Biochar Dosage Research Articles

Dosage- and site-dependent retention of black carbon and polycyclic aromatic hydrocarbons in farmland soils via long-term biochar addition

Biochar, a soil conditioner containing significant amounts of polycyclic aromatic hydrocarbons (PAHs), has gained widespread popularity in agricultural practices due to its advantages in improving soil fertility and carbon sequestration. While biochar may increase soil black carbon (BC) and PAH contents, the quantitative accumulation of BC and PAHs in different soil environments under varying biochar addition dosages remains poorly understood. Here, we investigated the content and composition of black carbon (evaluated using benzene polycarboxylic acids, BPCAs) and PAHs in soils treated with different biochar addition dosages from two long-term experimental farmlands in Ningxia (5-year) and Shandong (7- and 11-year), China. Results showed that increasing cumulative biochar dosage caused elevated contents of black carbon and PAHs, accompanied by decreases in their retention efficiencies. Contrasting retention was observed between sites, with the Shandong site characterized by higher retention efficiencies of BPCAs and lower retention efficiencies of PAHs, possibly owing to its higher temperature, more sandy soil texture, less irrigation, and lower sunlight intensity. Despite both black carbon and PAHs originating from biochar and sharing similar condensed aromatic structures, there was no significant correlation between the contents of black carbon and PAHs, indicating distinct behaviors and fates of these compounds. These findings emphasize the importance of optimizing biochar addition dosages and considering site-specific environmental factors for effective soil black carbon sequestration through biochar application.Graphical

Biochar as Alternative Material for Heavy Metal Adsorption from Groundwaters: Lab-Scale (Column) Experiment Review.

The purpose of this manuscript is to present a review of laboratory experiments (including methodology and results) that use biochar, a specific carbon obtained by a pyrolysis process from different feedstocks, as an alternative material for heavy metal adsorption from groundwater. In recent years, many studies have been conducted regarding the application of innovative materials to water decontamination to develop a more sustainable approach to remediation processes. The use of biochar for groundwater remediation has particularly attracted the interest of researchers because it permits the reuse of materials that would be otherwise disposed of, in accordance with circular economy, and reduces the generation of greenhouse gases if compared to the use of virgin materials. A review of the different approaches and results reported in the current literature could be useful because when applying remediation technologies at the field scale, a preliminary phase in which the suitability of the adsorbent is evaluated at the lab scale is often necessary. This paper is therefore organised with a short description of the involved metals and of the biochar production and composition. A comprehensive analysis of the current knowledge related to the use of biochar in groundwater remediation at the laboratory scale to obtain the characteristic parameters of the process that are necessary for the upscaling of the technology at the field scale is also presented. An overview of the results achieved using different experimental conditions, such as the chemical properties and dosage of biochar as well as heavy metal concentrations with their different values of pH, is reported. At the end, numerical studies useful for the interpretation of the experiment results are introduced.

Assessments of some animal bones biochar as paddy protectants against rice weevil, Sitophilus oryzae L. [Coleoptera: Curculionidae]

The main insect pest of stored paddy is Sitophilus oryzae (rice weevil). Huge amounts of rice are produced by peasant farmers each year, but the bulk of it is wasted due to insufficient storage facilities and insect pest attacks brought on by careless handling. In this study, the insecticidal effects of biochar on S. oryzae were assessed in femurs from Sus scrofa (pig), Gallus gallus (chicken), and Bos taurus (cattle). Adult mortality, adult emergence, weight loss, seed damage, and weevil perforation index are among the indicators evaluated. To apply the biochar, different dosages were used: 0.2, 0.4, 0.6, 0.8, and 1.0 g/20 g of paddy rice. In this work, the population of adult S. oryzae on paddy rice was dramatically reduced by all animal bones biochar tested for insecticidal activity (p < 0.05). The animal bone biochar became more effective with increasing dosage. After 24 h of treatment, pig biochar induced a 36.67 % mortality rate of adult S. oryzae, followed by cow biochar's 20 % mortality rate of rice weevils. The fatal dose of cattle, pig, and chicken biochar at which 50 % (LD50) of the population of adult S. oryzae responded after 24 h of treatment were 0.83g, 0.43g, and 0.90g, respectively. It should be encouraged to utilize biochar made from animal bones to combat the S. oryzae in stored paddy. They could be utilized as a green control measure to lessen the risk brought on by the usage of synthetic chemical insecticides in the environment.

