Eisenia fetida and biochar synergistically alleviate the heavy metals content during valorization of biosolids via enhancing vermicompost quality.

Impact of different biochars supplemented (10% w/w) to promote vermicomposting of sewage sludge (SS) and kitchen waste (KW) mixture (SS + KW, 70:30) was studied on the growth, reproduction and survival of earthworms, and ultimately the quality of vermicompost. Four types of biochar used as secondary material for preincubation (16 days) and vermicomposting (30 days) were: pine tree biochar (PTB), poplar plant biochar (PPB), wetland plant biochar (WPB) and yard waste biochar (YWB). Preincubation and vermicomposting of biomass mixture were undertaken in 60 L and 2 L capacity round-shaped bioreactors, respectively. Samples of biomass undergoing degradation were drawn after every 2 days during preincubation and with 5 days interval during vermicomposting to analyze them for plant nutrients and heavy metals contents. Amendment of vermicompost substrate (SS + KW) with biochars; PTB, PPB, WPB and YWB increased the reproduction rate of earthworms (Eisenia fetida) by 44.6, 53.9, 29.3 and 38.8%, respectively as compared to control (no biochar, NB). There has been significant reduction in total content of Cd (0.2-5.1%), Cr (7.3-10.8%), Cu (3.1-7.4%), Mn (3.2-8.4%), Pb (9.0-45.9%) and Zn (1.1-5.7%) by the application of different biochars as compared to NB after vermicomposting. The SEM/EDS images also reflected reduced concentration of these heavy metals in the final vermicompost as compared to initial mixtures. Progressively, biochar amendments increased the concentration of all macronutrients, viz., TN (15.8-31.0%), TP (8.6-9.9%), TK (2.8-17.3%), Ca (4.1-9.9%) and Mg (0.8-12.2%); while, reduced the pH (1.9-2.3%), content of Na (6.6-22.3%), TOC (6.6-15.4%), OM (5.0-8.2%) and C:N ratio (2.6-18.9%). Earthworm body accumulation factor (BAF) of heavy metals was: Cd > Zn > Pb > Cu > Mn > Cr at the termination stage of experiment. In conclusion, amending the SS + KW mixture with 10% (w/w) PPB for vermicomposting rendered higher count of cocoons, growth rate and reproduction rate of earthworms, which ultimately produce nutrients-rich vermicompost lower in heavy metals.

Using sequential extraction and DGT techniques to assess the efficacy of plant- and manure-derived hydrochar and pyrochar for alleviating the bioavailability of Cd in soils.

Biochar has emerged as a useful tool to reduce the bioavailability of heavy metals in contaminated soils. However, limited research has been directed towards determining the effects of pyrolysis conditions and feedstock types of biochar on the bioavailability of heavy metals in biochar-treated soils. This work evaluated the efficacy of plant- and manure-derived hydrochar and pyrochar for alleviating Cd bioavailability in soils using conventional chemical extraction, diffusive gradients in thin films (DGT) and plant uptake. For each feedstock type, hydrochar showed lower maximum adsorption capacity than pyrochar. As determined by diethylenetriamine pentaacetic acid, BCR extraction and DGT measurement, pyrochar significantly decreased the theoretical bioavailability of Cd. Moreover, a slight decrease in the ability of soil to resupply Cd to the solution was detected. Also, pyrochar induced a substantial reduction in Cd uptake in ryegrass. Corresponding to the high sorption capacity, swine solid-derived 450 °C pyrochar was the most effective in alleviating Cd bioavailability in soils, indicating its great potential for remediating Cd-contaminated soils. Additionally, the bioavailable Cd amount determined by DGT had the best correlation with the Cd content in ryegrass, showing that DGT technology could better represent the effects of biochars on Cd phytoavailability in the studied soil.

Physicochemical property and colloidal stability of micron- and nano-particle biochar derived from a variety of feedstock sources.

The ever-increasing land application of biochar may raise the environmental issue of micronparticle (MP) and nanoparticle (NP) biochars for their high mobility or as a carrier to facilitate transport of contaminants in soil. In this study, a variety of biochars were produced from pyrolysis of nine biomass sources and then subjected to the extraction of MP and NP biochars. The diverse physicochemical properties and electrokinetic stability of MP and NP biochars were further investigated. MP and NP biochars accounted for 1.43-20.5% and 0.99-15.3% of bulk biochar and had colloidal particle diameters mainly smaller than 1 µm and 100 nm, respectively. The MP and NP biochars contained more O-containing functional groups and mineral components but less aromatic clusters than bulk biochar. The yield of MP/NP biochars derived from plant sources such as woods, herbs, and agricultural waste was positively linear to the ash content of their bulk biochars but this relationship wasn't applied to the municipal sourced biochar such as manure and sewage sludge. More condensed aromatic rings and functional groups were found in MP/NP biochar from plant biomass than municipal sourced biochar. However, the latter was rich with minerals like carbonates, phosphates, and silicates. Higher functional groups in the plant sourced MP/NP wheat straw biochar accounted for the extremely high stability to resist the whole range of ionic strength studied, while the municipal sourced MP/NP dairy manure biochar with less functional groups and more minerals were readily destabilized, with the Critical Coagulation Concentration (CCC) values of 75 mM and 100 mM, respectively. Overall, this study revealed the size-dependent characteristics of composition and structure as well as high colloidal stability of MPs and NPs which are helpful for prediction of their environmental fate and risk.

