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1.
Bioresour Technol ; 300: 122741, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31956058

RESUMO

Algal bioremediation becoming most fascinating to produce biomass as biofuels feedstock while remediating wastes, also improving carbon-footprint through carbon capturing and utilization (CCU) technology. Non-algae process however offers effective treatment but metabolic CO2 emission is major drawback towards sustainable bioprocess. Mixotrophic cultivation strategy (MCS) enables to treat organic and inorganic wastes which broadly extend microalgae application towards cleaner and sustainable bioeconomy. Latest focus of global think-tanks to encourage bioprocess holding promise of sustainability via CCU ability as important trait. Several high CO2 emitting industries forced to improve their carbon-footprints. MCS driven microalgae treatment could be best solution for those industries. This review covers recent updates on MCS applications for waste-to-value (biofuels) and environment remediation. Moreover, recommendations to fill knowledge gaps, and commercial algal biofuel could be cost-effectiveness and sustainable technology for biocircular economy if fuelled by waste streams from other industries.


Assuntos
Recuperação e Remediação Ambiental , Microalgas , Biocombustíveis , Biomassa , Análise Custo-Benefício
2.
Bioresour Technol ; 298: 122468, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31839494

RESUMO

The difficulty of separating the powdered biochar from the environmental medium may lead to secondary pollution and hinder the large-scale application of biochar as an adsorbent. An effective strategy to solve this bottleneck is to introduce transition metals and their oxides into the biochar matrix, creating easily separable magnetic biochar. Magnetic biochar is also effective for the removal of pollutants from aqueous solution. This review comprises a systematic analysis of 109 papers published in recent years (From 2011 to June 2019), and summarises the synthetic methods and raw materials required for magnetic biochar preparation. The basic physicochemical properties of magnetic biochar are expounded, together with findings from relevant studies, and the application of magnetic biochar as an adsorbent or catalyst in environmental remediation are summarised. Other applications of magnetic biochar are also discussed. Finally, some constructive suggestions are given for the future direction of magnetic biochar research.


Assuntos
Recuperação e Remediação Ambiental , Poluentes do Solo , Adsorção , Carvão Vegetal , Poluição Ambiental , Fenômenos Magnéticos , Solo
3.
Ecotoxicol Environ Saf ; 188: 109888, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31706242

RESUMO

Eutrophication can induce hypoxia/anoxia and rich organic matter at the sediment-water interface in surface waters. When eutrophic waters are impacted with mercury (Hg) pollution, methylmercury (MeHg) production ability (MPA) of surface sediment would increase and more MeHg might be produced. To tackle this risk, this study firstly collected samples of surface sediment and overlying water from a typical eutrophic lake-Taihu Lake. Then from a sediment-water simulation system, we demonstrated that eutrophic waters were able to methylate Hg spontaneously, and that sediment is the major Hg sink in the system. After the addition of HgCl2 solution (approximately 1 mg L-1 in the slurry), MeHg concentrations in the sediment increased by 11.7 times after 48 h. The subsequent column experiments proved that O2 nanobubbles could significantly decrease the MPA of surface sediment, by up to 48%. Furthermore, we found that O2 nanobubbles could remediate anoxia mainly by increasing dissolved oxygen (from 0 to 2.1 mg L-1), oxidation-reduction potentials (by 37% on average), and sulfate (by 31% on average) in the overlying water. In addition, O2 nanobubbles could also help decrease organic matter concentration, as was revealed by the decline of dissolved organic carbon in the overlying water (by up to 57%) and total organic carbon in surface sediment (by up to 37%). The remediation of anoxia and reduction of organic matter could contribute to the decrease of hgcA gene abundance (by up to 86%), and thus result in the reduction of MPA after the addition of O2 nanobubbles. This study revealed the risk of MeHg production in case Hg pollution occurs in eutrophic waters and proposed a feasible solution for MeHg remediation.