Effective Carbon Dioxide Mitigation and Improvement of Compost Nutrients with the Use of Composts' Biochar.

Composting is a process that emits environmentally harmful gases: CO2, CO, H2S, and NH3, negatively affecting the quality of mature compost. The addition of biochar to the compost can significantly reduce emissions. For effective CO2 removal, high doses of biochar (up to 20%) are often recommended. Nevertheless, as the production efficiency of biochar is low-up to 90% mass loss-there is a need for research into the effectiveness of lower doses. In this study, laboratory experiments were conducted to observe the gaseous emissions during the first 10 days of composting with biochars obtained from mature composts. Biochars were produced at 550, 600, and 650 °C, and tested with different doses of 0, 3, 6, 9, 12, and 15% per dry matter (d.m.) in composting mixtures, at three incubation temperatures (50, 60, and 70 °C). CO2, CO, H2S, and NH3 emissions were measured daily. The results showed that the biochars effectively mitigate CO2 emissions during the intensive phase of composting. Even 3-6% d.m. of compost biochars can reduce up to 50% of the total measured gas emissions (the best treatment was B650 at 60 °C) and significantly increase the content of macronutrients. This study confirmed that even low doses of compost biochars have the potential for enhancing the composting process and improving the quality of the material quality.

Exploring metal(loid)s dynamics and bacterial community shifts in contaminated paddy soil: Impact of MgO-laden biochar under different water conditions

In this study, a soil incubation experiment was conducted to explore the influence MgO-treated corn straw biochar (MCB) on the bioavailability and chemical forms of cadmium (Cd), lead (Pb), and arsenic (As), alongside the impact on the bacterial community within paddy soil subjected to both flooded and non-flooded conditions. Raw corn straw biochar (CB) served as the unmodified biochar control, aiding in the understanding of the biochar's role within the composite. The results showed that even at a minimal concentration of 0.5 %, MCB exhibited higher effectiveness in reducing the bioavailability of Pb and Cd compared to 1 % CB. In non-flooded conditions, 0.5 % MCB reduced the bioavailable Pb and Cd by 99.7 % and 87.4 %, respectively, while NaH2PO4-extracted As displayed a 14.5 % increase. With increasing MCB concentrations (from 0.5 % to 1.5 %), soil pH, DOC, EC, available phosphorus, and bioavailable As increased, while bioavailable Pb and Cd exhibited declining tendencies. Flooding did not notably alter MCB's role in reducing Pb and Cd bioavailability, yet it systematically amplified As release. Heavy metal fractions extracted by acetic acid increased in the MCB groups under flooding conditions, especially for As. The inclusion of 0.5 % MCB did not noticeably affect bacterial diversity, whereas higher doses led to reduced diversity and substantial changes in community composition. Specifically, the groups with MCB showed an increase in the Bacteroidetes and Proteobacteria phyla, accompanied by a decrease in Acidobacteria. These alterations were primarily attributed to the increased pH and EC resulting from MgO hydrolysis. Consequently, for Pb/Cd stabilization and soil bacterial diversity, a low dosage of MgO-treated biochar is recommended. However, caution is advised when employing MgO-treated biochar in soils with elevated arsenic levels, particularly under flooded conditions.

Activated rice husk biochar for azo dye removal: batch adsorption, kinetics and thermodynamic studies

&lt;p&gt;The study aimed to analyze the adsorption behaviour of an activated rice husk biochar adsorbent in batch mode to expunge azo dye concentrations depletion from liquid solvents. The biochar adsorbent was formulated using different chemical synthesis processes, and its surface region was assessed using Nitrogen retention. The existence of the particular azo dyes was verified through SEM and EDX examinations. Additionally, XRD analysis was conducted to examine the intensity and crystalline structure of the activated biochar adsorbent. A batch mode study was conducted to ascertain the ideal adsorption parameters, including pH, contact time, biochar dose, and azo dye concentration. The adsorption kinetic studies supported the notion of a favourable adsorption interaction occurring through the mutual influence of the adsorbed matter and the adsorbing substrate. Most isotherm studies were well-fitted with regression values of isotherm models, indicating an adsorption process with non-uniform monolayer formation. Thermodynamic investigations validated that the binding forces between the adsorptive and the adsorbing phase are endothermic, and a significant amount of spent adsorbent was successfully recovered using a strong hydrochloric acid desorption process.&lt;/p&gt;

