Polycyclic aromatic hydrocarbon generation behavior in the process of carbonization of wood

Polycyclic Aromatic Hydrocarbons (PAHs) and Metals in Diverse Biochar Products: Effect of Feedstock Type and Pyrolysis Temperature

Biochar's agricultural and environmental benefits have been widely demonstrated; however, it may cause environmental contamination if it contains large amounts of pollutants such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs). Therefore, this study aimed to assess the contents of PAHs and HM in a range of biochars generated from different sources and pyrolysis temperatures. A range of feedstock was converted to biochar, including sewage sludge (SS), olive mill pomace (OP), feather meal (FM), soft offal meal (CSM), chicken manure (CM), and date palm residues (DPR). Each feedstock was then pyrolyzed at three temperatures of 300, 500, or 700 °C, thereby producing a total of 18 types of biochar. These biochar products were analyzed for 16 PAHs and eight metals (Cr, Mn, Fe, Ni, Cu, Zn, Cd, and Pb). Benzo[b]fluoranthene, benzo[k]fluoranthene, and benzo(a)pyrene were significantly greater in the biochar produced at 700 °C than in that produced at 300 °C, especially for CM. The concentrations of dibenz(a,h)anthracene were significantly lower at 700 °C but greater at 500 °C and 300 °C in DPR. Increasing the pyrolysis temperature from 300 to 700 °C significantly increased the concentrations of metals, including Cr in SS and OP; Mn in CM; and Fe, Ni, Cu, and Zn in SS. However, the concentration of Cd was significantly lower in the SS when biochar was produced at 700 °C than at 500 or 300 °C. The type of feedstock used and the pyrolysis temperature are key factors influencing the contents of PAHs and HMs in biochar, both of which need to be considered during the production and use of biochar. Further investigations are recommended to establish the relationships between pyrolysis temperature and types of feedstock and the formation of PAH or the concentrations of metals. Monitoring the concentrations of PAHs and HMs before applying biochar to soil is also recommended.

Polycyclic aromatic hydrocarbon occurrence in forest soils in response to fires: a summary across sites

Forest fires are important sources of polycyclic aromatic hydrocarbons (PAHs) in soils. However, factors controlling PAH production in soils subjected to fires in different sites are poorly understood. Here, we analyzed 143 sets of previously published data to evaluate the concentrations and composition profiles of PAHs in ash and soils associated with forest fires and to assess the impacts of soil depth, fire intensity, post-fire duration, and vegetation type on their occurrence. Compared to unburned soils, the total PAH concentrations increased by 205% (95% confidential interval of 152-269%; n = 136) in soils associated with fires. This increase surpassed that of PAH toxic equivalents (73%) because fires produce dominantly low-ring PAHs with relatively low toxicity. PAH concentrations in fire-impacted sites increased by 684%, 258%, and 155% in the ash, 0-5 cm soil depth interval, and >5 cm soil depth interval, respectively. The increases in PAH concentrations associated with mild-intensity fires (412%) exceeded those associated with moderate-intensity (163%) and high-intensity (168%) fires, which is possibly due to pyromineralization or volatilization of organic matters at high burning temperatures. These increases were highest within a month after the fire (280%), gradually decreasing over time, and showed no significant difference compared to the reference sites after 24 months. The concentration increases exhibit no major difference between various vegetation types (broad-leaved forest vs. coniferous forest vs. shrub). Assessments reveal that exposure to post-fire soil PAHs involves no serious human health risk. However, potential adverse effects of soil PAHs on other organisms (e.g., microbes and plants) and ecosystems should be further examined. The present study highlights the strong impacts of soil depth, fire intensity, and post-fire duration, and the relatively weak impact of the vegetation type on PAH concentrations in soils associated with fires in different areas.

