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Valorisation of bread waste for hydroxymethylfurfural (HMF) synthesis was examined in dimethyl sulfoxide (DMSO)-, tetrahydrofuran (THF)-, acetonitrile (ACN)-, and acetone-water (1:1 v/v), under heating at 140 °C with SnCl 4 as the catalyst. The overall rate of the process was the fastest in ACN/H 2 O and acetone/H 2 O, followed by DMSO/H 2 O and THF/H 2 O due to the rate-limiting glucose isomerisation. However, the formation of levulinic acid (via rehydration) and humins (via polymerisation) was more significant in ACN/H 2 O and acetone/H 2 O. The constant HMF maxima (26–27 mol%) in ACN/H 2 O, acetone/H 2 O, and DMSO/H 2 O indicated that the rates of desirable reactions (starch hydrolysis, glucose isomerisation, and fructose dehydration) relative to undesirable pathways (HMF rehydration and polymerisation) were comparable among these mediums. They also demonstrated higher selectivity towards HMF production over the side reactions than THF/H 2 O. This study differentiated the effects of polar aprotic solvent-water mediums on simultaneous pathways during biomass conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel and sustainable lignin recovery method developed using DES and microwaves. • DES susceptible to microwave heating, dielectric loss 3.4–12.0 from 20 to 80 °C. • Extraction yield of 95.5% lignin from CBS was achieved at 130 °C and 30 min. • DES-extracted lignin exhibits unique structural characteristics. • DES extraction is promising in the development of higher value lignin products. Lignin is the second most abundant natural polymer after cellulose, and valorisation of lignin-rich streams has attracted increasing attention recently. This paper presents a novel and sustainable method to recover lignin from Cocoa Bean Shells (CBS) using Deep Eutectic Solvents (DES) and microwaves. A DES containing p-toluenesulfonic acid, choline chloride and glycerol (2:1:1 M ratio) was selected based on its dielectric properties. Under 200 W microwave power, the optimum yield of 95.5 % lignin was achieved at 130 °C and 30 min. DES-extracted lignin exhibited unique structural characteristics including larger particle sizes (242.5 µm D50 size), structural diversity (410.4 µm D90-D10 size) and H/G sub-unit ratio (71.9 %) compared with commercial Kraft lignin (77.2 µm, 157.9 µm and 0.1 % respectively), indicating the potential of DES in the modification and upgrading of lignin for novel value-added products. [ABSTRACT FROM AUTHOR]

This work evaluates the environmental performance of using pulp and paper sludge as feedstock for the production of second generation ethanol. An ethanol plant for converting 5400 tons of dry sludge/year was modelled and evaluated using a cradle-to-gate life cycle assessment approach. The sludge is a burden for pulp and paper mills that is mainly disposed in landfilling. The studied system allows for the valorisation of the waste, which due to its high polysaccharide content is a valuable feedstock for bioethanol production. Eleven impact categories were analysed and the results showed that enzymatic hydrolysis and neutralisation of the CaCO 3 are the environmental hotspots of the system contributing up to 85% to the overall impacts. Two optimisation scenarios were evaluated: (1) using a reduced HCl amount in the neutralisation stage and (2) co-fermentation of xylose and glucose, for maximal ethanol yield. Both scenarios displayed significant environmental impact improvements. [ABSTRACT FROM AUTHOR]

