleaner Production.
The revolutionary course of was developed at the Laboratory of Bioengineering and Treatment of Water and Waste (Biotar) in the State University of Campinas’s School of Food Engineering (FEA-UNICAMP). The analysis group lead, Tânia Forster-Carneiro, is principal investigator for a undertaking supported by FAPESP.
Food processing factories have wastewater remedy crops, in compliance with the regulation, however don’t at all times deal with natural strong waste, which is usually shipped away to managed or sanitary landfills, or used to provide animal feed. “Research that adds value to organic solid waste is important for industry and society as a whole,” Forster-Carneiro stated. “In this study specifically, we pre-treated the waste with ultrasound, an incipient technology usually applied only in the lab and thereby obtained a higher level of methane production. The results were very positive.”
Postdoctoral fellow Luz Selene Buller and Ph.D. candidate William Sganzerla, each awardees of scholarships from FAPESP, are additionally members of the analysis group.
As Sganzerla defined, brewery wastes are lignocellulosic (comprising lignin, cellulose and hemicellulose), and the microorganisms that take part in anaerobic digestion can not simply penetrate the cell partitions. “Feeding an anaerobic digestion reactor with lignocellulosic raw material produces low levels of methane, as the microorganisms don’t consume this biomass, which has to be broken down by pre-treatment.”
The research additionally analyzed energy restoration routes all through the course of, concluding that electrical energy produced by the biogas offset 80% of the energy required for pre-treatment with ultrasound and anaerobic digestion, whereas additionally producing a 50% greater thermal energy surplus than the extra warmth that will be obtained with out the use of ultrasound.
“A technological challenge is how to apply sustainable pre-treatment that consumes little energy,” Sganzerla stated. “Pre-treatment with high energy consumption isn’t viable for industrial-scale applications. The electricity generated by combustion of the biogas will therefore be used for the ultrasound. The heat produced can be used in industry for the various processes that require thermal energy. All this follows the principles of the circular economy for food production with low carbon emissions.”
According to Buller, nutrient recycling and producing energy domestically from renewables are key to sustainable improvement and decarbonizing of meals manufacturing.
Detailed calculations
For Forster-Carneiro, the extremely detailed measurements made in the research are the foremost purpose why the article has drawn a lot consideration from the scientific neighborhood. “We calculated the balance of mass and energy in all inbound and outbound flows. We showed in detail that it’s possible to produce 0.23 megawatt-hours of electricity for every metric ton of barley bagasse processed,” she stated.
The research additionally presents the potential to generate energy from renewables to mitigate greenhouse gasoline emissions. For over 5 years, Forster-Carneiro has collaborated with Michael Timko, penultimate creator of the article. Timko is a professor at Worcester Polytechnic Institute in Massachusetts (U.S.) and in addition a specialist in waste valorization. “The study was excellent,” she stated. “Very few research projects detail the calculations for generating energy from methane.”
This experiment, amongst others, arose from the good relationship between FEA-UNICAMP and native brewers, mirrored in technical visits and donation of strong waste. The brewery involved produces 120-250 metric tons of barley bagasse per week. “The factory doesn’t recycle this waste at present. It simply gives it away for use in animal feed, but it could treat the bagasse and produce energy at the same time,” Forster-Carneiro stated.
In this context, Sganzerla famous the results of Brazil’s nationwide strong waste coverage (Law 12,305, enacted in 2010). “There will come a time when all manufacturers are obliged to treat the waste they produce,” he stated. “They will have to use the technologies available. Technically speaking, it’s already feasible. We point to various possibilities in our study. No manufacturers do so on a large scale at present because, although anaerobic digestion exists and is a viable technology for liquid and solid wastes, more in-depth research is required for solid and lignocellulosic wastes.”
Nutrient-rich
Brazil is amongst the high 5 beer producers in the world. In 2019, it produced 14 billion liters, in line with the article. Production of 100 liters of beer generates about 20 kg of barley bagasse, so some 2.8 million tons are generated yearly in Brazil. In 2020, Forster-Carneiro and her workforce patented the use of this natural waste in anaerobic reactors operated by brewers for the functions of wastewater remedy.
An article by Forster-Carneiro, Sganzerla, Buller, and Solange Mussatto, who’s affiliated with the Technical University of Denmark’s Department of Biotechnology and Biomedicine, printed in the Journal of Cleaner Production in March 2021, units out an in depth evaluation of the financial benefits of waste valorization, together with fertilizer manufacturing.
“The anaerobic digestion process treats waste with a high organic burden, generating nutrients as a result. The solid fraction left in the reactor, known as the biodigest, is basically made up of treated lignocellulosic material rich in nitrogen, phosphorus, potassium, and other minerals. In the case of malted barley bagasse, there’s a high proportion of nitrogen as well as protein, making it a good biofertilizer that can replace NPK [mineral fertilizer containing nitrogen, phosphorus and potassium],” Sganzerla stated.
Forster-Carneiro and her workforce are additionally researching hydrothermal pre-treatment of barley bagasse. “We feed the waste into a reactor, which under certain temperature and pressure conditions hydrolyzes the biomass [breaking down the molecules] to produce a hydrolyzate [liquid] with soluble nutrients. This is highly beneficial for fermentation processes. However, more in-depth research is needed so that we can arrive at an efficient and sustainable solution for the treatment of lignocellulosic wastes,” Sganzerla stated.
More data:
Luz Selene Buller et al, Ultrasonic pretreatment of brewers’ spent grains for anaerobic digestion: Biogas manufacturing for a sustainable industrial improvement, Journal of Cleaner Production (2022). DOI: 10.1016/j.jclepro.2022.131802
William Gustavo Sganzerla et al, Techno-economic evaluation of bioenergy and fertilizer manufacturing by anaerobic digestion of brewer’s spent grains in a biorefinery idea, Journal of Cleaner Production (2021). DOI: 10.1016/j.jclepro.2021.126600