COMBINING PHYTOREMEDIATION WITH BIOENERGY PRODUCTION: DEVELOPING A MULTI-CRITERIA DECISION MATRIX FOR PLANT SPECIES SELECTION

COMBINING PHYTOREMEDIATION WITH BIOENERGY PRODUCTION: A MULTICRITERIA DECISION MATRIX FOR PLANT SPECIES SELECTION O.N. Amabogha. D. Purchase*. H. Garelick, H. Jones. Department of Natural Sciences, Faculty of Science and Technology, Middlesex University. The Burroughs London NW4 4BT United Kingdom. *Corresponding author: D.purchase@mdx.ac.uk Abstract The use of plants to extract heavy metal contaminants from soils has been proposed as a cost-effective means of remediation; and utilizing energy crops for this phytoextraction process is a useful way of attaining added value from the process. To simultaneously attain both these objectives successfully, the kind(s) of species selected is crucial. The species selected needs to satisfy certain important criteria including translocation index, metal and drought tolerance, fast growth rate, high lignocellulosic content, good biomass production, adequate calorific value, second generation attribute and a good rooting system. It is therefore necessary to develop a set of comprehensive selection criteria to select the most appropriate plant species suited to attaining the desired objectives. In this study, we used a systematic review approach to develop a multicriteria decision matrix for species selection. Eight species (sunflower, Indian mustard, soybean, willow, poplar, Typha, Miscanthus, switch grass) were selected on the basis of amount of hits on a number of scientific search databases. We identified the relevant criteria required for these species and obtained corresponding data from the literature. We aggregated these raw data and normalize them by estimating their Z-score values and their suitability was analysed and compared. These criteria/indicators were weighted based on stipulated research objectives/priorities to form the basis of a final overall utility scoring. When values of the different parameters for all eight species were computed, analysed and compared, the results showed that soybean has the best translocation index rate; Miscanthus and switchgrass were the fastest growers; switchgrass, willow and poplar have a significantly higher metal tolerance index compared to the rest. On their bioenergy potentials, the results showed the lignocellulosic biomass percentage of poplar and sunflower are highest; with sunflower having the highest biomass production in tonnes per acre and poplar having the best calorific value among the species. When we applied our subjective priority ratings to these values, sunflower and Miscanthus emerged the top two candidates. These species will be further explored as candidates for phytoextraction of metals and energy recovery via pyrolysis and the findings will further seek to validate the multicriteria decision matrix. Our subsequent validation results will reveal the best candidates for a field based phytoextraction and bioenergy generation exercise.