Co-Action of Ionic Liquids with Alternative Sorbents for Removal of Reactive Azo Dyes from Polluted Wastewater Streams

In this study, the facile removal of the chromium-complex-based reactive azo dye C. I. Reactive Black 8 (RB8) from model wastewaters by the co-action of alternative sorbents—biochar (BC) and bentonite (BT)—with ionic liquids such as benzalkonium chloride (BAC) or Aliquat 336 (A336) was studied. The experiments using model RB8-containing wastewater proved that the co-action of BAC with BC is the most promising method of RB8 separation from wastewater containing 1 g L−1 of RB8 dye. The application of 2 g L−1 BC in co-action with 1.5 g L−1 BAC or 1 g L−1 BT in co-action with 2 g L−1 BAC enables the removal of more than 98% of contaminant RB8 after 30 min of action. Similar removal efficiency (RE) was achieved using 40 g L−1 of powdered activated carbon (PAC) after 180 min of action. To reach the same RE using real RB8-containing wastewater, a four times higher dose of BC and a four times higher dose of BAC per gram of removed RB8 were required. The proposed mechanism of RB8 removal by the co-action of alternative sorbents with BAC comprises a parallel effect of (i) sorption, (ii) the formation of less polar ion pairs accompanied by their sorption on an alternative sorbent and (iii) the separation of used alternative sorbents covered with ion pairs. The removal efficiency of organic contaminant(s) from both model and real wastewater was evaluated by VIS spectroscopy applying the Lambert–Beer law and by the determination of chemical oxidation demand (COD) and/or adsorbable organically bound halogen (AOX) parameters.

Integrating biochar and microbial community for detoxification of wastewater industry containing analgesics

Although anaerobic digestion is a simple, inexpensive, and viable technology for treating wastewater, its performance can be inhibited by the toxic effects of analgesics. Therefore, the objective of this study was to assess the effectiveness of biochar in driving the degradation of analgesics, shifting microbial communities, and biogas profitability in an anaerobic baffled reactor (ABR) for treating pharmaceutical wastewater containing analgesics. Biochar (BC) was synthesized from pomegranate peel and characterized in terms of its surface morphology, elemental composition, crystallization, and surface functional groups. ABR1, ABR2, ABR3, ABR4, and ABR5 were supplemented with mixed culture bacteria at biochar dosages of 0, 50, 75,100, and 150 mg BC/g VS. The removal efficiencies of ketoprofen, paracetamol, and salicylate were increased by values of 65.9 %, 20.4 %, and 53.6 %, respectively, in the ABR4 supplemented with 100 mg BC/gVS compared with the control reactor (ABR1). The bio-methane yield was significantly (p < 0.05) increased from 175.14 ± 13.67 mL/gCODremoved in the ABR1 to 225.58 ± 16.68 mL/g CODremoved in the ABR4. The relative abundances of Chlorobi, Bacteroidetes, Armatimonadetes, Synergistetes, Pseudomonas, Flavobacteriia, Euryarchaeota, Methanobacteria, and Methanomicrobia, resisting the analgesic toxicity and facilitating the organic bioconversion into CH4, were increased by 175.15 %, 112.45 %, 32.43 %, 29.21 %, 400 %, 200 %, 122.17 %, 70.3 %, and 230.5 %, respectively, after 100 mg BC/gVS application in the ABR4 compared with ABR1. Overall, 63 ± 3.9–71 ± 5.4 % and 23.2 ± 2–28.7 ± 2.1 % of the analgesics were primarily removed from wastewater via microbial biodegradation and biochar adsorption, respectively. Biochar application was associated with better biogas productivity, pollutant reduction, and carbon credits, which was equivalent to a profitable scenario with a payback period of 7.1 yr.