Assuntos
Recuperação e Remediação Ambiental/métodos , Sedimentos Geológicos/química , Compostos de Metilmercúrio/química , Oxigênio/química , Poluentes Químicos da Água/química , Eutrofização , Lagos/química , Mercúrio/análise , Mercúrio/química , Compostos de Metilmercúrio/análise , Compostos Orgânicos/análise , Compostos Orgânicos/química , Oxirredução , Oxigênio/análise , Poluentes Químicos da Água/análise
4.
Ecotoxicol Environ Saf ; 188: 109934, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31740234

RESUMO

Due to the presence of toxic pollutants, soils in former military areas need remedial actions with environmentally friendly methods. Greenhouse experiments were conducted to investigate the aided phytostabilization of multi-heavy metals (HMs), i.e. Cd, Cr, Cu, Ni, Pb, Zn, in post-military soil by Festuca rubra and three mineral amendments (diatomite, dolomite and halloysite). The amendments were applied at 0 and 3.0% to each pot filled with 5 kg of polluted soil. After seven weeks of the phytostabilization, selected soil properties, biomass yield of F. rubra and immobilization of HMs by their accumulation in plant and redistribution among individual fractions in soil were determined. In addition, ecotoxicology parameters of non-amended and amended soil were established using Phytotoxkit (Sinapsis alba) and Ostracodtoxkit (Heterocypris incongruens) tests. The addition of halloysite significantly increased F. rubra biomass. Diatomite significantly increased both the Cd, Cu, Pb and Cr concentrations in the roots and the pH of the soil. The application of halloysite significantly decreased the Cd and Zn contents of the soil after the completion of the experiment. Dolomite and halloysite were more effective in HM immobilization in soil by decreasing their content in an exchangeable fraction than diatomite. These soil amendments significantly differentiated the length of S. alba roots and had a positive effect on the development of H. incongruens.


Assuntos
Carbonato de Cálcio/química , Argila/química , Recuperação e Remediação Ambiental/métodos , Festuca/crescimento & desenvolvimento , Magnésio/química , Metais Pesados/análise , Instalações Militares , Poluentes do Solo/análise , Biodegradação Ambiental , Biomassa , Festuca/química , Raízes de Plantas/crescimento & desenvolvimento , Solo/química
5.
Water Res ; 171: 115385, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31855695

RESUMO

Controlled release materials (CRMs) are emerging oxidant delivery techniques for in-situ chemical oxidation (ISCO) for groundwater remediation. Successful implementation of CRM relies on good understandings of the kinetics and mechanism of controlled release of reactive agents. In this study, batch experiments and model simulations were conducted to explore the impacts of CRM properties (composition and size) and environmental conditions (temperature, pH, water volume and anions) on KMnO4 release from KMnO4 -paraffin controlled release beads. Experimental results indicated that higher KMnO4: paraffin mass ratio resulted in shorter release longevities and higher release rate. Larger bead resulted in lower release rate, longer release longevity, and more KMnO4 released. Higher incubation temperature resulted in higher release rate and shorter release longevity, but did not affect the total mass of KMnO4 released. Acidic pH decreased the total mass of KMnO4 released while alkaline pH did not affect KMnO4 release. The presence of SO42-, CO32-, Cl- and Br- had negligible impacts on KMnO4 release. A dissolution-diffusion conceptual model was developed. The above experimental observation and the associated controlled release mechanisms can be qualitatively explained by the conceptual model. A more detailed two-film boundary mathematical model was developed to simulate KMnO4 release process. Comparison of modeling results with experimental data suggest that the new mathematical model gave a good quantitatively predication. Overall, this study shows that properly designed CRM can sustain release for years, thus representing a cost-effective and low-maintenance groundwater remediation technology. Both CRM properties and environmental conditions significantly affect the release kinetics and longevity, therefore these factors should be considered in the design and maintenance of CRM-based ISCO system.


Assuntos
Recuperação e Remediação Ambiental , Água Subterrânea , Poluentes Químicos da Água , Preparações de Ação Retardada , Oxirredução , Permanganato de Potássio
6.
Chemosphere ; 239: 124707, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31479912

RESUMO

Site soils with persistent cyanide compounds (primarily iron-cyanide complex) pose potential hazards to the environment and require remediation before redevelopment. This study evaluated the possibility of thermal treatment on remediation of cyanide-contaminated soils via batch heating experiments spanning a wide temperature range (200-500 °C). The change with operation variables of total cyanide and some reaction intermediates (e.g. CN-) was analyzed in order to elucidate the optimal variables that guarantee cyanide removal while generating no hazardous byproducts. Temperature, heating time and cyanide species have been found to be important parameters influencing removal/destruction of cyanide in soils. For soils bearing K3[Fe(CN)6] and K4[Fe(CN)6], a removal efficiency of >99.9% can be obtained with temperatures over 350 °C at 1 h, while for samples bearing Fe4[Fe(CN)6]3, a higher temperature (>450 °C) is needed to obtain an equivalent efficiency. During heating, the iron-cyanide complexes decomposed, releasing highly toxic free cyanides, which will subsequently be oxidized. However, a small percentage of free cyanide can always be detected as a result of incomplete oxidation, thus caution should be taken to minimize the accumulation of free cyanide during thermal treatment.


