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1.
Sci Total Environ ; 773: 144564, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33940700

RESUMEN

Albic soil is a low-yielding soil that is widely distributed in Northeast China. The high viscosity and acidity and the lack of nutrients in the Albic layer limit the growth of crop. In our previous studies, we found that applying biochar as a soil amendment could improve the properties of Albic soil and promote soybean growth. Increases in the nitrogen contents of the soil and the soybeans were key aspects of these improvements. Soybean is a nitrogen-fixing crop, the increase in nitrogen in the Albic soil may have been due to an improvement in biological nitrogen fixation by the soybean with biochar amendment, but the function mechanism was still uncertain. We hypothesized that biochar could improve biological nitrogen fixation of soybean by affecting soybean root growth in the Albic soil. Therefore, we conducted pot experiments with five treatment levels (0, 10, 20, 30, and 40 g·kg-1 biochar) for two years to study how biochar affects the root growth strategy and biological nitrogen fixation of soybean based on its root structure and root nutrient acquisition ability at different stages. The soybean root structure and activity indexes, nodulation ability and nitrogen uptake were measured at different growth stages; in the second year, at the late seed-filling stage, the stable 15N isotope method was used to elucidate the biological nitrogen fixation process. Regarding root structure at the pod-setting stage, biochar resulted in increases in root length density, specific root length, root diameter and specific tip density but a decrease in root tissue mass density at the pod-setting stage. Biochar improved root nutrient acquisition by increasing root activity, root tip number and root-bleeding sap amount. The change in root growth strategy contributed to the promotion of biological nitrogen fixation by the rhizobia that live symbiotically with soybean, thereby increasing crop yield.


Asunto(s)
Suelo , Soja , Carbón Orgánico , China , Fijación del Nitrógeno
2.
Sci Total Environ ; 773: 145110, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33940716

RESUMEN

Although some studies have investigated the impact caused by chemicals used on water treatment (coagulants and oxidants) on cyanobacteria integrity, the isolated effect of shear stress during coagulation is still not fully understood. This study evaluated the impact of different velocity gradients, mixing times, and the addition of powdered activated carbon (PAC) on the integrity of Microcystis aeruginosa, Raphidiopsis raciborskii, and Dolichospermum circinale, known producers of toxin and taste and odor (T&O) compounds. No association was found between R. raciborskii cell lysis and velocity gradient, with or without PAC, demonstrating the high resilience of this taxon to shear stress. In contrast, an association was found for M. aeruginosa at the highest velocity gradient evaluated (1000 s-1) and for D. circinale above the lowest velocity gradient studied (600 s-1). After PAC addition, there was a reduction in the chances of finding M. aeruginosa intact cells above velocity gradient 800 s-1 at 45 s, while D. circinale show cell lysis in all the scenarios expect at 600 s-1 and 10 s of agitation. The additional impact of PAC on cell lysis may lead to more release of metabolites and shows the need to adjust the hydraulic conditions in the rapid mixing stage, especially when more "fragile" cyanobacteria are present. Neither cyanobacterial cell size nor morphology was shown to be relevant to shear stress sensitivity, indicating that cell wall composition might have been an important factor in controlling cell lysis.


Asunto(s)
Cianobacterias , Purificación del Agua , Carbón Orgánico , Cylindrospermopsis , Polvos
3.
Sci Total Environ ; 773: 145645, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33940745

RESUMEN

Biochar application is thought to improve crop yield and reduce N leaching and gas emissions; however, little is known about how field-aged biochar affects fertilizer N retention and N2O emissions. Here, a field microplot experiment is established in the North China Plain at maize season by applying 15N-labeled urea to the sandy loam soil both with (Biochar) and without (Control) application of 3-year field-aged biochar at 12 t ha-1. Overall, 25.6-26.2% of the urea N was taken up by maize aboveground biomass, field-aged biochar did not affect yield or fertilizer N recovery efficiency. After maize harvest, the residual ratio of applied N in the soil profile (0-40 cm) was 21.6 and 20.3% under Control and Biochar treatment, respectively, with an increase of 10.2% in the topsoil (0-20 cm) and decrease of 37.2% in the subsoil (20-40 cm) following biochar amendment, probably due to reduced NO3- leaching. Cumulative N2O emissions and urea N-induced N2O emissions under Control treatment were 2.06 and 0.78 kg N ha-1, and significantly decreased to 1.89 and 0.74 kg N ha-1 after Biochar treatment, respectively. N2O emissions derived from the applied N accounted for 38.0 and 39.4% of the total emissions under Control and Biochar treatment, respectively. N2O emissions from decomposition of soil organic N induced by the priming effect of the applied N was 0.69 and 0.56 kg N ha-1 under Control and Biochar treatment, respectively, contributing 33.7 and 29.7% of the total emissions. Overall, our results suggest that field-aged biochar increased the retention of fertilizer N in the topsoil by reducing NO3- leaching, while effectively reduced N2O emissions from fertilizer N and mineralization of organic N in the sandy loam soil.


