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1.
Bioresour Technol ; 302: 122892, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32028149

RESUMO

The impact of algal biochar addition on mesophilic and thermophilic anaerobic co-digestion of algal biomass and food waste was investigated with a focus on semi-continuous operations and functional microbial communities. Under batch co-digestion, the highest co-digestion synergy was observed for a mixture of 25% food waste and 75% algal biomass. During semi-continuous co-digestion of 25% food waste-75% algal biomass mixture, biochar amended digesters exhibited a 12-54% increase in average methane yield (275.8-394.6 mL/gVS) compared to the controls. Elevated temperature induced narrow distributions of volatile fatty acids (VFAs) by inhibiting the production of branched VFAs. Genus Proteiniphilum was selectively enriched by 3.2 folds in mesophilic digesters with biochar amendment while genus Defluviitoga was selectively enriched in thermophilic digesters due to elevated temperature. Methanogenic communities were significantly different in mesophilic and thermophilic digesters. Biochar amendment contributed to shifts in the predominant methanogens leading to a more balanced state of two methanogenic pathways.


Assuntos
Microbiota , Eliminação de Resíduos , Anaerobiose , Biomassa , Reatores Biológicos , Carvão Vegetal , Alimentos , Metano , Esgotos , Temperatura Ambiente
2.
Bioresour Technol ; 301: 122780, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31978702

RESUMO

In this study, horticultural waste (HW) and sewage sludge (SS) with different mass ratios were co-gasified with steam at different temperatures to investigate the product distribution, gas synergistic interaction, and optimal design for gas products from co-gasification process. Results showed that with the increase of SS ratio in blends, the H2 content was increased and the syngas yield was decreased. The synergistic interaction was more significant at higher temperature which promoted the H2 production probably due to the reduction and steam oxidation of Fe species in SS during co-gasification process. The optimized highest effective gas content (82.92 vol%) was achieved with the highest HHV (11.40 MJ/m3) at the conditions of SS ratio = 0.80 and temperature of 900 °C. It indicates that steam co-gasification of HW and SS is a promising technology to produce desired syngas towards a clean and efficient waste management process.


Assuntos
Vapor , Gerenciamento de Resíduos , Gases , Esgotos , Temperatura Ambiente
3.
Sci Total Environ ; : 135289, 2019 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-31839313

RESUMO

Alkaline activated materials such as geopolymers and cementitious materials derived from pozzolanic reactions offer several advantages over the currently widely used Portland cement, especially in terms of environmental sustainability and physiochemical properties. However due to the need of an alkaline activator, such as NaOH or KOH, which result in high production cost and requires skilled personnel, they have not been deeply explored and put to use. Here in this study, wood fly ash, a by product of wood combustion is used as an alternative source of alkaline activator for producing such alkaline activated materials along with coal fly ash, where the resulting geopolymer-cementitious hybrid (GCH) was characterized physico-chemically through electron microscopy, BET, FTIR, XRF & XRD. However, the leaching of heavy metals from the wood fly ash could potentially pose an environmental concern. Therefore, the focus of this study is to reduce the leachability factor of wood fly ash involved in the alkaline activated process and to understand the effects of various factors (i.e. water-to-ash ratio (w/a), method of curing, type of alkaline activator and ash sieving) on the leaching process, through factorial experimental analysis. The leaching patterns of various elements such as Pb, Zn, Cr, As. Hg, Se were studied along with the contributing factors and results showed that the dominant factor was the type of alkaline activator (i.e. Wood Fly Ash versus Na2SiO3). By comparing the leaching data to Denmark's leaching criteria, the best performing GCH sample was found to be 0.3DI_p_s (0.3 represents the w/a ratio, "p" denotes that samples were precured and "s" denotes sieving).

4.
Bioresour Technol ; 288: 121597, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31176202

RESUMO

To find the optimal operation parameters and provide an explanation of methanogenic pathway for methane production in mesophilic (35 °C) and thermophilic (55 °C) anaerobic digestion (MAD, TAD) of soybean curd residue (SCR), MAD and MAD were contrastively investigated for 95 days. The maximum available OLR was identified as 3.3 gVS/L for both MAD and TAD. Compared to MAD, TAD exhibited a 20% higher average methane yield (0.591 L/gVS) and a 7.5% higher volatile solids removal efficiency (74.1 ±â€¯10.4%). Bacterial phyla Bacteroidetes, Firmicutes and Proteobacteria dominated in MAD digesters while genus Defluviitoga was selectively enriched in TAD digesters due to higher temperature and organic loading pressure. Principal coordinates analysis of methanogen community showed that both temperature and OLR were crucial environmental variables shifting the taxonomic patterns of the methanogens. The enriched methanogen genus Methanothermobacter (93%) with a hydrogenotrophic methanogenic pathway had a close correlation with the TAD performance.


