Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 18.850
Filtrar
1.
J Environ Qual ; 49(3): 712-722, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016406

RESUMO

Chromite ore processing residue (COPR) is a waste derived from the chromate extraction from roasted ores and is deposited in some countries in landfills. The objective of this study was to investigate the leaching characteristics of hexavalent Cr [Cr(VI)] from two COPR samples obtained from unlined landfills in the Kanpur area of northern India. Column experiments were conducted under water-saturated conditions to simulate Cr release from the wastes caused by tropical heavy-rain events. Leached Cr(VI) decreased from 1,800 to 300 mg L-1 (Rania site) and 1,200 to 163 mg L-1 (Chhiwali site) during exchange of 12 pore volumes, which approximately corresponds to 2 yr of monsoon precipitation. Flow interruptions for 10, 100, and 1,000 h had little effect on Cr(VI) concentrations in the leachate, suggesting that Cr(VI) leaching was not limited by slow release kinetics. Calcium aluminum chromium oxide hydrates (CAC), and highly soluble phases such as Na2 CrO4 may play a role in controlling Cr(VI) concentration in the leachates. The amount of Cr(VI) leached from the columns accounted for 16% of the total Cr(VI) present in both COPR samples. A decrease in the solid-phase Cr(VI)/Crtotal ratio along the column was identified by X-ray absorption near edge structure (XANES) spectroscopy. Consistently, the smallest Cr(VI)/Crtotal ratios were found in the lower column section closest to the inflow. Our results suggest that Cr(VI) leaching from the unlined COPR landfills will continue for centuries, highlighting the urgent need to remediate these dumpsites.


Assuntos
Cromo/análise , Resíduos Industriais/análise , Índia , Espectroscopia por Absorção de Raios X
2.
Bioresour Technol ; 317: 124006, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32889176

RESUMO

The economy of the polyhydroxyalkanoate (PHA) production process could be supported by utilising the different by-products released simultaneously during its production. Among these, proteins are present in high concentrations in liquid stream which are released after the cell disruption along with PHA granules. These microbial proteins can be used as animal feed, adhesive material and in manufacturing of bioplastics. The recycling of the protein containing liquid stream also serves as a promising approach to maintain circular bioeconomy in the route. For this aim, it is important to obtain good yield and limit the drawbacks of protein recovery processes and associated costs. The review focuses on recycling of the liquid stream generated during acid/thermal-alkali treatment for PHA production that would close the gap in linear economy and attain circularity in the process. Examples to recover proteins from other industrial waste streams along with their applications have also been discussed.


Assuntos
Poli-Hidroxialcanoatos , Águas Residuárias , Animais , Reatores Biológicos , Resíduos Industriais , Indústrias
3.
Ecotoxicol Environ Saf ; 203: 110991, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888602

RESUMO

The stimulant and toxicity effects of reported organic (acetic acid, propionic acid, butyric acid, formic acid, oil & grease) and inorganic (copper) by-products presented in palm oil mill effluent on anaerobic bacterial population were examined in this paper. The toxicity test had shown that acetic, propionic and butyric acids tend to stimulate the bacterial density level (survival rate more than 50%), while formic acid, copper, oil and grease were shown to have suppressed the density level (survival rate less than 50%). The highest biomass recorded was 1.66 mg/L for the concentration of acetic acid at 216 mg/L and lowest biomass concentration, 0.90 mg/L for copper at 1.40 mg/L. Biohydrogen-producing bacteria have a favourable growth rate around pH 5.5. The comparison of half maximal effective concentration (EC50) values between two test duration on the effects of organic and inorganic by-products postulate that bacteria had a higher tolerance towards volatile fatty acids. While acetic, butyric and propionic acids had exhibited higher tolerance EC50 values for bacteria, but the opposite trend was observed for formic acid, copper and oil & grease.


