The role of thermo-catalytic reforming for energy recovery from food and drink supply chain wastes

Disposal of food and drink wastes, including packaging wastes, has a significant cost and environmental impact. All carbon containing wastes have an energy potential and the food industry should focus on recovering that energy to offset their reliance on fossil-fuel derived energy sources. This paper focuses on the novel use of intermediate pyrolysis for decarbonizing the food chain, through the treatment of food and packaging waste, to recover energy. The TCR is a versatile technology which overcomes many of the traditional problems associated with fast pyrolysis and can thermo-chemically convert a range of different feedstocks, including inaccessible lignin and some inorganic, recalcitrant materials. The feedstocks are converted into new fuel sources; char, bio-oil (thermally stable) and permanent gases, for further electrical and heat generation. Ultimately with the use of the TCR technology, the food production industry could look to using decentralized power generation located on-site of large food processing facilities to optimize their energy efficiencies

AgroCycle – developing a circular economy in agriculture

Continuing population growth and increasing consumption are driving global food demand, with agricultural activity expanding to keep pace. The modern agricultural system is wasteful, with Europe generating some 700 million tonnes of agrifood (agricultural and food) waste each year. The Agricultural Centre for Sustainable Energy Systems (ACSES) at Harper Adams University is involved in a major research and innovation project (AgroCycle) on the application of the ‘circular economy’ across the agri-food sector. In the context of the agrifood chain, the ‘circular economy’ aims to reduce waste while also making best use of the ‘wastes’ produced by using economically viable processes and procedures to increase their value . Led by University College Dublin, AgroCycle is a Horizon 2020 collaborative project with 26 partners. AgroCycle will address such opportunities directly by implementation of the ‘circular economy’ across the agri-food sector. The authors will present (a) a summary of the AgroCycle project and (b) the role played by Harper Adams in the project in evaluating the potential for small-scale anaerobic digestion (AD) technology that can be applied on farm to provide local heat, energy and nutrient recovery from mixed agricultural wastes

Responses of Lotus corniculatus to environmental change 3:The sensitivity of phenolic accumulation to growth temperature and light intensity and effects on tissue digestibility

The response of plant growth, phenolic accumulation and tissue digestibility to light and temperature was determined in clonal plants of three genotypes of Lotus corniculatus (birdsfoot trefoil) cv Leo, with low, intermediate or high levels of proanthocyanidins (condensed tannins). Plants were grown from 10 °C to 30 °C, or at light intensities from 20 to 500 µm m−2 s−1. Plants grown at 25 °C had the highest growth rate and highest digestibility, whereas the maximum tannin concentration was found in plants grown at 15 °C. Approximately linear increases in leaf flavonol glycoside levels were found with increasing growth temperature in the low tannin genotype. Tannin hydroxylation increased with increasing growth temperature but decreased with increasing light intensity. The major leaf flavonols were kaempferol glycosides of which kaempferol-3-glucoside and kaempferol-3,7-dirhamnoside were the major components. Increases in both tannin and total flavonol concentrations in leaves were linearly related to light intensity and were preceded by a specific increase in the transcript level of a non-legume type chalcone isomerase. Changes in growth temperature and light intensity, therefore, result in major changes in the partitioning of carbon into phenolics, which significantly affects tissue digestibility and nutritional quality with a high correlation between tannin concentration and leaf digestibility

Methods for genomic characterization and maintenance of anaerobic fungi

The rapid development of molecular biology and bioinformatics has fueled renewed interests in anaerobic fungi from the phylum Neocallimastigomycota. This chapter presents well-established methods for isolation, routine cultivation, and cryopreservation of anaerobic fungi. Moreover, detailed nucleic acid extraction protocols are provided, which should enable readers to isolate high-quality DNA and RNA from a variety of anaerobic fungal culture media for downstream applications such as next-generation sequencing

A novel nitrogen removal technology pre-treating chicken manure, prior to anaerobic digestion