Effects of biochar on the manganese enrichment and oxidation by a microalga Scenedesmus quadricauda in the aquatic environment

Microalgae play a significant impact in the biogeochemical cycle of Mn(II) in the aquatic ecosystem. Meanwhile, the inflow of biochar into the water bodies is bound to impact the aquatic organisms. However, the influence of biochar on the manganese transformation in algae-rich water has not drawn much attention. Thus, we studied the effects of rice straw biochar on manganese enrichment and oxidation by a common type of algae in freshwater (Scenedesmus quadricauda). The results showed that Mn(II) was absorbed intracellularly and adsorbed extracellularly by active algal cells. A significant portion of enriched Mn(II) was oxidized to amorphous precipitates MnO2, MnOOH, and Mn2O3. Moreover, the extracellular bound Mn(II) content in the coexistent system of algae and biochar increased compared with the pure Scenedesmus quadricauda system. Nevertheless, the intracellular Mn content was continually lowered as the biochar dose rose from an initial 0.2 to 2.0 g·L−1, suggesting that Mn assimilation of the cell was suppressed. It was calculated that the total enrichment ability of Scenedesmus quadricauda in the algae-biochar coexistent system was 0.31- 15.32 mg Mn/g biomass, more than that in the pure algae system. More importantly, with biochar in the algae system, the amount of generated MnOx increased, and more Mn(II) was oxidized into highly-charged Mn(IV). This was probably because the biochar could relieve the stress of massive Mn(II) on algae and support the MnOx precipitates. In brief, moderate biochar promoted the Mn(II) accumulation by algal cells and its oxidation activity. This study offers deeper insight into the bioconversion of Mn(II) by algae and the potential impact of biochar application to the aquatic system.

Enhancing the nitrogen and phosphorus content of faecal-derived biochar via adsorption and precipitation from human urine

Urine diversion in toilets is a promising strategy to maximise nutrient recovery and produce low-cost urine-derived fertilisers. There are various methods for nutrient recovery from urine, including precipitation and adsorption onto porous media, such as biochars. This study uses faecal-derived biochars to produce and, for the first time, comprehensively characterise enriched biochar fertilisers with the addition of fully hydrolysed undiluted human urine. The evolution of urea hydrolysis and nutrient content during urine storage was initially investigated over a 6-month storage period and NH4+ adsorption mechanisms studied under varying biochar doses and NH4–N concentrations. The process was further optimised by adding MgO to induce precipitation reactions, enabling the combined recovery of NH4+ and P. For NH4+ adsorption, experimental data exhibited a good fit to both the Freundlich (R2 = 0.989) and Langmuir (R2 = 0.974) isotherm models and the rate of the reaction was well described by a pseudo 2nd order kinetics model (R2 = 0.988). The NH4+ uptake was rapid during the initial 2 h of the reaction and the adsorption process reached completion after 24 h. The NH4–N adsorption capacity of the faecal-derived biochar was 19.8 mg/g and the main adsorption mechanism identified was ion exchange (K+ ↔ NH4+), as confirmed by XRD and ICP-OES. The effect of different biochar doses (0, 25, 50, 100 g/L) and MgO addition scenarios (Mg:P = 0, 1.5, 4) on N and P recovery showed that the combination of MgO (Mg:P = 1.5) with the lower biochar dose (25 g/L) produced the most NP-rich fertiliser product which was easily separated from the urine. Faecal-derived biochar had a limited adsorption capacity for P, with precipitation being the main mechanism for P recovery. When MgO was added to urine, >98% of total P was recovered via precipitation of struvite/struvite-K and substituted hydroxyapatite, as identified via SEM-EDX. Faecal-derived biochar was a successful carrier to recover the P-containing precipitates and facilitate liquid-solid separation after treatment. The findings of this study provide proof-of concept for the systemic management of source separated human excreta and pave the way for the production of marketable waste-derived fertilisers from on-site sanitation systems.