Assuntos
Bactérias Anaeróbias/efeitos dos fármacos , Óleo de Palmeira/toxicidade , Testes de Toxicidade/métodos , Relação Dose-Resposta a Droga , Hidrogênio/metabolismo , Resíduos Industriais/análise
4.
Chemosphere ; 258: 127388, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947665

RESUMO

Microplastics enter natural water bodies by a variety of pathways, one of them being wastewater streams. The role of industrial wastewater in overall microplastic emissions has so far only been estimated, because access is usually restricted. This is the first report providing quantitative data on microplastics in industrial wastewaters. The wastewater discharge of three different industrial sites was sampled in the size ranges of small microplastics (10-1000 µm) and large microplastics (1000-5000 µm). Differential scanning calorimetry (DSC) was used to detect and quantify semi-crystalline thermoplastics. Polyethylene (PE) and polypropylene (PP) were the most abundant polymers, but polyamide (PA) and polyethylene terephthalate (PET) were also found. As all three industrial sites had wastewater treatment plants (WWTP), the total concentrations were in the µg L-1 range, comparable to organic micropollutants in municipal WWTP effluents. At one industrial site, the removal capacity of the WWTP was evaluated by sampling and analyzing the influent as well as the effluent. The total microplastics concentration in the influent was in the g L-1 range, yielding a removal capacity of the industrial WWTP of >99.99 %.


Assuntos
Monitoramento Ambiental , Microplásticos/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise , Varredura Diferencial de Calorimetria , Resíduos Industriais/análise , Indústrias , Plásticos , Polietileno , Polímeros , Polipropilenos
5.
Ecotoxicol Environ Saf ; 202: 110939, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800222

RESUMO

Pulp and paper mill wastewater (PPMWW) contains high concentrations of recalcitrant compounds that cause toxicity to organisms. Advanced oxidation processes (AOPs) have the ability to degrade these compounds and reduce overall toxicity. Physicochemical characterization and Lactuca sativa toxicity test were conducted to compare the effectiveness of two post-treatments: UV/H2O2 and photo-Fenton. A comparison of four phytotoxicity indexes was carried out. PPMWW from a Brazilian treatment plant was characterized by high values of phenols, color, integrated spectral area (ISA), and chemical oxygen demand (COD), and caused significant inhibition to seedling development. The use of both post-treatments allowed the removal of over 75% of phenols, color, ISA, and COD. Although UV/H2O2 was more effective in removing phenols and ISA, photo-Fenton better reduced phytotoxicity. The most sensitive phytotoxicity indexes were RGIC0.8 and GIC80%, whereas SGC0, REC-0.25 and REC-0.50 better showed the effectiveness of the post-treatments. We suggest the combined use of two phytotoxicity indexes: one that evaluates the effects on seed germination and, another, on root elongation, e.g., SGC0 and RGIC0.8. Additionally, we recommend the use of ISA for monitoring programs of wastewater treatments because it is a cost-effective approach that allows narrowing down the search and identification of compounds present in complex mixtures.


Assuntos
Papel , Fenóis/toxicidade , Eliminação de Resíduos Líquidos/métodos , Análise da Demanda Biológica de Oxigênio , Brasil , Cor , Corantes/toxicidade , Peróxido de Hidrogênio/química , Resíduos Industriais/análise , Oxirredução , Fenóis/análise , Plantas/efeitos dos fármacos , Águas Residuárias/química
6.
Ecotoxicol Environ Saf ; 202: 110908, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800243

RESUMO

Chinese milk vetch is an efficient approach to reduce Cd accumulation in rice, nevertheless, its reduction mechanism is not well understood. In this study, we investigated the rice grain Cd, soil properties and microbial community in a Cd-polluted paddy field amended with milk vetch residue (MV) or without (CK) during rice growth period. We found that milk vetch residue averagely decreased the Cd content in rice grain by 45%. Decrease of Cd in rice mainly attributed to the inhibition of Cd activation by milk vetch residue at heading stage probably by the formation of HA-Cd (Humic Acid) and CdS. Increased pH and organic matter (OM) promoted the reduction of available Cd. In addition, nonmetric multidimensional scaling (NMDS) analysis revealed that microbial community structure was significantly different between MV and CK treatment (r = 0.187, p = 0.002), and the core functions of differentially abundant genera were mainly associated with N-cycling, organic matter degradation and sulfate-reducing. The application of milk vetch residue increased the abundance of sulfate-reducing bacteria (SRB) by 8-112% during the rice growth period, which may involve in promoting the transformation of Cd to a more stably residual Cd (CdS). Canonical correspondence analysis (CCA) and mantel test analysis indicated that available K (p = 0.004) and available N (p = 0.005) were the key environmental factors of shaping the SRB. Altogether, changes in soil properties affected microbial structure and functional characteristics, especially the response of SRB in MV treatment would provide valuable insights into reducing the bioavailability of Cd in soil.