Assuntos
Reatores Biológicos , Soja , Anaerobiose , Metano , Esgotos , Temperatura Ambiente
5.
Bioresour Technol ; 285: 121333, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31004947

RESUMO

A three-stage anaerobic digester setup was configured and evaluated for enhanced methane production during co-digestion of food waste and waste activated sludge and the corresponding bacterial and methanogen communities were characterized. Results showed that the average methane yield (0.496 L/gVS) in the three-stage digester was 13-52% higher than that of one- and two-stage digesters. Compared to controls, an increase of 12-47% in volatile solids reduction was achieved in the three-stage digester (69.3 ±â€¯6.7%). Bacterial phyla Proteobacteria, Firmicutes and Bacteroidetes dominated in one-, two- and three-stage digester while genera Pseudomonas, Tissierella, and Petrimonas were selectively enriched in the three-stage digester due to functional segregation. Taxonomic analysis identified 8 dominant methanogen genera, of which Methanosarcina, Methanosaeta, Methanobacterium and Methanolinea collectively accounted for 80%. With increasing OLR and digester stage number, the dominant methanogenic pathway shifted from hydrogenotrophic pattern to acetoclastic pattern and reached a final synergy of these two.


Assuntos
Archaea , Esgotos , Anaerobiose , Bactérias , Reatores Biológicos , Metano
6.
Int J Mol Sci ; 20(3)2019 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-30696017

RESUMO

Dry mouth or xerostomia is a frequent medical condition among the polymedicated elderly population. Systemic pilocarpine is included in the first line of pharmacological therapies for xerostomia. However, the efficacy of existing pilocarpine formulations is limited due to its adverse side effects and multiple daily dosages. To overcome these drawbacks, a localized formulation of pilocarpine targeting the salivary glands (SG) was developed in the current study. The proposed formulation consisted of pilocarpine-loaded Poly(lactic-co-glycolic acid) (PLGA)/poly(ethylene glycol) (PEG) nanofiber mats via an electrospinning technique. The nanofiber mats were fully characterized for their size, mesh porosity, drug encapsulation efficiency, and in vitro drug release. Mat biocompatibility and efficacy was evaluated in the SG organ ex vivo, and the expression of proliferation and pro-apoptotic markers at the cellular level was determined. In vivo short-term studies were performed to evaluate the saliva secretion after acute SG treatment with pilocarpine-loaded nanofiber mats, and after systemic pilocarpine for comparison purposes. The outcomes demonstrated that the pilocarpine-loaded mats were uniformly distributed (diameter: 384 ± 124 nm) in a highly porous mesh, and possessed a high encapsulation efficiency (~81%). Drug release studies showed an initial pilocarpine release of 26% (4.5 h), followed by a gradual increase (~46%) over 15 d. Pilocarpine-loaded nanofiber mats supported SG growth with negligible cytotoxicity and normal cellular proliferation and homeostasis. Salivary secretion was significantly increased 4.5 h after intradermal SG treatment with drug-loaded nanofibers in vivo. Overall, this study highlights the strengths of PLGA/PEG nanofiber mats for the localized daily delivery of pilocarpine and reveals its potential for future clinical translation in patients with xerostomia.


Assuntos
Sistemas de Liberação de Medicamentos , Nanofibras/química , Pilocarpina/administração & dosagem , Pilocarpina/farmacologia , Glândulas Salivares/fisiopatologia , Animais , Materiais Biocompatíveis/farmacologia , Compartimento Celular , Morte Celular/efeitos dos fármacos , Liberação Controlada de Fármacos , Feminino , Injeções Intradérmicas , Antígeno Ki-67/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos ICR , Nanofibras/ultraestrutura , Saliva/metabolismo , Glândulas Salivares/efeitos dos fármacos , Resultado do Tratamento
7.
J Hazard Mater ; 361: 237-244, 2019 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-30199823

RESUMO

In this work, we firstly examined the technical feasibility of geopolymer synthesis from the coal fly ash with high iron oxide (48.84 wt.%) and calcium oxide (22.15 wt.%) contents. The heat resistance of geopolymer was represented by the dry weight loss which ranged from 2.5 to 4.9% and was better than that (11.7%) of OPC. However, the high iron oxide content made the acid resistance (13-14%) of geopolymer inferior to OPC. The economics of geopolymer production changes significantly upon the variation in the arrangement of material use and geopolymer price. The costs of Na2SiO3 and NaOH and the benefit of geopolymer selling were the major factors affecting the economic feasibility of geopolymer production. When the Na2SiO3 price was around 400 USD/ton, the geopolymer production will be profitable even if the geopolymer price was as low as 50 USD/ton. It is possible to improve the economics of geopolymer production by varying the arrangement of material use while not impairing the performance of geopolymer.