Fe/BC co-conditioners with environmental and economic benefits on composting: reduced NH3 emissions and improved fertilizer quality

The significant volatilization of NH3 during aerobic composting causes nitrogen (N) losses and environmental risks. Both iron (Fe) and biochar (BC) can influence the N conversion process in composting. Fe application can delay the maturation of materials, while biochar can enhance the quality of organic fertilizer. The combination of these two conditioners may help decrease NH3 emissions and improve organic fertilizer quality. Therefore, this study investigates the effects of different doses of FeCl3 and BC on NH3 emissions and organic fertilizer quality during composting. The results demonstrated that Fe/BC co-conditioners reduced the accumulation of NH3 emissions during composting by 11.1–48.2%, increased the total nutrient content by 0.6–15.3%, and enhanced economic and environmental benefits by 0.1–23.6 $ t−1. At the high-temperature stage of composting, Fe/BC co-conditioners decreased the pH by 0.3–1.2, but there was no significant difference compared to the control at the end of composting, and they did not affect compost maturation. The structural equation model analysis suggested that the reduction in NH3 emissions was related to ammonia-oxidizing bacteria (AOB), NH4+–N, and total nitrogen (TN). As a result, the Fe/BC co-conditioners reduced NH3 emissions by lowering the pH at the beginning of composting and increasing the content of NH4+–N. This study concludes that Fe/BC co-conditioners could complement each other to significantly reduce NH3 emissions and improve the quality of organic fertilizers.Graphical

Thiol-modified olive-stone biochar preparation for Hg(II) removal from aqueous solutions

Mercury (Hg) is a heavy metal whose toxicity poses significant environmental and health risks. Utilising biochar prepared from biomass waste is a straightforward and effective method for removing mercury from water. This research centred on producing a thiol-functionalised biochar derived from olive-stone waste for the removal of mercury (II) from aqueous solutions. Characterisation analyses confirmed successful functionalisation. The biochar, despite having a limited specific surface area (4.14 m2/g) due to raw material nature and pyrolysis conditions, exhibited a notable ability for mercury (II) adsorption, primarily attributed to the thiol-modified surface. Adsorption was assessed using a 23 factorial design, with the variables being adsorption time, biochar dose and initial mercury (II) concentration in the solution. Biochar dose emerged as the most influential factor, followed by adsorption time and, lastly, initial mercury (II) concentration. The peak removal efficiency of the model stood at 98.19%. The kinetics aligned with the pseudo-first-order and intraparticle diffusion models, suggesting a surface adsorption mechanism coupled with pore diffusion. This work accentuates the potential of olive-derived biochar, when thiol enhanced, in treating aqueous systems contaminated with mercury (II).

Toxicity and Behavioral Effects of Amending Soils with Biochar on Red Imported Fire Ants, Solenopsis invicta.

Solenopsis invicta, often known as the red imported fire ants (RIFAs), is a well-known global invasive ant species that can be found in agricultural, urban, and natural environments worldwide. Simultaneously, it also inhabits the soil. Biochar is generated by the pyrolysis of organic matter under high-temperature anoxic environments and widely used in agricultural ecosystems and soil amendment. However, to date, it remains unknown as to whether soil application of biochar has a negative effect on RIFAs. In our study, we investigated the toxicity and irritability effects of different amounts of biochar (0%, 1%, 2%, 5%, 10%, and 20%) introduced into the soil on red fire ants; upon comparison with the control soil (0% biochar), the application of 1%, 2%, and 5% biochar did not result in significantly different results. But the utilization of biochar at a concentration over 10% effectively repelled the RIFAs, resulting in their departure from the treated soils. High doses of biochar were able to cause death of red fire ants; the mortality rate of red fire ants reached 55.56% after 11 days of 20% biochar treatment. We also evaluated the effects of biochar on four behaviors of red fire ants, namely aggregation, walking, grasping, and attacking; 20% of the biochar treatment group reduced aggregation by 64.22% and this value was 55.22%, 68.44%, and 62.36% for walking, grasping, and attacking. Finally, we measured the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) enzyme activity and malondialdehyde (MDA) content in red fire ants; the results showed that the activities of the three enzymes increased with the increase in biochar addition, which indicated that a high dose of biochar induced oxidative stress in red fire ants. Our results indicate that biochar has the potential to cause toxicity and repel red imported fire ants (RIFAs) in a manner that is dependent on the concentration. We propose that biochar could be utilized in the control and manufacturing of baits for red fire ant management. This work establishes a foundation for the prevention and management of red fire ants and the logical utilization of biochar.

