Risk management and regeneration of brownfields using bioenergy crops

Abstract

Purpose The potential of phytoremediation, as a costeffective in situ alternative to conventional technologies for remediation of contaminated brownfields, has often been pointed out. Yet, phyto-technologies have failed to find widespread adoption in practice. To gain social and commercial acceptance of these technologies, there is a clear requirement of field studies that provide information on success and failures. The aim of this study was to investigate benefits and potential risks with phyto-stabilisation on brownfields using bioenergy-crops. Materials and methods Two field trials with willow (Salix Klara and Salix Inger) were set up aiming for phytostabilisation on metal-contaminated sites. By the use of a tiered risk assessment approach, the cultivation's effect on ecological risks in different environmental compartments, such as soil, porewater and up-take to biota (including potential risks for wild grazers), was investigated before the cultivation was started and during following three growth seasons. Growth assessments were also made to evaluate the biomass' potential revenue. Results and discussionThe risks to the soil fauna proved to be unchanged or declining. The uptake in the plants was, as aimed for, low to moderate, and the growth rate depended on the soil texture rather than the contamination level of the sites. The low uptake indicated a negligible risk for wild grazers. The field trials were accomplished using no, or low, amounts of amendments, minimum soil interventions, no, or very simple, weeding control and conducted at sites with low annual temperature. Despite harsh conditions, the biomass production was high enough to potentially provide revenue. Conclusions This study shows that cultivation of brownfields using phytostabilising willow clones can reduce the ecological risks, improve the soil quality of the site and provide revenue if the biomass is sold for e.g. bioenergy production. By choosing phytostabilisation willow clones, potential risks associated with phytoextraction of metals, such as biomass combustion and food chain transfer of metals, were eliminated. Consequently, using bioenergy crops for phytostabilisation on brownfields can contribute to preserve and improve ecosystem services, create economic regeneration of these areas and at the same time be a sustainable risk management option.

Soil and brownfield bioremediation

“…have been successfully remediated using phytostabilization through willow plants (Salix Klara and Salix singer). This field trial has demonstrated that phytostabilization of brownfield sites with bioenergy crops can provide environmental benefits by turning these areas into economical and beneficial uses (Enell et al, 2016). Plants in association with microbes can be applied to remove the labile/bioavailable pool of inorganic contaminants from a site, remove or degrade organic contaminants, stabilize or immobilize contaminants (phytostabilization/in situ immobilization/Phyto-exclusion).…”

Biofuel Production Using Thermochemical Conversion of Heavy Metal-Contaminated Biomass (HMCB) Harvested from Phytoextraction Process

“…Lignocellulosic biomass has been mostly undergone in thermochemical conversion due to its low ash content and high-quality bio-oil [25]. Yet, plants and crops could be contaminated owing to their uptake of various pollutants during natural and/or engineered phytoremediation of polluted environments resulted from diverse anthropogenic activities [26][27][28][29]. Statistically, it has been estimated that more than one-third of the world's terrestrial resources are contaminated [30] (so-called brownfield sites [31]), however, the real rate of contaminated lands, plants and crops could be significantly higher even rather than whatever has been reported so far [32][33][34][35].…”

Greening the Browns: A Bio-Based Land Use Framework for Analysing the Potential of Urban Brownfields in an Urban Circular Economy

“…The possibility of contaminants in urban brownfields can be a constraint on urban agriculture even though there are guidelines available for determining safe practices [99,100]. The cultivation of bio-energy crops, on the other hand, can take place directly on contaminated soil, simultaneously reducing ecological and human health risks, improving soil quality, and providing revenue [101]. The critique of growing energy crops on prime, food-producing land can be addressed by producing biomass on marginal, brownfield land [78,102,103].…”