8.
J Hazard Mater ; 363: 127-137, 2019 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-30308351

RESUMO

This study assessed the developmental toxicities of water-soluble carbon black wastes (CBW) extract (1:5, w/v) in zebrafish embryos (Danio rerio). Acute embryonic toxicity was performed following OECD guideline 236. Analysis using ICP-OES revealed that nickel (Ni) and vanadium (V) were predominant in CBW. Embryos exposed to CBW exhibited developmental delay, along with pericardial and yolk sac edemas. Malformed heart chambers were found in the CBW-exposed embryos and heart rates were significantly reduced since 48 h post fertilization (hpf). After RT-qPCR analysis, two cardiac forming-related genes, amhc and nppa responsible for atrial cardiac myofibril assembly and cardiac muscle cell proliferation, were up-regulated after 96 hpf. The increased mortality and delayed yolk-sac development appeared related to CBW-induced decrease in pH to about 5.5. Individual treatments of Ni and V did not cause identical toxic effects as CBW showed. At 100 ppm, V had a pH of approximately 5.5, causing developmental delay and pericardial edema in zebrafish embryos. At the same pH, combined Ni and V induced morphological anomalies and reduced heart rates similar to CBW-exposed embryos. Conclusively, this study demonstrates that environmental runoff is a serious concern, and thus, CBW incineration bottom ash should be treated carefully before disposal in landfills.

9.
J Hazard Mater ; 365: 178-185, 2019 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-30439617

RESUMO

This study systematically investigated the biochar toxicity from the in vitro tests involving the use of human liver and lung cell lines, as well as in vivo tests using Drosophila melanogaster (fruit fly). Biochars used in this study were produced from vegetable waste, pine cone and their mixture (1:1 by weight) at two representative temperatures (200 and 500 °C). Two common toxicant groups in biochar, heavy metals (HM) and polycyclic aromatic hydrocarbons (PAHs) contents, were detected for clarification of the relationship between their toxicity behaviors and biochar bulk characteristics. The results showed that (1) no HMs can be found in the biochar if HMs are absence in their feedstock (2) PAHs were formed during the pyrolysis no matter what type of biomss used, but the concentration is low that can be acceptable for soil legislative criteria (3) biochars had limited impact to the viability of flies, but inhibited the growth of the cells (4) the low leaching potential of HMs and PAHs (total 16 USEPA) in the studied biochars may not be the major reason which put the harm to the cell, more effort on the identification need to be done. This work can provide a new picture to the biochar researchers for better understanding of the two faces of biochar.

10.
J Hazard Mater ; 365: 684-694, 2019 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-30472454

RESUMO

Compared to pyrolysis biochar (PBC), gasification biochar (GBC) differs in both composition and surface functionalities due to the use of an oxidizing purging gas. This work compares the effect of using PBC and GBC as soil amendments on the soil properties, trace metal bioavailability, soil microbial activity, and soil dissolved organic matter (DOM). Biochar-driven reduction of bioavailable metals does not necessarily result in a positive impact on the soil microbial growth. The DOM in the soil was strongly related to the soil microbial activity, as revealed by the strong correlation between the soil dehydrogenase activity (DHA) and soil dissolved organic carbon (r = 0.957, p < 0.01). Three identified fluorescent components (C1, C2, C3) in the soil DOM were closely associated with the soil microbial activity, for instance, with a clear positive correlation between the soil DHA and C1 (r = 0.718, p < 0.05) and a significant negative correlation between the total bacterial fatty acid methyl ester content and C3 (r = -0.768, p < 0.05). The bioavailability of Cd and Zn is not only related to the pH and surface functionalities of the biochar, but also to its aromatic carbon and inorganic mineral composition. This study further demonstrates that a fluorescence excitation-emission matrix coupled with parallel factor analysis is a useful tool to monitor changes in the soil quality after application of biochar, which is greatly relevant to the soil biota.