Evaluation of net carbon sequestration and ecological benefits from single biochar-incorporated sorghum farmland systems in saline-alkali areas of Inner Mongolia, China

Biochar is widely recognized as a soil amendment to reduce greenhouse gas emissions and enhance soil carbon storage in agroecosystems; however, the systematic focus on carbon balance and ecological benefits in cropping systems remains unclear in saline-alkali areas under water-saving irrigation. Here, a 2-yr field experiment with carbon footprint method was conducted to determine soil carbon budgets, biochar carbon efficiency performance, and the economic and ecological benefits of mulched drip-irrigated sorghum production, in an arid salinized region of Inner Mongolia, China. Corn straw-derived biochar dosages of 0 (CK), 15 (B15), 30 (B30), and 45 (B45) t hm−2 were just applied into the soil in the first crop growing season. A single application of biochar to soil significantly reduced CO2 emissions for the current and subsequent crop-growing seasons, with 13.1%, 16.7%, and 12.5% reductions for B15, B30, and B45, respectively. Compared with the non-biochar control plots, B15, B30, and B45 also increased NPP by 36.7%, 38.4%, and 27.1%, respectively. The actual effects on improving net carbon sequestration for B15, B30, and B45 in the first year were higher than those in the second year, with mean increases of 1.27, 1.47, and 1.36 times, respectively; however, the efficiencies of biochar for fixing carbon per biochar dosage input for B15 were 72.8% and 64.1% higher than those of B30 and B45, respectively. Net profits were significantly improved by 57.2–87.1% by biochar treatments. The environmental benefits of biochar carbon trading revenues for B15, B30, and B45 increased by 105.9%, 162.1%, and 109.6%, respectively. The minimum observation for carbon productivity and the maximum measurements for both the economic and ecological benefits were B15. The B15 also significantly increased sorghum yield and grain number. Results demonstrate that biochar application in the current growing season helps reduce soil carbon emissions, increases net carbon sequestration for current and subsequent sorghum agroecosystems, and enhances net profit and ecological benefits. The optimal positive synergistic effect was observed at a biochar application rate of 15 t hm−2 for reducing soil carbon emissions, increasing crop production, and improving the ecological environment.

Adsorption performance of Ni(II) by KOH-modified biochar derived from different microalgae species

Microalgae biochar is potential adsorbents to remove heavy metals from wastewater due to abundant functional groups, high porosity and wide sources, but performance is not fully developed since it depends on microalgae species attributing to distinct morphology and biomass compositions. Here, two microalgae species Chlorella Pyrenoidosa and Scenedesmus Obliquus were used for biochar preparation via KOH-modification, biochar properties and their influences on Ni(II) adsorption were investigated. Ni(II) adsorption performances responding to biochar properties and operating conditions were upgraded via progressive optimization and response surface methodology. Together, adsorption isotherms and kinetics were analyzed to obtain significant factors for Ni(II) removal. As results, 100 % of Ni(II) removal was achieved under 100 mg/L initial Ni(II) concentration as pH was higher than the biochar zero-charge point of 6.87 with low biochar dosage (0.5 g/L), which provides an efficient approach for heavy metal removal from wastewater with microalgae biochar.

Removal of methylene blue azo dye from aqueous solution using biosorbent developed from floral waste

Aim: The present study was carried out to prepare biosorbent from temple floral waste (Tagetes erecta) by pyrolysis and chemical activation method for removal of methylene blue dye from aqueous solution. Methodology: Floral waste of Tagetes erecta collected from the temples were segregated, washed and dried to form biochar by direct pyrolysis and chemical activation method. Followed by physio-chemical analysis of biosorbents the most efficient biochar was selected for the removal of methylene blue dye from aqueous solution. The adsorbent efficiency and percentage removal of methylene blue dye was studied using various doses of biochar (10, 20, 30, 40, 50, 60, and 70 mg 100 ml-1,), effect of pH (2.0 to 4.0, 6.0 to 8.0, and 10.0 to 12.0) and effect of contact time etc. Results: The comparative physio-chemical analysis of the bio chars suggested that the activated charcoal made from temple flower waste by the direct pyrolysis method showed better performance, with its low moisture content (5.3%), low ash content (4.3%), higher yield, larger surface area, and higher porosity (65.3%) as compared to the biochar obtained from chemical activation. The percent adsorption significantly increased (p&lt;0.05) from 76% to 87.0% on increasing biochar dose from 10.0 to 70.0 mg 100 ml-1. On increasing the pH of the solution from 4.0 to 6.0, Methylene blue removal significantly increased (p&lt;0.05) from 88.0% to 91.0%. Interpretation: It is possible to manage floral waste from temples in a sustainable and environmentally responsible manner by converting it into biochar and using it for the treatment of waste water in order to eliminate hazardous dyes. Key words: Activated carbon, Azo dye, Bioremediation, Biochar, Floral waste, Methylene blue

