Assessment of the Variations in Characteristics and Methane Potential of Major Waste Products from the Brazilian Bioethanol Industry along an Operating Season

Abstract

Anaerobic digestion appears to be a favorable option to optimize the energetic exploitation and reduce the environmental impacts of bioethanol waste products. Some analytical characteristics of these waste products are available in various sources. However, these data are too incomplete and unsystematic to be compared among the bioethanol industries. Design of biogas processes based on such data has to deal with considerable unknowns regarding the technical feasibility and operating costs. Therefore, to better understand and assess the applicability of these bioethanol waste products in anaerobic digestion, the micro-and macro-element concentrations, the physicochemical parameters, and the methane potential were analyzed. In addition to the assessment of seasonal variations, the effect of alkaline and mechanical treatments was also investigated for lignocellulosic bagasse samples. Possible deficiencies of the trace elements Ni, Co, Mo, Se, and W in vinasse as a substrate for anaerobic digestion were recorded. The correlation between the gradual increase in methane yields of vinasse and filter cake along the bioethanol operating season and the dynamic changes in the substrate characteristics was shown. Moreover, the methane yield of raw bagasse increased by 50% after applying both treatments in combination.

ADM1 modelling of large-scale covered in-ground anaerobic reactor treating sugarcane vinasse

“…The carbohydrates concentration is higher than lipids and proteins as found in Barrera et al (2015). However, it is noteworthy that protein content of the SV analysed in this study was relatively high when compared to other studies (Leite et al 2015, Barrera et al 2015. In the bioethanol distillery the yeast Saccharomyces cerevisiae resulting from alcohol fermentation is composed by 26.95% of crude protein, which may be lost during the process to the SV.…”

“…Only total VFA was routinely analysed by plant operators and most VFA in SV was assumed to be mostly acetate, as shown in Leite et al (2015). Inorganic carbon SIC, calculated through partial alkalinity measurements (real alkalinity for anaerobic reactors 5.75<pH initial<8) was set to zero, as the pH of the influent was always below 5.…”

“…Nevertheless, effective and economic biological treatment of SV, such as anaerobic digestion (AD) has been often cited as an option for mitigating the environmental impacts (Leite et al 2015, Moraes et al 2015.…”

“…AD arises as a sustainable bioprocess to unlock the value of SV as an energy feedstock. It is a biological engineering solution that improves the attractiveness of bioethanol as an alternative fuel, both as a means of pollution potential reduction and through recovery of biogas for renewable bioenergy generation (Barrera et al 2015, Leite et al 2015. Moreover, biogas produced by AD can replace the burning of bagasse, which is a by-product from the first-generation bioethanol production, to encourage second-generation bioethanol production from bagasse (Moraes et al 2015).…”

Impactos Ambientais Na Produção Do Etanol Brasileiro: Uma Breve Discussão Do Campo À Indústria

“…Diversos autores têm avaliado processos para obter maior rendimento dos gases hidrogênio (H 2 ) e metano (CH 4 ) (LEITE et al, 2015;REIS et al, 2015;LAZARO;SANTOS et al, 2014;BONOMI, 2015;FERRAZ JR. et al, 2014;POMPERMAYER;PAULA JR., 2000). Embora não reduza o alto teor de nutrientes, principalmente do potássio, a geração de energia proveniente da biodigestão da vinhaça é apresentada como alternativa para o seu tratamento no Brasil.…”