Effects of wood vinegar on properties and mechanism of heavy metal competitive adsorption on secondary fermentation based composts

Enhancement of nutrient use efficiency with biochar and wood vinegar: A promising strategy for improving soil productivity

BACKGROUND

The co-application of biochar and wood vinegar has demonstrated the potential to enhance premium crop production. The present study reveals the effects of co-applying rice husk biochar and wood vinegar (both foliar and soil application) on soil properties and the growth of Chinese cabbage (Brassica chinensis L.) in a two-season pot experiment.

RESULTS

The soil pH, electrical conductivity and dissolved organic carbon contents in combination treatments of wood vinegar and biochar were increased more when wood vinegar was applied to soils rather than to leaves, and the parameters were observed to surpass those for chemical fertilizer treatments. The biomass of Chinese cabbage shoots was significantly increased by 60.8- and 27.3-fold in the combined treatments compared to the control when 1% wood vinegar was sprayed to the leaves (WF1) in 2022 and 2023, respectively. Higher contents of vitamin C, soluble protein and soluble sugar were also observed in the combined wood vinegar and biochar treatments compared to chemical fertilizer treatments and the control; for example, the vitamin C content of plant shoot in WF1 was 21.3 times that of the control. The yield and quality of plants were decreased across all treatments in 2023 compared to 2022 but the combination treatments still displayed superiority.

CONCLUSION

The co-application of wood vinegar and biochar enhances the growth and improve the quality of Chinese cabbage through improving the soil properties and plant photosynthesis. Moreover, the foliage application of wood vinegar is more preferable compared to soil application. © 2024 Society of Chemical Industry.

Bio-chelate assisted leaching for enhanced heavy metal remediation in municipal solid waste compost

Municipal solid waste compost, the circular economy's closed-loop product often contains excessive amounts of toxic heavy metals, leading to market rejection and disposal as waste material. To address this issue, the study develops a novel approach based on: (i) utilizing plant-based biodegradable chelating agent, L-glutamic acid, N,N-diacetic acid (GLDA) to remediate heavy metals from contaminated MSW compost, (ii) comparative assessment of GLDA removal efficiency at optimal conditions with conventional nonbiodegradable chelator EDTA, and (iii) enhanced pre- and post-leaching to evaluate the mobility, toxicity, and bioavailability of heavy metals. The impact of treatment variables, such as GLDA concentration, pH, and retention time, on the removal of heavy metals was investigated. The process was optimized using response surface methodology to achieve the highest removal effectiveness. The findings indicated that under optimal conditions (GLDA concentration of 150 mM, pH of 2.9, retention time for 120 min), the maximum removal efficiencies were as follows: Cd-90.32%, Cu-81.96%, Pb-91.62%, and Zn-80.34%. This process followed a pseudo-second-order kinetic equation. Following GLDA-assisted leaching, the geochemical fractions were studied and the distribution highlighted Cd, Cu, and Pb's potential remobilization in exchangeable fractions, while Zn displayed integration with the compost matrix. GLDA-assisted leaching and subsequent fractions illustrated transformation and stability. Therefore, this process could be a sustainable alternative for industrial applications (agricultural fertilizers and bioenergy) and social benefits (waste reduction, urban landscaping, and carbon sequestration) as it has controlled environmental footprints. Hence, the proposed remediation strategy, chemically assisted leaching, could be a practical option for extracting heavy metals from MSW compost, thereby boosting circular economy.

Foliar application of pyroligneous acid acts synergistically with fertilizer to improve the productivity and phytochemical properties of greenhouse-grown tomato

Pyroligneous acid (PA) is rich in bioactive compounds and known to have the potential to improve crop productivity and phytochemical content. However, the synergistic effect of PA and fertilizer has not been thoroughly studied. In this study, we assessed the biostimulatory effect of different rates of foliar PA application (i.e., 0, 0.25, 0.5, 1, and 2% PA/ddH2O (v/v)) combined with full rate (i.e., 0.63, 0.28, 1.03 g) and half rate of nitrogen-phosphorus-potassium (NPK) fertilizer on the yield and nutritional quality of greenhouse-grown tomato (Solanum lycopersicum 'Scotia'). Plants treated with 0.25% and 0.5% PA showed a significantly (p < 0.001) higher maximum quantum efficiency of photosystem II (Fv/Fm) and increased potential photosynthetic capacity (Fv/Fo), especially when combined with the full NPK rate. Leaf chlorophyll was significantly (p < 0.001) increased by approximately 0.60 and 0.49 folds in plants treated with 2% PA and full NPK rate compared to no spray and water, respectively. Total number of fruits was significantly (p < 0.001) increased by approximately 0.56 folds with the 2% PA irrespective of the NPK rate. The combined 2% PA and full NPK rate enhanced total fruit weight and the number of marketable fruits. Similarly, fruit protein, sugar and 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity were significantly (p < 0.001) enhanced by the combined 2% PA and full NPK rate. In contrast, the 0.5% PA combined with half NPK rate increased fruit carotenoid and phenolic contents while the 2% PA plus half NPK rate enhanced fruit flavonoid content. Generally, the synergistic effect of PA and NPK fertilizer increased fruit elemental composition. These showed that foliar application of 2% PA with full NPK rate is the best treatment combination that can be adopted as a novel strategy to increase the productivity and quality of tomato fruits. However, further study is required to investigate the molecular basis of PA biostimulatory effect on plants.