Asunto(s)
Fertilizantes , Urea , Agricultura , Carbón Orgánico , China , Óxido Nitroso/análisis
4.
Sci Total Environ ; 773: 145662, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33940750

RESUMEN

Biochar is a highly effective adsorbent for nitroaromatic compounds (NACs), and acts as an electron shuttle that mediates the reduction of NACs. Hence, when biochar is used to mediate NAC reduction, adsorption and reduction will occur simultaneously and affect each other. However, the effect of biochar-mediated NAC reduction on sorption remains unknown. Eight biochars with different physicochemical properties were used to adsorb m-nitrotoluene and mediate its reduction. The results showed that the adsorption of m-nitrotoluene onto the various biochars facilitated its reduction, whereas biochar-mediated reduction retarded and weakened contaminant adsorption, which increased the environmental risk posed by m-nitrotoluene. Nevertheless, biochars with a high graphitization degree and developed porosity not only had a great catalytic ability, but also significantly alleviated the negative effect of reduction on adsorption. This was ascribed to the π-π interaction and pore-filling effect, which played more important roles than the hydrophobic effect in adsorbing the reduction product (m-toluidine) onto the studied biochars during reduction. Furthermore, the methanol extraction results indicated that the eight biochars presented significantly stronger sequestration abilities for adsorbed m-toluidine than for adsorbed m-nitrotoluene. This resulted from the hydrogen bonding and the Lewis acid-base effect between m-toluidine and each biochar, which were absent for m-nitrotoluene. These results suggest that biochars with a high graphitization degree and developed porosity are applicable for mediating reduction-enhancing sequestration of NACs, which could be a novel strategy for NAC remediation.


Asunto(s)
Carbón Orgánico , Tolueno , Adsorción , Tolueno/análogos & derivados
5.
Sci Total Environ ; 773: 145677, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33940757

RESUMEN

Microbial electrosynthesis (MES) holds tremendous large scale energy storage potential. By promoting the bioconversion of carbon dioxide (bicarbonate) into useful chemical commodities, this technique utilizes renewable energy and reduces carbon footprint. However, expensive electrode materials, low current densities, and multiple electrosynthesis products are major challenges to this field. To this end, this study examines a multilayered and conductive MXene structure that was coated on a cost-effective biochar substrate and tested as a MES cathode. These results show this coating yielded improved electrical conductivity, increased charge transfer efficiency, and selective microbial enrichment characteristics, resulting in a 2.3-fold increase in cathodic current production in comparison to the uncoated biochar. Moreover, an increase in active sites improved mass transfer and microbial growth, producing 1.7-fold increase in butyrate in comparison to the uncoated control. Considering that electrode attached microbial communities play a major role in final products, microbial community analyses was completed, suggesting that selective microbial enrichment was promoted as Firmicutes (66%), Proteobacteria (13%), and Bacteroidetes (12%) (i.e., exoelectrogenic and butyrate producing phyla) which were dominant in the MXene-coated biochar biofilm. These results show that biochar modification is an effective technique for achieving selective products through MES.


