Biochar Concentration Research Articles

Arsenic release from arsenopyrite weathering in acid mine drainage: Kinetics, transformation, and effect of biochar

Arsenopyrite (FeAsS) oxidative dissolution provides an important source for the occurrence of high arsenic in acid mine drainage (AMD). Biochar is a potent material that can dramatically sequestrate an array of heavy metals in water. However, little is known about the role of biochar on the fate of As from arsenopyrite in AMD. This study investigates the effects of biochar concentrations, AMD acidities, and temperatures on the release of As from arsenopyrite in a simulated AMD over a range of environmentally relevant conditions. Results show that biochar inhibits As release and further acidification without changing the arsenopyrite weathering mechanism. Arsenopyrite is first oxidized to Fe(II), As(III) and S0 and ultimately oxidized to Fe(III), As(V) and SO42-, respectively. Higher concentration, temperature or higher acidity promotes the arsenic release rate. Electrochemical studies showed that biochar inhibited As release and acidification for reduced the charge transfer resistance at the double layer and film resistance at the passivation layer, which was mainly attributed to Fe(III) ions in AMD being adsorbed, oxidized, and As complexed to biochar-Fe-As(V). This study reveals the release mechanism of As from arsenopyrite weathering in AMD and suggests the applicability of biochar in mitigating arsenic pollution and further acidification in sulfide mineral mine drainage.

Black Carbon-Amended Engineered Media Filters for Improved Treatment of Stormwater Runoff.

Urban stormwater runoff is a significant driver of surface water quality impairment. Recently, attention has been drawn to potential beneficial use of urban stormwater runoff, including augmenting drinking water supply in water-stressed areas. However, beneficial use relies on improved treatment of stormwater runoff to remove mobile dissolved metals and trace organic contaminants (TrOCs). This study assesses six engineered media mixtures consisting of sand, zeolite, high-temperature gasification biochar, and regenerated activated carbon (RAC) for removing a suite of co-contaminants comprising five metals, three herbicides, four pesticides, a corrosion inhibitor, six per- and polyfluoroalkyl substances (PFASs), five polychlorinated biphenyls (PCBs), and six polycyclic aromatic hydrocarbons (PAHs). This long-term laboratory-scale column study uses a novel approach to generate reproducible synthetic stormwater that incorporates catch basin material and straw-derived dissolved organic carbon. Higher flow conditions (20 cm hr-1), larger sized media (0.42-1.68 mm), and downflow configuration with outlet control increase the relevance of this study to better enable implementation in the field. Biochar- and RAC-amended engineered media filters removed nearly all of the TrOCs in the effluent over the course of three months of continuous flow (480 empty bed volumes), while sample ports spaced at 25% and 50% along the column depth provide windows to observe contaminant transport. Biochar provided greater benefit to TrOC removal than RAC on a mass basis. This study used relatively high concentrations of contaminants and low biochar and RAC content to observe contaminant transport. Performance in the field is likely to be significantly better with higher biochar- and RAC-content filters and lower ambient stormwater contaminant concentrations. This study provides proof-of-concept for biochar- and RAC-amended engineered media filters operated at a flow rate of 20 cm hr-1 for removing dissolved TrOCs and metals and offers insights on the performance of biochar and RAC for improved stormwater treatment and field trials.

Biochar application enhanced rice biomass production and lodging resistance via promoting co-deposition of silica with hemicellulose and lignin

Biochar, an environmentally friendly soil amendment, is created via a series of thermochemical processes from carbon-rich organic matter. The biochar addition enhances soil characteristics dramatically and increases crop growth and yields. However, the mechanism by which biochar improves plant lodging resistance, which is heavily influenced by cell walls, remains unknown. Three rice cultivars were grown in an experimental field provided with four concentrations of biochar (10, 20, 30, 40 t ha−1). The biochar application enhanced biomass production and lodging resistance in all three cultivars by up to 29 % and 22 %, respectively, with the largest improvement at a biochar application rate of 30 t ha−1. Biochar application significantly enhanced stem cell wall-related characteristics, with an increase in stem breaking force, wall thickness, and plumpness of 52 %, 32 %, and 21 %, respectively, which are suggested to be major contributors to enhanced lodging resistance and biomass yield. Notably, cell wall composition and silica content analysis indicated a significant increase in hemicellulose, lignin, and silica content in biochar-treated samples up to 36 %, 13 %, and 58 %, respectively, when compared to plants not treated with biochar. Integrative analysis suggested that silica, hemicellulose, and lignin were co-deposited in cell walls, which influenced biomass production and lodging resistance. Furthermore, the transcriptome profile revealed that biochar application increased the expression of genes involved in biomass production, cell wall formation, and silica deposition. This study suggests that biochar application might improve both biomass production and lodging resistance by promoting the co-deposition of silicon with hemicellulose and lignin in cell walls.

