Biomethane Production from Sugarcane Vinasse in a Circular Economy: Developments and Innovations

Abstract

Sugarcane ethanol production generates about 360 billion liters of vinasse, a liquid effluent with an average chemical oxygen demand of 46,000 mg/L. Vinasse still contains about 11% of the original energy from sugarcane juice, but this chemical energy is diluted. This residue, usually discarded or applied in fertigation, is a suitable substrate for anaerobic digestion (AD). Although the technology is not yet widespread—only 3% of bioethanol plants used it in Brazil in the past, most discontinuing the process—the research continues. With a biomethane potential ranging from 215 to 324 L of methane produced by kilogram of organic matter in vinasse, AD could improve the energy output of sugarcane biorefineries. At the same time, the residual digestate could still be used as an agricultural amendment or for microalgal production for further stream valorization. This review presents the current technology for ethanol production from sugarcane and describes the state of the art in vinasse AD, including technological trends, through a recent patent evaluation. It also appraises the integration of vinasse AD in an ideal sugarcane biorefinery approach. It finally discusses bottlenecks and presents possible directions for technology development and widespread adoption of this simple yet powerful approach for bioresource recovery.

Methane Production from Sugarcane Vinasse Biodigestion: An Efficient Bioenergy and Environmental Solution for the State of São Paulo, Brazil

“…However, limitations in wastewater management still impose challenges on the environmental suitability of sugarcane processing towards ethanol [1,6]. Focus is given to vinasse, the primary wastewater from distillation, which concentrates high amounts of organic and inorganic Methane 2024, 3 315 constituents [7,8]. The potassium-rich character of vinasse stimulates its use in the fertirrigation of sugarcane fields as a strategy to recycle water and nutrients as well as to minimize costs of mineral fertilization [7].…”

“…Anaerobic digestion (AD) is considered by far the best technological approach to manage sugarcane vinasse, considering a series of benefits: (i) minimization of the polluting organic load, (ii) opportunity for recovering bioenergy in the methane-rich biogas stream and (iii) maintenance of the nutrient-rich character of fresh vinasse in the digestate [1,6,8]. Despite all these advantages, real-scale experiences with vinasse AD are very restricted in Brazil, with the recent implementation of only some lagoon-based bioenergy-producing plants [16,17].…”