Asunto(s)
Carbón Orgánico , Microbiota , Dióxido de Carbono , Electrodos
6.
Water Res ; 197: 117079, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33819664

RESUMEN

Along with the rise of biological active granular activated carbon (bGAC) filtration as advanced treatment technology for wastewater treatment plant (WWTP) effluents, the mathematical representation of such systems is gaining increasing importance. This work introduces a model that describes the performance of bGAC-filters for Dissolved Organic Carbon (DOC) removal from a WWTP effluent. The DOC removal within bGAC-filters is accomplished by two mechanisms: adsorptive removal and biological transformation. An appropriate representation of the adsorptive removal requires the DOC to be divided into fictive fractions according to its adsorbability. Likewise, a further DOC classification according to its biodegradability is necessary. Modeling a bGAC-filter then becomes a multi-component adsorption problem, with the simultaneous occurrence of DOC degradation within a biofilm. For dealing with this modeling task, this work integrated the Ideal Adsorbed Solution (IAS) theory into a traditional biofilm model compatible with the Activated Sludge Model (ASM) Framework. For the description of the adsorption dynamics, a Freundlich isotherm for the equilibrium and a pseudo first order model for the kinetics were selected. The biofilm consisted of heterotrophic bacteria able to oxidize DOC using oxygen as electron acceptor. The correctness of the model was evaluated using experimental data from a pilot plant. The predicted DOC breakthrough curve satisfactorily fitted the experimental measurements for empty bed contact times (EBCT) of 6, 12, 24 and 33 min. Moreover, the model predicted the relationship between EBCT, DOC removal and bGAC-filter lifespan. The developed model is the first that combines multi-component adsorption and biofilm kinetics in a wastewater treatment context.


Asunto(s)
Contaminantes Químicos del Agua , Purificación del Agua , Adsorción , Biopelículas , Carbón Orgánico , Cinética , Eliminación de Residuos Líquidos , Contaminantes Químicos del Agua/análisis
7.
Bioresour Technol ; 331: 124934, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33798864

RESUMEN

This study investigates the potential of producing graphene oxide (GO) from biomass via green (comparatively) processing and the impact of graphitization temperature on GO quality. Our findings show that it is possible to convert biomass into highly pyrolytic biochar, followed by shear exfoliation to produce few-layer GO. However, pyrolysis temperature is key in ensuring that the biochar is suited for effective exfoliation. Low temperatures (<1000 °C) would preserve undesirable heterogenous, complex cellular structure of biomass whilst excessive temperatures (≥1300 °C) result in uncontrolled melting, coalescence and loss of functional groups. Results show 1200 °C to be the optimum graphitization temperature for miscanthus, where the resultant biochar is highly aromatic with sufficient functional groups to weaken van der Waals forces, thus facilitating exfoliation to form 6-layer GO with specific surface area of 545.3 m2g-1. This study demonstrates the potential of producing high quality, fit-for-purpose graphene materials from renewable sources.


Asunto(s)
Grafito , Pirólisis , Biomasa , Carbono , Carbón Orgánico , Calor , Temperatura
8.
Bioresour Technol ; 331: 125052, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33812134

RESUMEN

Septic tanks have been widely used for blackwater treatment in developing countries, while high-rate septic tanks with improved methane recovery are yet to be achieved. This study investigated biosolids-derived biochar (synthesized at 300℃, 425℃, and 550℃) as an additive for developing high-rate septic tanks. The experiments were conducted with anaerobic bioreactors operated with synthetic blackwater under septic tank conditions. All biochar amended reactors demonstrated a steady increase in daily methane production for increasing OLR from 0.08 to 3 g COD/L/d. The control reactor showed significant process disturbances at OLRs ≥ 2 g COD/L/d with an accumulation of volatile fatty acids followed by pH drop. At OLR of 3 g COD/L/d, the daily methane production from biochar amended reactors was ~ 4.3 times higher than the control (300 vs. 70 mL per day). Biochar addition established a robust microbiome consisted of a higher abundance of hydrogenotrophic and acetoclastic methanogens and hydrogen-producing fermentative bacteria.


Asunto(s)
Reactores Biológicos , Metano , Anaerobiosis , Biosólidos , Carbón Orgánico , Temperatura
9.
Bioresour Technol ; 331: 125051, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33812137

RESUMEN

A food waste treating system was proposed in this study by combining biochar-assisted high-solid anaerobic digestion and subsequent steam gasification of the digestate. The effect of solid level, biochar dosage in anaerobic digestion on the properties of biogas, syngas, and final biochar products were investigated. Results showed that at a high total solid level and biochar dosage of 25 g/L and 50 g/L, the accumulative methane yield reached 110.3 mL CH4/g VS and 126.7 mL CH4/g VS, respectively. From steam gasification of different digestates under 850 °C for 15 min, a maximum of 34.92 mmol/g for the hydrogen yield and 11.44 MJ/m3 for the higher heating value could be obtained for the syngas. Furthermore, the by-product produced from steam gasification was a nutrient-enriched porous biochar, which was suitable to be used as compost. This study demonstrated a pathway for food waste treating to produce methane-enriched biogas, hydrogen-enriched syngas, and nutrient-enriched biochar.