Impact of hydrochar on rice paddy CH4 and N2O emissions: A comparative study with pyrochar.

Hydrothermal carbonization (HTC) thermally converts wet biomasses to carbon materials, dramatically reducing energy use for drying and improving solid product yield compared to pyrolysis process. However, researches regarding agricultural usage of hydrochar (HC) are limited. In the present study, the influence of HC amendment on CH4 and N2O emissions, as well as global warming potential (GWP) and greenhouse gas intensity (GHGI) were investigated. Additionally, pyrochar (PC) treatments as well as two char-free control treatments with (CKU) or without (CK) N fertilizer were also included for comparison. Chars were produced from wheat straw (WC) and saw dust (SC) and applied at different rates (0.5% and 3%, w/w). Both hydrochar and pyrochar decreased paddy CH4 emissions when amended at a lower rate (0.5%) compared to CKU treatment, which was more obvious for pyrochar when applied at the rate of 3%. Contrarily, 3%-HC significantly stimulated CH4 emissions, which were around 5 and 3 times higher than that of CKU for WC and SC, respectively. Furthermore, hydrochar showed the potential to decrease paddy N2O emissions (6.06-32.32%) at both application rates. However, N2O emissions with PC treatments varied depending on application rate (20.20-75.76%). GWP and GHGI values of 0.5%-HC and PC treatments were similar, 6.67-25.00% and 3.85-25.00% lower than those of CKU treatment, respectively. However, 3%-HC amendments led to significantly increased GWP and GHGI. This study suggested that application rate of hydrochar used in rice fields should be taken into serious consideration to fulfill its potential in GHGs mitigation and minimize environmental side effects.

Research report: Charcoal type used for hookah smoking influences CO production.

A hookah smoker who was treated for severe carbon monoxide poisoning with hyperbaric oxygen reported using a different type of charcoal prior to hospital admission, i.e., quick-light charcoal. This finding led to a study aimed at determining whether CO production differs between charcoals commonly used for hookah smoking, natural and quick-light. Our hypothesis was that quick-light charcoal produces significantly more CO than natural charcoal. A medium-sized hookah, activated charcoal filter, calibrated syringe, CO gas analyzer and infrared thermometer were assembled in series. A single 9-10 g briquette of either natural or quick-light charcoal was placed atop the hookah bowl and ignited. CO output (ppm) and temperature (degrees C) were measured in three-minute intervals over 90 minutes. The mean CO levels produced by quick-light charcoal over 90 minutes was significantly higher (3728 ± 2028) compared to natural charcoal (1730 ± 501 ppm, p = 0.016). However, the temperature was significantly greater when burning natural charcoal (292 ± 87) compared to quick-light charcoal (247 ± 92 degrees C, p = 0.013). The high levels of CO produced when using quick-light charcoals may be contributing to the increase in reported hospital admissions for severe CO poisoning.

Remoción de colorantes sintéticos mediante el proceso Fentonheterogéneo usando Fe2O3 soportado en carbón activado obtenido a partir de residuos de rosas / Removal of synthetic dyes by Fenton process using activated carbon-supported Fe2O3 obtained from rose remnants

