The impact of enhanced and non-enhanced biochars on the catabolism of  14C-phenanthrene in soil

Abstract

Biochar is a by-product from the pyrolysis of biomass and has a great potential in soil amendment due to its carbon and nutrient-rich properties. The aim of this study was to investigate the impact of increasing amounts (0, 0.01, 0.1, 0.2, 0.5 and 1.0%) of two types of biochar (so-called enhanced and non-enhanced) to soil on the biodegradation of 14 C-phenanthrene. Enhanced biochar contains inoculants which are designed to potentially stimulate microbial activity and promote biological function in soil. After 100 d of incubation, the addition of 0.5% and 1% enhanced (EbioC) and non-enhanced biochars (NEbioC) led to longer lag phases, reduced rates and extents of 14 C-phenanthrene in amended soil. However, in soils amended with 0.01%, 0.1% and 0.2% amendments, extents of mineralisation of 14 Cphenanthrene increased and were found to be higher in the EBioC-as compared to the NEbioC-amended soils. Increasing soil-phenanthrene contact time also increased 14 C-phenanthrene mineralisation in soil which had received smaller amounts of EBioC. Application of both EbioC and NEbioC also enriched the soil microbial populations during the incubation. However, it was found that phenanthrene-degrading microbial populations declined as soil contact time increased; this was particularly true for soils receiving larger amounts of due to reduction in the mobile/bioaccessible fraction of the phenanthrene in soil. The findings revealed the importance of the type and amount of biochar that may be added to soil to stimulate or enhance organic contaminant biodegradation.

Biochar can mitigate co-selection and control antibiotic resistant genes (ARGs) in compost and soil

“…The use of <1% biochar in soil amendment is effective and can prevent certain toxic effects of biochar on organisms ( Godlewska et al., 2021 ). A 0.01%–0.2% biochar was more effective than 0.5%–1.0% biochar amendment in both enhanced and non-enhanced microcosms ( Omoni et al., 2020 ). Therefore, high biochar application may not be necessary to achieve desired result.…”

Effects of biological pre-treatment of lignocellulosic waste with white-rot fungi on the stimulation of 14C-phenanthrene catabolism in soils

“…Fresh SBG was collected from Lancaster Brewery in UK, having an initial moisture content of 81% and was dried to 60% using a low-heat oven for 6 h at 60 0 C before solid-state fermentation. Other properties of SBG are described in Table S1 (Omoni et al, 2020a). SBG (250 g ; dry matter = 40%) was transferred in sterile 1 l glass bottles and was aerated with sterile moist air then aseptically seeded with a four day old homogenised mycelial pellet (fungal strains designated, A -E) to a final dry weight of 2.5 g (0.01 g/g SBG).…”

“…Subsequently, the 12 C-phenanthrene spiked soil was amended with 20% of SBG. The amount of SBG added to phenanthrene spiked soil was based on our previous study (Omoni et al, 2020a). These mixtures were mixed with a stainless-steel spoon for homogeneous distribution in the soil.…”

“…The indigenous microbial population (total heterotrophs and phenanthrene-degraders) was quantified through the cell numbers in fungal pre-treated SBG-amended soils at each ageing period (1, 25, 50, 75, and 100 d) using the spread plate technique as described previously (Okere et al, 2012;Omoni et al, 2020a). Microbial numbers were assessed as colonyforming units per grams soil dry weight (CFUs/gdw soil, n =3).…”

“…Lignocellulosic waste materials, especially those generated from the agro-industrial processes, such as rice straw, sugarcane bagasse, corn cobs, spent brewery grains are potential sources of organic nutrients for microbial growth and metabolism in PAH contaminated soils (Brändli et al, 2005;Ren et al, 2018;Omoni et al, 2020a). Soil amended with lignocellulosic materials can provide organic carbon, nitrogen and phosphorus to the soil biota (Larney and Angers, 2012;Chojnacka et al, 2020).…”