Assuntos
Cianetos/análise , Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/análise , Temperatura Ambiente , Cianetos/química , Poluição Ambiental/prevenção & controle , Ferrocianetos/análise , Ferrocianetos/química , Oxirredução , Poluentes do Solo/química
7.
Chemosphere ; 239: 124706, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31493754

RESUMO

The remediation effect of organic acids in heavy metal contaminated soil was widely studied. However, the comprehensive evaluation of organic acids on micro-ecological environment in heavy metal contaminated soil was less known. Herein, this experiment was conducted to investigate the impact of malic acid, citric acid and oxalic acid on soil fertility, cadmium (Cd) speciation and ecotoxicity in contaminated soil. Especially, to evaluate the ecotoxicity of Cd, high-throughput sequencing was used to investigate the soil bacterial community structure and diversity after incubation with organic acids. The results showed that obvious changes in soil pH were not observed. Whereas, the contents of available phosphorus (Olsen-P) and alkali hydrolysable nitrogen (Alkeline-N) evidently increased with a significant difference. Furthermore, compared to control, the proportion of acetic acid-extractable Cd increased by 3.06-6.63%, 6.11-9.43% and 1.91-6.22% respectively in the groups amended with malic acid, citric acid and oxalic acid, which indicated that citric acid did better in improving the availability of Cd than malic acid and oxalic acid. In terms of biological properties, citric acid did best in bacteria count increase, enzyme activities and bacterial community structure improvement. Accordingly, these results provided a better understanding for the influence of organic acids on the micro-ecological environment in Cd contaminated soil, based on physicochemical and biological analysis.


Assuntos
Cádmio/toxicidade , Ácidos Carboxílicos/farmacologia , Recuperação e Remediação Ambiental/métodos , Microbiologia do Solo , Poluentes do Solo/química , Bactérias/efeitos dos fármacos , Cádmio/análise , Cádmio/química , Ácidos Carboxílicos/química , Ácido Cítrico/química , Ácido Cítrico/farmacologia , Ecotoxicologia , Poluição Ambiental/análise , Malatos/química , Malatos/farmacologia , Ácido Oxálico/química , Ácido Oxálico/farmacologia , Solo/química , Poluentes do Solo/análise
8.
Chemosphere ; 239: 124738, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31494316

RESUMO

Stabilization/Solidification (S/S) has been widely used in soil remediation to both improve physical properties and immobilize extensive contaminants. GGBS (granulated ground blast furnace slag)-MgO-CaO (GMCs) was used to treat Pb/Zn contaminated soil. The physical and microstructural characteristics of stabilized/solidified contaminated soil were investigated in this study. Microstructural analysis showed that the main hydration products of GMC treated contaminated soil were C-S-H and hydrotalcite like gels (Ht), which dominated the physical strength of S/S soil. The unconfined compressive strength (UCS) and the leachability of GMC treated contaminated soil were improved with the increase in GMC proportion (5%-15%), curing time (7 days and 28 days) and temperature (5 °C, 21 °C and 45 °C) due to the enhanced hydration. The compressive strengths of the majority mixes met the US EPA criterion (0.35 MPa). The strength of S/S soils was less affected by the increase of curing temperature after a longer curing period (28 days). According to the XRD and SEM results, both Pb and Zn in S/S contaminated soil could be immobilized by the precipitation and the adsorption on the surface of calcium silicate hydrate (C-S-H). Zn can also be incorporated into the structure of C-S-H and Ht. The addition of Pb/Zn decreased the physical strength in the order of: Pb(5000 mg/kg)>Pb(10000 mg/kg)>Zn/Pb(5000 mg/kg)>Pb(20000 mg/kg).