Characterization of Microbial Communities and Naturally Occurring Radionuclides in Soilless Growth Media Amended with Different Concentrations of Biochar

Biochar, derived from the pyrolysis of plant materials has the potential to enhance plant growth in soilless media. Howevetar, little is known about the impact of biochar amendments to soilless growth media, microbial community composition, and fate of chemical constituents in the media. In this study, different concentrations of biochar were added to soilless media and microbial composition, and chemical constituents were analyzed using metagenomics and gamma spectroscopy techniques, respectively. Across treatments, carboxyl-C, phenolic-C, and aromatic-C were the main carbon sources that influenced microbial community composition. Flavobacterium (39.7%), was the predominantly bacteria genus, followed by Acidibacter (12.2%), Terrimonas (10.1%), Cytophaga (7.5%), Ferruginibacter (6.0%), Lacunisphaera (5.9%), Cellvibrio (5.8%), Opitutus (4.8%), Mucilaginibacter (4.0%) and Bryobacter (4.0%). Negative relationships were found between Cytophaga and 226Ra (r = −0.84, p = 0.0047), 40K (r = −0.82, p = 0.0069) and 137Cs (r = −0.93, p = 0.0002). Similarly, Mucilaginibacter was negatively correlated with 226Ra (r = −0.83, p = 0.0054) and 137Cs (r = −0.87, p = 0.0021). Overall, the data suggest that high % biochar amended samples have high radioactivity concentration levels. Some microorganisms have less presence in high radioactivity concentration levels.

Biochar promotes the growth of apple seedlings by adsorbing phloridzin

Apple replant disease (ARD) has been reported in all major apple-growing regions of the world, and abiotic (phenolic compounds including phloridzin) and biological (bacteria, fungi and nematode) factors are important causes of ARD. This study aimed to assess the effect of phloridzin adsorption on biochar pyrolyzed at different temperatures and the effectiveness of biochar addition on the growth of Malus hupehensis Rehd. seedlings under phloridzin stress. Three biochar treatments were considered (BC300, BC400 and BC500), pyrolyzed at three different temperatures (300°C, 400°C and 500°C, respectively). Batch adsorption experiments revealed that BC300 had the maximum adsorption efficiency. The BC300 treatment was then selected for isotherm and kinetic fitting to investigate the influence of pH on the adsorption process and determine the phloridzin adsorption mechanism. The biochar was found to have a single-layer phloridzin adsorption effect, and the adsorption rate was related to the biochar concentration and pyrolysis temperature. A outdoorpot experiment was conducted to analyze the biochar adorption to phloridzin in soil. Phloridzin addition significantly inhibited seedling growth and biochar significantly reduced the soil phloridzin content. BC300 had the best adsorption effect of the three biochar treatments. Compared with the replant soil (CK), biochar (especially BC300) increased the biomass of the seedlings and the antioxidant enzyme activity in the leaves. The soil enzyme activity, organic matter and bacteria numbers increased significantly after biochar addition. The best seedling growth and soil conditions were found for BC300. These results reveal that biochar addition can significantly reduce the phloridzin content and promote seedlings growth, and the effectiveness of the biochar depends on the pyrolysis temperature.