Effect of the addition of biochar and wood vinegar on the morphology of heavy metals in composts

In the experiment, the morphology of heavy metals (Pb, Cr, Cd, and Ni, HMs) was characterized using flame atomic absorption spectroscopy. In addition, Fourier transform infrared spectroscopy (FTIR) and three-dimensional excitation-emission matrix fluorescence spectroscopy (3D-EEM) were used to characterize the correlation between environmental factors and metal morphology in the rotting compost from several angles. The results showed that the humus treated with wood vinegar solution had a high degree of humification and rich aromatic structure. FTIR spectroscopy confirmed that the degree of humus aromatization gradually increased during the composting process, which enhanced the complexation of humus (HS) with HMs but had less effect on Ni. In addition, the optimum concentration of wood vinegar (WV) was determined to be 1.75%. The results of the study showed that in the Pb passivation treatment group, the proportion of soluble (Red) and exchangeable states (Exc) converted to oxidized (Oxi) and residual states (Res) was 8%, 14%, 6%, 1%, and 12% in the CK, T1, T2, T3, and T4 treatment groups, respectively; in the Cr passivation treatment group, the proportion of Cr-Red and Cr-Exc converted to oxidized and residual states was 31%, 33%, 25%, 29%, and 25%; in the Cd passivation treatment group, the proportions of Cd-Red and Cd-Exc converted to oxidized and residual states were 5%, 15%, 4%, 9%, and 11%, respectively; whereas the Ni treatment group did not show any significant passivation effect. The proportion of Pb-Oxi was relatively stable, Cr-Oxi was converted to Cr-Res, whereas Cd showed the conversion of Cd-Oxi to Cd-Exc. SUVA254 and SUVA280 showed significant positive correlations with Pb-Res, Cr-Res and Ni-Res, and significant positive correlations with moisture content (MC); whereas MC was significantly negatively correlated with each form of HMs. Total potassium (TK), total nitrogen (TN), and both carbon (TOC) were negatively correlated with Pb-Res and Pb-Exc. Structural equation modeling verified the relationship between environmental factors and HMs, and the composting results showed that the addition of biochar (BC) and a higher percentage of WV could increase compost decomposition and passivate HMs to improve its agronomic function.

Qualitative and Quantitative Investigation of Biochar-Cu0 Composite for Nickel Adsorption

The current investigation deals with the treatment of water pollution that is caused by the leaching of nickel ions from the metallurgical industry and new-energy batteries. Therefore, an eco-friendly treatment of nickel through the use of a composite of cotton stalk biochar with nanozerovalent copper has been presented in this investigation signifying the impact of zerovalent copper in enhancing the adsorption capacity of biochar for nickel adsorption. Thermogravimetric analysis data showed the adsorbent to be significantly stable in the higher thermal range, whereas transmission electron microscopy analysis confirmed the particles to be 27 nm and also showed the cubic geometry of the particles. A much closer scanning electron microscopy analysis shows the morphology of particles to be cubic in shape. Batch adsorption indicated a positive influence of pH increase on adsorption due to the electrostatic attraction between positive nickel ions and post point of zero charge (pHPZC) negative surface of copper biochar composite (pH > 5.5). A high adsorption rate was observed in the first 60 min, whereas adsorption increased with the increase in temperature from 303 to 318 K. Kinetic modeling confirmed the pseudo-first-order to fit best to the data. The apparent activation energy (11.96 kJ mol-1) is indicative of the chemical nature of the process. The adsorption data fitted well to the Langmuir adsorption model. The negative values of apparent ΔG° and the positive values of apparent ΔH° indicate the spontaneity and endothermicity of the process, respectively, whereas the positive values of apparent ΔS° point toward increased randomness during the process. Postadsorption XPS suggests the adsorption of nickel on the surface of biochar composites in the form of Ni(OH)2 and NiO(OH).

Physicochemical properties and risk assessment of perishable waste primary products

Fertilization has become one of the most important ways to recycle perishable waste. In order to reveal the effect of the nutrient of the perishable waste primary products on the market and the possible impact of their application, 136 perishable waste primary products were sampled in nine cities in Zhejiang province, China. The result shows that these products have high nutrient content (average nutrient content was 5.00%). However, the conductivity (7.19 mS/cm) total soluble salt content (12.07%), and grease content (5.99%) were too high. The excessive salt and grease may cause harm to soil and crops, and become the main limiting factors for the fertilizer utilization of perishable waste. Heavy metal content of most of the samples met current commercial organic fertilizer standards, except that lead and chromium content of some samples exceeded the limit standard. Toluene, ethylbenzene, m & p-xylene were generally detected in the samples. These toxic and harmful substances have brought risks to the safe use of perishable waste into fertilizers.

Green remediation of Ni, Zn, and Cu in an electroplating contaminated site by wood vinegar with optimization and risk assessment

Wood vinegar (WV) is a renewable organic compound, possessing characteristics such as high oxygenated compound content and low negative impact on soil. Based on its weak acid properties and complexing ability to potentially toxic elements (PTEs), WV was used to leach Ni, Zn, and Cu contaminated soil in electroplating sites. In addition, the response surface methodology (RSM) based on the Box-Behnken design (BBD) was established to clarify the interaction between each single factor, and finally completed the risk assessment of the soil. The amounts of PTEs leached from the soil climbed with the increase of WV concentration, liquid-solid ratio, and leaching time, while they surged with the decrease of pH. Under optimal leaching circumstances (the concentration of WV= 100 %; washing time= 919 min; pH= 1.00), the removal rates of Ni, Zn, and Cu could reach 91.7 %, 57.8 %, and 65.0 %, respectively, and the WV-extracted PTEs were mainly from the Fe-Mn oxides fraction. After leaching, the Nemerow integrated pollution index (NIPI) decreased from an initial value of 7.08 (indicating severe pollution) to 0.450 (indicating no pollution). The potential ecological risk index (RI) dropped from 274 (medium level) to 39.1 (low level). Additionally, the potential carcinogenic risk (CR) values reduced by 93.9 % for both adults and children. The results revealed that the washing process significantly reduced the pollution level, potential ecological risk, and health risk. Coupled with FTIR and SEM-EDS analysis, the mechanism of WV removal of PTEs could be explained from three aspects: acid activation, H⁺ ion exchange, and functional group complexation. In summary, WV is an eco-friendly and high-efficiency leaching material for the remediation of PTEs polluted sites, which will maintain soil function and protect human health.