Asunto(s)
Eliminación de Residuos , Vapor , Anaerobiosis , Carbón Orgánico , Alimentos , Metano , Porosidad
10.
Bioresour Technol ; 331: 125061, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33823487

RESUMEN

Granular biochar made from walnut shells was layered into sand-based constructed wetlands (CWs) to treat simulated mining-impacted water (MIW). The results showed that the biochar media exhibited markedly high capacities for metal binding and acidity neutralization, supported notably better plant growth and mitigated metal transfer from the plant roots to the shoots. The addition of organic liquid wastes (domestic sewage and plant straw hydrolysation broth) stimulated biogenic sulfate reduction after 40 d of adaptation to effectively remove multiple heavy metals in the MIW. The microbial community compositions were prominently regulated by organic carbon, with desirable communities dominated by Cellulomonas and Desulfobulbus formed in the CWs for MIW biotreatment. The role of macrophytes in the CWs in MIW treatment was insignificant and was dependent on operation conditions and metal species. A biochar-packed CW system with liquid organic waste supplementation was effective in metal removal and acidity neutralization of MIW.


Asunto(s)
Metales Pesados , Humedales , Adsorción , Carbón Orgánico , Metales Pesados/análisis , Eliminación de Residuos Líquidos , Aguas Residuales , Agua
11.
Water Sci Technol ; 83(7): 1548-1565, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33843742

RESUMEN

Methylene blue (MB) is the cationic dye that is widely used for coloring cotton, wool, and silk. Since MB is harmful to human beings and toxic to microorganisms, there is the need to find cheap and efficient methods for removal of MB from wastewater prior to disposal into natural waters. In the present study, MB adsorption potential of MgO/AC prepared using a sol-gel-thermal deep-coating method was compared with the activated carbon (AC). The central composite design (CCD) as a method of the response surface methodology (RSM) was applied to minimize the number of runs and process optimization. The characterization of the microporous MgO/AC composite showed that the magnesium oxide nanoparticles were successfully coated on the AC and the BET specific surface area of AC and MgO/AC were 1,540 and 1,246 m2/g, respectively. The MB removal efficiency and the maximum adsorption capacity of AC and MgO/AC were 89.6, 97.5% and 571.7, 642.3 mg/g, respectively under optimum operational conditions of initial dye concentration of 100.9 mg/L, the adsorbent dosage of 69.4 mg/100 mL, pH of 10.2 and contact time of 149.1 min. According to an analysis of variance (ANOVA), the initial dye concentration and its interaction with the other effective factors have a large impact on adsorption efficiency. Furthermore, the mechanism of adsorption followed the Langmuir isotherm (R2 = 0.9935, Δqe = 2.9%) and adsorption kinetics fitted by the pseudo-second-order model (R2 = 0.9967, Δqe = 6.6%). Finally, our results suggest that the prepared MgO/AC is an efficient and promising material for dye wastewater treatment.


Asunto(s)
Azul de Metileno , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico , Colorantes , Humanos , Concentración de Iones de Hidrógeno , Cinética , Óxido de Magnesio , Azul de Metileno/análisis , Contaminantes Químicos del Agua/análisis
12.
Artículo en Inglés | MEDLINE | ID: mdl-33835910