Biochar amendment of aerobic composting for the effective biodegradation of heavy oil and succession of bacterial community

Soil pollution caused by petroleum pollutants from production trade activities in petroleum-related factories contributes serious threat to the environment and human health. Composting is technically-feasible and cost-effective in the biodegradation of heavy oil pollutants. This composting experiment was developed with four rice husk biochar (RHB) concentrations of 0 wt% (CK), 5 wt% (S1), 10 wt% (S2) and 15 wt% (S3) for the degradation of heavy oil. The results showed that RHB amendment could strengthen the degradation performance of heavy oil, and the degradation efficiencies for CK, S1, S2 and S3 were 59.67%, 65.00%, 73.29% and 74.82%, respectively. Microbial community succession process was investigated through high-throughput sequencing technology, and the RHB addition regulated bacterial community succession and further effectively facilitated the biodegradation of heavy oil in composting. This study substantiated that biochar materials-amended aerobic composting would be a promising strategy for the biodegradation of petroleum pollutants.

Effect of biochar on methane production and structural characteristics in the anaerobic digestion (AD) of rape straw

This study investigated the mesophilic and thermophilic anaerobic fermentation of rape straw with biochar addition. The effects of biochar on the biogas yield, degradation of lignocellulose, bacterial community, and crystallinity were explored. The results showed that the biogas yield and methane content increased as the biochar concentration was increased. The biochar concentration of 5.0% resulted in a high biogas yield in mesophilic and thermophilic anaerobic digestion at 142.2 mL/g and 193.5 mL/g, respectively, which were 40.5% and 21.0% improvements compared with the control. The corresponding methane contents were 59.4% and 57.0%, respectively. For the lignocellulose degradation, the cellulose content in the mesophilic AD decreased from 54.0% in the pretreated rape straw to between 18.7% and 25.0%. The microbial community results showed that as the biochar concentration was increased, the relative abundance of Firmicutes initially increased before it decreased. Among the microbial community results, the relative abundances of Firmicutes and Bacteroides in the biogas residue of the mesophilic anaerobic digestion were the highest in the biogas residue with the 5.0% biochar concentration sample in the mesophilic AD, at 27.06% and 39.20%, respectively. This result revealed the mechanism of biochar to improve the biogas production of rape straw in anaerobic fermentation.

Effects of Iron-Loaded Biochar on the Anaerobic Co-Digestion of Food Waste and Sewage Sludge and Elucidating the Mechanism Thereof

The inhibition of volatile fatty acid (VFA) production is an important factor affecting biogas (methane) production in the anaerobic co-digestion systems comprising food waste and sewage sludge. In this study, batch experiments were conducted at medium temperature (36 ± 0.5 °C), during which the biogas production index and material–liquid characteristic parameters of the anaerobic digestion systems containing different concentrations of iron-loaded biochar (Fe-BC) were monitored. The cumulative biogas production data were analyzed using a modified Gompertz kinetic model to determine the effect of the Fe-BC on biogas production in the anaerobic co-digestion system. Studies have shown that addition of Fe-BC does not significantly influence the hydrolysis and acidification stages of anaerobic co-digestion, but does have a significant effect on promoting methanogenesis by alleviating the accumulation of VFAs and improving both the buffer capacity of the system and the efficiency of substrate-to-biogas conversion. When the Fe-BC concentration was 16 g·L−1, the cumulative biogas production reached 329.42 mL·g-VS−1, which was 49.7% higher than the blank group, and the lag period was 3.55 d, which was 42% shorter than the blank group. Mechanistic studies have shown that Fe-BC increased the concentration of coenzyme F420 and the conductivity of the digestate in the co-digestion system, which increased the activity of methanogens in the anaerobic digestion system, thereby promoting methanogenesis.

Biochar Additions Alter the Abundance of P-Cycling-Related Bacteria in the Rhizosphere Soil of Portulaca oleracea L. under Salt Stress