Assuntos
Recuperação e Remediação Ambiental/métodos , Chumbo/química , Poluentes do Solo/química , Solo/química , Zinco/química , Hidróxido de Alumínio/química , Compostos de Cálcio/química , China , Hidróxido de Magnésio/química , Óxido de Magnésio/química , Microscopia Eletrônica de Varredura , Óxidos/química , Silicatos/química , Temperatura Ambiente , Difração de Raios X
9.
Chemosphere ; 239: 124702, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31520979

RESUMO

Restoration of submerged macrophytes is widely applied to counteract eutrophication in shallow lakes. However, proliferation and accumulation of filamentous algae (possessing free-floating and periphytic life forms) hamper growth of submerged macrophytes. Here, we explored factors triggering the excessive proliferation of filamentous algae during lake restoration using field investigations and laboratory experiments. Results showed that, compared with free-floating Oscillatoria sp. (FO), periphytic Oscillatoria sp. (PO) showed faster growth rate, greater photosynthetic capacities and higher phosphorus (P) affinity. Therefore, PO was physiologically competitively superior to FO under low P concentration and improved light conditions. And proliferation of filamentous algae was mainly manifested in periphytic life form. Besides, field results showed that density of filamentous algae in water column might be related to substrate types. Some macrophyte (Ceratophyllum oryzetorum and Potamogeton crispus) might provide proper substrates for proliferation of filamentous algae. Further physiological experiments found that Oscillatoria showed specific eco-physiological responses to different macrophyte species. Hydrilla verticillata and C. oryzetorum promoted growth and photosynthetic activity of Oscillatoria, while Potamogeton malaianus inhibited growth and P uptake of PO. Myriophyllum spicatum exhibited no impact on growth of Oscillatoria. Our results revealed the intrinsic (physiological differences between free-floating and periphytic life forms of filamentous algae) and extrinsic (different macrophytes) factors affect the proliferation of filamentous algae, which are important for guidance on planting of submerged macrophytes during lake restoration.


Assuntos
Recuperação e Remediação Ambiental/métodos , Eutrofização , Hydrocharitaceae/crescimento & desenvolvimento , Lagos , Potamogetonaceae/crescimento & desenvolvimento , Proliferação de Células , Cianobactérias , Citoesqueleto , Fotossíntese , Água
10.
Chemosphere ; 239: 124807, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31520982

RESUMO

The characteristics of polyvinylpyrrolidone (PVP)-stabilised nano-zero-valent iron (PVP-NZVI) and its application, combined with surfactant, to trichloroethylene (TCE)-contaminated soil were investigated. Two surfactants (cetyltrimethylammonium bromide [CTAB] and sodium dodecyl sulphate [SDS]) were tested for their ability to enhance the remedial activity of PVP-NZVI in 3 h batch experiments. The prepared PVP-NZVI formed nanoparticles ∼70 nm in diameter. The isoelectric point of PVP-NZVI was about 8.51, similar to the initial pH. X-ray diffraction and X-ray photoelectron spectroscopy analyses revealed that ZVI was the main active component of PVP-NZVI, and carbonised products of the target were observed. The TCE dechlorination efficiency by PVP-NZVI was about 84.73%; the efficiency by PVP-NZVI was about 20% higher when combined with SDS than with CTAB. Therefore, application of PVP-NZVI with SDS represents a potential remediation approach for TCE-contaminated soil.


Assuntos
Recuperação e Remediação Ambiental/métodos , Ferro/química , Solo/química , Tensoativos/química , Tricloroetileno/química , Halogenação , Nanopartículas/química , Espectroscopia Fotoeletrônica , Povidona/química , Dodecilsulfato de Sódio , Poluentes do Solo/química , Poluentes do Solo/isolamento & purificação , Difração de Raios X
11.
Chemosphere ; 239: 124733, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31526991