This work investigates the potential for polyhydroxybutyrate (PHB) production from wastewater, from a techno-economic and an environmental perspective, examining scale-up opportunities and bottlenecks prior to commercialisation. Conceptual process design, economic, environmental impacts and sensitivity analysis are developed for one fermentation process and three downstream processing routes, based on alkali, surfactant-hypochlorite and solvent treatments. Environmentally and cost-wise, the alkali treatment is the most favourable with production costs of 1.40 €/kg PHB, global warming potential of 2.4 kg CO 2 -eq/kg PHB and non-renewable energy use of 106 MJ/kg PHB. The solvent-based process yields the highest costs and environmental burdens: 1.95 €/kg PHB, 4.30 kg CO 2 -eq/kg PHB and 156 MJ/kg PHB. The production of PHB from wastewater is identified as an interesting alternative to pure culture-polyhydroxyalkanoates production from sugars. However, these results are not yet competitive with those for the petrochemical counterparts. Additional performance improvements may be possible, through process integration and optimisation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Comprehensive process developed for MC production from wastewater via PHA platform. • The simulation results were in great agreement with experimental data. • The origin of the wastewater has great influence on the MC quantity and purity. • Intracellular PHA reduces the purification steps with little effects on MC purity. This work simulates the production of methyl crotonate from various industrial wastewaters. In the upstream process, wastewater is fermented into volatile fatty acids which are then converted into polyhydroxyalkanoates (PHA) by means of mixed microbial cultures. In the downstream, PHA undergoes a series of thermolysis and esterification reactions to produce methyl crotonate. The origin of the wastewater was found to have a great influence on the composition of the PHA with the effluent of a candy bar factory producing a high polyhydroxybutyrate/polyhydroxyvalerate ratio of 86/14 in favour of methyl crotonate production. It was observed that the use of intracellular polyhydroxybutyrate, instead of purified, significantly lowers the number of separation steps and yet reduces the methyl crotonate recovery by only 20 %. An operating pressure higher than 18 bar led to more transesterification of polyhydroxybutyrate, producing byproducts instead of methyl crotonate. Finally, a 3 h reaction was found sufficient for completion of polyhydroxybutyrate conversion. [ABSTRACT FROM AUTHOR]

Abstract: Manure is a rich organic waste which, apart from its traditional use as a fertilizer, could be used as a bioenergy feedstock. In this sense, its utilization as a sole fuel or its co-combustion together with coal would be a choice for the management of this sort of biowaste. However, little is known about the behavior of this biowaste when submitted to high-temperature energy-conversion processes. Thus, the separate combustion of swine manure and coal and their co-combustion (10% dried weight of manure) were studied by simultaneous TG/MS dynamic runs. TG–MS analysis was successfully used as an easy rapid tool to assess the combustion of manure, alone or together with coal. Furthermore, non-isothermal kinetic analysis showed that the Arrhenius activation energy corresponding to the combustion of the blend (125.8–138.9kJ/mol) was only slightly higher than that of manure (106.4–114.4kJ/mol) or coal (107.0–119.6kJ/mol). [Copyright &y& Elsevier]

• Green co-solvent systems enhanced cellulose depolymerization and product yield. • Maximum 32% of levulinic acid (LA) yielded in GVL/H 2 O solvent at 200 °C. • GVL/H 2 O system maintained high availability of soluble sugars. • Acetone/H 2 O solvent generated 17 Cmol% of LA at a lower temperature (180 °C) • Higher temperature induced polymerization of sugars in acetone/H 2 O solvent. Lignocellulosic wastes constitute a significant portion of the municipal solid waste, which should be valorised for the synthesis of value-added chemicals to achieve circular bioeconomy. This study evaluates the use of γ-valerolactone (GVL) and acetone as green co-solvents to produce levulinic acid (LA) from lignocellulosic paper towel waste at different temperatures using dilute H 2 SO 4. At the highest reaction temperature (200 °C), H 2 O-only system achieved ~15 Cmol% of LA at maximum. while GVL/H 2 O and acetone/H 2 O co-solvent systems enhanced the depolymerisation of paper towel waste and the subsequent conversion to LA, with the highest yield amounted to ~32 Cmol%. Acetone/H 2 O solvent system generated ~17 Cmol% LA at a lower temperature (180 °C), while higher temperature induced polymerisation of soluble sugars and intermediates, hindering further conversion to LA. In contrast, the availability of soluble sugars was higher in the GVL/H 2 O system, which favoured the production of LA at higher temperatures. [ABSTRACT FROM AUTHOR]