Characterization and Determination of the Toxicological Risk of Biochar Using Invertebrate Toxicity Tests in the State of Aguascalientes, México

Abstract

Following a quantitative analysis of adequate feedstock, comprising 11 woody biomass species, four biochars were generated using a Kon-Tiki flame curtain kiln in the state of Aguascalientes, Mexico. Despite the high quality (certified by European Biochar Certificate), the biochars contain substantial quantities of hazardous substances, such as polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, and heavy metals, which can induce adverse effects if wrongly applied to the environment. To assess the toxicity of biochars to non-target organisms, toxicity tests with four benthic and zooplanktonic invertebrate species, the ciliate Paramecium caudatum, the rotifer Lecane quadridentata, and the cladocerans Daphnia magna and Moina macrocopa were performed using biochar elutriates. In acute and chronic toxicity tests, no acute toxic effect to ciliates, but significant lethality to rotifers and cladocerans was detected. This lethal toxicity might be due to ingestion/digestion by enzymatic/mechanic processes of biochar by cladocerans and rotifers of toxic substances present in the biochar. No chronic toxicity was found where biochar elutriates were mixed with soil. These data indicate that it is instrumental to use toxicity tests to assess biochars’ toxicity to the environment, especially when applied close to sensitive habitats, and to stick closely to the quantitative set-point values.

A comprehensive review of biochar in removal of organic pollutants from wastewater: Characterization, toxicity, activation/functionalization and influencing treatment factors

“…The world population increase over the past two decades led to an increasing demand in water volume, both for human consumption and for the industry sector, which results to increased wastewater volumes released in the aquatic environment. A variety of pollutants are detected in wastewater streams and have been reported in literature, such as; carcinogenic heavy metals [1], petroleum hydrocarbons [2], polycyclic aromatic hydrocarbons (PAHs) [3], organic dyes [4], phenols, pesticides, pharmaceuticals and veterinary antibiotics [5]. A diversity of pollutant treatment techniques has been extensively discussed in literature [6][7] [8].…”

Isolation and identification of a 2,3,7,8-Tetrachlorodibenzo-P-dioxin degrading strain and its biochemical degradation pathway

“…The parent 2,3,7,8-TCDD [ 1 ] was first transformed into produce 4,5-Dichloro-1,2-benzoquinone [ 2 ] and 2-Hydroxy-1,4-benzoquinone [ 4 ]. 4,5-Dichlorocatechol [ 3 ] was intermediate. 2-Hydroxy-1,4-benzoquinone [ 4 ] then transformed into 1,2,4-Trihydroxybenzene and finally, β-ketoadipic acid [ 5 ] was obtained by undergoing aromatic ring cleavage and further metabolism.…”

“…For example, in the process of producing caustic soda by Chor-alkali method, a large amount of salt sludge is produced, and its composition and discharge are closely related to the content of raw salt impurities as well as the production process. Generally, every 1 ton of caustic soda will produce 40-60kg (dry base) of salt sludge [ 3 , 4 ]. The concentration of dioxins in electrolytic salt sludge of a Chor-alkali plant was as high as 378.85ug/kg, and its toxic equivalent I-TEQ value was 21.65ug/kg.…”

Feasibility of Coupling Anaerobic Digestion and Hydrothermal Carbonization: Analyzing Thermal Demand

“…Further research is needed to find optimal configurations and evaluate the plant's electrical demand once the solid content of the slurry is established. Another relevant factor is the possible toxicity of hydrochar material when used in biological processes, just as it has already been reported for biochar [110]. Table 5 summarizes benefits and disbenefits of the three scenarios evaluated, being coincident in the need of finding a practical solution to the energy demand associated with the thermal treatment.…”