Does biochar accelerate the mitigation of greenhouse gaseous emissions from agricultural soil? - A global meta-analysis

Greenhouse gaseous (GHGs) emissions from cropland soils are one of the major contributors to global warming. However, the extent and pattern of these climatic breakdowns are usally determined by the management practices in-place. The use of biochar on cropland soils holds a great promise for increasing the overall crop productivity. Nevertheless, biochar application to agricultural soils has grown in popularity as a strategy to off-set the negative feedback associated with agriculture GHGs emissions, i.e., CO₂ (carbon dioxide), CH₄ (methane), and N₂O (nitrous oxide). Despite increasing efforts to uncover the potential of biochar to mitigate the farmland GHGs effects, there has been little synthesis of how different types of biochar affect GHGs fluxes from cropland soils under varied experimental conditions. Here, we presented a meta-analysis of the interactions between biochar and GHGs emissions across global cropland soils, with field experiments showing the strongest GHG mitigation potential, i.e. CO₂ (RR = -0.108) and CH₄ (RR = -0.399). The biochar pyrolysis temperature, feedstock, C: N ratio, and pH were also found to be important factors influencing GHGs emissions. A prominent reduction in N₂O (RR = -0.13) and CH₄ (RR = -1.035) emissions was observed in neutral soils (pH = 6.6-7.3), whereas acidic soils (pH ≤ 6.5) accounted for the strongest mitigation effect on CO₂ compared to N₂O and CH₄ emissions. We also found that a biochar application rate of 30 t ha^-1 was best for mitigating GHGs emissions while achieving optimal crop yield. According to our meta-analysis, maize crop receiving biochar amendment showed a significant mitigation potential for CO₂, N₂O, and CH₄ emissions. On the other hand, the use of biochar had shown significant impact on the global warming potential (GWP) of total GHGs emissions. The current data synthesis takes the lead in analyzing emissions status and mitigation potential for three of the most common GHGs from cropland soils and demonstrates that biochar application can significantly reduce the emissions budget from agriculture.

Effect of biochar on Cd and pyrene removal and bacteria communities variations in soils with culturing ryegrass (Lolium perenne L.)

Organic contaminations and heavy metals in soils cause large harm to human and environment, which could be remedied by planting specific plants. The biochars produced by crop straws could provide substantial benefits as a soil amendment. In the present study, biochars based on wheat, corn, soybean, cotton and eggplant straws were produced. The eggplant straws based biochar (ESBC) represented higher Cd and pyrene adsorption capacity than others, which was probably owing to the higher specific surface area and total pore volume, more functional groups and excellent crystallization. And then, ESBC amendment hybrid Ryegrass (Lolium perenne L.) cultivation were investigated to remediate the Cd and pyrene co-contaminated soil. With the leaching amount of 100% (v/w, mL water/g soil) and Cd content of 16.8 mg/kg soil, dosing 3% ESBC (wt%, biochar/soil) could keep 96.2% of the Cd in the 10 cm depth soil layer where the ryegrass root could reach, and it positively help root adsorb contaminations. Compared with the single planting ryegrass, the Cd and pyrene removal efficiencies significantly increased to 22.8% and 76.9% by dosing 3% ESBC, which was mainly related with the increased plant germination of 80% and biomass of 1.29 g after 70 days culture. When the ESBC dosage increased to 5%, more free radicals were injected and the ryegrass germination and biomass decreased to 65% and 0.986 g. Furthermore, when the ESBC was added into the ryegrass culture soil, the proportion of Cd and pyrene degrading bacteria Pseudomonas and Enterobacter significantly increased to 4.46% and 3.85%, which promoted the co-contaminations removal. It is suggested that biochar amendment hybrid ryegrass cultivation would be an effective method to remediate the Cd and pyrene co-contaminated soil.

Biochar impacts on nutrient dynamics in a subtropical grassland soil: 2. Greenhouse gas emissions

Land application of biochar reportedly provides many benefits, including reduced risk of nutrient transport, greenhouse gas (GHG) emission mitigation, and increased soil C storage, but additional field validation is needed. We evaluated the effectiveness of biochar in controlling the lability of nutrients in agricultural land. This study was designed to evaluate the impacts of biochar co-applied with various N and P sources on GHG fluxes from a subtropical grassland. Nutrients (inorganic fertilizer and aerobically digested Class B biosolids) were surface applied at a rate of 160 kg plant available N ha^-1  yr^-1 with or without biochar (applied at 20 Mg ha^-1 ). Greenhouse gas (CO₂ , CH₄ , and N₂ O) fluxes were assessed using static chambers and varied significantly, both temporally and with treatments. Greenhouse gas fluxes ranged from 1,247 to 23,160, -0.7 to 42, and -1.4 to 376 mg m^-2 d^-1 for CO₂ , N₂ O, and CH₄ , respectively. Results of the 3-yr field study demonstrated strong seasonal variability associated with GHG emissions. Nutrient source had no effect on soil CO₂ and CH₄ emissions, but annual and cumulative (3-yr) N₂ O emissions increased with biosolids (8 kg N₂ O ha^-1  yr^-1 ) compared with inorganic fertilizer (5 kg N₂ O ha^-1  yr^-1 ) application. Data suggested that environmental conditions played a more important role on GHG fluxes than nutrient additions. Biochar reduced CO₂ emissions modestly (<9%) but had no effects on N₂ O and CH₄ emissions.