Chicken manure is an agricultural by-product that is a problematic feedstock for anaerobic digestion due to its high nitrogen content inhibiting methane yields. This research examines a novel pilot-scale method of ammonia stripping, the nitrogen recovery process (NRP) developed by Alchemy Utilities Ltd. The NRP was designed to remove and recover nitrogen from chicken manure and two different operating conditions were examined. Both operating conditions demonstrated successful nitrogen removal and recovery. The biochemical methane potential assays were used to compare the digestibility of the NRP-treated chicken manures to that of a fresh chicken manure control. Overall, the biochemical methane potential assays demonstrated that some NRP-treated chicken manure treatments produced significantly more methane compared to untreated manure, with no inhibition occurring in relation to ammonium. However, some of the NRP-treated chicken manures produced similar or lower methane yields compared to fresh chicken manure. The NRP requires further development to improve the efficiency of the pilot-scale unit for commercial-scale operation and longer-term continuous anaerobic digestion trials are required to determine longer-term methane yield and ammonium inhibition effects. However, these initial results clearly demonstrate the technology’s potential and novel application for decentralised, on-farm nitrogen recovery and subsequent anaerobic digestion of chicken manure

Increasing the methane potential of oat husks using a novel extrusion pre-treatment technology prior to anaerobic digestion

Oat husks are produced during the milling process of oats. Oat husks are a lignocellulosic material that have the potential for valorization thereby improving the circular economy of agricultural by-products. However, due to the high lignocellulosic content, there are limited valorization pathways for oat husks. To improve the anaerobic digestibility of oat husks, pre-treatment was investigated as a method to aid valorization. A novel extrusion process was used in an attempt to fragment the lignocellulosic structure of oat husks prior to anaerobic digestion. The extrusion pre-treatment was investigated to determine the effect it may have on altering the methane yield and digestibility of oat husks. Biochemical methane potential assays were undertaken using oat husks with no pre-treatment and extruded oat husks. These assays demonstrated that extruded oat husks produced a significantly higher methane yield of 264 ml/gVS fed, which was 27% greater than the methane yield produced from the untreated oat husks. Similarly, the total solids degradation was also significantly higher for extruded oat husks treatment compared to the untreated oat husks. Overall, the extrusion process demonstrated an increased methane yield for oat husks compared to previously published data. The biomethane potential tests suggest that extruded oat husks would be a feedstock suitable for anaerobic digestion

The anaerobic fungi: challenges and opportunities for industrial lignocellulosic biofuel production

Lignocellulose is a promising feedstock for biofuel production as a renewable, carbohydrate-rich and globally abundant source of biomass. However, challenges faced include environmental and/or financial costs associated with typical lignocellulose pretreatments needed to overcome the natural recalcitrance of the material before conversion to biofuel. Anaerobic fungi are a group of underexplored microorganisms belonging to the early diverging phylum Neocallimastigomycota and are native to the intricately evolved digestive system of mammalian herbivores. Anaerobic fungi have promising potential for application in biofuel production processes due to the combination of their highly effective ability to hydrolyse lignocellulose and capability to convert this substrate to H2 and ethanol. Furthermore, they can produce volatile fatty acid precursors for subsequent biological conversion to H2 or CH4 by other microorganisms. The complex biological characteristics of their natural habitat are described, and these features are contextualised towards the development of suitable industrial systems for in vitro growth. Moreover, progress towards achieving that goal is reviewed in terms of process and genetic engineering. In addition, emerging opportunities are presented for the use of anaerobic fungi for lignocellulose pretreatment; dark fermentation; bioethanol production; and the potential for integration with methanogenesis, microbial electrolysis cells and photofermentation

The anaerobic digestion of pig carcase with or without sugar beet pulp, as a novel on-farm disposal method