11.
J Pharm Sci ; 108(5): 1736-1745, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30552956

RESUMO

Surface-modified poly(d,l-lactic-co-glycolic acid) PLGA nanoparticles (NPs) were fabricated via nanoprecipitation for obtaining therapeutic concentration of paclitaxel (PTX) in brain tumor. The cellular uptake and cytotoxicity of NPs were evaluated on C6 glioma cells in vitro, and BALB/c mice were used to study the brain penetration and biodistribution upon intravenous administration. Results showed that by finely tuning nanoprecipitation parameters, PLGA NPs coated with surfactants with a size around 150 nm could provide a sustained release of PTX for >2 weeks. Surface coatings could increase cellular uptake efficiency when compared with noncoated NPs, and d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) showed the most significant enhancement. The in vivo evaluation of TPGS-PLGA NPs showed amplified accumulation (>800% after 96 h) of PTX in the brain tissue when compared with bare NPs and Taxol®. Therefore, PLGA-NPs with PLGA-TPGS coating demonstrate a promising approach to efficiently transport PTX across blood-brain barrier in a safer manner, with the advantages of easy formulation, lower production cost, and higher encapsulation efficiency.

12.
J Hazard Mater ; : 121147, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-32145924

RESUMO

Biochar is newly proposed as an innovative and cost-effective material to capture CO2. In this study, biochar was produced from feedstock mixtures of food waste and wood waste (i.e., 20%:80% WFW20, 30%:70% WFW30 and 40%:60% WFW40) by gasification. The two biochar adsorbents containing the highest percentage of food waste, i.e., WFW40-K and WFW40-KC, were activated by KOH and KOH + CO2, respectively. The biochar adsorbents were then tested for CO2 adsorption at room temperature of 25 °C by using a volumetric sorption analyzer. The WFW20 showed the highest CO2 adsorption capacity, while higher percentage of food waste in the feedstock was unfavorable for the CO2 adsorption. The presence of N and S on the biochar surface was the primary contributor to the high CO2 uptake on WFW20. The development of micropores by KOH activation significantly increased the CO2 adsorption on WFW40-K, but KOH + CO2 activation could not further increase the development of micropores and subsequent CO2 adsorption. Moreover, WFW40-K showed >99% recyclability during 10 consecutive adsorption-desorption cycles. The biochars derived from biowaste (food waste and wood waste) could be effective adsorbents for CO2 capture by providing green solution for food waste recycling.

14.
Adv Drug Deliv Rev ; 132: 104-138, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30415656

RESUMO

With the advancement in medical science and understanding the importance of biodistribution and pharmacokinetics of therapeutic agents, modern drug delivery research strives to utilize novel materials and fabrication technologies for the preparation of robust drug delivery systems to combat acute and chronic diseases. Compared to traditional drug carriers, which could only control the release of the agents in a monotonic manner, the new drug carriers are able to provide a precise control over the release time and the quantity of drug introduced into the patient's body. To achieve this goal, scientists have introduced "programmed" and "on-demand" approaches. The former provides delivery systems with a sophisticated architecture to precisely tune the release rate for a definite time period, while the latter includes systems directly controlled by an operator/practitioner, perhaps with a remote device triggering/affecting the implanted or injected drug carrier. Ideally, such devices can determine flexible release pattern and intensify the efficacy of a therapy via controlling time, duration, dosage, and location of drug release in a predictable, repeatable, and reliable manner. This review sheds light on the past and current techniques available for fabricating and remotely controlling drug delivery systems and addresses the application of new technologies (e.g. 3D printing) in this field.


Assuntos
Sistemas de Liberação de Medicamentos , Liberação Controlada de Fármacos , Humanos
15.
Environ Pollut ; 242(Pt B): 1108-1118, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30096549