Numerous reports confirm a positive impact of biochar amendments on soil enzyme activities, nutrient cycles, and, finally, plant growth and development. However, reports explaining the process behind such diverse observations are scarce. The aim of the present study was (1) to evaluate the effect of biochar on the growth of purslane (Portulaca oleracea L.) and nutrients; (2) to determine the response of rhizosphere enzyme activities linked to soil phosphorus cycling after bio-char amendment under non–saline and saline soil conditions. Furthermore, we investigate whether adding biochar to soil alters the abundance of P-cycling-related bacteria. Two rates of biochar (2% and 4%) were applied in pot experiments. Biochar addition of 2% significantly increased plant growth under non-saline and saline soil conditions by 21% and 40%, respectively. Moreover, applying biochar increased soil microbial activity as observed by fluorescein diacetate (FDA) hydrolase activity, as well as phosphomonoesterase activities, and the numbers of colony-forming units (CFU) of P-mobilizing bacteria. Soil amended with 2% biochar concentration increased total soil nitrogen (Nt), phosphorus (P), and total carbon (Ct) concentrations by 18%, 15%, and 90% under non-saline soil conditions and by 29%, 16%, and 90% in saline soil compared the control, respectively. The soil FDA hydrolytic activity and phosphatase strongly correlate with soil Ct, Nt, and P contents. The rhizosphere soil collected after biochar amendment showed a higher abundance of tricalcium phosphate-solubilizing bacteria than the control soil without biochar. Overall, this study demonstrated that 2% maize-derived biochar positively affects halophyte plant growth and thus could be considered for potential use in the reclamation of degraded saline soil.

The effects of g-C3N4/biochar and g-C3N4 on bacterial community in riverbed sediment.

Biochar had been widely used to improve the activity of photocatalysts, the biochar-based photocatalysts had more potential for environmental pollution remediation, but their effect on the sediment remained unknown. To understand these, the typical photocatalyst g-C3N4 was modified by biochar to develop g-C3N4/biochar with enhanced photocatalytic ability. Riverbed sediment was exposed to g-C3N4 and g-C3N4/biochar respectively for 30days, and Illumina sequencing was utilized to examine the changes in the bacterial community in the sediment. The results showed that in riverbed sediment, g-C3N4 exposure had a concentration-dependent effect on the diversity of bacteria, while g-C3N4/biochar exposure had a slight influence on the bacterial diversity and the diversity almost maintained stable with different g-C3N4/biochar concentration. The application of g-C3N4 exhibited an inhibition influence on the growth of Acidobacteria, Gemmatimonadetes, and Rokubacteria in sediment, whose relative abundance increased when g-C3N4 was 25mg/kg, and then decreased when g-C3N4 beyond this concentration. The presence of g-C3N4/biochar increased the relative abundance of Cyanobacteria in sediment and showed no obvious impact on other dominant phyla. Both g-C3N4 and g-C3N4/biochar could alter the levels of TP, NN, and AN in the sediment, but the magnitude of the changes of these physicochemical factors caused by g-C3N4/biochar was much smaller than those caused by g-C3N4. In addition, the complexity of the bacterial community network was reduced in a high concentration of g-C3N4, while it remained stable with different concentrations of g-C3N4/biochar treatments. Totally, this study demonstrated that, compared to g-C3N4, g-C3N4/biochar was able to maintain the relative stability of the bacterial community in riverbed sediment and mitigate the negative effects of photocatalysts to some extent, making biochar an ecological remediation agent with great potential for application.

Biochar-Stimulated Pumpkin Performance Under Cadmium Stress Is Strongly Linked to Metabolite Pattern.

In this study, pumpkin seedlings were subjected to cadmium stress (100mg/L cadmium ion solution, 10days) without or with wheat straw biochar at different concentrations (0%, 0.5%, 1%, and 2% w/v). As the biochar concentration increased, the amount of cadmium accumulated in the root and stem of pumpkin seedlings decreased and the fresh weight of root, stem and leaf increased. The highest cadmium concentration was in the root, followed by the stem and then the leaf. 1% and 2% biochar treatments reduced the oxidative stress of cadmium to seedlings, and added the contents of fatty acid, carbohydrate, amino acid and indoleacetic acid in the root. With the increase of biochar concentration, the metabolites promoting root growth increased. These results provide new information about how biochar alleviates cadmium stress by affecting the metabolic response.

Structural, optical, and thermal properties of PEO/PVP blend reinforced biochar

In this paper, composites of PEO/PVP reinforced with different biochar loadings (0, 0.5,1, and 2 wt %) were obtained via the solution casting method. The crystallite size of the blend is increased by increasing the biochar up to 1 wt%. This behaviour is due to the increasing intermolecular interaction between biochar and blend. The strong interaction between C–O/C–O–C of blend and biochar caused altering the crystalline regions deduced from FTIR. The optical properties of the composite are dependent on the biochar content, where the direct and indirect optical band gaps are decreased upon the addition of the biochar up to 1 wt%. The refractive index values at 650 nm increased by increasing biochar concentration in PEO/PVP blend. Urbach tail energy is increased by adding biochar to 1 wt%. This behaviour is because increasing traps in the blend result in a lower energy transition. The effect of different concentrations of the biochar on the blends’ optical parameters such as optical conductivity, optical dielectric constant, and extinction coefficient is also studied. The thermal stability of the blend increased with increasing biochar content up to 1 wt% due to an increased degree of crystallinity. Further addition of biochar reduced the thermal stability of the blend due to aggregation of biochar particles.