Anaerobic digestion was investigated as a potential method for on-farm disposal of fallen stock (pig carcases), degrading the carcase material to produce biogas and digestate. The effects of feedstock (sugar beet pulp or pig carcase material or a 50:50 mix) and organic loading rate (50 g-TS L−1 or 100 g-TS L−1), during mesophilic (35 °C) anaerobic digestion were investigated. Anaerobic digestion was achieved for all experimental treatments, however the pig carcase material at the higher organic loading rate produced the second highest methane yield (0.56 Nm3 kg-VS−1 versus a range of 0.14–0.58 Nm3 kg-VS−1 for other treatments), with the highest percentage of methane in total biogas (61.6% versus a range of 36.1–55.2% for all other treatments). Satisfactory pathogen reduction is a legislative requirement for disposal of carcase material. Pathogens were quantified throughout the anaerobic digestion process. Enterococcus faecalis concentrations decreased to negligible levels (2.8 log10 CFU g-TS−1), whilst Clostridium perfringens levels remained unaffected by treatment throughout the digestion process (5.3 ± 0.2 log10 CFU g-TS−1)

Evaluation of pyrolysis chars derived from marine macroalgae silage as soil amendments

Sections PDFPDF Tools Share Abstract Pyrolysis char residues from ensiled macroalgae were examined to determine their potential as growth promoters on germinating and transplanted seedlings. Macroalgae was harvested in May, July and August from beach collections, containing predominantly Laminaria digitata and Laminaria hyperborea ; naturally seeded mussel lines dominated by Saccharina latissima ; and lines seeded with cultivated L. digitata . Material was ensiled, pressed to pellets and underwent pyrolysis using a thermo‐catalytic reforming (TCR) process, with and without additional steam. The chars generated were then assessed through proximate and ultimate analysis. Seasonal changes had the prevalent impact on char composition, though using mixed beach‐harvested material gave a greater variability in elements than when using the offshore collections. Applying the char at 5% (v/v)/2% (w/w) into germination or seedling soils was universally negative for the plants, inhibiting or delaying all parameters assessed with no clear advantage in harvesting date, species or TCR processing methodology. In germinating lettuce seeds, soil containing the pyrolysis chars caused a longer germination time, poorer germination, fewer true leaves to be produced, a lower average plant health score and a lower final biomass yield. For transplanted ryegrass seedlings, there were lower plant survival rates, with surviving plants producing fewer leaves and tillers, lower biomass yields when cut and less regrowth after cutting. As water from the char‐contained plant pots inhibited the lettuce char control, one further observation was that run‐off water from the pyrolysis char released compounds which detrimentally affected cultivated plant growth. This study clearly shows that pyrolysed macroalgae char does not fit the standard assumption that chars can be used as soil amendments at 2% (w/w) addition levels. As the bioeconomy expands in the future, the end use of residues and wastes from bioprocessing will become a genuine global issue, requiring consideration and demonstration rather than hypothesized use

Metabolic characterization of anaerobic fungi provides a path forward for bioprocessing of crude lignocellulose

The conversion of lignocellulose-rich biomass to bio-based chemicals and higher order fuels remains a grand challenge, as single-microbe approaches often cannot drive both deconstruction and chemical production steps. In contrast, consortia based bioprocessing leverages the strengths of different microbes to distribute metabolic loads and achieve process synergy, product diversity, and bolster yields. Here, we describe a biphasic fermentation scheme that combines the lignocellulolytic action of anaerobic fungi isolated from large herbivores with domesticated microbes for bioproduction. When grown in batch culture, anaerobic fungi release excess sugars from both cellulose and crude biomass due to a wealth of highly expressed carbohydrate active enzymes (CAZymes), converting as much as 49% of cellulose to free glucose. This sugar-rich hydrolysate readily supports growth of Saccharomyces cerevisiae, which can be engineered to produce a range of value-added chemicals. Further, construction of metabolic pathways from transcriptomic data reveals that anaerobic fungi do not catabolize all sugars that their enzymes hydrolyze from biomass, leaving other carbohydrates such as galactose, arabinose, and mannose available as nutritional links to other microbes in their consortium. Although basal expression of CAZymes in anaerobic fungi is high, it is drastically amplified by cellobiose breakout products encountered during biomass hydrolysis. Overall, these results suggest that anaerobic fungi provide a nutritional benefit to the rumen microbiome, which can be harnessed to design synthetic microbial communities that compartmentalize biomass degradation and bioproduct formation