RESUMO

Gasification and pyrolysis technologies have been widely employed to produce fuels and chemicals from solid wastes. Rare studies have been conducted to compare the particulate emissions from gasification and pyrolysis, and relevant inhalation exposure assessment is still lacking. In this work, we characterized the particles emitted from the gasification and pyrolysis experiments under different temperatures (500, 600, and 700 °C). The collection efficiencies of existing cyclones were compared based on particle respiratory deposition. Sensitivity analysis was conducted to identify the most effective design parameters. The particles emitted from both gasification and pyrolysis process are mainly in the size range 0.25-1.0 µm and 1.0-2.5 µm. Particle respiratory deposition modelling showed that most particles penetrate deeply into the last stage of the respiratory system. At the nasal breathing mode, particles with sizes ranging from 0.25 to 1.0 µm account for around 91%, 74%, 76%, 90%, 84%, and 79% of the total number of particles that deposit onto the last stage in the cases of 500 °C gasification, 600 °C gasification, 700 °C gasification, 500 °C pyrolysis, 600 °C pyrolysis, and 700 °C pyrolysis, respectively. At the oral breathing mode, particles with sizes ranging from 0.25 to 1.0 µm account for around 92%, 77%, 79%, 91%, 86%, and 81% of the total number of particles that deposit onto the last stage in the six cases, respectively. Sensitivity analysis showed that the particle removal efficiency was found to be most sensitive to the cyclone vortex finder diameter (D0). This work could potentially serve as the basis for proposing health protective measures against the particulate pollution from gasification and pyrolysis technologies.


Assuntos
Poluentes Atmosféricos/análise , Modelos Teóricos , Material Particulado/análise , Sistema Respiratório/metabolismo , Poluição do Ar/prevenção & controle , Biomassa , Humanos , Exposição por Inalação/prevenção & controle , Tamanho da Partícula , Resíduos Sólidos , Gerenciamento de Resíduos/métodos
16.
Adv Drug Deliv Rev ; 132: 296-332, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29990578

RESUMO

3D bioprinting is a pioneering technology that enables fabrication of biomimetic, multiscale, multi-cellular tissues with highly complex tissue microenvironment, intricate cytoarchitecture, structure-function hierarchy, and tissue-specific compositional and mechanical heterogeneity. Given the huge demand for organ transplantation, coupled with limited organ donors, bioprinting is a potential technology that could solve this crisis of organ shortage by fabrication of fully-functional whole organs. Though organ bioprinting is a far-fetched goal, there has been a considerable and commendable progress in the field of bioprinting that could be used as transplantable tissues in regenerative medicine. This paper presents a first-time review of 3D bioprinting in regenerative medicine, where the current status and contemporary issues of 3D bioprinting pertaining to the eleven organ systems of the human body including skeletal, muscular, nervous, lymphatic, endocrine, reproductive, integumentary, respiratory, digestive, urinary, and circulatory systems were critically reviewed. The implications of 3D bioprinting in drug discovery, development, and delivery systems are also briefly discussed, in terms of in vitro drug testing models, and personalized medicine. While there is a substantial progress in the field of bioprinting in the recent past, there is still a long way to go to fully realize the translational potential of this technology. Computational studies for study of tissue growth or tissue fusion post-printing, improving the scalability of this technology to fabricate human-scale tissues, development of hybrid systems with integration of different bioprinting modalities, formulation of new bioinks with tuneable mechanical and rheological properties, mechanobiological studies on cell-bioink interaction, 4D bioprinting with smart (stimuli-responsive) hydrogels, and addressing the ethical, social, and regulatory issues concerning bioprinting are potential futuristic focus areas that would aid in successful clinical translation of this technology.


Assuntos
Bioimpressão , Impressão Tridimensional , Medicina Regenerativa , Engenharia Tecidual , Humanos
17.
J Control Release ; 285: 212-229, 2018 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-30009891

RESUMO

Convection enhanced delivery is promising to overcome the blood brain barrier. However, the treatment is less efficient in clinic due to the rapid elimination of small molecular drugs in brain tumours. In this study, numerical simulation is applied to investigate the convection enhanced delivery of liposome encapsulated doxorubicin under various conditions, based on a 3-D brain tumour model that is reconstructed from magnetic resonance images. Treatment efficacy is evaluated in terms of the tumour volume where the free doxorubicin concentration is above LD90. Simulation results denote that intracerebral infusion is effective in increasing the interstitial fluid velocity and inhibiting the fluid leakage from blood around the infusion site. Comparisons with direct doxorubicin infusion demonstrate the advantages of liposomes in enhancing the doxorubicin accumulation and penetration in the brain tumour. Delivery outcomes are determined by both the intratumoural environment and properties of therapeutic agents. The treatment efficacy can be improved by either increasing the liposome solution concentration and infusion rate, administrating liposomes in the tumour with normalised microvasculature density, or using liposomes with low vascular permeability. The delivery is less sensitive to liposome diffusivity in the examined range (E-11~E-7 cm2/s) as convective transport is dominative in determining the liposome migration. Drug release rate is able to be optimised by keeping a trade-off between enhancing the drug penetration and providing sufficient free doxorubicin for effective cell killing. Results from this study can be used to improve the regimen of CED treatments.