Removal of heavy metals from binary and multicomponent adsorption systems using various adsorbents - a systematic review

The ecosystem and human health are both significantly affected by the occurrence of potentially harmful heavy metals in the aquatic environment. In general, wastewater comprises an array of heavy metals, and the existence of other competing heavy metal ions might affect the adsorptive elimination of one heavy metal ion. Therefore, to fully comprehend the adsorbent's efficiency and practical applications, the abatement of heavy metals in multicomponent systems is important. In the current study, the multicomponent adsorption of heavy metals from different complex mixtures, such as binary, ternary, quaternary, and quinary solutions, utilizing various adsorbents are reviewed in detail. According to the systematic review, the adsorbents made from locally and naturally occurring materials, such as biomass, feedstocks, and industrial and agricultural waste, are effective and promising in removing heavy metals from complex water systems. The systematic study further discovered that numerous studies evaluate the adsorption characteristics of an adsorbent in a multicomponent system using various important independent adsorption parameters. These independent adsorption parameters include reaction time, solution pH, agitation speed, adsorbent dosage, initial metal ion concentration, ionic strength as well as reaction temperature, which were found to significantly affect the multicomponent sorption of heavy metals. Furthermore, through the application of the multicomponent adsorption isotherms, the competitive heavy metals sorption mechanisms were identified and characterized by three primary kinds of interactive effects including synergism, antagonism, and non-interaction. Despite the enormous amount of research and extensive data on the capability of different adsorbents, several significant drawbacks hinder adsorbents from being used practically and economically to remove heavy metal ions from multicomponent systems. As a result, the current systematic review provides insights and perspectives for further studies through the thorough and reliable analysis of the relevant literature on heavy metals removal from multicomponent systems.

Effects of biochar-based materials on nickel adsorption and bioavailability in soil

The potential for toxic elements to contaminate soil has been extensively studied. Therefore, the development of cost-effective methods and materials to prevent toxic element residues in the soil from entering the food chain is of great significance. Industrial and agricultural wastes such as wood vinegar (WV), sodium humate (NaHA) and biochar (BC) were used as raw materials in this study. HA was obtained by acidizing NaHA with WV and then loaded onto BC, which successfully prepared a highly efficient modification agent for nickel-contaminated soil, namely biochar-humic acid material (BC-HA). The characteristics and parameters of BC-HA were obtained by FTIR, SEM, EDS, BET and XPS. The chemisorption of Ni(II) ions by BC-HA conforms to the quasi-second-order kinetic model. Ni(II) ions are distributed on the heterogeneous surface of BC-HA by multimolecular layer adsorption, which accords with the Freundlich isotherm model. WV promotes better binding of HA and BC by introducing more active sites, thus increasing the adsorption capacity of Ni(II) ions on BC-HA. Ni(II) ions in soil are anchored to BC-HA by physical and chemical adsorption, electrostatic interaction, ion exchange and synergy.

Aging of polylactic acid microplastics during hydrothermal treatment of sewage sludge and its effects on heavy metals adsorption

Microplastics' (MPs) aging process and environmental behavior have attracted extensive attention due to the potential long-term ecological impact. MPs enriched in sludge may accelerate aging during sludge treatment and the affecting environmental behavior, i.e., adsorption performance for pollutants. However, the related studies have not been well researched, especially for the biodegradable MPs. This study revealed the influences of hydrothermal treatment on the characteristics of polylactic acid microplastics (PLA-MPs) and the consequences on heavy metals adsorption. The changes in PLA-MPs' physiochemical properties were characterized and compared. PLA-MPs' surface became irregular, and the oxygen-containing functional groups increased through FTIR and XPS analysis. Meanwhile, the molecular weight and crystallinity of PLA-MPs decreased significantly with the rising in hydrothermal temperature. Accordingly, the adsorption capacity of PLA-MPs for Pb²⁺ increased from 93.97 μg g^-1 for the raw PLA-MPs to 1058.03 μg g^-1 for the aged PLA-MPs. Multiple adsorption kinetics and isotherms were discussed for the Pb²⁺ adsorption onto PLA-MPs with different aging of the PLA-MPs. The adsorption mechanisms of Pb²⁺ relate to electrostatic interaction and complexation. The main difference is that the adsorption for raw PLA-MPs is dominated by physical and chemical adsorption, whereas the adsorption for the aged PLA-MPs prefers chemical adsorption. In addition, we carefully evaluated the influences of pH, dissolved organic matter, and ionic strength on the PLA-MPs adsorption. The present study highlighted the significance of hydrothermal treatment on the MPs aging and the adsorption performance.