Se estudió la remoción de colorantes negro reactivo 5 ycristal violeta, mediante la reacción Fenton empleando catalizadoresde Fe2O3 (0-10% m/m de Fe) soportados en carbón activadoobtenido a partir de residuos de rosas. El carbón activado fueobtenido por pirólisis a 500 ºC (1h) seguido de activación con NaOH(1:2 en peso). El soporte fue caracterizado empleando diferentestécnicas químicas y físicas. Los catalizadores de Fe fueron sintetizadosmediante impregnación incipiente. Los tratamientos Fenton y deadsorción fueron realizados en un reactor Batch, concentración de 10mgL-1 de los colorantes, 0,25 mgmL-1 de catalizador, pH=3,7, 20±2ºC, 750 rpm y presión atmosférica. El carbón activado empleadocomo soporte presentó alta basicidad, presencia de grupos polares ensuperficie, alto contenido de cenizas (22,85%) y de oxígeno (43,93%)y fue mayoritariamente microporoso con un área superficial BETde 520 m2g-1. La máxima remoción lograda para el negro reactivo 5se obtuvo con el catalizador de 3% Fe (98,33%) luego de 180 min.mientras que para el cristal violeta se obtuvo con el catalizador de1% de Fe (63,95%) después de 180 min. La remoción mediante eltratamiento Fenton fue dependiente del contenido de Fe, tamaño departícula del sitio activo y del tipo de colorante. La remoción de negroreactivo 5 alcanzó un máximo con 3% de Fe mientras que para elcristal violeta disminuyó con el incremento del contenido de Fe. Eltratamiento planteado en el presente trabajo es promisorio para laeliminación de colorantes sintéticos presentes en aguas contaminadas...

Fe2O3-catalysts (0-10% m/mof Fe) supported on activated carbon obtained fromrose remnants were used to study the removal of dyesreactive black 5 and crystal violet by the Fenton reaction.The activated carbon was obtained from pyrolysis at 500°C (1h) followed by activation with NaOH (1:2 wt.). Thesupport was classified using several chemical and physicaltechniques. Fe-catalysts were synthesized by incipientimpregnation. Fenton and adsorption treatments wereperformed in a batch reactor, concentration of dye of10 mgL-1, 0.25 mgmL-1 catalyst, pH = 3.7, 20 ± 2 ° C,750 rpm and atmospheric pressure. The activated carbonused as support showed high basicity, presence of polargroups on the surface, high ash content (22.85%) andoxygen (43.93%) and was mostly of the microporoustype with a BET surface area of 520 m2g-1. The maximumdiscoloration achieved for black reactive 5 was obtainedwith the catalyst of 3% Fe (98.33%) after 180 min. whilefor the crystal violet it was obtained with the catalyst of1% Fe (63.95%) after 180 min. Discoloration by Fentontreatment is dependent on the Fe content, the particlesize of the active site and the type of dye. The removalof reactive black 5 reached a maximum at 3% Fe whilethe crystal violet decreased by increasing Fe content. Thetreatment proposed in this paper is promising for theremoval of synthetic dyes present in contaminated water...

Se estudo a remoção de corantes violeta de cristal e reativopreto 5 pela reação de Fenton utilizando diferentes concentraçõesdos catalisadores de Fe2O3 (0-10% m/m de Fe) suportados em carvãoativado obtido a partir de resíduos de rosas. O carvão ativado foiobtido por pirólise a 500 °C (1h) seguido por ativação com NaOH(1:2 em peso). O suporte foi caracterizado utilizando diferentestécnicas químicas e físicas. Os catalisadores de Fe foram sintetizadospor impregnação incipiente. Os tratamentos de adsorçao e de Fentonforam realizados num reator batch, com concentração de 10 mgL-1de corante, 0,25 mgmL-1 de catalisador, em pH = 3,7, 20 ± 2 °C,750 rpm e pressão atmosférica. O carvão ativado usado comosuporte mostrou basicidade elevada, a presença de grupos polaresna superfície, elevado teor de cinzas (22,85%) e oxigênio (43,93%) efoi principalmente microporoso com uma área de superfície BET de520 m2g-1. O valor máximo obtido para a descoloração reativo preto5 foi obtido com o catalisador de 3% Fe (98,33%) após 180 min.Enquanto para o violeta de cristal foi obtido com o catalisador de 1%Fe (63,95%) após 180 min. A descoloração por tratamento de Fentoné dependente do teor de Fe, tamanho de partícula do sítio ativo e dotipo de corante. A remoção de preto reativo 5 atinge um máximo emFe3%, enquanto que para o violeta de cristal diminui com o aumentodo teor de Fe. O tratamento proposto neste trabalho é promissorpara a remoção de corantes sintéticos presentes na água contaminada...

One step forward toward characterization: some important material properties to distinguish biochars.

Terra Preta research gave evidence for the positive influence of charred organic material (biochar) on infertile tropical soils. Facing global challenges such as land degradation, fossil energy decline, water shortage, and climate change, the use of biochar as a soil amendment embedded into regional matter cycles seems to provide an all-round solution. However, little is known about biochar effects on individual ecosystem processes. Besides, the term is used for a variety of charred products. Therefore, the aim of this study was to investigate principal material properties of different chars to establish a minimum set of analytical properties and thresholds for biochar identification. For this purpose, chars from different production processes (traditional charcoal stack, rotary kiln, Pyreg reactor, wood gasifier, and hydrothermal carbonization) were analyzed for physical and chemical properties such as surface area, black carbon, polycyclic aromatic hydrocarbons, and elemental composition. Our results showed a significant influence of production processes on biochar properties. Based on our results, to identify biochar suitable for soil amendment and carbon sequestration, we recommend using variables with the following thresholds: O/C ratio <0.4, H/C ratio <0.6, black carbon >15% C, polyaromatic hydrocarbons lower than soil background values, and a surface area >100 m g.