Responses of microbial community composition and function to biochar and irrigation management and the linkage to Cr transformation in paddy soil

Combining biochar with irrigation management to alter the microbial community is a sustainable method for remediating soils contaminated by heavy metals. However, studies on how these treatments promote Cr(VI) reduction are limited, and the corresponding microbial mechanisms are unclear. Therefore, we conducted a pot experiment to explore the responses of soil microbial communities to combined biochar amendment and irrigation management strategies and their involvement in Cr transformation in paddy soils. Six treatments were established using varying concentrations of biochar (0, 1, and 2% [w/w]) combined with two irrigation management strategies (continuous flooding [CF] and dry–wet alternation [DWA]). The results showed that the combined biochar addition and irrigation management strategy significantly altered soil pH, redox potential, organic matter content, and Fe(II) and sulfide concentrations. In addition, the Cr(VI) concentration under CF irrigation management was conspicuously lower (48.2–54.4%) than that under DWA irrigation management. Biochar amendment also resulted in a substantial reduction (8.8–27.4%) in Cr(VI) concentration. Moreover, the changes in soil physicochemical properties remarkably affected the soil microbial community. The microbial diversity and abundance significantly increased with biochar amendment. Furthermore, the combined biochar amendment and CF strategy stimulated the growth of Geobacter- and Anaeromyxobacter-related Fe(III)-reducing bacteria, Gallionella-related Fe(II)-oxidizing bacteria, and Desulfovibro- and Clostridium-related sulfate-reducing bacteria, which simultaneously facilitated the generation of Fe(II) and sulfide, thereby enhancing Cr(VI) reduction. Consequently, our results suggest that the effectively increased abundance of Fe-reducing/oxidizing bacteria and sulfate-reducing bacteria via combined CF irrigation management and biochar addition may be a key factor in reducing Cr(VI) in paddy soil. The keystone genera responsible for Cr(VI) reduction were Geobacter, Anaeromyxobacter, Gallionella, Desulfovibro, and Clostridium. This study provides novel insights into the coupling mechanism of the Fe/S/Cr transformation mediated by Fe-reducing/oxidizing bacteria and sulfate-reducing bacteria.

Characterization of organophosphate pesticide sorption of potato peel biochar as low cost adsorbent for chlorpyrifos removal

There has been a growing interest in the scientific world in the production of biochar from natural organic wastes as potential sustainable precursors for bioremediation. Potato peel biochar was produced by slow pyrolysis method under oxygen-limited conditions and used as bio adsorbent in bioremediation of commercial pesticide having Chlorpyrifos as an active component. Chlorpyrifos is an organophosphate pesticide, highly neurotoxic, and primarily targets the central nervous system of pests and insects. The excess residues of chlorpyrifos are hazardous to environmental flora and fauna. Chlorpyrifos was treated against biochar at varying physical parameters and further optimized by using response surface methodology through Box-Behnken design (BBD). 72.06% of pesticide removal was observed post 24 h of treatment against a pesticide concentration of 1346.85 μg/ml with a biochar concentration of 1.04 mg/ml under room temperature at pH 5.04. Biochar was characterized by proximate and ultimate analysis, FTIR, and SEM-EDX. Characterization by SEM-EDX showed the surface morphology and minerals on the peel and biochar. Microgram of potato peel shows pores of larger size than biochar having many cavities with different dimensions. In the plant system, growth morphology, nutritional status, polyphenols, total antioxidant content, and free radical scavenging activity were assessed. Enhancement in presence of biochar was recorded in growth morphology and plant biomolecules including photosynthetic pigments. Better translocation of the nutrient is recorded in biochar treated plants, as evidenced by the low amount of carbohydrate and protein in treated leaves. Biocompatibility assessment of chlorpyriphos in fish erythrocytes showed 43.26% hemolysis by pesticide-treated biochar. The practical use of this approach can also be best utilized if applied to those geographical regions where the soil pH is acidic. Biochar is a marketable bio-product, which can have a positive impact in agriculture, industries, and the energy sector creating a bio-based economy with reduced environmental pollution.