RESUMO

Lignin, natural aromatic polymer derived from plant dry matter, is second abundant biopolymer. Recently, interest in applications of lignin, especially as an adsorbent material is increasing. However, the physicochemical complexity of lignin significantly reduces access to practical environmental remediation processes. Also, there is a limitation because the adsorption performance of the pristine lignin materials is not superior to that of commercial adsorbent and ion exchange resin material. In this study, spherical lignin particles with high physicochemical stability and excellent Cr(VI) adsorption capacity are prepared using a polyethylenimine (PEI) modification strategy. This modification process significantly improves the mechanical properties and water stability of lignin by complementing the instability of lignin particles. In addition, the PEI-lignin particles exhibit a superior Cr(VI) removal capability (657.9 mg/g, the highest value for a PEI-modified natural adsorbent), which is attributed to their structural stability and introduced amine functional groups. The Cr(VI) removal with PEI-lignin particles is performed via intra-particle diffusion and adsorption followed by covalent bonding combined with a reduction process. Moreover, the PEI-lignin particles exhibit excellent reusability, which sustains their high adsorption efficiency over a long and repeated adsorption period. The results herein strongly support the potential use of PEI-lignin particles as a high performance bio-sorption material for heavy metal removal and its detoxification in aqueous wastewater streams. Evidently, this lignin-based bio-sorbent manufacturing system can provide sustainable bio-resource recycling and cost efficiency.


Assuntos
Cromo/isolamento & purificação , Lignina/química , Adsorção , Cromo/química , Recuperação e Remediação Ambiental , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia Fotoeletrônica , Polietilenoimina/química , Espectroscopia de Infravermelho com Transformada de Fourier , Eliminação de Resíduos Líquidos/métodos , Água/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
12.
Chemosphere ; 240: 124842, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31574436

RESUMO

With a wide range of raw materials, low cost and large specific surface area, biochar has been widely used in environmental remediation. However, the biochar has a saturated adsorption capacity when it is used as a pollutant adsorbent. Recent efforts have been made to prepare biochar and biochar-based catalysts with enhanced catalytic properties to expand their potential applications. The environmental persistent free radicals (EPFRs) of biochar could react with O2 to induce hydroxyl radicals (•OH) without the addition of oxidants. When oxidants were added, biochar and biochar-based catalysts could activate them to generate •OH and sulfate radicals (SO4•-), respectively. Moreover, biochar could act as an electron acceptor to improve the photodegradation capacity of catalysts. With reference to the information regarding biochar and biochar-based catalysts, this work provides a critical review on recent research development as follows: 1) the preparations of various types of biochar and biochar-based catalysts are summarized; 2) the effects of the synthetic conditions and transition metals on the catalytic activity of biochar-based catalysts are discussed; (3) methods for characterizing the active sites of the biochar-based catalysts are described; and (4) the environmental applications of biochar and biochar-based catalysts are discussed with regards to three aspects based on the interaction mechanisms, namely, oxidation, reduction, and photocatalysis. The synthesis conditions and loading of metal/metal-free catalyst are key parameters controlling the catalysis activity of biochar and biochar-based catalysts. This review provides new insights into the application of biochar in catalysis. Key challenges and further research directions are proposed as well.


Assuntos
Carvão Vegetal/química , Recuperação e Remediação Ambiental/métodos , Catálise
13.
Chemosphere ; 239: 124730, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31726518

RESUMO

The impact of electrolytes on the adsorption of emerging pollutants: pharmaceuticals onto layered materials: a raw clay mineral and its nonionic and cationic organoclay derivatives was studied. The selected pharmaceuticals: amoxicillin, norfloxacin, sulfamethoxazole, metoprolol, carbamazepine, and trimethoprim show different electric charges: zwitterionic, anionic, cationic and neutral and hydrophobic character (different LogP). Without any salts, the set of complementary data obtained by UV and infrared spectroscopies, X-ray diffraction points out the importance of the electric charge which represents a key parameter in both the spontaneity and feasibility of the adsorption. In contrast, the hydrophobicity of the analytes plays a minor role but determines the magnitude of the adsorbed amount of pharmaceuticals onto organoclays. With a dual hydrophilic and hydrophobic behavior, nonionic organoclay appears to be the most polyvalent material for the removal of the pharmaceuticals. In the presence of electrolytes (NaCl at a concentration of 1 × 10-2 mol L-1), both nonionic and cationic organoclays show a decrease of their efficiencies, whereas the adsorption is particularly enhanced for Na-Mt except for the cationic species (trimethoprim and metoprolol). Thus, in realistic experimental conditions close to those of natural effluents, raw clay mineral appears as the most appropriate sorbent for the studied pharmaceuticals while it raises the question of the usefulness of organoclays in water remediation strategy.