Sustainable upcycling of artificial lightweight cold-bonded aggregates (ALCBAs) designed by biochar and concrete slurry waste (CSW) into porous carbons materials for CO2 sequestration

CSW (Concrete Slurry Waste) is a hazardous solid waste due to its high alkalinity, and traditional landfill disposal wastes a lot of land. To effectively recycle CSW, this project applied it, ordinary Portland cement (OPC), and Biochar (BC) into designing artificial lightweight cold-bonded aggregates (ALCBAs) by disc granulation. A new test device for evaluating the amount of carbon absorption in ALCBAs was designed and ALCBAs adding ultra-high volume of CSW (CSW-ALCBAs) with BC dosage of 0%, 5%, 10%, and 15% were designed, respectively. The compressive strength, water absorption rate, carbon-sequestration efficiency, pores, hydration phase, and ecological properties of CSW-ALCBAs were also investigated under standard, carbonation, and sealing curing conditions. The results showed that CSW-ALCBAs had obvious carbon-sequestration potential, and the maximum carbon absorption was 18.2 wt% at 15% BC dopsage and the minimum carbon absorption was 16.2 wt% at 5% BC doping. Also, the carbon absorption of CSW-ALCBAs increases with the rise in BC dosage. Besides, the compressive strength in standard and sealed curing conditions peaked at 5% BC dosage, about 2.76 MPa, and then decreased rapidly with increasing BC dosage, and the compressive strength drops to 1.86 MPa at 15% BC dosage. Carbonization condition can improve the mechnaical and physical properties of CSW-ALCBAs with water absorption rate in the range of 6%− 13%, and the maximum compressive strength was about 6.18 MPa. And the compressive strength with the lowest and highest increasing rate in the groups under 28-d carbonized condition were in groups B5 and B10, where the compressive strength increased by 56% and 215%, respectively. Additionally, the total porosity of CSW-ALCBAs is in 13%− 23%, and the BC can provide abundant harmless pores (<50 nm) and store sufficient water. The BC could result in the internal curing effect, and the hydration products such as CH, CC, C-S-H, and AFt could be clearly observed. The choice of 5% BC doping for developing green CSW-ALCBAs is very promising. Overall, this study provides a novel method for the production of carbon-negative aggregates, which not only helps to address the recycling of massive CSW, but also opens up new channels for CSW recycling and CO2 sequestration. Meanwhile, compared with the previous reports about the recycling of CSW has been explored in various ways of utilization and curing regimes, this project explores its potential for carbon capture and investigates the changes in various properties of CSW-ALCBAs after carbonization.

Biochar na fertilidade do solo, morfometria e produção de cultivares de capim elefante

ABSTRACT Among the various forage species used in ruminant feeding, elephant grass (Pennisetum purpureum Schum.) is notable as it is a perennial plant and has a high potential for dry matter production. The present study evaluated the performance of elephant grass cultivars and soil chemical characteristics under different biochar addition levels and at different evaluation times under irrigation in the dry season. The treatments were arranged in a factorial randomized complete block design (CBD) and analyzed in a split-plot design according to cultivar (BRS Capiaçu and BRS Kurumi) x biochar dose (0, 8, 16 and 24 t ha-1); the subplots consisted of four evaluation times (71, 225, 335 and 447 days after application of biochar), with four replicates. The soil chemical characteristics were evaluated without inclusion of the time factor according to a CBD in a 2 x 4 factorial scheme, with 4 replications. The attributes analyzed were soil fertility, morphometry and elephant grass yield. The performance of the cultivars improved at 225 days (2nd evaluation) and 335 days (3rd evaluation) after biochar application. The biochar doses did not significantly increase morphometric attributes, cultivar productivity or soil fertility. The application of biochar did not improve the yield attributes or crude protein of elephant grass cultivars under the conditions of this study.