Benzothiophene Adsorptive Desulfurization onto trihexYl(tetradecyl)phosphonium Dicyanamide Ionic-Liquid-Modified Renewable Carbon: Kinetic, Equilibrium and UV Spectroscopy Investigations

The negative environmental and industrial impacts of the presence of sulfur compounds such as benzothiophene in fuels have led to a greater interest in desulfurization research. In this work, carbon from palm waste sources was modified with trihexYl(tetradecyl)phosphonium dicyanamide-ionic liquid and characterized by SEM, EDS, XRD and FTIR to assess surface properties. Then, the prepared carbon and carbon modified with ionic liquid were evaluated for the adsorption of benzothiophene by investigating the effects of time. The equilibrium occurred after 120 min, recording adsorption capacities of 192 and 238 mg/g for carbon and carbon modified with ionic liquid, respectively. The effect of the adsorbent dose on the adsorption of benzothiophene was evaluated, indicating that the maximum adsorption capacities were obtained using a dose of 1 g/L for both carbon and carbon modified with ionic liquid. The kinetic investigation for the adsorption of benzothiophene onto carbon and carbon modified with ionic liquid indicated that the second-order kinetic model is well fitted with the adsorption data rather than the first-order kinetic model. The equilibrium investigations for the adsorption of benzothiophene onto carbon and carbon modified with ionic liquid with Langmuir and Freundlich isotherm models reveals that the Freundlich model is the most suitable for describing the adsorption process, suggesting a multilayer adsorption mechanism. The desulfurization process showed a high impact on environmental safety due to the possibility of regenerating and reusing the prepared adsorbents with promising results up to five cycles.

Greenhouse gas reduction and nitrogen conservation during manure composting by combining biochar with wood vinegar

The constant greenhouse gases (GHGs) and ammonia emissions during pig manure (PM) composting have made large contributions to air pollution and global temperature rise. This study aimed to evaluate the addition of biochar (B) and wood vinegar (WV) to reduce GHGs emissions and improve nitrogen retention and microbial activities during PM composting. Different treatments, carried out under a 1:2 ratio (dry weight) of PM and sawdust mixture with the addition of B (5%) and various proportions of WV, include a control treatment (CT) without the addition of B and WV and, B, B+0.5%WV, B+1.0%WV, B+1.5%WV, and B+2.0%WV treatments. The results indicated that the addition of B could accelerate the composting process in contrast to CT. In addition, various amounts of WV with B decreased NH₃, CO₂, CH₄ and N₂O emissions by 18.82-35.88%, 1.38-15.39%, 16.98-62.73%, and 4.47-19.91%, respectively. Furthermore, in contrast to the B treatment, WV addition was more effective in decreasing GHGs and NH₃ emissions, and the B+1.0% WV treatment displayed the lowest nitrogen loss (2.12%) and GHGs emissions (11.62 g/kg). The bacterial community analysis demonstrated that synergistic application of WV and B can increase the relative abundance of Proteobacteria which can contribute to nitrogen fixation and reduction of nitrogen loss. The results proved that combining B with WV can be a feasible strategy to effectively reduce GHGs emissions and improve nitrogen conservation in the composting industry.

Effects of different additives and aerobic composting factors on heavy metal bioavailability reduction and compost parameters: A meta-analysis

Additives are considered a promising approach to accelerate the composting process and alleviate the dissemination of pollutants to the environment. However, nearly all previous articles have focused on the impact of additive amounts on the reduction of HMs, which may not fully represent the main factor shaping HMs bioavailability status during composting. Simultaneously, previous reviews only explored the impacts, speciation, and toxicity mechanism of HMs during composting. Hence, a global-scale meta-analysis was conducted to investigate the response patterns of HMs bioavailability and compost parameters to different additives, composting duration, and composting factors (additive types, feedstock, bulking agents, and composting methods) by measuring the weighted mean values of the response ratio "[ln (RR)]" and size effect (%). The results revealed that additives significantly lessened HMs bioavailability by ≥ 40% in the final compost products than controls. The bioavailability decline rates were -40%, -60%, -57%, -55%, -42%, and -44% for Zn, Pb, Ni, Cu, Cr, and Cd. Simultaneously, additives significantly improved the total nitrogen (TN) (+16%), pH (+5%), and temperature (+5%), and decreased total organic carbon (TOC) (-17%), moisture content (MC) (-18%), and C/N ratio (-19%). Furthermore, we found that the prolongation of composting time significantly promoted the effect of additives on declining HMs bioavailability (p < 0.05). Nevertheless, increasing additive amounts revealed an insignificant impact on decreasing the HMs bioavailability (p > 0.05). Eventually, using zeolite as an additive, chicken manure as feedstock, sawdust as a bulking agent, and a reactor as composting method had the most significant reduction effect on HMs bioavailability (p < 0.05). The findings of this meta-analysis may contribute to the selection, modification, and application of additives and composting factors to manage the level of bioavailable HMs in the compost products.

Improving the humification and phosphorus flow during swine manure composting: A trial for enhancing the beneficial applications of hazardous biowastes

Improving the recovery of organic matter and phosphorus (P) from hazardous biowastes such as swine manure using acidic substrates (ASs) in conjunction with aerobic composting is of great interest. This work aimed to investigate the effects of ASs on the humification and/or P migration as well as on microbial succession during the swine manure composting, employing multivariate and multiscale approaches. Adding ASs, derived from wood vinegar and humic acid, increased the degree of humification and thermal stability of the compost. The ³¹P nuclear magnetic resonance spectroscopy and X-ray absorption near-edge structure analyses demonstrated compost P was in the form of struvite crystals, Ca/Al-P phases, and Poly-P (all inorganic P species) as well as inositol hexakisphosphate and Mono-P (organophosphorus species). However, the efficiency of P recovery could be improved by generating more struvite by adding the ASs. The flows among nutrient pools resulted from the diversity in the dominant microbial communities in different composting phases after introducing the ASs and appearance of Bacillus spp. in all phases. These results demonstrate the potential value of ASs for regulating and/or improving nutrients flow during the composting of hazardous biowastes for producing higher quality compost, which may maximize their beneficial benefits and applications.

