Screening and Ranking Methodology Applied to Biochars Aimed at Acidic and Calcareous Sandy Soil Improvement

Abstract

The application of biochar (the by-product of biomass pyrolysis), as a soil amendment has been accepted as a sustainable solution to improve soil quality. The current study aims to establish a decision support tool for characterizing, ranking, and selecting biochars of different origins for soil improvement, thereby contributing to the development of a systematic approach, which lacks in the existing literature.The development of a Multi-Criteria Decision Support Approach applying a banded and weighted rating and scoring system allowed the selection and ranking of various biochars suitable for improving sandy soils before application. First, 14 selected, different biochar products (produced from industrial by-products, herbaceous, wood-based and manure-based feedstocks) were characterized with several physicochemical, biological and ecotoxicological methods taking into account both the technological and the environmental efficiency aspects of biochar utilization. Then, a system for the assessment and ranking of biochars for acidic, and calcareous neutral sandy soil improvement was developed, which could be flexibly adapted to different soil problems as well. Based on their performance in the tests, scores from (−5) to (+5) were assigned to each biochar. As a result, the grain husks and paper fiber sludge biochar was ranked as the most suitable for both acidic and neutral calcareous sandy soil improvement, with 55 and 43 scores, respectively (from the maximum 100). The applicability of this innovative multicriteria scoring-ranking system, as a tool for potential biochar users, was verified in microcosms and field-scale experiments, demonstrating the positive influence of this biochar on the acidic sandy soil.

Ecotoxicity attenuation by acid-resistant nanofiltration in scandium recovery from TiO2 production waste

“…Based on our results and experience with the ecotoxicity testing of wastes (red mud, fly ash, waste-derived biochars, transformer oil-contaminated soil and groundwater, soil contaminated with mazout, Zn, Cd, Pb contaminated soils and mine wastes, groundwater contaminated with chlorinated aliphatic hydrocarbons, etc.) [ 44 , 58 , [90] , [91] , [92] , [93] , [94] , [95] ] and considering the reported, diverse challenges (inhomogeneity, phase-separation, extreme pH, precipitation of contaminants due to pH adjustment) [ 41 , 89 ] that often arise during the testing of complex waste samples of varying physico-chemical characteristics, in our opinion, the use of a routine ecotoxicity characterisation approach of wastes should not be proposed in terms of the strict restrictions on the applied test methods. Instead, the use of a set of generally sensitive, high-throughput and time- and cost-effective ecotoxicity methods could be more straightforward and efficient, with specific recommendations for the most appropriate assays to test a particular waste sample.…”

Building a risk matrix for the safety assessment of wood derived biochars

“…recommended in nutrient-depleted soils as in this case N is too low to mobilize microbes (Clough et al, 2013;Farkas et al, 2021). Therefore, MT biochar should be used with caution, maybe in parallel with the addition of N fertilizers.…”

“…At the end of all the required analyses, the risk of adding biochar to the soil is assessed to determine if any safety issue arises and, as in any other environmental risk assessment procedure, a risk score matrix is defined (Table 4). To do this, we applied the scoring-ranking system described by Farkas et al (2021) and corrected considering the important factors as previously described (Lehmann et al, 2020). In Farkas et al, the authors described the development of a "Multi-Criteria Decision Support System"(MCDSS) associated with a scoring system, ranging from +5 to −5, for each of major parameters necessary to describe biochar characteristics as suggested by IBI and EBC.…”

“…Biochar risk matrix. Most of the scores were given following the MCDSS (Multi-Criteria Decision Support System) described by Farkas et al (2021), while scores for GI, SRI and mutagenicity index were defined within this work. Sums are reported considering the possible amelioration of acidic or neutral soils using biochar.…”

“…were given considering the aim of improving acidic soils (seeFarkas et al, 2021), 2: scores were given considering the aim of improving neutral soils (seeFarkas et al, 2021), 3: scores were given considering only the 0.5% (w/w) concentration. *Considering the important factors to improve and or maintain soil health, the main positive factors identified inLehmann et al (2020) received an additional 50% score to underline their importance.…”