Operational and biochemical aspects of co-digestion (co-AD) from sugarcane vinasse, filter cake and deacetylation liquor

Abstract

This work performed co-AD from the vinasse and filter cake (from 1G ethanol production) and deacetylation liquor (from the pre-treatment of sugarcane straw for 2G ethanol production) in a semi-Continuous Stirred Tank Reactor (s-CSTR) aiming to provide optimum operational parameters for continuous CH4 production. Using filter cake as co-substrate may allow the reactor to operate throughout the year, as it is available in the sugarcane off-season, unlike vinasse. A comparison was made from the microbial community of the seed sludge and the reactor sludge when CH4 production stabilized. Lactate, butyrate and propionate fermentation routes were denoted at the start-up of the s-CSTR, characterizing the acidogenic phase: the Oxidation-Reduction Potential (ORP) values ranged from -800 to -100 mV. Once the methanogenesis was initiated, alkalizing addition was no longer needed as its demand by the microrganisms was supplied by the alkali-characteriscs of the deacetylation liquor. The gradual increase of the applied Organic Load Rates (OLR) allowed stabilization of the methanogenesis from 3.20 gVS L-1 day-1: the highest CH4 yield (230 NmLCH4 gSV-1) and average organic matter removal efficiency (83% + 13) was achieved at ORL of 4.16 gVS L-1day-1. The microbial community changed along the reactor operation, presenting different metabolic routes mainly due to the used lignocellulosic substrates. Bacteria from the syntrophic acetate oxidation (SAO) process coupled to hydrogenotrophic methanogenesis were predominant (~ 2% Methanoculleus) during the CH4 production stability. The overall results are useful as preliminary drivers in terms of visualizing the co-AD process in a sugarcane biorefinery integrated to scale.

Liquefied biomethane from sugarcane vinasse and municipal solid waste: Sustainable fuel for a green-gas heavy duty road freight transport corridor in Sao Paulo state

“…of ethanol (2G Ethanol) which may result in an increment of up to 50%-60% of its current production. Interestingly, the biodigestion of residues from the 1G2G sugarcane ethanol biorefinery has been demonstrated in batch experiments with useful results as preliminary drivers to scale up [40]. Once more, expenditure with electricity had the highest impact on the operating costs, representing more than 80% of shares at the refuelling stations (Figure 6E and F).…”

“…kg -1 CODremoved with a pollutant load decrement of 60%, indicating that the AD of SCV is a reliable technology and fully available to the sugarcane mills. It should be recalled that thermophilic AD of SCV was considered, in this study, as operating condition (55 °C) due to its superior stability [15,40]. Furthermore, SCV leaves the distillation operation in the temperature range of 85-90 °C, thus, representing no additional costs to the process.…”

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Diversifying the energy components of a country's transport sector is essential to guarantee the fuel supply to consumers and increase the market dynamics and competitiveness.Among the known alternative fuels, biogas is a renewable source and after upgrading to biomethane, it presents a similar composition to natural gas (> 90% of CH4;(35)(36)(37)(38)(39)(40) ). In addition, it can be produced from a wide variety of biological resources and at different scales In this study, two scenarios have been developed that evaluate the use of liquefied biomethane (LBM) as a diesel replacement option in the freight sector of an area of 248,223 km 2 (equivalent to the area of the UK).

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