Polluted lignocellulose-bearing sediments as a resource for marketable goods—a review of potential technologies for biochemical and thermochemical processing and remediation

Abstract

Lignocellulose-bearing sediments are legacies of the previously unregulated wastewater discharge from the pulp and paper industry, causing large quantities of toxic organic waste on the Baltic Sea floor and on the bottom of rivers and lakes. Several km2 are covered with deposits of lignocellulosic residues, typically heavily contaminated with complex mixtures of organic and inorganic pollutants, posing a serious threat to human and ecological health. The high toxicity and the large volume of the polluted material are challenges for remediation endeavours. The lignocellulosic material is also a considerable bioresource with a high energy density, and due to its quantity, it could appeal to commercialization as feedstock for various marketable goods. This study sets out to explore the potential of using this polluted material as a resource for industrial production at the same time as it is detoxified. Information about modern production methods for lignocellulosic material that can be adapted to a polluted feedstock is reviewed. Biochemical methods such as composting, anaerobic digestion, as well as, thermochemical methods, for instance, HTC, HTL, pyrolysis, gasification and torrefaction have been assessed. Potential products from lignocellulose-bearing sediment material include biochar, liquid and gaseous biofuels, growing substrate. The use of a contaminated feedstock may make the process more expensive, but the suggested methods should be seen as an alternative to remediation methods that only involve costs. Several experiments were highlighted that support the conception that combined remediation and generation of marketable goods may be an appropriate way to address polluted lignocellulose-bearing sediments. Graphic abstract

Unveiling the resistance of native weed communities: insights for managing invasive weed species in disturbed environments

“…The presence of pollutants can alter the control methods and complicate the overall management process (Badrzadeh et al, 2022). A comprehensive assessment of the pollution sources and their impact on the ecosystem is necessary, followed by implementation of appropriate pollution-control measures such as sediment dredging, phytoremediation, or the introduction of pollutant-degrading microorganisms (Haller et al, 2021).…”

“…The presence of pollutants can alter the control methods and complicate the overall management process (Badrzadeh et al ., 2022). A comprehensive assessment of the pollution sources and their impact on the ecosystem is necessary, followed by implementation of appropriate pollution‐control measures such as sediment dredging, phytoremediation, or the introduction of pollutant‐degrading microorganisms (Haller et al ., 2021). Simultaneously, targeted management strategies such as biological (predators, parasites, or pathogens), chemical (herbicides or pesticides or soil‐sterilisation techniques such as soil fumigation or solarization), and physical (manual removal, cutting, mowing, or physical barriers) measures must be employed to combat the invasive species (Table 5; Wangchuk, Lepcha & Ghimiray, 2022).…”

A sustainable waste-to-protein system to maximise waste resource utilisation for developing food- and feed-grade protein solutions

“…Technologies such as pressurised liquid extraction (PLE), supercritical fluid extraction (SFE) and subcritical water extraction have shown promising effectiveness at reducing the content of organic pesticides and heavy metals contained in lignocellulosic waste streams. [54][55][56][57][58] However, they are rarely employed for industrial processing due to their high cost. 57,58 Furthermore, due to the high purity requirements required for human and animal consumption, intense research efforts are required to optimise pre-treatment to achieve maximum contaminant reduction while mitigating deleterious chemical alterations of feedstock compounds, which can significantly reduce downstream efficiency and yield of protein extraction and bioconversion processes.…”

“…57,58 Furthermore, due to the high purity requirements required for human and animal consumption, intense research efforts are required to optimise pre-treatment to achieve maximum contaminant reduction while mitigating deleterious chemical alterations of feedstock compounds, which can significantly reduce downstream efficiency and yield of protein extraction and bioconversion processes. 56 Combined contaminant remediation and protein value-upgrading is a promising approach that integrates process stages through multi-objective bioconversion. For example, one strategy is the use of fungal strains capable of simultaneously degrading pollutants/contaminants while assimilating lignocellulose into biomass through subsequent saccharification and fermentation (SSF).…”