Assuntos
Eletrólitos/química , Recuperação e Remediação Ambiental/métodos , Preparações Farmacêuticas/análise , Poluentes do Solo/análise , Solo/química , Poluentes Químicos da Água/análise , Adsorção , Amoxicilina/análise , Amoxicilina/química , Carbamazepina/análise , Carbamazepina/química , Cátions/análise , Interações Hidrofóbicas e Hidrofílicas , Metoprolol/análise , Metoprolol/química , Norfloxacino/análise , Norfloxacino/química , Preparações Farmacêuticas/química , Poluentes do Solo/química , Sulfametoxazol/análise , Sulfametoxazol/química , Trimetoprima/análise , Trimetoprima/química , Água/química , Poluentes Químicos da Água/química , Difração de Raios X
14.
Chemosphere ; 240: 124885, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31568939

RESUMO

Chromium (Cr)-bearing electroplating sludge is a hazardous solid waste and has a detrimental effect on human health and the environment. In this study, an alkali-activated slag binders, namely, formed by the reaction of blast furnace slag (BFS) with alkali, was applied to the stabilization/solidification (S/S) of electroplating sludge. The effects of liquid-solid ratio, water glass modulus ratio (molar ratio of SiO2 to Na2O), water glass dosage, and electroplating sludge amount on the compressive strength and Cr leachability of binders were analyzed. The related mechanism of the S/S of electroplating sludge was discussed on the basis of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy coupled with energy-dispersive spectrometry (SEM-EDS). Results showed that the compressive strength of the alkali-activated slag binder first increased and then remained stable with the increase in liquid-solid ratio, water glass modulus ratio, and water glass dosage. By contrast, the leaching concentrations of Cr(VI) and total Cr decreased with the increase in liquid-solid ratio, water glass modulus ratio, water glass dosage, and curing time. In addition, XRD, FTIR, and SEM-EDS revealed that the hydration products of the binders were mainly low-crystallinity and dense calcium silicate hydrate gels, and Cr(VI) had been effectively immobilized in the structure. The reduction in Cr(VI) by the reductive components in the BFS boosted the stabilization of Cr-bearing electroplating sludge. Overall, the BFS binders containing electroplating sludge had relatively high compressive strengths and low Cr(VI) leaching concentrations. The physical encapsulation, chemical bonding, and absorption contributed the Cr immobilization during the S/S process of electroplating sludge.


Assuntos
Álcalis/química , Cromo/química , Galvanoplastia , Recuperação e Remediação Ambiental , Resíduos Perigosos/análise , Esgotos/química , Humanos
15.
Sci Total Environ ; 699: 134302, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31522046

RESUMO

Quantifying the catchment water balance and the characterization of its water quality changes are effective tools for establishing the response of catchments to shifting land management practices. Here we assess long-term hydrological partitioning and stream water chemistry over a 30-year period in a rural mixed land use catchment in northern Germany undergoing riparian wetlands and widespread re-colonization by beavers (Castor fiber) along the river network. We used long-term spatially distributed stream discharge, groundwater levels and surface water quality data with a simple monthly water balance model, changes in the variability in discharge measurements, and statistical analysis of spatio-temporal changes in stream water quality to assess long-term changes. Water balance estimates indicated high proportions of evapotranspiration loss (~90% of total precipitation) and relatively low groundwater recharge (<5% of total precipitation) prior to riparian rehabilitation in 2000. Increasing groundwater levels from 2000 to 2017 and the relatively linear nature of the catchment storage - discharge relationship, indicate a gradual increase in groundwater recharge (buts still <10% of total precipitation). Wetland rehabilitation, greatly enhanced by increasing beaver populations, resulted in longer water transit times in the stream network, less linear storage-discharge relationship and a loss of daily stream variability, increased DOC concentrations, isotopic evaporative enrichment downstream, and moderated stream temperatures. There was limited long-term water quality improvements from wetland rehabilitation on either nitrate or total phosphorus concentrations, with unchanged seasonal summer and winter peak concentrations for phosphorus and nitrate, respectively. This likely reflects the long-term legacy of fertilizer use on nutrient reservoirs in the catchment's soils, aquifers, and stream network. These long-term changes in hydrology and stream chemistry resulting from riparian rehabilitation and changes in agricultural management practices provide invaluable insights into catchment functioning and an evidence base for future planning in relation to long-term climatic changes.


