Advances in research on the use of biochar in soil for remediation: a review

Abstract

Purpose Soil contamination mainly from human activities remains a major environmental problem in the contemporary world. Significant work has been undertaken to position biochar as a low-cost material useful for the management of contaminants in various environmental media notably soil. Here, we review the increasing research on the use of biochar in soil for the remediation of some organic and inorganic contaminants. Materials and methods Bibliometric analysis were carried out within the past 10 years to determine the increasing trend in research related to biochar in soil for contaminant remediation. Five exemplar contaminants were reviewed in both laboratory and field-based studies. These included two inorganic (i.e. As and Pb), and three organic classes (i.e. sulfamethoxazole, atrazine, and PAHs). The contaminants were selected based on bibliometric data and as representatives of their various contaminant classes. For example, As and Pb are potentially toxic elements (anionic and cationic, respectively) while sulfamethoxazole, atrazine, and PAHs represent antibiotics, herbicides and hydrocarbons, respectively. Results and discussion The interaction between biochar and contaminants in soil is largely driven by biochar precursor material and pyrolysis temperature as well as some characteristics of the contaminants such as octanolwater partition coefficient (KOW) and polarity. The structural and chemical characteristics of biochar in turn determine the major sorption mechanisms and define biochar's suitability for contaminant sorption. Based on the reviewed literature, a soil treatment plan is suggested to guide the application of biochar in various soil types (paddy soils, brownfield and mine soils) at different pH levels (4-5.5) and contaminant concentrations (< 50 and > 50 mg kg-1). Conclusions Research on biochar has grown over the years with significant focus on its properties, and how these affect biochar's ability to immobilize organic and inorganic contaminants in soil. Few of these studies have been field-based. More studies with greater focus on field-based soil remediation are therefore required to fully understand the behavior of biochar under natural circumstances. Other recommendations are made aimed at stimulating future research in areas where significant knowledge gaps exist.

Effect of feedstock and microwave pyrolysis temperature on physio-chemical and nano-scale mechanical properties of biochar

“…Due to the unique structure of this carbon-based material, it has already seen use in carbon sequestration and wastewater treatment applications. Further consideration to this technology is given in terms of potential use for soil remediation in agriculture (Zama et al 2018), hipower battery (Saavedra et al 2018), and high-strength composite materials (Das et al 2015a(Das et al , 2016a applications. With current and prospective utilization of biochar increasing, it is inevitable that large-scale manufacturing demands will increase.…”

Thallium contamination in agricultural soils and associated potential remediation via biochar utilization

“…Specifically, Tl can be rapidly immobilized by the applied biochar in agricultural soils, and this mitigates the plant uptake of Tl. Practically, biochar can be aged while entering into agricultural soils, thereby affecting the remediation of Tl, which can be affected by ambient (micro) organisms and many corresponding factors including clay minerals, pH, and organic matter (Li et al 2018a, Wang et al 2017a, b, Yue et al 2019, Zama et al 2018. Additionally, biochar exhibits a bulk density that is significantly lower than that of mineral soil and can decrease the majority density of the soil (Tack and Egene 2019), and thus the minerals which include phosphate and carbonates present in biochar can reduce the mobility and bioavailability of Tl in soil via a precipitation method among salts and Tl .…”

The Impact of Soil-Applied Biochars From Different Vegetal Feedstocks on Durum Wheat Plant Performance and Rhizospheric Bacterial Microbiota in Low Metal-Contaminated Soil

“…Biochar may have variable effects on (i) soil properties, (ii) soil biota, including microbiota (Lehmann et al, 2011), (iii) plant growth and crop yield (Biederman and Harpole, 2013;Jefferey et al, 2015;Pandit et al, 2018;Sun et al, 2019), (iv) roots (Brennan et al, 2014;Prendergast-Miller et al, 2014;Xiang et al, 2017) and the rhizosphere microbiome (De Tender et al, 2016;Kolton et al, 2017), and (v) crop resistance to disease (Elad et al, 2011;Frenkel et al, 2017). Biochar has also been proved to be effective in the remediation of soils with both heavy metal and organic pollutants (Brennan et al, 2014;Zama et al, 2018), playing a critical role in reducing ecological and human health risks associated with heavy metal contamination.…”