Immobilization properties and adsorption mechanism of nickel(II) in soil by biochar combined with humic acid-wood vinegar

Biochar (BC) combined with humic acid (HA) and wood vinegar (WV) was designed and prepared as an inexpensive, effective, and environmentally friendly immobilization material (BHW) for metal-polluted soil. The influences of the wood vinegar and humic acid on the immobilization properties and adsorption mechanism of this new material were also investigated. The remediation performance was evaluated using a laboratory-made, nickel-contaminated soil with a Ni²⁺ concentration of 200 mg per kg surface soil (top 20 cm from agricultural land). The results indicated that the immobilization ratio sequence of nickel (II) in the soil was BC< BH< BHW. The maximum adsorption capacity increased in the same order: BC< BH< BHW. All three adsorption isotherms were better fitted by the Freundlich model, which were consistent with the surface heterogeneity of the remediation materials. The cause of this surface heterogeneous migration may be due to the increase in oxygen-containing groups in the BC introduced by the HA and WV. The WV can increase the number of the oxygen-containing groups in the BC combined with HA, which enhanced the adsorption and immobilization of Ni²⁺ ions. The results suggested that BHW is recommended for the remediation of metal-contaminated soils, because of its high efficacy, economic feasibility, environmental and food safety.

Wood vinegar enhances humic acid-based remediation material to solidify Pb(II) for metal-contaminated soil

Heavy metal lead is a typical widespread potentially toxic element (PET) contamination due to their extensive and wide applications in industrial processes. The development of cost-effective methods for preventing potentially toxic element lead residues from soil into food is thus highly desirable. A new type of humic acid-based remediation material (HA/WV) incorporating humic acid salt (HA), biochar powder (BC), and wood vinegar (WV), which is a cheap and environmentally friendly industrial by-product from charcoal processing, was prepared and evaluated. The results showed that 0.10 g remediation material HA/WV with a mass ratio of 1:1 was added to 1 kg surface soil of 0-20 cm from agricultural land contaminated by 300 mg Pb²⁺, the reduction ratio of available Pb in soil can reach 61.4%. Especially, wood vinegar can enhance the reduction ratio of available Pb by at least 14.7% over without wood vinegar. Furthermore, according to the analysis of adsorption interaction and the electrostatic attraction between Pb(II) and oxygen-containing functional groups on HA/WV are the dominant mechanisms responsible for Pb(II) sorption. The wood vinegar liquid can improve the oxygen-containing group in HA/WV, which can enhance the complexation of remediation materials and Pb(II) ion.

Bamboo Tar as a Novel Fungicide: Its Chemical Components, Laboratory Evaluation, and Field Efficacy Against False Smut and Sheath Blight of Rice and Powdery Mildew and Fusarium Wilt of Cucumber

The application of agricultural and forest residues can benefit the environment and the economy; however, they also generate a large amount of byproducts. In this study, bamboo tar (BT), a waste product of bamboo charcoal production, was dissolved in natural ethanol and the surfactant alkyl glucoside to manufacture a 50% (wt/wt) BT emulsifiable concentrate (BTEC) biopesticide. BTEC was screened for fungicidal activity against pathogens. The greatest activity was seen against Ustilaginoidea virens with a half-maximal effective concentration (EC₅₀) value of 6 mg/liter. Four phytopathogenic fungi, Podosphaera xanthii, Rhizoctonia solani, Fusarium oxysporum, and Botrytis cinerea, showed EC₅₀ values of <60 mg/liter. Greenhouse tests in vivo showed 2,000 mg/liter BTEC had a 78.4% protective effect against U. virens, and replicated treatments had an 80.6% protective effect. In addition, replicated 2-year field trials were conducted in two geographic locations with four plant diseases: false smut (U. virens), rice sheath blight (Thanatephorus cucumeris [Frank] Donk), cucumber powdery mildew (P. xanthii), and cucumber Fusarium wilt (F. oxysporum). Results showed that 1,000 to 2,000 mg/liter BTEC significantly inhibited these diseases. Gas chromatography-mass spectrometry analysis showed that the total phenolic mass fractions of two BT samples were 45.39 and 48.26%. Eleven components were detected, and their percentage content was as follows (from high to low): 2,6-dimethoxyphenol > 2- or 4-ethylphenol > 2- or 4-methylphenol > phenol > 4-ethylguaiacol > dimethoxyphenol > 4-methylguaiacol > 4-propenyl-2,6-dimethoxyphenol > 2,4-dimethylphenol. Some of the phenolic compounds identified from the tar might be fungicidally active components. BT is a biochar waste, which has potential as a biofungicide and has promise in organic agriculture. The value of this tar may not be because of any fundamental physical differences from other synthetic fungicides but rather caused by reduced production expenses and more efficient use of waste products.

EDTAD-modified cassava stalks loaded with Fe3O4: highly efficient removal of Pb2+ and Zn2+ from aqueous solution

In this study, a novel magnetic cassava stalk composite (M-EMCS) was prepared through modification with ethylenediamine tetraacetic anhydride (EDTAD) and loading of Fe₃O₄. The surface morphology, molecular structure, and magnetic characteristics of the composite were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), vibrating-sample magnetometer (VSM), and X-ray diffraction (XRD). It was shown that EDTAD and Fe₃O₄ were successfully modified and loaded in cassava straw (CS), respectively. The capacity of M-EMCS to absorb heavy metals under different influencing factors was tested by atomic absorption spectroscopy. The adsorption processes of both Pb²⁺ and Zn²⁺ were suitably described by second-order kinetic models and Langmuir models, indicating monolayer chemisorption. M-EMCS had high adsorption rates and adsorption capacities for these two metal ions. The adsorption of Pb²⁺ and Zn²⁺ reached a plateau after 10 min, and the adsorption capacity of Pb²⁺ (163.93 mg/g) was higher than that of Zn²⁺ (84.74 mg/g). Thermodynamic analysis showed that the adsorption of two metals by M-EMCS was spontaneous, endothermic, and irreversible. XPS analysis showed that M-EMCS mainly removes Pb²⁺ and Zn²⁺ through ion exchange, chelation, and redox. Graphical abstract.