Assuntos
Monitoramento Ambiental , Roedores , Áreas Alagadas , Agricultura , Animais , Recuperação e Remediação Ambiental , Alemanha , Água Subterrânea , Hidrologia , Nitratos , Nitrogênio , Fósforo , Rios , Solo , Água , Movimentos da Água , Qualidade da Água
16.
Chemosphere ; 238: 124600, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31446277

RESUMO

A high-gravity rotating packed bed (HiGee RPB) is very efficient at removing pollution because it exerts a strong high centrifugal and allows tiny droplets to form, which allows the control of gaseous and particulate air pollution. In this study, fine particles that are removed from integrated circuit (IC) chip carbonization process using a RPB are evaluated under different high gravity factors and liquid-to-gas ratios. The greatest number of particles captured per energy consumption is 17.77 mg kWh-1 in a RPB. This allow greater energy efficiency for the HiGee technology prevents an air-energy nexus. The maximum available particle removal efficiency for a RPB is determined using a response surface model (RSM). 99.5% of particles are removed at a high gravity factor of 262 and a liquid-to-gas ratio of 0.24. A semi-theoretical model is developed to determine the particle removal efficiency individually in packing and cavity zones of the RPB. More particles are removed in a cavity zone than in the packing zone as the high gravity factor increases. An empirical model shows that the particle removal efficiency depends on the operating factors. Finally, a comparison analysis of particulate matter treatment in various types of RPB is used to validate the performance in terms of particle removal using high-gravity technology for different industries.


Assuntos
Poluição Ambiental/análise , Recuperação e Remediação Ambiental/métodos , Material Particulado/análise , Carbono , Centrifugação/métodos , Gases , Tamanho da Partícula
17.
J Environ Sci (China) ; 87: 299-309, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31791503

RESUMO

The residual effect of tobacco biochar (TB ≥ 500°C) mono and co-application with Ca-hydroxide (CH), Ca-bentonite (CB) and natural zeolite (NZ) on the bio-availability of trace elements TE(s) in alkaline soils has not been deeply studied yet. A pot study that had earlier been investigated TB mono and blended with CH, CB and NZ on the immobilization of Pb, Cu Cd, and Zn by Chinese cabbage. Maize crop in the rotation was selected as test plant to assess the residual impact of amendments on stabilization of Pb, Cu Cd, and Zn in mine polluted (M-P), smelter heavily and low polluted (S-HP and S-LP, respectively) soils. The obtained results showed that stabilization of Pb, Cd, Cu and Zn reached 63.84% with TB + CB, 61.19% with TB + CH, 83.31% with TB + CH and 35.27% with TB + CH for M-P soil, 36.46% with TB + NZ, 38.46% with TB + NZ, 19.40% with TB + CH and 62.43% with TB + CH for S-LP soil, 52.94% TB + NZ, 57.65% with TB + NZ, 52.94% with TB + NZ, and 28.44% with TB + CH for S-LP soil. Conversely, TB + CH and TB alone had mobilized Pb and Zn up to 19.29% and 34.96% in M-P soil. The mobility of Zn reached 8.38% with TB + CB and 66.03% with TB for S-HP and S-LP soils. The uptake and accumulation of Pb, Cd, Cu and Zn in shoot and root were reduced in three polluted soils. Overall, the combination of TB along with CH, CB and NZ has been proven to be effective in Pb, Cd, Cu and Zn polluted mine/smelter soils restoration.


Assuntos
Carvão Vegetal/química , Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/química , Oligoelementos/química , Poluentes do Solo/análise , Tabaco
18.
Chemosphere ; 238: 124558, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31442772

RESUMO

Graphene-based nanomaterials (GNMs) have been touted as miracle materials due to their extraordinary properties that can benefit many industries, including in agriculture and for environmental remediation. While improvement in nutrient delivery and the ability to adsorb environmental contaminants have been demonstrated, what happens to GNMs in soil is a question that has not been addressed. The main aim of this study was to investigate their degradation in soil to have a better understanding of their environmental fate. Using radioisotope techniques, this study assessed the potential mineralisation and release of graphene oxide (GO), one of the most commonly used forms of graphene. Results revealed that the conversion of GO to carbon dioxide was negligible (<2%) in microbially-active soils. GO remaining in soil was also not readily released by water extractions. The lack of mineralisation and release is indicative of GO's high (bio)degradation stability which is likely due to its limited availability resulting from its rapid homo/hetero-aggregation. Over-all, the results provide new and important information on the environmental fate of graphene nanomaterials applied to soils.