RESUMEN

A beige-pigmented, oxidase-positive bacterial isolate, Wesi-4T, isolated from charcoal in 2012, was examined in detail by applying a polyphasic taxonomic approach. Cells of the isolates were rod shaped and Gram-stain negative. Examination of the 16S rRNA gene sequence of the isolate revealed highest sequence similarities to the type strains of Pseudomonas matsuisoli and Pseudomonas nosocomialis (both 97.3 %). Phylogenetic analyses on the basis of the 16S rRNA gene sequences indicated a separate position of Wesi-4T, which was confirmed by multilocus sequence analyses (MLSA) based on the three loci gyrB, rpoB and rpoD and a core genome-based phylogenetic tree. Genome sequence based comparison of Wesi-4T and the type strains of P. matsuisoli and P. nosocomialis yielded average nucleotide identity values <95 % and in silico DNA-DNA hybridization values <70 %, respectively. The polyamine pattern contains the major amines putrescine, cadaverine and spermidine. The quinone system contains predominantly ubiquinone Q-9 and in the polar lipid profile diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine are the major lipids. The fatty acid contains predominantly C16 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and summed feature 8 (C18 : 1ω7c and/or C18 : 1 ω6c). In addition, physiological and biochemical tests revealed a clear phenotypic difference from P. matsuisoli. These cumulative data indicate that the isolate represents a novel species of the genus Pseudomonas for which the name Pseudomonas carbonaria sp. nov. is proposed with Wesi-4T (=DSM 110367T=CIP 111764T=CCM 9017T) as the type strain.


Asunto(s)
Carbón Orgánico , Filogenia , Pseudomonas/clasificación , Alabama , Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano/genética , Ácidos Grasos/química , Genes Bacterianos , Tipificación de Secuencias Multilocus , Hibridación de Ácido Nucleico , Fosfolípidos/química , Pseudomonas/aislamiento & purificación , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Ubiquinona/química
13.
J Environ Manage ; 289: 112484, 2021 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-33813296

RESUMEN

In this study, the activation with ZnCl2 and heat treatment at 950 °C were performed to polyacrylonitrile-based carbon fiber and phenol resin to prepare two types of activated carbon fibers (ACFs) with different amounts of quaternary nitrogen (N-Q). In order to investigate the effect of chemical properties of ACFs on nitrate adsorption, various experiments and assess were conducted on these samples. The pHpzc of Py-7.0Z4-9.5HT10 and PhR-6.0Z4-9.5HT30 was about 7.1 and 7.0, respectively, and was no significant difference in the results. The C-π sites had a large effect on the amount of nitrate adsorption, and its adsorption capacity was greatest when the solution pH was about 3. However, the adsorption affinity (Ke) of C-π sites was weaker than that of N-Q, and the contribution for adsorption was small when the solution was low concentration or neutral, while the N-Q was the dominant adsorption site of ACFs. It is expected that the N-Q affected the adsorption kinetics, and the higher the amount of N-Q, the faster the adsorption rate. Py-7.0Z4-9.5HT10 had a large amount of C-π sites and N-Q. Therefore, the equilibrium adsorption amount (Qe) of Py-7.0Z4-9.5HT10 was 1.02 mmol/g at solution pH 3, and the adsorption kinetics were also fast.


Asunto(s)
Carbón Orgánico , Nitratos , Adsorción , Fibra de Carbono , Concentración de Iones de Hidrógeno , Cinética , Nitrógeno
14.
J Environ Manage ; 289: 112490, 2021 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-33819651

RESUMEN

The removal of toxic metals from the aquatic ecosystem is one of the most pressing environmental and public health concerns today. A strong potential has recently emerged for the removal of such metals using biochar sorbents. Biosorption technology could make a significant difference in the future. It is a viable and cost-effective alternative to the remediation of toxic pollutants utilizing various biomaterials. In the current study, batch and fixed-bed studies were performed to evaluate the performance of Capsicum annuum L. seeds biochar (CASB) as an alternative material in removing toxic Pb(II) from aqueous solutions. Removal characteristics were investigated by considering the equilibrium and kinetic aspects. Biosorption equilibrium was established within 40 min. The optimum dosage of CASB for Pb(II) removal was determined as 2.0 g L-1. Biosorption data were well predicted by a non-linear Langmuir isotherm model. Monolayer biosorption occurred for CASB with a maximum capacity of 36.43 mg g-1. Biosorption kinetics fitted well with a pseudo-first-order kinetic model. The external mass transfer may control Pb(II) transport mechanism. Dynamic flow mode biosorption and regeneration potential of CASB were also examined. The application of CASB exhibited a 100% removal yield in real apple juice samples spiked with low concentrations of Pb(II). Exhausted points for the CASB packed columns were recorded as 195 and 320 min for simulated wastewater (SW) and synthetic Pb(II) solution, respectively. FTIR, BET, SEM-EDX analysis, and zeta potential measurements were used for the characterization of biochar and assessment of the metal ion-biosorbent interaction mechanism. Finally, our study provides a practical approach for the uptake of Pb(II) ions from contaminated solutions.