N-doped graphitic biochars from C-phycocyanin extracted Spirulina residue for catalytic persulfate activation toward nonradical disinfection and organic oxidation

Biochars are low-cost and environmental-friendly materials, which are promising in wastewater treatment. In this study, biochars were manufactured from C-phycocyanin extracted (C-CP) Spirulina residue (SDBC) via thermal pyrolysis. Simultaneously, N-doping was also achieved from the protein in the algae for obtaining a high-performance carbocatalyst for peroxydisulfate (PDS) activation. The SDBC yielded large specific surface areas, nitrogen loading, and good conductivity, which demonstrated excellent oxidation efficiencies toward a wide array of aqueous microcontaminants. An in-depth mechanistic study was performed by integrating selective radical scavenging, solvent exchange (H₂O to D₂O), diverse organic probes, and electrochemical measurement, unveiling that SDBC/PDS did not rely on free radicals or singlet oxygen but a nonradical pathway. PDS intimately was bonded with a biochar (SDBC 900-acid, pyrolysis at 900 °C) to form a surface reactive complex that subsequently attacked an organic sulfamethoxazole (SMX) adsorbed on the biochar via an electron-transfer regime. During this process, the SDBC 900-acid played versatile roles in PDS activation, organic accumulation and mediating the electron shuttle from SMX to PDS. This nonradical system can maintain a superior oxidation efficiency in complicated water matrix and long-term stable operation. More importantly, the nonradical species in SDBC 900-acid/PDS system were capable of inactivating the bacteria (Escherichia coli) in wastewater. Therefore, the biochar based nonradical system can provide a mild and high-efficiency strategy for disinfection in waste and drinking water by green carbocatalysis. This study provides not only a value-added biochar catalyst for wastewater purification but also the first insight into the bacteria inactivation via nonradical oxidation.

Polycyclic aromatic hydrocarbons (PAHs) formation during the fast pyrolysis of hazardous health-care waste

Health-care waste management is a challenge for the health sector. Currently, pyrolysis technologies are being used to treat medical waste that can convert it to a hydrocarbon fuel. In the present study, hazardous health-care waste was pyrolyzed using a continuous tubular fast pyrolysis reactor. Mass balance analysis and formation of the 16 polycyclic aromatic hydrocarbons (PAHs), characterized by USEPA as priority pollutants, and was studied during the pyrolysis process in a wide range of operation conditions, i.e., reaction temperature (300-700 °C), residence time (100-190 s) and waste particle size (1-3 cm). Response surface methodology (RSM) and central composite design (CCD) were applied to optimize the operating variables. Cracking and decomposition of feedstock occurred almost optimally in 700 °C resulting in the generation of 73.4% liquid and 24.1% char. The PAHs were characterized in significant concentrations in pyrolytic oil (121-29440 mg/lit) and char (223-1610 mg/kg) products. The formation of total USEPA listed PAH components varied by the operating ranges of temperature, residence time and waste size. In the pyrolytic oil phase, the formation of total PAHs was drastically increased by increasing the waste particle size. It is also found that increasing the temperature and having longer residence times have a high influence on the total 16 USEPA PAHs formation rate in the char phase. It is concluded that fast pyrolysis of hazardous health-care waste, as thermal treatment method, would influence the formation and destruction of PAHs and their fraction to a different extent depending on the role of operating variables.

Negative Impacts of Biochars on Urease Activity: High pH, Heavy Metals, Polycyclic Aromatic Hydrocarbons, or Free Radicals?