Assuntos
Antibióticos Antineoplásicos/farmacocinética , Neoplasias Encefálicas/tratamento farmacológico , Encéfalo/metabolismo , Doxorrubicina/análogos & derivados , Algoritmos , Antibióticos Antineoplásicos/administração & dosagem , Transporte Biológico , Encéfalo/efeitos dos fármacos , Neoplasias Encefálicas/metabolismo , Convecção , Difusão , Doxorrubicina/administração & dosagem , Doxorrubicina/farmacocinética , Liberação Controlada de Fármacos , Humanos , Modelos Biológicos , Polietilenoglicóis/administração & dosagem , Polietilenoglicóis/farmacocinética
18.
Adv Drug Deliv Rev ; 132: 270-295, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30055210

RESUMO

Bioprinted skin tissue has the potential for aiding drug screening, formulation development, clinical transplantation, chemical and cosmetic testing, as well as basic research. Limitations of conventional skin tissue engineering approaches have driven the development of biomimetic skin equivalent via 3D bioprinting. A key hope for bioprinting skin is the improved tissue authenticity over conventional skin equivalent construction, enabling the precise localization of multiple cell types and appendages within a construct. The printing of skin faces challenges broadly associated with general 3D bioprinting, including the selection of cell types and biomaterials, and additionally requires in vitro culture formats that allow for growth at an air-liquid interface. This paper provides a thorough review of current 3D bioprinting technologies used to engineer human skin constructs and presents the overall pipelines of designing a biomimetic artificial skin via 3D bioprinting from the design phase (i.e. pre-processing phase) through the tissue maturation phase (i.e. post-processing) and into final product evaluation for drug screening, development, and drug delivery applications.


Assuntos
Bioimpressão , Impressão Tridimensional , Pele/citologia , Materiais Biomiméticos/química , Humanos , Engenharia Tecidual
19.
Sci Total Environ ; 640-641: 704-713, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29870947

RESUMO

This study is a comparison of the effect of biochar produced by bioenergy systems, via the pyrolysis and gasification processes, on the immobilization of metals/metalloids in soil. Because the processes for these two techniques vary, the feedstocks undergo different heating regimens and, as a result, their respective char products exhibit different physico-chemical properties. Therefore, this study focuses on (1) the characterization of derivative biochar from the bioenergy system to understand their features and (2) an exploration of various biochar impacts on the mobility of As and Pb in contaminated soil. The results showed bioenergy biochars (BBCs) performed well in mitigating Pb extractability (1 M ammonium acetate) with a Pb immobilization >80%, but unfavorably mobilized the bioavailable As, likely because of electrostatic repulsion and ion exchange competition. The BBC surface functional group would chemically bond with the As and remain stable against the pH change. An increment in aromatic carbon would effectively enhance cation-π interaction for Pb immobilization. Nevertheless, an amendment with richer condensed structure and higher inorganic minerals (Ca2+, K+, Mg2+, and Na+) can lead to better performance in retaining Pb.

20.
J Hazard Mater ; 357: 63-72, 2018 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-29864689

RESUMO

This study evaluated the potential of utilising sewage sludge incineration ash as a land reclamation material. Toxicity assessment of the leachate of the ash was carried out for both terrestrial and marine organisms. Both the fruit fly Drosophila melanogaster and barnacle Amphibalanus amphitrite showed that both bottom and fly ash leached at liquid-to-solid (L/S) ratio 5 did not substantially affect viabilities. The leachate carried out at L/S 10 was compared to the European Waste Acceptance Criteria and the sewage sludge ashes could be classified as non-hazardous waste. The geotechnical properties of the sewage sludge ash were studied and compared to sand, a conventional land reclamation material, for further evaluation of its potential as a land reclamation material. It was found from direct shear test that both bottom and fly ashes displayed similar and comparable shear strength to that of typical compacted sandy soil based on the range of internal friction angle obtained. However, the consolidation profile of bottom ash was significantly different from sand, while that of fly ash was more similar to sand. Our study showed that the sewage sludge ash has the potential to be used as a land reclamation material.


Assuntos
Incineração , Esgotos , Resíduos Sólidos , Poluentes Químicos da Água/toxicidade , Animais , Drosophila melanogaster/efeitos dos fármacos , Recuperação e Remediação Ambiental , Feminino , Masculino , Thoracica/efeitos dos fármacos
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