Asunto(s)
Plomo , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico , Ecosistema , Concentración de Iones de Hidrógeno , Cinética , Contaminantes Químicos del Agua/análisis
15.
J Environ Manage ; 289: 112439, 2021 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-33819657

RESUMEN

Per- and polyfluoroalkyl substances (PFAS) are a large class of chemicals widely used for many commercial and industrial applications and have resulted in contamination at sites across globally. Pump-and-treat systems, groundwater extraction, and ex situ treatment using granular activated carbon (GAC) are being implemented, either in full or pilot scale, to treat PFAS-impacted groundwater and drinking water. The only current method of regenerating spent GAC is to reactivate it at temperatures greater than 1000 °C, which requires large amounts of energy and is quite expensive. This research focused on development and demonstration of an effective GAC regeneration technology using a solvent-based method for PFAS-laden GAC used in water treatment. Two different organic solvents (ethanol and isopropyl alcohol) with 0.5% and 1.0% ammonium hydroxide (NH4OH) as a base additive were tested to determine the most effective regenerant solution to remove PFAS from the contaminated GAC. Based on column tests using laboratory-contaminated GAC with perfluorooctanoic acid (PFOA) and perfluorooctanoic sulfonate (PFOS), the solvent-base mix (SBM) of ethanol with 0.5% NH4OH was found to be the optimum performing regenerant solution. The GAC life span assessment showed that solvent-regenerated GAC performed similar to virgin GAC without losing its optimal performance of PFAS sorption. Further, the solvent-regenerated GAC showed optimal performance even after four cycles of solvent regenerations tested using the optimum SBM. Average percent removal in laboratory-contaminated GAC using the optimum SBM was 65% and 93% for PFOS and PFOA, respectively. Four field-spent GAC samples were also regenerated using the optimum SBM. Percent removal from these samples was found to be in range of 55%-68%. The type of GAC used, level of contamination and type of PFAS present, water type and quality, and the presence of co-contaminants may have influenced the removal capacity. Distillation experiments have shown that it is feasible to concentrate the spent solvent prior to disposal, which reduces the amount of PFAS-contaminated solvent waste produced in regeneration cycles.


Asunto(s)
Fluorocarburos , Contaminantes Químicos del Agua , Purificación del Agua , Carbón Orgánico , Fluorocarburos/análisis , Solventes , Tecnología , Contaminantes Químicos del Agua/análisis
16.
Bioresour Technol ; 332: 125086, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33838451

RESUMEN

An iron-based composite adsorbent with biochar as the support was prepared by coprecipitation and the sol-gel method. Both single-iron-based modified biochar without doping with other metals and iron-based modified biochar doped with multiple metals (Ce, Cu, Co, Mn) were synthesised. The adsorption kinetics were analysed, and temperature-programmed desorption measurements were performed to reveal the inherent difference in mechanism between the oxidation and adsorption of Hg0 by the modified biochar and to elucidate the key mechanism of Hg0 removal. The results show that the removal of Hg0 by the modified biochar mainly includes adsorption and oxidation processes. The adsorption process is divided into two stages, external and internal mass transfer, both of which occur via multilayer adsorption. HgO and Hg-OM are the main forms of Hg0 present on the modified biochar surface. Doped metal oxides can play a synergistic role in enhancing the mercury removal performance of the modified biochar.


Asunto(s)
Mercurio , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico , Hierro , Contaminantes Químicos del Agua/análisis
17.
Bioresour Technol ; 332: 125109, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33839508

RESUMEN

Anaerobic digestion (AD) systems with high substrate concentrations are characterized by high viscosity, which affects material and energy transfer efficiencies, thereby influencing methane production efficiency. In this study, adding granular activated carbon (GAC) and increasing the temperature decreased the viscosity by 4.56-10.19% and 27.13-28.85%, respectively, and improved AD efficiency. Adding GAC and increasing the temperature enhanced the methane yields by 34.37-38.15% and 25.60-28.31%, respectively. Distance-based redundancy analysis showed that the viscosity, temperature, and GAC had the greatest effects on the composition of the microbial community. The dominant bacteria in the medium-temperature AD system at the phylum level belonged to Firmicutes, Bacteroidetes, and Euryarchaeota. In addition to the dominant bacteria in the medium-temperature AD system, the thermophilic phylum Thermotogae was abundant in the high-temperature AD system. Moreover, the relative abundance of Euryarchaeota, which contained most of the methanogens, was higher in the high-temperature AD system than in the medium-temperature AD system.