Assuntos
Astrágalo (Planta)/metabolismo , Cádmio/metabolismo , Oryza/metabolismo , Poluentes do Solo/metabolismo , Animais , Astrágalo (Planta)/microbiologia , Disponibilidade Biológica , Grão Comestível/química , Substâncias Húmicas/análise , Resíduos Industriais , Microbiota , Leite , Solo/química , Poluentes do Solo/análise
7.
Bioresour Technol ; 316: 123946, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32769001

RESUMO

The agri-food waste (AW) require amendments for composting to adjust nutritional and physicochemical deficiencies. The theoretical mixtures formulation is difficult to reach on an industrial scale. The main objective of this work was to evaluate to what extent the composition of AW-based mixtures determines the quality of the final compost produced at the industrial scale. Raw materials having the same AW share characteristics, irrespectively of the amendments added, but their compost were different. All the materials were biological stable at the cooling phase, and mature enough at the end, although the degree of humification did not match with the absence of phytotoxicity. The final compost had sufficient quality even though the AW-based raw materials have a low C/N ratio (<20) and other characteristics such as high electrical conductivity (13 mS·cm-1) and pH (<8.5) that are unfavorable for composting. The management operations during industrial composting correct the deficiencies of raw materials.


Assuntos
Compostagem , Eliminação de Resíduos , Carbono , Alimentos , Resíduos Industriais/análise , Nitrogênio/análise , Solo
8.
Science ; 369(6506): 910-911, 2020 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-32820108
9.
J Environ Manage ; 273: 111039, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32741763

RESUMO

In the present study, efficiency of electro-coagulation-flotation (EC-F) process using waste metal scrap of Al and Fe collected from construction and demolition waste of Indian Institute of Technology Madras (IIT M) campus for the removal of double azo bond dye Acid Red 66 (AR66) was studied. The key operating parameters such as current density and electrical conductivity were optimized individually with an initial dye concentration of 50 mg/L, at pH 7. Different electrode combinations and connection modes (parallel MP-P, series (MP-S, BP-S)) were tested, at pre-optimized conditions, in order to achieve better removal of AR66 dye with minimum energy consumption. Series connection in bipolar electrode mode (BP-S) showed better COD reduction from 164 mg/L to 26.2 mg/L with complete decolourization (BDL). Hybrid electrode system of Fe-Al-Fe-Al-Fe-Al showed maximum reduction of COD from 164 mg/L to 11.3 mg/L along with 86.3% TSS reduction and complete decolourization. LC-MS analysis showed the formation of intermediates with m/z 195, m/z 210.6 and m/z 159.3 due to the destruction of AR66 dye during electrolysis. Highest current efficiency (CE φ = 107%) was observed in case of hybrid electrode system compared to Al (φ = 30.1%) and Fe (φ = 98.3%) electrode system at similar operating conditions. Compared to the same electrode material as anode and cathode, use of appropriate hybrid electrode combination can improve the removal efficiency and reduce the energy consumption (ENC). The influence of aeration on the performance of the system was also studied. Aeration significantly improved the COD removal efficiency (98.3%) along with complete decolourization (100%). The use of waste metal scrap as electrodes reduced the overall cost of the treatment process from 1.6 $/m3 to 0.06 $/m3. Using waste metal scrap as electrodes not only reduces the metal accumulation in the environment but also reduces the cost of EC-F process.


