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2017_07: Phytoremediation for Renewable Energy: Energy Production During Decontamination Supervisors: Dr Jason Hallett ([email protected]), Dr Paul Fennell, and Dr Jeremy Woods (Centre for Environmental Policy) Department: Chemical Engineering Increasing energy demand necessitates the development of renewable fuels. These fuels can be made from virgin biomass, though this brings into question their sustainability (land use, food / fuel issues) and presents a significant economic challenge due to high feedstock prices. Simultaneously, there are currently ca. 300,000 contaminated land sites in Europe, mostly due to industrial activity. This includes nearly 1,000 UK sites contaminated by heavy metal pollutants (Pb, Cr, Cu, As, Ni, Zn, Cd and Hg) and therefore unsuitable for agriculture. Phytoremediation relies on the ability of plants to remove hazardous compounds from the soil by integrating them into plant metabolism. The most efficient method is phytoextraction, where some plants (hyperaccumulators) can extract 1 – 10,000 mg metal kg-1 dry mass. Phytoextraction of heavy metals is a cheap alternative to soil removal, an in situ remediation that is aesthetically appealing and technologically simple, while maintaining soil biodiversity without producing any waste – if the metals are recovered and sold (phytomining) it can also provide some small revenue. Unfortunately, neither phytoremediation nor phytomining are economically viable, as the remediation process is slow and hyperaccumulators rarely combine significant metal uptake with a fast growing cycle. At present, “phytominers” burn all of the biomass to recover the metal and use the ash as fertilizer, an inefficient use of the plant. This project aims to grow a phytoaccumulator plant with high biomass yield from which to extract the contaminant metal using ionic liquids. We will develop methodologies to CO2 – neutral fuels from metal contaminated biomass, fuel whose cost is subsidized by the phytoremediation. After 4-10 years of bioenergy crop growth, we will have produced 2nd generation bioethanol, biochar, bio-oils, metals, and new cropland. This will increase the economic viability of both biorefining and phytoremediation, and increase food production through biofuel production. This requires a low-cost, low-energy process to separate lignin from cellulose, for which we recently developed the use of novel, low-cost ionic liquids, which have high efficiency, insensitivity to biomass inputs, and ease of product recovery. We will contaminate soil with mine-level Ni and Zn salts to provide a synthetic contaminated soil. We will then grow hyperaccumulating plants (willow, sunflowers) For more information on how to apply visit us at www.imperial.ac.uk/changingplanet Science and Solutions for a Changing Planet for 4-12 weeks, with control plants available from Canadian remediation projects. These will then be deconstructed using ILs that fractionate wood by extracting lignin, leaving a cellulose pulp which is filtered and processed to bioethanol; addition of water to the remaining IL solution precipitates lignins for pyrolysis to produce bio-oils and biochar. This project will focus on re-developing the IL-based pretreatment strategies used for waste wood (with 98-99% metal removal) and virgin biomass through the incorporation of phytoremediation. The pretreatments will be performed to determine the optimum conditions for delignification, and understand the effect of the metals on biopolymer quality. Key outcomes will be the amount of metal removed from soil, the amount of sugar produced, and the chemical or energy value of recovered lignin. Finally, we will develop high-level models to project the positive implications of this technique for land use. For more information on how to apply visit us at www.imperial.ac.uk/changingplanet