Although biochars show promise for soil remediation, their negative impacts have not been systematically assessed. This study investigated the effects of corn cob biochars on urease-mediated urea hydrolysis and attempted to determine the mechanisms underlying those effects. The results showed that biochars inhibited urease activity (indicated by the NH₄⁺ generation). Released heavy metals and polyaromatic hydrocarbons explained the 20% inhibition of urease activity in biochar supernatants (200 °C) but could not explain the 70% inhibition in particle systems (400 °C). The levels of protein carbonyl and nitrotyrosine, common oxidative damagers of urease, were high in particle systems but very low in biochar supernatants. The electron paramagnetic resonance signal intensity reached its highest level in the 400 °C biochar and decreased in the 500 °C biochar, possibly due to the decomposition of organic molecules. The observed inhibition of urease activity may be the result of oxidative reactions with free radicals on the biochar surface or oxidative reactions with reactive oxygen species promoted by free radicals. We suggest that these potential hazards be evaluated further to gauge the relevance of these findings to field conditions and to assist in the development of safe and sustainable application schemes for biochars.

Fates of Chemical Elements in Biomass during Its Pyrolysis

Biomass is increasingly perceived as a renewable resource rather than as an organic solid waste today, as it can be converted to various chemicals, biofuels, and solid biochar using modern processes. In the past few years, pyrolysis has attracted growing interest as a promising versatile platform to convert biomass into valuable resources. However, an efficient and selective conversion process is still difficult to be realized due to the complex nature of biomass, which usually makes the products complicated. Furthermore, various contaminants and inorganic elements (e.g., heavy metals, nitrogen, phosphorus, sulfur, and chlorine) embodied in biomass may be transferred into pyrolysis products or released into the environment, arousing environmental pollution concerns. Understanding their behaviors in biomass pyrolysis is essential to optimizing the pyrolysis process for efficient resource recovery and less environmental pollution. However, there is no comprehensive review so far about the fates of chemical elements in biomass during its pyrolysis. Here, we provide a critical review about the fates of main chemical elements (C, H, O, N, P, Cl, S, and metals) in biomass during its pyrolysis. We overview the research advances about the emission, transformation, and distribution of elements in biomass pyrolysis, discuss the present challenges for resource-oriented conversion and pollution abatement, highlight the importance and significance of understanding the fate of elements during pyrolysis, and outlook the future development directions for process control. The review provides useful information for developing sustainable biomass pyrolysis processes with an improved efficiency and selectivity as well as minimized environmental impacts, and encourages more research efforts from the scientific communities of chemistry, the environment, and energy.

Organic pollutants profiling of wood ashes from biomass power plants linked to the ash characteristics

PURPOSE

Wood ash, characterized by high content of certain nutrients and charcoal, can be applied to soils as a means of managing this waste product improving the soil quality. The associated environmental risk must be assessed. The objective of this study was to characterize the bottom and fly ash collected from 15 biomass power plants in Spain by determining the benzene, toluene, ethylbenzene, xylene and styrene (BTEX+S), PAHs and aliphatic hydrocarbon contents of both types of ash. Biochar was also used for comparison purposes.

METHODS

Gas chromatography-mass spectrometric methods were used for the identification and determination of both BTEX+S and aliphatic hydrocarbon contents in bottom and fly ashes, as well as biochar. High performance liquid chromatography with fluorescence detection was used for PAHs measurements. Multivariate correlation analysis was used to determine the relationship between sample characteristics and pollutants identified by partial least squares regression analysis.

RESULTS AND DISCUSSION

In general, the degree to which organic matter in the sample is burned increases with T50 or the "50% burn off" temperature (possibly due to the addition of fuel), and the BTEX+S also tended to increase. However, as the Q/MO (the heat of combustion divided by organic matter mass) increased, the combustion decreased or proceeded with less oxygen, which appears to be related to an increased presence of PAHs. The results confirm that the amounts of organic pollutants (PAHs and BTEX+S, together with total aliphatic hydrocarbons) in the wood ash do not exceed limits established for different soil or industrial uses.

CONCLUSIONS

Both types of ash, together with biochar, may therefore be suitable for application to soil as a fertilizer and an organic amendment, taking into account the target organic pollutants.