Assuntos
Poluentes Químicos da Água/análise , Purificação da Água , Eletrodos , Índia , Resíduos Industriais , Metais , Eliminação de Resíduos Líquidos , Águas Residuárias
10.
J Environ Manage ; 273: 111154, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32771852

RESUMO

The frequent environment-unfriendly treatments of agro-industrial bio-wastes cause severe pollution through air pollution and through residual effluents and hazardous solid waste. These bio-wastes can contain phenolic compounds, forms of phenolic acids and flavonoids in plants. They are however the most abundant class of many phytochemicals and have been given great interest due to their health advantage and high economic value. An interesting upgrading of these bio-wastes may consist in obtaining a concentrated extract of phenolic compounds using no-toxic solvents, hence protecting the environment and human health. In this work, different alternatives of the extraction process were evaluated using an exergetic analysis. The energy and water consumptions, CO2 emissions, exergetic yield, wasted and destroyed exergy were calculated. It was found that several alternatives for recycle streams were convenient (streams with higher chemical exergy were not discharged into the environment). The energy and water consumption for the best alternative (ethanol-water ratio 1/1 including recycle stream, named E-W 1/1 Rec) were 567 MJ/h and 105 kg/h, respectively and the CO2 emission was 105 kg/h. The calculated exergy destruction indicated that the evaporation and distillation stages may be optimized towards a more sustainable operation. It is not advisable to dry the bio-waste if it will be immediately processed once generated.


Assuntos
Poluição do Ar , Resíduos Industriais , Flavonoides , Humanos , Fenóis , Reciclagem
11.
Waste Manag ; 117: 32-41, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32805599

RESUMO

This study conducted a survey at 15 building construction and demolition sites in Hanoi, Vietnam in order to identify waste generation rates (WGR), composition, and current handling practices of construction and demolition waste (CDW). Waste quantification based on CDW layout, image analysis to identify CDW components, and face-to-face interviews with construction and demolition contractors to reveal CDW flows were performed. WGRs of 79.3 kg/m2 and 1,030 kg/m2 were determined in small- and large-scale construction sites, respectively, whilst WGRs at small and large demolition sites were 610 kg/m2 and 318 kg/m2. The composition analysis identified soil, concrete, and brick as the major CDW components, consistent with building structures in Vietnam. The interviews discovered that merely 10% of total CDW flows was from recycled and reused CDW. Reuse and recycling rates were most significant for metal and were lower (in descending order) for brick, concrete, and soil. These findings raise a need for aggressive and integrated strategies to promote more sustainable CDW management in the country, including the development of recycled CDW product standards, policies that facilitate recycling, and more importantly, a sustainable business model for CDW recycling, for which future evaluations of economic feasibility are of great importance.


Assuntos
Indústria da Construção , Gerenciamento de Resíduos , Materiais de Construção , Resíduos Industriais/análise , Reciclagem , Vietnã
12.
Waste Manag ; 117: 179-187, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32861080

RESUMO

Steel slags are generally alkaline with a high calcium content and are viewed as a potential feedstock for carbon dioxide sequestration and utilization, mostly through aqueous mineral carbonation routes. For recovery of multiple metals such as Ca, Fe, Mg, and Si, and generation of value-added products by dissolution and precipitation reactions in aqueous media, enhancing the metal selectivity and extraction efficiency are important. However, there is limited understanding of independent parameters that influence these important characteristics. In this work, a systematic attempt was made to correlate these key dissolution characteristics of basic oxygen furnace slag in acidic media with its mineralogical and physical characteristics, the changes in aqueous chemistry, and the role of potential secondary precipitates. The findings from this study substantiate that steel slag is a potential feedstock because of the calcium being mainly present as orthosilicates, which were found to leach congruently without forming a leached layer that might hinder calcium extraction. The leaching of Fe(II) from the slag is the main source of impurity and its slow oxidation-precipitation leads to a pH plateau at the end of the dissolution step. Oxidation-precipitation of Fe(II) is controlled by hydroxyl concentration in the aqueous solution, which necessitates a pH-swing step by addition of a base after dissolution. Use of surface complexing agents, such as sodium molybdate, can significantly reduce iron impurity in the leachate and obtain an iron-rich slag residue for recycle to iron and steel industry.


