Initial Study on Phytoextraction for Recovery of Metals from Sorted and Aged Waste-to-Energy Bottom Ash

Karin Karlfeldt Fedje,Viktoria Edvardsson,David Dalek

doi:10.3390/soilsystems5030053

Karin Karlfeldt Fedje, Viktoria Edvardsson + Show 1 more

Open Access

https://doi.org/10.3390/soilsystems5030053

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Journal: Soil Systems	Publication Date: Aug 31, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: Chalmers University of Technology

Abstract

Sorted and aged bottom ash from Waste-to-Energy plants, i.e., MIBA (the Mineral fraction of Incinerator Bottom Ash) are potential source of metals that could be utilized to meet the increased demand from society. In this work, sunflowers (Helianthus annuus) and rapeseed (Brassica napus) were cultivated in conventional MIBA to evaluate the possibility for phytoextraction, mainly of Zn, during the period of one cultivation season in the Nordic climate. The results show that metal extraction from MIBA using rapeseed and sunflowers is workable but that neither of the used plants is optimal, mainly due to the inhibited root development and low water- and nutrient-holding capacities of MIBA. The addition of fertilizer is also important for growth. There was a simultaneous accumulation of numerous metals in both plant types, and the highest metal content was generally found in the roots. Calculations indicated that the ash from rapeseed root incineration contained about 2% Zn, and the contents of Co, Cu, and Pb were comparable to those in workable ores. This initial study shows that cultivation in and phytoextraction on MIBA is possible, and that the potential for increased metal extraction is high.

Highlights

IntroductionIn Sweden alone, almost 1 million tons of this type of bottom ash is produced annually; in the EU, Norway, and Switzerland, the corresponding amount is approximately 18 Mt/year [2,3]
This paper discusses for the first time, to the knowledge of the authors, the potential of cultivating annual plants in conventional MIBA in order to generate metal-enriched biomass fuel, which is to be used for metal recovery
The results show that cultivation of rapeseed and sunflowers in conventional MIBA is challenging

Summary

Introduction

In Sweden alone, almost 1 million tons of this type of bottom ash is produced annually; in the EU, Norway, and Switzerland, the corresponding amount is approximately 18 Mt/year [2,3] These ashes contain significant amounts of metals, and the most common treatment method for bottom ash is mechanical separation, where pieces of metal are recovered and combined with natural weathering, i.e., carbonation. Ash having had this treatment is referred to as MIBA, the Mineral fraction of Incinerator Bottom Ash, to distinguish it from untreated bottom ash [3].

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