A new approach for the rapid destruction of human waste using smouldering combustion is presented. Recently, self-sustaining smouldering combustion was shown to destroy the organic component of simulated human solid waste and dog faeces resulting in the sanitization of all pathogens using a batch process (Yermán et al., 2015). Here, a continuous smouldering process is demonstrated for the first time, allowing for a much smaller reactor size and much less energy input per mass of waste treated. The self-sustained smouldering of simulated human faeces mixed with sand is evaluated over long periods (more than 16 h) based on a single ignition. The key process of intermittent self-sustained smouldering, in which the reaction is terminated and restarted by only turning the air off and on, is demonstrated. Experiments examine the influence of two key operator controls: airflow rate and set elevation of the quasi-steady-state smouldering front in a 37 cm high reactor. Quasi-steady-state fuel destruction rates from 93 g/h to 12 g/h were achieved by varying the superficial flow velocity from 7.4 cm/s to 0.11 cm/s, the latter with a velocity approximately an order of magnitude lower than possible for a self-sustaining reaction in an equivalent batch system. Excess energy of up to 140 J/g of sand was recovered from the clean sand produced in each cycle, which could be used to further increase the energy efficiency of this novel waste treatment system.
Understanding the changes in the microstructures and structures of clays with varying intercalated metal ions at elevated temperatures is of importance for many applications ranging from the recovery of shale gas from unconventional formations to developing effective nuclear waste containment technologies, and engineering materials such as ceramics for fuel cell applications. In this study, synchrotron-based in-operando multi-scale X-ray scattering analyses are used to determine dynamic microstructural and crystal structural changes in Na- and Ca-montmorillonite on heating from 30 °C to 1150 °C. Larger cations such as Ca2+ confer more defined morphological regimes compared to Na+ ions in compacted clays, as evident from the ultra-small-angle X-ray scattering results. The hierarchical morphology of clays is characterized to distinguish between nano-scale interlayer swelling porosity, meso-scale porosity, and intergranular pore spaces between powdered clay grains. On heating from ambient temperature to 200 °C, the removal of interlayer water reduced the basal distances to 9.6 Å. On further heating to 800 °C, gradual dehydroxylation of the clay sheets is evident from the structural changes. The effects of sintering at temperatures greater than 800 °C are evident from significant reductions in the intrinsic porosities of the clay sheets, and the formation of newer phases such as mullite. By connecting the in-operando microstructural and structural changes across spatial scales ranging from micrometers to Angstroms, the possibility of engineering high temperature processes for achieving morphologies and chemical compositions of interest is presented.
Biodiesel is increasingly being used in automotive and other engine applications because of its potential to contribute to the reduction of CO 2 and other harmful emissions. However, biodiesel is known to be more corrosive in contact with metallic components than petroleum diesel. This work explores the corrosion of aluminium, steel, brass and copper metallic coupons exposed to B100 biodiesel at 25, 80, 90, 100, 110 and 120 °C. The metals that were chosen are commonly found in automotive engines. The B100 in each experiment was sampled at 48, 100, 150, 200 and 270 h and examined by GCMS to determine compositional changes. It was found that corrosion rates for copper were 10x faster than brass and approximately 100x faster than for mild steel, Al7075 and Al1050. Activation energies for corrosion were calculated from mass loss and ICP, with good correlation between the two methods for Cu containing samples. By mass loss, the activation energies for Cu, Brass, Al7075 and Al1050 were calculated to be −47.9 kJ mol −1 , −85.4 kJ mol −1 , −86.7 kJ mol −1 and −54.4 kJ mol −1 , respectively. By ICP analysis, the activation energies for Cu, Brass, and Al7075 were calculated to be −57.9 kJ mol −1 , −90 kJ mol −1 and −140 kJ mol −1 , respectively. Corrosion rates in brass and copper samples were faster owing to the direct reaction of copper with the fatty acid. The copper was found to cause chain scission and greater degradation of the biodiesel.
The cereal infecting fungus Fusarium graminearum is predicted to possess a single homologue of plant RALF (rapid alkalinisation factor) peptides. Fusarium mutant strains lacking FgRALF were generated and found to exhibit wildtype virulence on wheat and Arabidopsis floral tissue. Arabidopsis lines constitutively overexpressing FgRALF exhibited no obvious change in susceptibility to F. graminearum leaf infection. In contrast transient virus-mediated over-expression (VOX) of FgRALF in wheat prior to F. graminearum infection, slightly increased the rate of fungal colonisation of floral tissue. Ten putative Feronia (FER) receptors of RALF peptide were identified bioinformatically in hexaploid wheat ( Triticum aestivum ). Transient silencing of two wheat FER homoeologous genes prior to F. graminearum inoculation did not alter the subsequent interaction outcome. Collectively, our VOX results show that the fungal RALF peptide may be a minor contributor in F. graminearum virulence but results from fungal gene deletion experiments indicate potential functional redundancy within the F. graminearum genome. We demonstrate that virus-mediated over-expression is a useful tool to provide novel information about gene/protein function when results from gene deletion/disruption experimentation were uninformative.