Assuntos
Dióxido de Carbono/metabolismo , Radioisótopos de Carbono/análise , Recuperação e Remediação Ambiental , Grafite/análise , Minerais/metabolismo , Nanoestruturas/administração & dosagem , Solo/química , Adsorção , Agricultura , Grafite/química
19.
J Environ Manage ; 253: 109769, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31675593

RESUMO

A novel approach for the remediation of clayey sediment in intertidal zones was proposed, which entails increasing the soil permeability using an active capping agent. The agent, granulated coal ash (GCA), was developed using the granulation processes for coal fly ash. The GCA increased the permeability coefficient of the sediment by seven times, changing its the properties from a typical clayey silt to that of silt, according to the soil classification standards based on permeability coefficient. Increased permeability was attributed to Ca2+ ions, and adsorbed Na+ was immediately discharged, leading to a decrease in the sodium adsorption ratio. The activated flow of pore water stimulated nutrient loadings; PO4-P and NH4-N loads decreased by 55% and 44%, respectively. The GCA increased the dissolved oxygen by 1.8 mg/L and increased the redox potential in pore water from -370 to -306 mV vs. Ag/AgCl. According to the results presented in this study, active capping with GCA to increase soil permeability is a novel and promising technology for reducing the nutrient loads and increasing the oxidation of contaminated clayey sediment in intertidal zones.


Assuntos
Recuperação e Remediação Ambiental , Adsorção , Carvão Mineral , Cinza de Carvão , Sedimentos Geológicos , Permeabilidade
20.
Sci Total Environ ; 698: 134344, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31783438

RESUMO

Around 3 billion tonnes of bauxite residue (BR), the by-product of alumina extraction, have been produced and stockpiled worldwide, representing a potential risk for the environment due to the high alkalinity and the presence of relatively high concentrations of trace elements. Phytoremediation (or simply revegetation) is regarded as the most promising in situ remediation option to mitigate the environmental risk that might arise from the land-disposal of BR. Rehabilitation strategies (including the incorporation of amendments such as gypsum and organic matter) have been employed to address the main limitations to plant establishment and growth on BR, typically the high alkalinity, salinity and sodicity. However, the potential for trace element uptake and phytotoxicity have been largely unreported in revegetated BRs. In order to assess the ecotoxicological risk, samples of previously revegetated BR were collected from the field, characterized in the laboratory, and used to conduct ex-situ plant bioassays (Phytotoxkit™ and the RHIZOtest). Without rehabilitation, fresh BR severely inhibits seed germinationand root/shoot development in test species Lepidium sativum, Sinapis alba and Sorghum saccharatum. Plant uptake for Al, As, Cr, V was assessed with RHIZOtest bioassay trials with Lolium perenne and demonstrated that plants exposed to fresh BR take up and translocated trace elements to their shoots at concentrations (As = 4.13 mg/kg dm; Cr = 3.29 mg/kg dm; V = 85.66 mg/kg dm) exceeding phytotoxic levels (vanadium) or maximum levels specified for animal feed (arsenic), showing visible stress symptoms in the seedlings. Conversely, revegetated BR show improved chemical properties, allow seed germination, and permits seedling growth with no evidence of trace element phytotoxicity. However, Na can be taken up at concentrations that could elicit phytotoxicity and impair the success of revegetation. For future rehabilitation programmes, direct revegetation on BR after the incorporation of amendments such as gypsum and organic matter is recommended.


Assuntos
Óxido de Alumínio/análise , Recuperação e Remediação Ambiental , Poluentes do Solo/análise , Óxido de Alumínio/toxicidade , Biodegradação Ambiental , Ecotoxicologia , Medição de Risco , Salinidade , Sinapis , Solo/química , Microbiologia do Solo , Poluentes do Solo/toxicidade , Sorghum
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