An index-based approach to assessing recalcitrance and soil carbon sequestration potential of engineered black carbons (biochars).

The ability of engineered black carbons (or biochars) to resist abiotic and, or biotic degradation (herein referred to as recalcitrance) is crucial to their successful deployment as a soil carbon sequestration strategy. A new recalcitrance index, the R(50), for assessing biochar quality for carbon sequestration is proposed. The R(50) is based on the relative thermal stability of a given biochar to that of graphite and was developed and evaluated with a variety of biochars (n = 59), and soot-like black carbons. Comparison of R(50), with biochar physicochemical properties and biochar-C mineralization revealed the existence of a quantifiable relationship between R(50) and biochar recalcitrance. As presented here, the R(50) is immediately applicable to pre-land application screening of biochars into Class A (R(50) ≥ 0.70), Class B (0.50 ≤ R(50) < 0.70) or Class C (R(50) < 0.50) recalcitrance/carbon sequestration classes. Class A and Class C biochars would have carbon sequestration potential comparable to soot/graphite and uncharred plant biomass, respectively, whereas Class B biochars would have intermediate carbon sequestration potential. We believe that the coupling of the R(50), to an index-based degradation, and an economic model could provide a suitable framework in which to comprehensively assess soil carbon sequestration in biochars.

The role of black carbon as a catalyst for environmental redox transformation.

Black carbon (BC) is an important class of geosorbents that control the fate and transport of organic pollutants in soil and sediment. We previously demonstrated a new role of BC as an electron transfer mediator in the abiotic reduction of nitroaromatic and nitramine compounds by Oh and Chiu (Environ Sci Technol 43:6983-6988, 2009). We proposed that BC can catalyze the reduction of nitro compounds because it contains microscopic graphitic (graphene) domains, which facilitate both sorption and electron transfer. In this study, we assessed the ability of different types of BC--graphite, activated carbon, and diesel soot--to mediate the reduction of 2,4-dinitrotoluene (DNT) and 2,4-dibromophenol (DBP) by H(2)S. All three types of BC enhanced DNT and DBP reduction. H(2)S supported BC-mediated reduction, as was observed previously with a thiol reductant. The results suggest that BC may influence the fate of organic pollutants in reducing subsurface environments through redox transformation in addition to sorption.

[Comparison of toluene adsorption with two kinds of modified activated carbon].

Granular activated carbon (GAC) was modified by microwave irradiation and electrical heating. The characters and toluene adsorption capacity of modified GAC were studied. The results showed that for microwave heating, with the temperature increasing, the activated carbon's ability of toluene adsorption and content of the surface basic functional group were increased, specific surface area was decreased. After heated at 850 degrees C, GAC had the highest ability for toluene adsorption, at 650 degrees C and 450 degrees C, the ability for toluene adsorption of GAC were similar. For the electrical heating, the same results were obtained. But the GAC modified with electrical heating had lower capacity of toluene adsorption than microwave modified GAC. The SEM photos showed that thermal modification made the porous structure of modified GAC smoother than original GAC, but the structure of GAC shrink at high temperature. Finally, all the experimental data and SEM photos were analyzed; it indicated that due to the difference of heating mechanism and heat transmission direction, the modified GAC have different characters.

Selection of activated charcoal products for the treatment of poisonings.

OBJECTIVE: To determine if differences exist among currently available activated charcoal products, and if an evaluation of risk versus benefit provides a guide to product selection. DESIGN: National survey by mail. PARTICIPANTS: US manufacturers of activated charcoal products. RESULTS: Six companies market activated charcoal products in ready-to-use containers. The products differ in surface area of charcoal, sorbitol content, and packaging (aqueous or powdered form). No significant differences were noted in the cost of 25- to 30-g units or efficacy based on surface area of activated charcoal. The addition of sorbitol to activated charcoal, particularly at high concentrations, increases the incidence of adverse effects, especially in children. CONCLUSIONS: Although differences do exist among currently marketed activated charcoal products, the clinical significance of these variations is unknown. Based on an evaluation of risks and benefits, any activated charcoal product that does not contain sorbitol appears to be a suitable choice for treating poisoning victims.