Effect of rice husk and palm tree-based biochar addition on the anaerobic digestion of food waste/sludge

This study explored the impact of different types of biochar on the anaerobic digestion (AD) of food waste and sludge and the biochar-enhanced mesophilic AD of food waste for methane production. A particular focus was placed on the process and underlying mechanisms. Rice husk biochar (RHB550) and palm tree biochar (PTB400) were loaded at levels of 5, 10, and 15 g/L. The results showed that 5 g/L of RHB550 led to an increase in methane yields of 455.83 ± 17.9 mL/gVSadd compared to the control yield of 333.32 ± 14.9 mL/gVSadd. The addition of an adequate amount of biochar improved the cumulative methane yield, whereas excessive amounts inhibited the AD process. RHB550 biochar improved the process stability, which was favourable for syntrophic volatile fatty acid (VFA) oxidation, and consequently increased the cumulative methane yield by up to 36.75 ± 2.9%. Earlier stagnation was also shown to be caused by the elimination of VFAs and ammoniacal-nitrogen and the degradation of chemical oxygen demand (COD). Increasing the concentrations of RHB550 biochar enabled significant improvement in methane yield by increasing the pH and COD removal, which could be a useful strategy in AD to further increase the organic loading rate.

Mechanical and durability properties of biochar concrete

Cement production, which now accounts for over 7% of global CO2 emissions, could be a major roadblock to the Paris Agreement's goal of net-zero emissions by 2050. Greenhouse gas emissions during cement production arise from the processing of clinker where a large amount of fossil fuel is burnt for energy generation, and the remaining part comes from the energy it takes to get to the necessary high temperatures. Partial replacement of cement by residuals from agricultural industries is one of the key strategies to mitigate CO2 emissions and help promote sustainability. The objective of the present research work is to investigate biochar, prepared by pyrolyzing rice husk (RH) at 550 °C, as an alternate supplementary cementitious material (SCM). The physical and chemical properties of biochar were characterized using elemental analysis, scanning electron microscopy, thermogravimetric, and energy-dispersive X-ray spectroscopy. Compressive strength, flexural strength, water loss, permeability, and resistance to sulfate attack tests were used to investigate the mechanical and durability features of concrete containing varied concentrations of biochar. Chapelle test was conducted to determine the pozzolanic activity of the biochar. The results indicate that concrete containing 4% biochar improved compressive strength by 2.32%, flexural strength by 23.52%, and durability by 17.3% because the finer biochar particles have a packing effect resulting in the formation of a dense matrix.

Impact of Biochar Soil Amendment on Tomato mosaic virus Infection, Growth and Nutrients Uptake of Tomato Plants

Biochar soil amendment was applied as an eco-friendly approach to control Tomato mosaic virus (ToMV) and improve tomato growth and nutritional status. Three concentrations of biochar, 0.5, 1.0 and 1.5% were used as soil amendments. Using biochar at the rate of 1 and 1.5% reduced the ToMV incidence and delayed symptoms appearance as compared with plants grown in non-amended soil. Infection percentage and disease severity of ToMV were reduced by 33.3 and 50%, respectively, 15 days after inoculation of plants of soil amended with 1.5% biochar. ToMV relative concentration, using indirect ELISA was significantly reduced in plants of biochar 1% and 1.5% treatments. The lowest virus concentration was recorded at 21 days after inoculation in plants of 1.5% biochar amended soil. The shoot fresh weight was increased at biochar rates of 1.5 and 0.5% in non-infected and ToMV infected tomato, respectively. Significant increase was obtained in shoot K content amended with 1.0 and 1.5% biochar treatments of healthy and ToMV-infected tomato plants, respectively. Whereas, shoot Na content was diminished in infected plants grown in biochar amended soil at all tested biochar concentrations. Overall, the biochar application to soil enhanced resistance to ToMV infection, stimulated growth and K content increment and Na content decrement in tomato plants. In conclusion, application of biochar to agricultural soil could be considered a practical tool for minimizing the change effects of climate through carbon sequestration, improve plant productivity and increase diseases tolerance for sustainable agriculture.