Asunto(s)
Carbón Orgánico , Metano , Anaerobiosis , Reactores Biológicos , Temperatura , Viscosidad , Zea mays
18.
Bioresour Technol ; 332: 125102, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33853722

RESUMEN

Environmental pollutants including emerging contaminants are a growing concern worldwide. Organic wastes, such as food waste, compost, animal manure, crop residues, and sludge are generally used as feedstock. The conventional treatment methodologies (primary and secondary treatment process) do not mitigate or remove pollutants effectively. Hence, an effective, low-cost, and environmentally friendly tertiary treatment process is an urgent need. Biochar finds interesting applications in environmental processes like pollutant remediation, greenhouse gas mitigation, and wastewater treatment. Studies have shown that different types of adsorbents (biochars) like, native and engineered biochar are being used in the removal or mitigation of heavy metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, pesticides, disinfectants, polychlorinated dibenzofurans, and dibenzo-p-dioxins from contaminated sites for environmental management. The review discusses ample studieswhich can offer solutions for environmental sustenance and managementand the emerging trends and techno-economic prospectives of biochar for sustainable environmental management.


Asunto(s)
Bifenilos Policlorados , Hidrocarburos Policíclicos Aromáticos , Eliminación de Residuos , Contaminantes del Suelo , Animales , Carbón Orgánico , Alimentos , Bifenilos Policlorados/análisis , Hidrocarburos Policíclicos Aromáticos/análisis , Contaminantes del Suelo/análisis
19.
Bioresour Technol ; 332: 125130, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33857865

RESUMEN

Codigestion is an emerging approach to improve wastewater sludge biogas production and valorize food waste (FW). This study explores FW-derived biochar as a codigestion amendment for the first time and reports a matrix experiment using four diverse biochar amendments (mixed food waste, pinewood, bonechar, unamended control) across four FW types (vegetable, rice, chicken, mixed). It demonstrated that biochar derived from mixed FW can greatly improve the performance of biogas production and yield relative to unamended control and other biochars. The mixed food waste (MFW) biochar amendment led to 34.5%, 35.6%, and 47.5% increase in methane production from mixed FW compared to biochars made of wood, bone and non-amendment control, and the maximum methane production rate of MFW biochar reactors could be up to 6.7-9.9 times of the control. These results suggest that a more circular utilization of FW by integrating biochar production with codigestion can bring great benefits to FW management.


Asunto(s)
Alimentos , Eliminación de Residuos , Anaerobiosis , Reactores Biológicos , Carbón Orgánico , Digestión , Metano , Aguas del Alcantarillado
20.
Bioresour Technol ; 332: 125070, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33878542

RESUMEN

The influence of biomass cellulosic content on biochar nanopore structure and adsorption capacity in aqueous phase was scarcely reported. Commercial cellulose (100% cellulose), oil palm frond (39.5% cellulose), and palm kernel shell (20.5% cellulose) were pyrolyzed AT 630 °C, characterized and tested for the adsorption of iodine and organic contaminants. The external surface area and average pore size increased with cellulosic content, where commercial cellulose formed biochar with external surface area of 95.4 m2/g and average pore size of 4.1 nm. The biochar from commercial cellulose had the largest adsorption capacities: 371.40 mg/g for iodine, 86.7 mg/L for tannic acid, 17.89 mg/g for COD and 60.35 mg/g for colour, while biochar from palm kernel shell had the least adsorption capacities. The cellulosic content reflected the differences in biochar nanopore structure and adsorption capacities, signifying the suitability of highly cellulosic biomass for producing biochar to effectively treat wastewater.


Asunto(s)
Nanoporos , Adsorción , Biomasa , Carbón Orgánico
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