Bioaccumulation of polycyclic aromatic hydrocarbons and survival of earthworms (Eisenia andrei) exposed to biochar amended soils

Biochar has a charcoal polycyclic aromatic structure which allows its long half-life in soil, making it an ideal tool for C sequestration and for adsorption of organic pollutants, but at the same time raises concerns about possible adverse impacts on soil biota. Two biochars were tested under laboratory-controlled conditions on Eisenia andrei earthworms: a biochar produced at low temperature from wine tree cuttings (WTB) and a commercial low tar hardwood lump charcoal (HLB). The avoidance test (48-h exposure) showed that earthworms avoid biochar-treated soil with rates higher than 16 t ha(-1) for HLB and 64 t ha(-1) for WTB. After 42 days, toxic effects on earthworms were observed even at application rates (100 t ha(-1)) that are generally considered beneficial for most crops. The concentration of HLB and WTB required to kill half of earthworms' population (LC50; 95% confidence limits) in the synthetic OECD soil was 338 and 580 t ha(-1), respectively. Accumulation of polycyclic aromatic hydrocarbons (PAH) in earthworms exposed to the two biochar types at 100 t ha(-1) was tested in two soils of different texture. In biochar-treated soils, the average earthworm survival rates were about 64% in the sandy and 78% clay-loam soils. PAH accumulation was larger in the sandy soil and largest in soils amended with HLB. PAH with less than four rings were preferentially scavenged from the soil by biochars, and this behaviour may mask that of the more dangerous components (i.e. four to five rings), which are preferentially accumulated. Earthworms can accumulate PAH as a consequence of exposure to biochar-treated soils and transfer them along the food chain. Soil type and biochar quality are both relevant in determining PAH transfer.

Biochar efficiency in pesticides sorption as a function of production variables--a review

Biochar is a stabilized, carbon-rich by-product derived from pyrolysis of biomass. Recently, biochar has received extensive attentions because of its multi-functionality for agricultural and environmental applications. Biochar can contribute to sequestration of atmosphere carbon, improvement of soils quality, and mitigation of environmental contaminations. The capability of biochar for specific application is determined by its properties which are predominantly controlled by source material and pyrolysis route variables. The biochar sorption potential is a function of its surface area, pores volume, ash contents, and functional groups. The impacts of each production factors on these characteristics of biochar need to be well-understood to design efficient biochars for pesticides removal. The effects of biomass type on biochar sorptive properties are determined by relative amounts of its lingo-cellulosic compounds, minerals content, particles size, and structure. The highest treatment temperature is the most effective pyrolysis factor in the determination of biochar sorption behavior. The expansion of micro-porosity and surface area and also increase of biochar organic carbon content and hydrophobicity mostly happen by pyrolysis peak temperature rise. These changes make biochar suitable for immobilization of organic contaminants. Heating rate, gas pressure, and reaction retention time after the pyrolysis temperatures are sequentially important pyrolysis variables effective on biochar sorptive properties. This review compiles the available knowledge about the impacts of production variables on biochars sorptive properties and discusses the aging process as the main factor in post-pyrolysis alterations of biochars sorption capacity. The drawbacks of biochar application in the environment are summarized as well in the last section.

Characterization of contaminants and evaluation of the suitability for land application of maize and sludge biochars

Prior to the application of biochar as an agricultural improver, attention should be paid to the potential introduction of toxicants and resulting unintended impacts on the environment. In the present study, the concentrations of polycyclic aromatic hydrocarbons (PAHs), heavy metals, and mineral elements were determined in maize and sludge biochars produced at 100 °C increments between 200 and 700 °C. The concentration ranges of total PAHs were 358-5,136 μg kg(-1) in maize biochars and 179-70,385 μg kg(-1) in sludge biochars. The total heavy metals were detected at the following concentrations (mg kg(-1)): Cu, 20.4-56.7; Zn, 59.7-133; Pb, 1.44-3.50; Cd, <0.014; Cr, 8.08-21.4; Ni, 4.38-9.82 in maize biochars and Cu, 149-202; Zn, 735-986; Pb, 54.7-74.2; Cd, 1.06-1.38; Cr, 180-247; Ni, 41.1-56.1 in sludge biochars. The total concentrations of PAHs and heavy metals in all maize biochars and most sludge biochars were below the control standards of sludge for agricultural use in China, the USA, and Europe. The leachable Mn concentrations in sludge biochars produced at below 500 °C exceeded the groundwater or drinking water standards of these countries. Overall, all the maize biochars were acceptable for land application, but sludge biochars generated at temperatures between 200 and 500 °C were unsuitable for application as soil amendments due to their potential adverse effects on soil and groundwater quality.