Assuntos
Resíduos Industriais/análise , Aço , Dióxido de Carbono , Metais , Solubilidade
13.
Environ Sci Pollut Res Int ; 27(31): 39343-39353, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32648223

RESUMO

The leather industry is one of the major producers of wastewater, releasing large amounts of various chemicals into the environment. Chromium (Cr) is the most commonly used agent in the tanning industry. Accumulation in the animal body can adversely affect the functioning of animal tissues. The current study investigated the toxic effects of Cr on lung, kidney, liver, and testicular tissues in Libyan jirds (Meriones libycus) inhabiting the area surrounding Ghazghan leather industrial town, Mashhad, Iran. Average Cr concentrations were found to be significantly higher in samples from contaminated areas than controls (p < 0.05). The highest accumulation of Cr was found in lung tissue, while the liver tissue showed the lowest. The results also showed that sex and age had no significant effect on Cr accumulation in any tissue at either sampling area (p < 0.05). Histological analyses showed that Cr accumulation had caused changes in tissue samples from Libyan jirds from the contaminated area. Hyperemia was observed in all tissues. In kidney tissue, necrosis and degeneration of the epithelial cells of the tubules were seen as well, and in one case, we also observed hemorrhage. In liver tissue, necrosis, degeneration, and inflammation were observed, along with one case, of fibrosis. In lung tissue, we observed emphysema, hemorrhage, and inflammation. Testicular tissue also showed a considerable lesion. Given the proximity of specimens' habitat to an area of importance, i.e., the industrial town, and the species' dependence on its habitat for nutrition, Libyan jirds are particularly useful for monitoring. Thus, they can be used to monitor the level of contamination in future studies.


Assuntos
Cromo/análise , Indústrias , Animais , Gerbillinae , Resíduos Industriais/análise , Irã (Geográfico) , Curtume , Águas Residuárias/análise
14.
Environ Sci Pollut Res Int ; 27(31): 39442-39465, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32651783

RESUMO

With the rapid growth of economy, the environmental pollution problem is becoming increasingly prominent. How to promote the coordinated and balanced development of economy and environment is a strategic problem of great significance that we face urgently. Taking Wuhan City of China as the research object, this paper selects the key indexes of economic growth and environmental pollution and studies the interactive influence between economic growth and environmental pollution in Wuhan. On the one hand, the impact of Wuhan's economic growth on environmental pollution is analyzed by the proposed time-delay correlation analysis method and the time-delay EKC (Environment Kuznets Curve) models. On the other hand, the impact of Wuhan's environmental pollution on environmental growth is studied. By establishing the LARS-LASSO (least angle regression-least absolute shrinkage and selection operator) regression model and the stepwise regression model, the main factors affecting economic growth in preliminary environmental pollution indexes are analyzed, and then, an interaction model is established to study the impact of the interaction between any two main environmental factors on economic growth. The results of empirical analysis show that the main factors affecting economic growth are industrial wastewater emissions, industrial waste gas emissions, and industrial smoke and dust emissions, and the interaction between industrial waste gas emissions and industrial wastewater emissions restrains economic growth.


Assuntos
Desenvolvimento Econômico , Poluição Ambiental/análise , Dióxido de Carbono/análise , China , Cidades , Resíduos Industriais , Indústrias
15.
Waste Manag Res ; 38(9): 923-941, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32635832

RESUMO

Waste from the construction sector poses huge challenges for sustainable waste management. This is not only due to the vast amount of waste produced in construction and demolition activities, but also due to pollutants potentially contained in these products. Subject to these conditions, waste management must ensure recovery of as many resources as possible, while making sure to keep material loops clean. This demanding task requires more knowledge about the existing building stock and an adaptation of current demolition processes. Innovative technologies, such as Building Information Modelling, or modern frameworks, such as Geographic Information Systems, offer a high potential to synoptically provide stock material information for future demolition activities for individual objects to be deconstructed as well as for whole cities as a basis for managing the anthropogenic stock and potential urban mining. Suitable methods of data collection allow for acquiring the desired input for the generation of building stock models enriched with demolition-related information. With the latter, selective deconstruction strategies as well as appropriate waste stream routing agendas can be planned and executed, thereby securing safety at work during the demolition process itself and a waste stream routing according to the waste hierarchy. This review article gives an overview of currently deployed building material assessment tools (data capture and visualisation), both a prerequisite for improved information on materials and geometry (and thereby mass/volume). In addition, this article describes workflows employable for the purpose of urban mining in end-of-life buildings, of which one holistic approach will be described in depth.