Pyroligneous acid mitigated dissemination of antibiotic resistance genes in soil

Strategies to mitigate the spread of antibiotic resistance genes (ARGs) in soils are urgently needed. Therefore, a pristine pyroligneous acid (PA) from pyrolyzing blended woody waste at 450 °C and its three fractions distilled at 98, 130, and 220 °C (F1, F2, and F3) were used to evaluate their feasibility of reducing ARGs in soil. Application of PA, F2, and F3 effectively decreased the relative ARG abundance by 22.4-75.4% and 39.7-66.7% in the rhizosphere and bulk soil relative to control, respectively, and the removal efficiency followed an order of F3 > PA > F2. Contrarily, F1 increased the abundance of ARGs. The decreased abundance of two mobile genetic elements and impaired conjugative transfer of RP4 plasmid in the presence of PA, F2 and F3 demonstrated that the weakened horizontal gene transfer (HGT) contributed to the reduced ARG level. Variation partitioning analysis and structural equation models confirmed that ARG reduction was primarily driven by the weakened HGT, followed by the decreased co-selection of heavy metals and shifted bacterial community (e.g., reduced potential host bacteria of ARGs). Our findings provide practical and technical support for developing PA-based technology in remediating ARG-contaminated soil to ensure food safety and protect human health.

A cellulose degrading bacterial strain used to modify rice straw can enhance Cu(II) removal from aqueous solution

The development of lignocellulose-based adsorbents for the removal of heavy metals from wastewater has attracted much recent attention. In this work, a high-yield cellulose bacterial strain Comamonas testosteroni FJ17 was evaluated for its capacity to modify rice straw towards increased Cu(II) removal. For optimum modification time (45.5 h), inoculum concentration (1.25%), and rice straw dose (12.6 g L^-1) the optimized adsorption capacity was 28.4 mg g^-1. After strain FJ17 modification the equilibrium adsorption percentage of rice straw for Cu(II) increased from 6.6 to 27.4% at an initial concentration of 100 mg L^-1. This increase was attributed to an increase in rice straw surface modification, leading to improved adsorption ability. SEM-EDS indicated that, following strain FJ17 treatment, the surface of the rice straw became more disintegrated and the specific surface area consequentially increased from 1.9 to 3.7 m² g^-1. FTIR analysis also showed new functional groups (carbonyl) appearing, and CC and CH₃CR functionality being enhanced after biomodification. Functional groups associated with the benzene ring, silicified polymer and carbohydrates were all involved in the adsorption process. Adsorption of Cu was well described by the Freundlich isotherm model (R² > 0.98) where adsorption was endothermic with potential for both chemical and physical interactions to coexist. Reusability experiments showed that the removal efficiency of Cu(II) decreased from 96.9 to 73.2% after five cycles. Overall C.testosteroni-treated rice straw had significant potential as a heavy metal biosorbent.

Continuous Anaerobic Digestion of Wood Vinegar Wastewater From Pyrolysis: Microbial Diversity and Functional Genes Prediction

Wood vinegar wastewater (WVWW) is the main by-product of biomass pyrolysis process, which is more suitable to use anaerobic digestion (AD) to achieve energy recovery due to its large amount of organic matter. In this study, the up-flow anaerobic sludge bed (UASB) reactor was used to investigate the continuous anaerobic transformation of WVWW with gradient concentrations (0.3, 0.675, 1, 2, 3, 4, 5, 6, and 7 g COD/L). Then, the changes of microbial community, diversity index and functional gene were analyzed in detail. The results revealed that WVWW showed good AD performance in continuous fermentation. WVWW of organic loading rate (OLR) of >8.58 g COD/L⋅d showed severe inhibition on biodegradability and methane production, which is mainly due to the toxic substances as compared with the control group. The bacterial communities were dominated by phyla of Chloroflexi, Firmicutes, Proteobacteria, Acidobacteria, Synergistetes, and Actinobacteria. The gene abundances related to energy production, carbohydrate transport and metabolism were relatively high, which are mainly responsible for carbon forms conversion and carbohydrate degradation. This study will provide a basis for the screening and enrichment of functional bacteria and genes.

Aging mechanism of microplastics with UV irradiation and its effects on the adsorption of heavy metals

Microplastics are formed by the degradation of plastic wastes under the action of physicochemical mechanisms in environment, and they are becoming a new type of pollutant that is attractings global attention. However, research on the aging characteristics and mechanism of microplastics is limited. The aging mechanism of Polystyrene (PS) with UV irradiation under different conditions (air, pure water and seawater) and the effect of aging on heavy metal adsorption were studied. The results show that PS have different characteristics with UV irradiation under different conditions, and the aging of PS is the most obvious in air. Based on the 2D-COS analysis, different aging mechanisms were identified under different aging conditions, aging sequence of aged PS functional groups in air and water were clearly definited. An isothermal adsorption model shows that aging can significantly increase the adsorption of heavy metals by PS. The adsorption of heavy metals is also affected by different aging methods. Over all, a 2D-COS analysis was an effective method for understanding the aging process of PS. These results further clarify the aging mechanism of PS, and provides a theoretical basis for the assessment of environmental behavior and ecological risk when microplastics and heavy metals coexist.

