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A cost efficient synergistic strategy combining mild alkaline pretreatment (0.5-5% NaOH at 70 °C for 60 min) and bovine serum albumin (BSA) blocking of lignin was evaluated for effective conversion of poplar. The highest glucose yield of 69.2% was obtained for 5% alkaline pretreated sample, which was 4.4 times that of untreated sample. The enhanced enzymatic hydrolysis was attributed to significant hemicelluloses removal with limited delignification. Delignification mainly occurred in secondary wall, leading to more open cell wall structure, thus facilitating better transport of enzyme. Hemicelluloses removal helped split adjacent microfibrils, thus increased the specific sites for cellulase binding. After BSA addition in enzymatic hydrolysis, cellulose conversion further improved to 78.4% with 33% reduction of cellulase dosage due to decreased non-specific adsorption of cellulase on residual lignin. The utilization of synergistic alkaline pretreatment - BSA strategy may improve the overall economics of biomass conversion and successful commercial implementation of biorefineries.

Bioenergy is considered a sustainable substitute to fossil-fuel resources and the development of a prudent combination of renewable and innovative conversion technologies are essential for the valorization and effective conversion of biowaste to value-added commodities. Here, a negative pressure-induced carbonization process was proposed for the valorization of lignin-enriched biowaste precursor to bio-oil and environmental materials (biochar) at various temperatures. The high heating values (HHV) of the as-prepared biochars from the lignin enriched precursor under negative pressure (low-medium vacuum) were within 25.9-31.5 MJ/kg, which matched satisfactorily to the commercial charcoal. Whereas, the bio-oils produced from the lignin enriched precursor under vacuum conditions was a blend of complex aromatic and straight-chain hydro-carbons, including aldehyde, ketone, phenol, and furans, exhibiting ability as potential heating-oil with HHV within 21.2-28.2 MJ/kg. Moreover, the biochars produced under vacuum environments at higher temperature showed greater stability (22.5-35.9%) than those produced under N2 atmosphere.

Cylindrical graphite microbial fuel cell (MFC) configuration designed by eliminating distinct casing and membrane was evaluated for bioelectrogenesis and treatment of real-field wastewaters. Both petroleum refinery wastewater (PRW) and Labanah whey wastewater (LW) were used as substrates, and investigated for electricity generation and organic removal under batch mode operation. PRW showed higher bioelectricity generation (current and power generation of 3.35mA and 1.12mW at 100Ω) compared to LW (3.2mA and 1.02mW). On the contrary, higher substrate degradation efficiency was achieved using LW (72.76%) compared to PRW (45.06%). Superior function of MFC operation in terms of volumetric power density (PRW, 28.27W/m3; LW, 23.23W/m3) suggesting the feasibility of using these wastewaters for bioelectricity generation. Large sources of wastewater that generating in the Middle-East countries have potential to produce renewable energy from the treatment, which helps for the sustainable wastewater management and simultaneous renewable energy production.

Although recent research has demonstrated that waste orange peel (WOP) is a potentially valuable resource that can be transformed into high value products, heat generation, biomethanisation and composting might be considered the most feasible alternatives in terms of yield. This study revealed that WOP can be successfully valorised through combustion. However, a previous drying step, which generates hazardous wastewater, is required and harmful NOx are emitted with the flue gases. In contrast, a high yield of renewable methane (280LSTPCH4/kg added COD, chemical oxygen demand) and an organic amendment can be obtained through the thermophilic biomethanisation of WOP following the removal of valuable essential oils from the peel. Co-composting of WOP combined at different proportions (17-83%) with the organic fraction of municipal solid waste (OFMSW) was also demonstrated to be suitable. Moreover, a 37% reduction in odour generation was observed in co-composting of WOP compared to single composting of OFMSW.

Renewable energies will represent an increasing share of the electricity supply, while flue and gasification-derived gases can be a promising CO2 feedstock with a heat load. In this study, microbial electrosynthesis of organic compounds from CO2 at high temperature was proposed as an alternative for valorising energy surplus and decarbonizing the economy. The unremitting fluctuation of renewable energy sources was assessed using two bioreactors at 50 °C, under circumstances of continuous and intermittent power supply (ON-OFF; 8-16 h), simulating an off-grid photovoltaic system. Results highlighted that maximum acetate production rate (43.27 g m-2 d-1) and columbic efficiency (98%) were achieved by working with an intermittent energy supply, while current density was reduced three times. This boosted the production of acetate per unit of electricity provided up to 138 g kWh-1 and reinforced the robustness of the technology by showing resilience to tolerate perturbations and returning to its initial state.

Hydrothermal treatment (HTT) was used to convert residual bacterial biomass (RBB), recovered from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) production, into valuable bioproducts. The effect of processing temperatures (150, 200, and 250°C) on the bioproducts (water-solubles (WSs), bio-oil, insoluble residue, and gas) was investigated. The yields of bio-oil and gas were higher at higher temperatures. The maximum WS content (28 wt%) was obtained at 200°C. GCMS analysis showed higher content of aromatics and N-containing compounds with increasing temperature. ESI-MS revealed chemical compounds (e.g. protein, carbohydrate, lipids, and lignin) associated with RBB are fragmented into smaller molecules (monomers) at higher HTT temperatures. The WS fraction contained totally 838, 889 and 886mg/g acids and 160, 31 and 21 mg/g carbohydrate for HTT at 150, 200, and 250°C, respectively. The solid residues contain unconverted compounds, especially after HTT at 150°C. The WS products (acids and carbohydrates) could be used directly for PHA biosynthesis.

The effects of dilute acid hydrolysis conditions were investigated on total sugar (glucose and xylose) yields after enzymatic hydrolysis with additional analyses on glucose and xylose monomer and oligomer yields from the individual hydrolysis steps for aspen (a hardwood), balsam (a softwood), and switchgrass (a herbaceous energy crop). The results of this study, in the form of measured versus theoretical yields and a severity analysis, show that for aspen and balsam, high dilute acid hydrolysis xylose yields were obtainable at all acid concentrations (0.25-0.75 wt.%) and temperatures (150-175 degrees C) studied as long as reaction time was optimized. Switchgrass shows a relatively stronger dependence on dilute acid hydrolysis acid concentration due to its higher neutralizing mineral content. Maximum total sugar (xylose and glucose; monomer plus oligomer) yields post-enzymatic hydrolysis for aspen, balsam, and switchgrass, were 88.3%, 21.2%, and 97.6%, respectively. In general, highest yields of total sugars (xylose and glucose; monomer plus oligomer) were achieved at combined severity parameter values (log CS) between 2.20 and 2.40 for the biomass species studied.

The relative effects of three precise nitrogen limitation regimes on green micro-algae were assessed using the Trebouxiophycean alga Coccomyxa subellipsoidea grown in a chemostatic bioreactor system. The data provides further evidence that growth and triglyceride (TAG) accumulation are concurrent and independently proportional to the degree of nitrogen limitation in algae. Additionally, TAG accumulation was observed to proceed via oscillations with respect to time and percent dry weight quantity. The predator-prey model was applied to fit the experimental data and to obtain the physiological significance of these oscillations. The results determine the conditions of maximum neutral lipid productivity with respect to nitrate stress and highlight an area of potential future research.