Assuntos
Indústria da Construção , Gerenciamento de Resíduos , Cidades , Materiais de Construção , Documentação , Sistemas de Informação Geográfica , Resíduos Industriais , Reciclagem
16.
Chemosphere ; 259: 127468, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32603966

RESUMO

In this study, two native duckweeds (Lemna minor and Azolla pinnata) were cultivated in Palm Oil Mill Effluent (POME) to extract nutrients from the effluent. Five grams of A. pinnata and 2 g of L. minor were transferred to 2 L POME (Initial concentrations: 198 mg/L COD, 4.3 mg/L nitrates, pH 9.53, 4 mg/L phosphate, 2.98 mg/L ammonia) with four different dilutions (2.5%, 5%, 10%, 15%) under greenhouse conditions. Samples of POME were taken every two days up to 10 days. Growth parameter, phosphate, ammonia, nitrates, pH, and COD were monitored within 10 days to select the most suitable growth medium for both plants. Results showed that 2.5% POME dilution had positive effect on L. minor growth and A. pinnata (wet weight increased by 8.7 g and 9.8 g, respectively), with all plants able to survive until the final day of exposure. The highest removal of ammonia was accomplished in 5% POME dilution by A. pinnata (98%) and L. minor (95.5%). The maximum phosphate removal was obtained in 10% POME dilution with 93.3% removal by A. pinnata and 86.7% by L. minor. Significant COD removal in 15% POME was obtained by L. minor (78%) and A. pinnata (66%). Both plants responded positively to the phytoremediation process, especially for A. pinnata which showed significant decreases in all parameters. The nutrient extraction by both plants from POME showed a positive effect on growth parameter, which has further promising potential to be used as animal feedstock.


Assuntos
Biodegradação Ambiental , Resíduos Industriais , Óleo de Palmeira , Animais , Araceae , Gleiquênias , Nutrientes , Óleos Vegetais
17.
Environ Sci Pollut Res Int ; 27(32): 40088-40100, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32656751

RESUMO

Due to the complexity and variability of textile wastewater composition, a constant search for new treatment strategies that are efficient, eco-friendly, and cost-effective is mandatory. In the present study, the efficiency of coagulation-flocculation using biocoagulants derived from cactus Opuntia ficus indica and eggplant Solanum melongena to remove toxic compounds from Tunisian textile wastewater samples was evaluated by combining assays to investigate physicochemical properties and in vitro (geno)toxicity with analytical chemistry. Both natural coagulants could significantly improve the physicochemical properties of the textile wastewater samples compared to the traditionally used chemical coagulant. The highest rate of decolorization was achieved after treatment with the cactus-derived coagulant. The analytical study revealed the presence of only crystal violet dye (CV) in only one sample. Both natural coagulants were able to remove CV, which may (partially) explain the decolorization of the treated samples. Only one untreated textile effluent induced a genotoxic response in the VITOTOX® assay. The genotoxic effect was not linked to the presence of CV and was no longer observed after treatment with each of the natural coagulants, suggesting the effectiveness of the remediation treatments to remove potentially genotoxic compound(s). However, in the other genotoxicity tests, no biologically relevant effects were observed for any of the tested samples. In conclusion, although the physicochemical data indicate that the use of natural coagulants (cactus and eggplant) could be an interesting alternative treatment process to the chemical coagulant for detoxifying textile effluents, these results were only partially supported by the toxicological and analytical data.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Floculação , Resíduos Industriais/análise , Indústria Têxtil , Têxteis , Eliminação de Resíduos Líquidos , Águas Residuárias/análise , Poluentes Químicos da Água/análise
18.
Environ Sci Pollut Res Int ; 27(32): 40101-40108, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32656754