An analysis of the versatility and effectiveness of composts for sequestering heavy metal ions, dyes and xenobiotics from soils and aqueous milieus

The persistence and bioaccumulation of environmental pollutants in water bodies, soils and living tissues remain alarmingly related to environmental protection and ecosystem restoration. Adsorption-based techniques appear highly competent in sequestering several environmental pollutants. In this review, the recent research findings reported on the assessments of composts and compost-amended soils as adsorbents of heavy metal ions, dye molecules and xenobiotics have been appraised. This review demonstrates clearly the high adsorption capacities of composts for umpteen environmental pollutants at the lab-scale. The main inferences from this review are that utilization of composts for the removal of heavy metal ions, dye molecules and xenobiotics from aqueous environments and soils is particularly worthwhile and efficient at the laboratory scale, and the adsorption behaviors and effectiveness of compost-type adsorbents for agrochemicals (e.g. herbicides and insecticides) vary considerably because of variabilities in structure, topology, bond connectivity, distribution of functional groups and interactions of xenobiotics with the active humic substances in composts. Compost-based field-scale remediation of environmental pollutants is still sparse and arguably much challenging to implement if, furthermore, real-world soil and water contamination issues are to be addressed effectively. Hence, significant research and process development efforts should be promptly geared and intensified in this direction by extrapolating the lab-scale findings in a cost-effective manner.

Comparative study of individual and Co-Application of biochar and wood vinegar on blueberry fruit yield and nutritional quality

Biochar and its by-product, wood vinegar, have attracted extensive attention owing to their great potentials in improving degraded soil, which is a global concern because of the threats to soil productivity and food security. However, the effect of biochar or wood vinegar on blueberry production is unknown. Therefore, a field trial was conducted to investigate the effects of individual and co-application of biochar (BC450) and wood vinegar (WV450) derived from blended wood waste on the blueberry tree (Vaccinium corymbosum L.) growth, fruit yield, appearance, and nutritional quality as well as the soil properties and nutrient availability. Regardless of individual or co-application, all the amendments had little effect on tree growth. Although BC450 and WV450 increased the fruit yield, the differences between the amended treatments were non-significant. Both the amendments had little effect on the apparent fruit quality, but improved the nutritional quality has been improved (e.g., increased vitamin C and decreased titratable acidity). Additionally, the individual or co-application of BC450 and WV450 had little effect on soil properties (except for soil organic matter), but increased the soil nutrient availability (e.g., NH₄⁺-N, NO₃⁻-N, and Mg). The enhancement in the nutritional quality of the blueberry fruit can be mainly attributed to the increased nutrient availability. This is the first preliminary study that demonstrates that the individual or co-application of biochar and wood vinegar can be a potential strategy for reclaiming degraded soil and enhancing blueberry production.

Responses of ammonia volatilization from rice paddy soil to application of wood vinegar alone or combined with biochar

Wood vinegar (WV) was applied alone or combined with biochar (BC) to observe their efficiency on suppressing the ammonia (NH₃) volatilization from rice paddy soil. Five treatments, i.e., control (240 kg N ha^-1 applied in urea), WV-5 and WV-10 (240 kg N ha^-1 plus 5 and 10 t WV ha^-1, respectively), and their counterparts WV-5-BC and WV-10-BC (WV-5 and WV-10 plus 7 t BC ha^-1), were evaluated by a soil columns experiment. The N fertilizer was split applied as basal and two supplementary fertilizations (named BF, SF1 and SF2, respectively). The results showed that WV-5 treatment increased rice grain yield up to 11.2% compared to the control. Compared with the control, four WV-amended treatments, exhibited lower pH values of the floodwater (7.94-8.18 vs 8.47 and 7.85-7.91 vs 7.98) and the topsoil (6.52-6.76 vs 6.82 and 6.82-6.92 vs 6.99) during the BF and SF1 periods. Both WV-5 and WV-10 increased the NH₄⁺-N contents of topsoil by 10.9-17.8% and 16.1-36.2% after BF and SF1, respectively, than control treatment. Additionally, the floodwater of the WV-amended treatments had higher NH₄⁺-N concentration than control during the first three days after N fertilization, which can be attributed to the stimulating effect of WV on soil urease enzyme activity. WV did not effectively reduce NH₃ volatilization as hypothesized. Interestingly, four WV-amended had relatively reduced the yield-scale NH₃ volatilization by 13.6% than the control. It is suggested that WV needs to be applied with BC at a moderate rate to achieve optimum rice yield and mitigate NH₃ volatilization.

Functional group-rich hyperbranched magnetic material for simultaneous efficient removal of heavy metal ions from aqueous solution

In order to achieve the purpose of simultaneous removal of coexisting heavy metal ions, in this work, functionalized magnetic mesoprous nanomaterials (Fe₃O₄-HBPA-ASA) with high density and multiple adsorption sites were designed and prepared. The obtained Fe₃O₄-HBPA-ASA was characterized by SEM, FTIR, VSM, TGA and zeta potential. Cu(II), Pb(II) and Cd(II) were chosen as the model heavy metal ions, the adsorption experiments showed that Fe₃O₄-HBPA-ASA showed hightheoretical adsorption capacitiesin individual system, and the maximum adsorption capacity was 136.66 mg/g, 88.36 mg/g and 165.46 mg/g, respectively. In the binary and ternary systems, the competitive adsorption leads to a decrease in the adsorption capacity of Cu(II), Pb(II) and Cd(II). However, in the ternary system with a concentration lower than 15 mg/L, the simultaneous removal rate was still higher than 90%. The adsorption isotherms and kineticswere well fitted by Langmuir and pseudo-second-order models, respectively. The XPS and density functional theory (DFT) analysis have confirmed that the adsorption of metal ions was related to various types of functional groups on the surface of Fe₃O₄-HBPA-ASA, while the adsorption mechanisms of Cu(II), Cd(II) and Pb(II) were different.

