Browsing by Author "Coles, Stuart R."

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    Phytoremediation combined with biorefinery on the example of two agricultural crops grown on Ni soil and degraded by P. chrysosporium
    (Taylor and Francis, 2016-12-12) Sotenko, Maria; Coles, Stuart R.; Barker, Guy; Song, Lijiang; Jiang, Ying; Longhurst, Philip J.; Romanova, Tamara; Shuvaeva, Olga; Kirwan, Kerry
    During the last few decades, phytoremediation process has attracted much attention because of the growing concerns about the deteriorating quality of soil caused by anthropogenic activities. Here, a tandem phytoremediation/biorefinery process was proposed as a way to turn phytoremediation into a viable commercial method by producing valuable chemicals in addition to cleaned soil. Two agricultural plants (Sinapis alba and Helianthus annuus) were grown in moderately contaminated soil with ca. 100 ppm of Ni and further degraded by a fungal lignin degrader - Phanerochaete chrysosporium. Several parameters have been studied: the viability of plants, biomass yield and their accumulating and remediating potentials. Further down-stream processing showed that up to 80% of Ni can be easily extracted from contaminated biomass by aqueous extraction at mild conditions. Finally, it was demonstrated that the grown onto contaminated soil plants can be degraded by Phanerochaete chrysosporium and the effect of nickel and biomass pre-treatment on the solid state fermentation was studied. The proposed and studied in this work methodology can pave the way to successful commercialization of the phytoremediation process in the near future
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    Recovery of ammonia from wastewater through chemical precipitation
    (Springer, 2019-12-11) Bianchi, Lavinia; Kirwan, Kerry; Alibardi, Luca; Pidou, Marc; Coles, Stuart R.
    Chemical precipitation is a consolidated technique applied in wastewater treatment to remove and recover phosphorous and ammonium that remain in the effluent after the anaerobic digestion treatment. The precipitate is magnesium ammonium phosphate hexahydrate (MgNH4PO4·6H2O), also known as struvite, and it is sold as a slow-release fertiliser. However, the value of struvite is quite low and has a limited market. Furthermore, it precipitates with heavy metals and other impurities that need to be removed to make the fertiliser commercially viable. This study looked at the thermal decomposition of struvite to recover added value products and recycle the magnesium for further precipitation. A kinetic study was carried out to understand the mechanism of decomposition and the formation of the different solid phases, which is fundamental for the design and optimisation of the technology. The thermogravimetric study confirmed that thermal decomposition is possible, but ammonia could not be completely released below 250 °C. The thermal analysis also led to the determination of the energy required for the decomposition, found to be 1.87 kJ g−1, which also includes the evaporation of water and ammonia. The kinetic study through the isoconversional method showed the presence of two major reactions, and the model-fitting approach identified the diffusion model as the best fit for the first reaction. The activation energy of the first reaction found with this method was 0.24 kJ g−1, comparable with the data obtained from the isoconversional method. The two-stage decomposition reactions were proposed, and the final calcination product was confirmed as magnesium pyrophosphate, which could be used in agriculture or dissolved in diluted mineral acids solution to separate the phosphate from the magnesium.