Characterization, Concentration of Biochar and Titanspheres and Heavy Metals Assessment of Quercus Suber Cork Powder Fly Ash Fractions

Cork powder is categorized in the group of the biodegradable fraction of products and waste. In Portugal, the cork powder production ranges between 32 000 and 37 000 tons/year and is used as fuel, which generates ash. For this ash characterization and possible recycling, sieving (dry and wet) and pre-treatments (ultrasounds and polycarboxylate) were tested in order to concentrate biochar, titanspheres and assess the fractions more suitable for fertilizer material. The samples were characterized via a combination of techniques: SEM/EDS, RLM, XRF, MRS and ICP-MS. For size-fractionation of cork powder fly ash, dry sieving is not an efficient method, however, improved efficiency, especially in the <25 μm size-fraction, can be attained by preceding wet sieving with a combined pre-treatment of ultrasounds and polycarboxylate. A sequence method was applied for biochar concentration and purification, however the amount of final biochar obtained is very low (1%wt.). The ICP-MS results indicate that the use of cork powder ash as fertilizer material in plant crops intended for human and animal consumption is not recommended, whereas other uses in soils are possible.

Efficient removal of heavy metals from artificial wastewater using biochar

Increase environmental pollution, especially water contaminated with heavy metals has led to various problems in human life. Accumulation and magnification of heavy metals in human tissues through consumption of contaminated water can cause hazardous impacts on health. In the present study, bio-char was prepared from the shoot and root culture of in-vitro grown Plumbago zeylanica. Effect of bio-char (prepared from both the plant materials) on removal of chromium and cadmium from synthetic water was evaluated. Change in cadmium and chromium absorbance was recorded at every hour interval up to six hours using UV–Visible spectrophotometer. It was observed that after six-hour of incubation there was no further removal of heavy metals. Further optimization of different parameters such as concentration of heavy metal, solution pH and bio char concentration were performed. At 100 ppm concentration of heavy metals maximum removal was obtained. Furthermore, it was observed that pH 7 and 2 mg/ml bio char concentration showed maximum removal efficiency. The result showed that shoot derived bio char has more potential to remove cadmium and chromium as compared to the root derived bio char. In-vitro grown shoot culture provides an effective method to remove pollutants as it grows faster compared to wild type culture. Therefore, this method is useful for heavy metals removal from wastewater.

Biochar Amendments Improve Licorice (Glycyrrhiza uralensis Fisch.) Growth and Nutrient Uptake under Salt Stress.

Licorice (Glycyrrhiza uralensis Fisch.) is a salt and drought tolerant legume suitable for rehabilitating abandoned saline lands, especially in dry arid regions. We hypothesized that soil amended with maize-derived biochar might alleviate salt stress in licorice by improving its growth, nutrient acquisition, and root system adaptation. Experiments were designed to determine the effect of different biochar concentrations on licorice growth parameters, acquisition of C (carbon), nitrogen (N), and phosphorus (P) and on soil enzyme activities under saline and non-saline soil conditions. Pyrolysis char from maize (600 °C) was used at concentrations of 2% (B2), 4% (B4), and 6% (B6) for pot experiments. After 40 days, biochar improved the shoot and root biomass of licorice by 80 and 41% under saline soil conditions. However, B4 and B6 did not have a significant effect on shoot growth. Furthermore, increased nodule numbers of licorice grown at B4 amendment were observed under both non-saline and saline conditions. The root architectural traits, such as root length, surface area, project area, root volume, and nodulation traits, also significantly increased by biochar application at both B2 and B4. The concentrations of N and K in plant tissue increased under B2 and B4 amendments compared to the plants grown without biochar application. Moreover, the soil under saline conditions amended with biochar showed a positive effect on the activities of soil fluorescein diacetate hydrolase, proteases, and acid phosphomonoesterases. Overall, this study demonstrated the beneficial effects of maize-derived biochar on growth and nutrient uptake of licorice under saline soil conditions by improving nodule formation and root architecture, as well as soil enzyme activity.