The adsorption behavior of metals in aqueous solution by microplastics effected by UV radiation

Microplastics are considered as the carrier to heavy metals in the environment. But the sorption ability of microplastics influenced by photo-aging is remaining unclear. In the present study, the sorption of two kinds of metal ions (Cu²⁺ and Zn²⁺) in the aqueous solution by both the virgin and aged microplastics was investigated. Polyethylene terephthalate (PET) debris, one of the typical kinds of microplastics was chosen in this study. Photo-aging of microplastics in environment was simulated using UV radiation in the laboratory. Date analysis indicated that the aged microplastics had higher adsorption capacity of heavy metals than original ones. This could be related to the increased surface area and oxygen containing function appeared in the surface of aged microplastics after UV radiation. When prolonging the time of radiation, the enhanced adsorption capacities of microplastics appeared for Cu²⁺ and Zn²⁺. These results showed a great interaction between the aging degree of plastics and sorption capacity to heavy metals. Meanwhile, external conditions including temperature and pH value were also showed great influence to the adsorption behavior.

Spectroscopic investigation of Cu2+, Pb2+ and Cd2+ adsorption behaviors by chitosan-coated argillaceous limestone: Competition and mechanisms

In the present study, the competitive adsorption of Cu²⁺, Pb²⁺, and Cd²⁺ by a novel natural adsorbent (i.e., argillaceous limestone) modified with chitosan (C-AL) was investigated. The results demonstrated that both intraparticle diffusion and chemisorption marked significant contributions to the Cu²⁺ adsorption process by both raw argillaceous limestone (R-AL) and C-AL in mono-metal adsorption systems. Antagonism was found to be the predominant competitive effect for Cu²⁺, Pb²⁺ and Cd²⁺ adsorptions by C-AL in the multi-metal adsorption system. The three-dimensional simulation and FTIR analysis revealed that the presence of Cu²⁺ suppressed Pb²⁺ and Cd²⁺ adsorptions, while the effect of Cd²⁺ on Cu²⁺ and Pb²⁺ adsorptions was insignificant. The spectroscopic analyses evidenced that amide groups in C-AL played a crucial role in metal adsorption. The preferential adsorptions of Pb²⁺ > Cu²⁺ > Cd²⁺ were likely due to the different affinities of the metals to the lone pair of electrons on the N atom from the amide groups and/or the O atoms from the -OH and -COO^- groups on C-AL. The interactions between C-AL and metal ions and between various metal species influenced their competitive adsorption behaviors. C-AL exhibited a superior metal adsorption capacity in comparison with that the capacities of other natural adsorbents reported during the last decade, suggesting its potential practical applications.

Adsorption behaviours and mechanisms of heavy metal ions' impact on municipal waste composts with different degree of maturity

Composting may change the adsorption characteristics and mechanisms of organic materials due to their differences in organic chemical functional groups and surface structures. The adsorption properties of heavy metals onto the municipal solid waste compost (MSW-C) and its secondary fermentation form (MSW-SC) were comparatively investigated in single, binary and multiple solutions by batch experiments. In the single-metal system, the maximum adsorption capacities of Cu, Zn, Cd and Ni onto MSW-SC were 29.2, 26.3, 38.1 and 22.0 mg g^-1, respectively, and showed higher than that of MSW-C. The adsorption fitted best with the pseudo-second-order kinetics and Langmuir isotherms. The competitive adsorption results indicated that the composts exhibited good selectivity in the adsorption of Cu over Cd, Zn and Ni; thus, for the quaternary-metal systems, the adsorption sequence was Cu > Zn > Cd > Ni. Humic acid content, cation exchange capacity and surface area were increased following the secondary composting. FTIR analysis indicated amine and aromatic compounds were main binding sites accounting for metal sorption. SEM-EDX analysis suggested that the MSW-SC had rough surfaces and stronger adsorption capacity. Decreasing percentage of exchangeable metals was found in the metal-loaded MSW-SC based on a speciation analysis. This study highlights the interactive impacts of different metals during adsorption by compost with different maturity, the secondary composting process was a multifunctional improvement of sorption characteristics and MSW-SC was developed to be a highly efficient biosorbent.

Disinfection and removal performance for Escherichia coli, toxic heavy metals and arsenic by wood vinegar-modified zeolite

Zeolite has traditionally been used to remediate wastewater and soil. The present study shows a new method for natural zeolite (NZ) modification with wood vinegar (WV). The optimal conditions for NZ modification with WV were determined, and the adsorption capacities towards lead (Pb), cadmium (Cd) and arsenic (As), antimicrobial activities against Escherichia coli, heavy metal(loid) fraction and characterizations of selected modified zeolites (MZs) were also investigated. The results indicate that 50-fold dilution of WV, 5 g of NZ dosage, 105 °C of drying temperature, 4 h and 95 °C of water bath are preferred for NZ modification with WV. The WV+NaOH-MZ exhibited the best performance in heavy metal removal and the most powerful antimicrobial activity among all the zeolites. The sequence of WV+NaOH-MZ for the maximum single metal(loid) adsorption capacities was Pb (48.67 mg/g) >Cd (23.67 mg/g) > As (0.024 mg/g). The WV+NaOH and WV modifications also can increase the stabilities of heavy metals in the MZs. The residual fractions of single Pb and Cd in WV+NaOH-MZ and WV-MZ were 50%, 55%, 34% and 30%, respectively. The pore size of WV+NaOH-MZ (11.73 nm) was bigger than that of NZ or WV-MZ. Additionally, the proportion of clinoptilolite in WV+NaOH-MZ was also higher than other zeolites. The surfaces of WV+alkali-MZs were rougher than that of NZ. Considering the low cost and environmental risk of WV, this work provides some useful information for management of agricultural and industrial residues, environment and food safety.