Synergistic effects (adsorption and biodegradation) of Streptomyces hydrogenans immobilization on nano-reed biochar for further application in upflow anaerobic sludge blanket.

Water pollution due to wastewater is a serious issue that needs to be studied as many organic compounds are released from wastewater, affecting the ecosystem. Therefore, appropriate treatment methods should be used to prevent these effects. Phragmites australis biochar immobilized with bacteria was prepared in this study for use as an adsorbent in a pilot-scale up-flow anaerobic sludge blanket (UASB) to remove organic matter from wastewater in a buffalo farm. Combining reed biochar and immobilized Streptomyces hydrogenans introduces a synergistic effect: reed biochar serves as a substrate for microbial colonization and provides a conducive environment for microbial growth while Streptomyces hydrogenans, immobilized on the biochar, enhances the degradation of organic matter through its metabolic activities. Suitable techniques were employed, including infrared spectroscopy (FTIR) to determine the functional groups before and after adsorption, scanning electron microscopy (SEM) to determine the morphology of the composite before and after adsorption, X-ray diffraction (XRD) to examine the mineralogical changes through reflectometry, high-resolution diffraction and Brunauer-Emmett-Teller (BET) analyses to determine the surface area that always carried out by nitrogen adsorption/desorption technique based on the BET isotherm. Two-level factorial design experiments optimized using biochar, immobilized with bacteria, were employed to enhance the UASB performance. Chemical oxygen demand (COD) removal and biogas production were studied as a function of four experimental parameters: biochar dose, buffalo sludge dose, pH, and bacteria type. The buffalo sludge (manure) dose negatively affected the model's performance. The results showed better COD removal with Streptomyces hydrogenans S11 inoculation. The optimum biochar dose, buffalo sludge dose, and pH were 20 g L-1, 0%, and 7.5, respectively. The COD removal efficiency under these experimental conditions reached 92.70% with a biogas production of 5.0 mL. The experimental results of a validated point from the model were 90.80% for COD removal ratio and 4.80 mL for biogas production at 2 g L-1 biochar dose, 0% buffalo sludge dose, and pH 7.5 using Streptomyces hydrogenans S11 bacteria. A buffalo wastewater (BWW) anaerobic digestion experimental model was best fitted to the data under optimal conditions. This study aligns with the United Nations Sustainable Development Goals (SDGs), specifically SDG 6 (clean water and sanitation) and SDG 12 (responsible consumption and production). The implications of our work extend to large-scale applications, promising a greener and more sustainable future for wastewater treatment.

Utilization of banana waste biochar to reduce heavy metal contamination in soil and maize plants

There are indications of heavy metal contamination in soil and agricultural products on paddy fields in Subak Kerdung, Bali. Soil amendments are needed to reduce heavy metal content in contaminated soil to minimize heavy metals in plants. Biochar that contains high organic carbon material and is highly resistant to decomposition is claimed to inhibit and reduce the content of heavy metals in soil and plants. Banana wastes containing cellulose and lignin are considered good as biochar raw materials. This research that aimed to observe the ability of banana waste biochar to reduce heavy metals in soil taken from Subak Kerdung, Bali, was conducted in a greenhouse using maize plants as control plants. The treatments tested consisted of two factors. The first factor was the type of banana waste as biochar-making material consisting of banana stem biochar, banana peel biochar, banana fruit bunch biochar, and mixed biochar (banana stem + banana peel + banana fruit bunch). The second factor was the biochar dosage, which consists of four contents, namely 0 t/ha, 5 t/ha, 10 t/ha, and 15 t/ha. All treatment combinations were arranged in a two-factor, randomized block design with three replications. The results showed that mixed biochar (banana stem + banana peel + banana fruit bunch) effectively reduced Pb and Cu in maize plants. In contrast, banana peel biochar could optimally reduce Cd content in soil and its content in plants. Based on the dose, 15 t/ha of mixed biochar reduced Pb and Cd contents, while 10 t/ha of mixed biochar reduced Cu content.