Generation of polycyclic aromatic hydrocarbons (PAHs) during woodworking operations

Occupational exposures to wood dust have been associated with an elevated risk of sinonasal cancer (SNC). Wood dust is recognized as a human carcinogen but the specific cancer causative agent remains unknown. One possible explanation is a co-exposure to; wood dust and polycyclic aromatic hydrocarbons (PAHs). PAHs could be generated during incomplete combustion of wood due to heat created by use of power tools. To determine if PAHs are generated from wood during common wood working operations, PAH concentrations in wood dust samples collected in an experimental chamber operated under controlled conditions were analyzed. In addition, personal air samples from workers exposed to wood dust (n = 30) were collected. Wood dust was generated using three different power tools: vibrating sander, belt sander, and saw; and six wood materials: fir, Medium Density Fiberboard (MDF), beech, mahogany, oak and wood melamine. Monitoring of wood workers was carried out by means of personal sampler device during wood working operations. We measured 21 PAH concentrations in wood dust samples by capillary gas chromatography-ion trap mass spectrometry (GC-MS). Total PAH concentrations in wood dust varied greatly (0.24-7.95 ppm) with the lowest being in MDF dust and the highest in wood melamine dust. Personal PAH exposures were between 37.5-119.8 ng m(-3) during wood working operations. Our results suggest that PAH exposures are present during woodworking operations and hence could play a role in the mechanism of cancer induction related to wood dust exposure.

Quantifying the total and bioavailable polycyclic aromatic hydrocarbons and dioxins in biochars

Biochar soil amendment is advocated to mitigate climate change and improve soil fertility. A concern though, is that during biochar preparation PAHs and dioxins are likely formed. These contaminants can possibly be present in the biochar matrix and even bioavailable to exposed organisms. Here we quantify total and bioavailable PAHs and dioxins in a suite of over 50 biochars produced via slow pyrolysis between 250 and 900 °C, using various methods and biomass from tropical, boreal, and temperate areas. These slow pyrolysis biochars, which can be produced locally on farms with minimum resources, are also compared to biochar produced using the industrial methods of fast pyrolysis and gasification. Total concentrations were measured with a Soxhlet extraction and bioavailable concentrations were measured with polyoxymethylene passive samplers. Total PAH concentrations ranged from 0.07 μg g(-1) to 3.27 μg g(-1) for the slow pyrolysis biochars and were dependent on biomass source, pyrolysis temperature, and time. With increasing pyrolysis time and temperature, PAH concentrations generally decreased. These total concentrations were below existing environmental quality standards for concentrations of PAHs in soils. Total PAH concentrations in the fast pyrolysis and gasification biochar were 0.3 μg g(-1) and 45 μg g(-1), respectively, with maximum levels exceeding some quality standards. Concentrations of bioavailable PAHs in slow pyrolysis biochars ranged from 0.17 ng L(-1) to 10.0 ng L(-1)which is lower than concentrations reported for relatively clean urban sediments. The gasification produced biochar sample had the highest bioavailable concentration (162 ± 71 ng L(-1)). Total dioxin concentrations were low (up to 92 pg g(-1)) and bioavailable concentrations were below the analytical limit of detection. No clear pattern of how strongly PAHs were bound to different biochars was found based on the biochars' physicochemical properties.

Mutagenicity and PAH contents of soil in forests or planted areas in Japan

We investigated the behavior of mutagenic substances in the soil of forests or planted areas. Mutagenicity and concentration was examined for 16 types of PAHs in soil samples collected at a depth of 1 m in 10 forests in Iwate, Ibaraki, Tokyo, Kanagawa, Yamanashi and Shizuoka prefectures in Japan. Mutagenicity and PAHs were detected mostly in soil from the surface to a depth of 30 cm when strains TA100, TA98 and YG1024 were used. In addition, a significant correlation was not found between the concentration of BaP, and specific mutagenic activity (TA98 without S9mix, r = 0.285).

Behavior of cadmium and lead contained in wood during the carbonization process

The behavior of heavy metals in wood during its carbonization process was examined. Cadmium in wood samples was found to be volatile when the samples were carbonized at 600 degrees C or higher, which demonstrated that removal of cadmium was feasible. Meanwhile, lead was found to be barely volatile even if the wood samples were carbonized at 1,000 degrees C or higher, which demonstrated that lead was difficult to remove and recover. The possibility of removing/recovering lead contained in wood by energization was then examined. By examining the concentration of sulfuric acid used as an electrolyte as well as load voltage, approximately 10% of lead was found to be recoverable.