Macroalgae (seaweeds) represent an emerging resource for food and the production of commodity and specialty chemicals. In this study, a single-step microwave process was used to depolymerise a range of macroalgae native to the United Kingdom, producing a growth medium suitable for microbial fermentation. The medium contained a range of mono-and polysaccharides as well as macro-and micronutrients that could be metabolised by the oleaginous yeast Metschnikowia pulcherrima. Among twelve macroalgae species, the brown seaweeds exhibited the highest fermentation potential, especially the kelp Saccharina latissima. Applying a portfolio of ten native M. pulcherrima strains, yeast growth kinetics, as well as production of lipids and 2-phenylethanol were examined, with productivity and growth rate being strain dependent. On the 2 L scale, 6.9 g L −1 yeast biomassa yield of 0.14 g g −1 with respect to the supplied macroalgaecontaining 37.2% (w/w) lipid was achieved through utilisation of the proteins, mono-and polysaccharides from S. latissima, with no additional enzymes. In addition, the yeast degraded a range of fermentation inhibitors released upon microwave processing at high temperatures and long holding times. As macroalgae can be cultured to food grade, this system offers a novel, potentially low-cost route to edible microbial oils as well as a renewable feedstock for oleochemicals.

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Bilberry presscake, a byproduct from juice production, contains abundant polysaccharides that can be recovered by thermal treatment. In this research, microwave hydrolysis and extraction were carried out using only water as the processing medium, thus ensuring all products (mainly saccharides) are suitable for food grade status applications. This research aims to propose an approach to fulfill multiple chemicals recovery, including anthocyanins, saccharides, proteins, and even inorganic salts. Statistical analysis suggested the conversion of bilberry presscake was accurately predictable (R 2 of 0.986) from conditions. Of the variables temperature, holding time, and solid content, the solid content affects conversion most significantly. A 30 min microwave hydrolysis gives mono-/disaccharides with a high total yield of 24.9%, which is more than three times the yield of a 24 h Soxhlet extraction (7.1%). The yield of rhamnose is particularly high (10.8%), most likely as a result of pectin degradation on microwave irradiation. In addition to the lab scale research, pilot scale microwave extractions are carried out with high conversion (especially glucose 4.4%, xylose 4.0%, and pectin 6.3%), suggesting the feasibility of low-temperature (95 °C) microwave hydrolysis of bilberry presscake for industrial application. With this preliminary study, it is believed microwave hydrolysis offers an efficient and green approach to convert bilberry presscake into value-added products for food industry and biorefinery.

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<p>Rising energy costs and net zero carbon goals mean that the UK needs plentiful and clean energy sources. Current clean energy sources (biomass/ heat pumps) in the country are insufficient to meet residential space heating demands. Further with the advent of higher energy costs, residents are expected to start burning more solid fuel in their homes, as opposed to using gas-based central heating. The UK generates 222.2 million tonnes of waste annually, of which only ~45% is recyclable. The typical calorific value of municipal solid waste and agricultural/garden waste is ~10 MJ/kg and ~20 MJ/kg respectively. Traditionally, waste to energy (WtE) for the circular economy has been associated with waste incineration, but it could be used for household heating. Efficient utilization of waste through different thermochemical transition pathways has been primarily explored at an incineration plant scale (~50 MW heat) and not at a scale of residential heating stove (~5 kW). In the present study, we will use thermogravimetric analyzer- mass spectrometer (TGA-MS) to simulate conditions inside a heating stove. Reaction parameters would include packed bed temperature of 650 °C and heating rate of 10 °C/min for characterisation and assessment of the volatile species evolved during the thermal degradation of several waste materials. Pyrolysis behaviour of some typical household wastes would be analysed through characteristic reaction temperatures and evaluation of mass loss rates. The results from this study can contribute to better evaluation and testing of different waste materials with the aim to know their technical and economic feasibility for heat generation at a small scale.</p>

The exploration of cucumber waste as a potential biorefinery feedstock is reported. Initially, extractives (essential oils) were isolated from cucumber waste via vacuum microwave hydro-distillation (VMHD). The yield and quality of the extractive were compared with respect to traditional hydro-distillation (HD). The essential oils were obtained over a range of microwave power (500, 750, 1000 W) and vacuum pressures (100, 200, 300 mbar). The highest quality (0.49 wt %) was obtained at a microwave irradiation power of 500 W and a vacuum of 300 mbar. VMHD is much quicker and more energy-efficient than HD. Within the context of a zero-waste biorefinery, the extractive-free residues were the solid residues from two different extraction methods were compared and characterized by ATR-IR, 13C solid-state NMR spectroscopy, SEM, TGA, and CHN elemental analysis. The resultant residues are cellulosic-rich, and no significant changes were observed with VMHD and HD treatment. The results indicated that the utilization of these residues can provide an efficient, inexpensive, and environment-friendly platform for the production of cellulosic materials.