RESUMO

The oily wastewater was treated by electrocoagulation with Fe78Si9B13 amorphous ribbons as anode and graphite plates as cathode under such processing parameters as different pH values and current density, respectively. The degradation effect on the oily wastewater was characterized by chemical demand oxygen (COD), while the ribbons before and after using were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results indicate that under the conditions of pH = 3 and current density being 3.125 A/cm2, the optimal COD removal efficiency was obtained to be 73.22%. Compared with the ordinary crystalline iron plate, the COD removal efficiency of resultant wastewater degraded by the amorphous ribbons is more than doubled. Simultaneously, the Fe78Si9B13 amorphous ribbons exhibit good structural stability even after four cycles of using.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Análise da Demanda Biológica de Oxigênio , Eletrocoagulação , Eletrodos , Concentração de Íons de Hidrogênio , Resíduos Industriais/análise , Óleos , Eliminação de Resíduos Líquidos
19.
Chemosphere ; 260: 127642, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32683030

RESUMO

The former Pb-Zn mining town of Kabwe in central Zambia is ranked amongst the worst polluted areas both in Africa and in the world. The fine dust particles from the ISF and Waelz slags deposited in Kabwe represent a health risk for the local population. Here, we combined a detailed multi-method mineralogical investigation with oral bioaccessibility testing in simulated gastric fluid (SGF; 0.4 M glycine, pH 1.5, L/S ratio of 100, 1 h, 37 °C) to evaluate the risk related to the incidental dust ingestion. The slag dust fractions contain up to 2610 mg/kg V, 6.3 wt% Pb and 19 wt% Zn. The metals are mainly bound in a slag glass and secondary phases, which formed during the slag weathering or were windblown from nearby tailing stockpiles (carbonates, Fe and Mn oxides, phosphates, vanadates). The bioaccessible fractions (BAFs) are rather high for all the main contaminants, with the BAF values generally higher for the ISF slags than for the Waelz slags: Pb (24-96%), V (21-100%) and Zn (54-81%). The results clearly indicate the potential risks related to the incidental slag dust ingestion. Even when a conservative value of the dust daily intake (100 mg/day) is considered, the daily contaminant intake significantly exceeds the tolerable daily intake limits, especially for Pb â‰« V > Zn. At higher ingestion rates, other minor contaminants (As, Cd) also become a health risk, especially for children. The slag heaps in Kabwe should be fenced to prevent local people entering and should be covered to limit the dust dispersion.


Assuntos
Exposição Ambiental , Resíduos Industriais , Criança , Cidades , Poeira/análise , Monitoramento Ambiental , Poluentes Ambientais , Humanos , Metais/análise , Mineração , Zâmbia
20.
Environ Monit Assess ; 192(7): 480, 2020 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-32617674

RESUMO

Polymers are currently used in the industry as raw material, yet they are rapidly eliminated and largely contaminate the environment. To address this issue, there is a special interest in biodegradable polymers, namely, polyhydroxyalkanoates (PHAs), produced by microorganisms. This study identifies PHA-producing bacteria from two industrial wastewaters of Manizales, Colombia. The samples were cultured in mineral salt medium with glucose as the carbon source in the presence of Nile red stain. The fluorescent colonies were independently transferred to another medium and assessed through fluorescence microscopy with Nile blue stain. The fluorescent strains under Nile blue staining were purified in Nutrient Agar, and their morphological and microbiological characteristics were determined. The bacteria positive for red-orange fluorescence were purified in Nutrient Agar medium, and molecular analyses were performed by PCR amplification of a 650-bp fragment of the 16S ribosomal DNA gene. The bacteria were also assessed in terms of PHA production. We confirmed the identity of 12 out of 14 PHA-positive strains, which belonged to the following genera: Bacillus, Lactococcus, Citrobacter, Enterobacter, and Acinetobacter. Five of the isolates (Enterobacter cloacae, Enterobacter sp., Enterobacter ludwigii, Bacillus thuringiensis, and Bacillus safensis) are promising strains for PHA production, with production values ranging from 0.360 to 0.9960 g/L. Bacteria that produce more than 0.3 g/L are considered useful for the industrial manufacture of bioplastic. We recommend performing large-scale studies on these strains to assess their use for the industrial production of biopolymers, allowing to generate high-impact bioconversion processes of industrial interest.


Assuntos
Poli-Hidroxialcanoatos , Bacillus , Bactérias , Colômbia , Enterobacter , Monitoramento Ambiental , Resíduos Industriais
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA