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1.
J Environ Sci (China) ; 85: 17-34, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31471024

RESUMO

Is our food safe and free of the crisis of antibiotics and antibiotic resistance (AR)? And will the derived food waste (FW) impose AR risk to the environment after biological treatment? This study used restaurant FW leachates flowing through a 200 tons-waste/day biological treatment plant as a window to investigate the fate of antibiotics and antibiotic-resistance genes (ARGs) during the acceptance and treatment of FW. Sulfonamides (sulfamethazine, sulfamethoxazole) and quinolones (ciprofloxacin, enrofloxacin, ofloxacin) were detected during FW treatment, while tetracyclines, macrolides and chloramphenicols were not observable. ARGs encoding resistance to sulfonamides, tetracyclines and macrolides emerged in FW leachates. Material flow analysis illustrated that the total amount of antibiotics (except sulfamethazine) and ARGs were constant during FW treatment processes. Both the concentration and total amount of most antibiotics and ARGs fluctuated during treatment, physical processes (screening, centrifugation, solid-liquid and oil-water separation) did not decrease antibiotic or ARGs concentrations or total levels permanently; the affiliated wastewater treatment plant appeared to remove sulfonamides and most ARGs concentrations and total amount. Heavy metals Ni, Co and Cu were important for disseminating antibiotics concentrations and MGEs for distributing ARGs concentrations. Humic substances (fulvic acids, hydrophilic fractions), C-associated and N-associated contents were essential for the distribution of the total amounts of antibiotics and ARGs. Overall, this study implied that human food might not be free of antibiotics and ARGs, and FW was an underestimated AR pool with various determinants. Nonetheless, derived hazards of FW could be mitigated through biological treatment with well-planned daily operations.


Assuntos
Antibacterianos/análise , Resistência Microbiana a Medicamentos/genética , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise , Genes Bacterianos , Metais Pesados/análise , Restaurantes , Águas Residuárias/química , Águas Residuárias/microbiologia
2.
Bioresour Technol ; 291: 121853, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31377510

RESUMO

The concentration of antibiotics in anaerobically digested swine wastewater (ADSW) usually gradually increases due to the addition of antibiotics in livestock feed. Lemna aequinoctialis was used to treatment synthetic ADSW contaminated by oxytetracycline (OTC) whose concentrations were 0.05, 0.25, 0.50 and 1.00 mg/L, and its influences on NH3-N and TP remove were investigated. The fresh weight, photosynthetic pigment and protein content of duckweed were also investigated. Results have shown that nutrient removal and duckweed growth followed the "dose-response" relationships, and 0.05 mg/L OTC could significantly promote the synthesis of photosynthetic pigments and proteins in duckweed. Meanwhile, the protein content gradually decreased during investigation. More important, the degradation products and possible degradation pathways of OTC were diagrammatized via liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), and twelve intermediates were detected in the duckweed systems. This study can offer a novel view for phytoremediation of ADSW containing antibiotics by aquatic plants.


Assuntos
Antibacterianos/metabolismo , Araceae/metabolismo , Nutrientes , Oxitetraciclina/metabolismo , Águas Residuárias/química , Anaerobiose , Animais , Biodegradação Ambiental , Cromatografia Líquida , Suínos , Espectrometria de Massas em Tandem
3.
Bioresour Technol ; 291: 121844, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31400704

RESUMO

A low-temperature sodium hydroxide (NaOH) pretreatment for sugarcane bagasse (SCB) was obtained via the surface response design in this study. However, a large quantity of water consumption and wastewater generation which have been the common problems for alkaline pretreatment of lignocellulose still exists in this pretreatment. In order to reduce water consumption and wastewater generation, this study attempted to perform enzymatic hydrolysis and fermentation of NaOH-treated SCB without washing process. It showed that after pretreatment and solid-liquid separation, NaOH-treated SCB could be directly hydrolysed by cellulase via pH and solid-liquid adjustment without washing steps, and the maximum enzymatic hydrolysis efficiency could reach to 70.2%. A domesticated Saccharomyces cerevisiae Y2034 which can endure 6-times diluted BL was obtained, and realized 67.5% ethanol yield from the enzymatic hydrolysate of unwashed NaOH-treated SCB. It provided a clue for converting NaOH-treated lignocellulose to ethanol at low water consumption and wastewater generation.


Assuntos
Celulose/química , Etanol/química , Saccharum/química , Hidróxido de Sódio/química , Celulose/metabolismo , Temperatura Baixa , Etanol/metabolismo , Fermentação , Hidrólise , Lignina/química , Lignina/metabolismo , Saccharomyces cerevisiae/metabolismo , Saccharum/metabolismo , Águas Residuárias/química
4.
Bioresour Technol ; 291: 121888, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31374413

RESUMO

A coupled microbial fuel cell (MFC) system, consisting of a nitrifying sulfide removal MFC and a denitrifying sulfide removal MFC, was assembled to simultaneously treat ammonium and sulfide in wastewater. It provided a promising approach to recover electricity from wastewater containing sulfide and ammonium. Considering both substrate removal and electricity generation performance, the desirable feeding S/N molar ratio was deemed as 3 and the optimal temperature was found to be 30 °C. Under this condition, the coupled MFC achieved a sum coulomb production of 554.8 C/d, a total nitrogen removal efficiency of 58.7 ±â€¯1.3% and a sulfur production percent of 27.4 ±â€¯0.4-33.3 ±â€¯0.9%. The introduction of nitrifiers and electroactive oxic microbes from the oxic-cathode chamber into the anoxic-cathode chamber favored nitrogen removal.


Assuntos
Fontes de Energia Bioelétrica , Nitrogênio/isolamento & purificação , Sulfetos/isolamento & purificação , Águas Residuárias/química , Compostos de Amônio/química , Desnitrificação , Eletricidade , Eletrodos
5.
Bioresour Technol ; 291: 121890, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31378447

RESUMO

In recent impetus of phycological research, microalgae have emerged as a potential candidate for various arena of application-driven research. Omics-based tactics are used for disentangling the regulation and network integration for biosynthesis/degradation of metabolic precursors, intermediates, end products, and identifying the networks that regulate the metabolic flux. Multi-omics coupled with data analytics have facilitated understanding of biological processes and allow ample access to diverse metabolic pathways utilized for genetic manipulations making microalgal factories more efficient. The present review discusses state-of-art "Algomics" and the prospect of microalgae and their role in symbiotic association by using omics approaches including genomics, transcriptomics, proteomics and metabolomics. Microalgal based uni- and multi-omics approaches are critically analyzed in wastewater treatment, metal toxicity and remediation, biofuel production, and therapeutics to provide an imminent outlook for an array of environmentally sustainable and economically viable microalgal applications.


Assuntos
Microalgas/metabolismo , Animais , Genômica/métodos , Humanos , Metabolômica , Proteômica , Águas Residuárias/química
6.
Bioresour Technol ; 291: 121836, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31344632

RESUMO

The aim of this work was to study the biotreatment of mixed wastewaters collected from two points of MnO2 industry by Chlorella vulgaris. Their growth rates in four mixed wastewaters with mass ratio of wastewater 1#:2# of 20:1, 50:1, 100:1, and 200:1 were characterized, and the lag phase was shortened with increase of nitrate concentrations. The N, P, and metal removal kinetics were quantified each other day to evaluate the bio-treatment efficiencies of high-nitrate wastewaters from MnO2 industry. 84.68% and 98% of N, P has been removed. The Ca, Zn, Mn, and Si in mixed wastewaters was removed with maximum removal efficiencies of 97.91%, 99.37%, 99.44%, and 81.68%, respectively. The compositions of Chlorella vulgaris cultured in mixed wastewaters, including proteins, lipids, ash contents, and carbohydrates, were investigated in detail. The optimum HHV of Chlorella vulgaris about 18 MJ/Kg presented a potential to decrease the cost of algal biofuel.


Assuntos
Chlorella vulgaris/metabolismo , Compostos de Manganês/metabolismo , Nitratos/metabolismo , Óxidos/metabolismo , Águas Residuárias/química , Óxidos de Nitrogênio/metabolismo , Eliminação de Resíduos Líquidos/métodos
7.
Bioresour Technol ; 289: 121702, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31260935

RESUMO

In this study, a newly discovered microalga Parachlorella kessleri QWY28 with a superior ability to treat real swine wastewater, was isolated and explored. The optimal culture conditions of 30 °C and 600 µmol/m2·s were set to improve the practical application potential, achieving maximum pollutant removal efficiencies of 88% COD, 95% TN and almost 100% TP, with carbohydrate production at 646 mg/L·d. These results present the highest efficiencies reported to date, for non-sterilized real swine wastewater without pretreatment. These findings support the practical feasibility of combined microalgal swine wastewater purification and energy production systems.


Assuntos
Carboidratos/biossíntese , Clorófitas/metabolismo , Microalgas/metabolismo , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Animais , Suínos
8.
Bioresour Technol ; 289: 121718, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31296361

RESUMO

There is an exponential increase in swine farms around the world to meet the increasing demand for proteins, resulting in a significant amount of swine/piggery wastewater. The wastewater produced in swine farms are rich in ammonia with high eutrophication potential and negative environmental impacts. Safe methods for treatment and disposal of swine wastewater have attracted increased research attention in the recent decades. Conventional wastewater treatment methods are limited by the high ammonia content and chemical/biological oxygen demand of swine wastewater. Recently, microalgal cultivation is being proposed for the phytoremediation of swine wastewater. Microalgae are tolerant to high ammonia levels seen in swine wastewater and they also ensure phosphorus removal simultaneously. This review first gives a brief overview on the conventional methods used for swine wastewater treatment. Microalgae-based processes for the clean-up of swine wastewater are discussed in detail, with their potential advantages and limitations. Future research perspectives are also presented.


Assuntos
Microalgas/metabolismo , Águas Residuárias/química , Amônia/metabolismo , Animais , Análise da Demanda Biológica de Oxigênio , Fósforo/metabolismo , Suínos
9.
Bioresour Technol ; 289: 121714, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31323719

RESUMO

In this study, multistage contact oxidation reactor (MCOR) with a novel carrier was used for treatment of high-strength sodium saccharin wastewater (SSW) under stepwise increasing salinities from 1.0% to 8.0%. The results revealed that MCOR could effectively remove the organic pollutants from SSW when influent salinity was no more than 4.5%; the chemical oxygen demand (COD) and NH4+-N removal efficiency under the optimal operating parameters ranged up to 91.5% and 92.7%, respectively. Microbial diversity analysis illustrated that the dominant microbes in SSW treatment system were substantially distinct at different salinities. Pseudomonas was predominant at salinity of 3.5%, while Marinobacterium (a species involved in COD removal) was enriched to a greater degree at salinity of 7.0%. CCA suggested that salinity was the main factor for dynamic evolutions of microbial community structures. This work demonstrated that MCOR is an appropriate method for the treatment of high-strength, high-salinity SSW.


Assuntos
Microbiota , Sacarina/metabolismo , Águas Residuárias/química , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos/microbiologia , Oxirredução , Sacarina/análise , Salinidade
10.
Bioresour Technol ; 289: 121716, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31323721

RESUMO

This study integrated the sugar and carboxylate platforms to enhance duckweed processing in biorefineries. Two or three bioprocesses (ethanol fermentation, acidogenic digestion, and methanogenic digestion) were sequentially integrated to maximize the carbon-to-carbon conversion of wastewater-derived duckweed into bioproducts, through a series of laboratory-scale experiments. Reactors were fed either raw (dried), liquid-hot-water-pretreated, or enzymatically-saccharified duckweed. Subsequently, the target bioproduct was separated from the reactor liquor and the residues further processed. The total bioproduct carbon yield of 0.69 ±â€¯0.07 g per gram of duckweed-C was obtained by sequential acidogenic and methanogenic digestion. Three sequential bioprocesses revealed nearly as high yields (0.66 ±â€¯0.08 g of bioproduct-C per duckweed-C), but caused more gaseous carbon (dioxide) loss. For this three-stage value cascade, yields of each process in conventional units were: 0.186 ±â€¯0.001 g ethanol/g duckweed; 611 ±â€¯64 mg volatile fatty acids as acetic acid/g VS; and 434 ±â€¯0.2 ml methane/g VS.


Assuntos
Araceae/metabolismo , Águas Residuárias/química , Ácido Acético/metabolismo , Anaerobiose , Araceae/química , Etanol/metabolismo , Euryarchaeota/metabolismo , Fermentação , Metano/biossíntese
11.
Water Sci Technol ; 79(10): 1887-1896, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31294705

RESUMO

The paper discusses how citizen science within an ecosystem services (ESS) framework may enhance evaluation of de-centralized water solutions. In a demonstration case in Oslo, citizens were engaged in long-term monitoring and evaluation of two solutions for treatment of combined sewer overflows. The citizens participated in the design of the study, systematic observations, and final evaluation, via interviews and workshops. A wealth of real-time information was collected, supplementing simulation data and water sampling results. The concept of ESS drew attention to benefits that tend to be ignored in standard evaluations. It is, however, most elaborate for ecological services, and less developed for social aspects. Involving the citizens complemented the framework in these areas, while providing new insights into the contextual interactions influencing ESS and benefits of local treatment. Both solutions, a cross-flow lamella settler and a high-rate filtration system, were quite efficient in removing suspended solids, with a strong impact on visual appearance. A range of wider benefits were identified. These were difficult to monetize, but the citizens' evaluation provided an alternative measure. The study highlights the benefits of citizen science in local water management and suggests the need for more research on beneficiaries in ESS evaluation.


Assuntos
Participação da Comunidade , Eliminação de Resíduos Líquidos/métodos , Ecossistema , Humanos , Pesquisa , Águas Residuárias/química , Água
12.
An Acad Bras Cienc ; 91(2): e20180394, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31269105

RESUMO

The petrochemical industry has played a considerable role in generation and release of waste in the environment. Activated sludge and facultative lagoons are commonly used for domestic and industrial wastewater treatment due to their low-cost and minimal need for operational requirements. Microorganisms present in wastewater treatment plant (WWTP) are responsible for most nutrient removal. In this study, microbiological and physicochemical parameters were used to estimate changes in bacterial community in a petrochemical industrial WWTP. The activated sludge was the place with higher heterotrophic bacterial quantification. Denitrifying bacteria was reduced at least 5.3 times throughout all collections samples. We observe a decrease in the total Kjeldahl nitrogen, oxygen demand and phosphate throughout the WWTP. In this work, we also use Matrix-Assisted Laser Desorption Ionisation-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) for bacteria isolates identification comparing with 16S rDNA sequencing. The MALDI-TOF MS allowed the identification of 93% of the isolates and only 5% show different results from 16S rDNA sequencing showing that the MALDI-TOF MS can be a tool for identifying environmental bacteria. The observation of microbial community dynamics in the WWTP is important in order to understand the functioning of the ecological structure formed in a specific environment.


Assuntos
Bactérias/metabolismo , Águas Residuárias/química , Águas Residuárias/microbiologia , Purificação da Água/métodos , Bactérias/classificação , Técnicas de Tipagem Bacteriana , DNA Bacteriano/genética , Espectrometria de Massas , Indústria de Petróleo e Gás , RNA Ribossômico 16S/genética , Eliminação de Resíduos Líquidos/métodos
13.
Bioresour Technol ; 289: 121754, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31323714

RESUMO

Acetonitrile (ACN) is a very volatile, toxic and nitrogen-rich organic compound. To enhance ACN wastewater treatment, a novel hybrid membrane-aerated bioreactor (MAB) containing aerated and non-aerated zones was established. A polypropylene hollow fiber membrane module (HF) and a silicone rubber membrane module (SR) were separately used as the bubble-free aeration diffuser and the biofilm carrier, and the non-aerated zones of these two types of reactors were packed with ceramsite. When the influent ACN loading was 1.200 kg/m3·d, under aeration pressures of 20 kPa in the HF-MAB and 40 kPa in the SR-MAB, ACN removal loadings of 1.116 kg/m3·d and 1.004 kg/m3·d, respectively, were achieved, and the TN (total nitrogen) removal loadings were 0.267 kg/m3·d and 0.246 kg/m3·d, respectively. In the MABs, different stratified biofilm structures of the two zones and the diffusion and counter-diffusion of oxygen synergistically promoted ACN degradation, nitrification and denitrification.


Assuntos
Reatores Biológicos , Águas Residuárias/química , Acetonitrilos/metabolismo , Biofilmes , Análise da Demanda Biológica de Oxigênio , Desnitrificação , Nitrificação , Nitrogênio/química , Oxigênio/metabolismo , Eliminação de Resíduos Líquidos
14.
Bioresour Technol ; 289: 121742, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31323725

RESUMO

A novel partial nitritation-anammox (PNA) reactor configuration was piloted for 250 days. Primary effluent from full-scale municipal wastewater treatment plant was treated in a two-stage biofilm system incorporating innovative process control for cold partial nitritation. Partial nitritation was combined with carbon removal in a moving bed biofilm reactor (MBBR) to achieve high-rate treatment and nitritation was obtained with dissolved oxygen to total ammonium nitrogen (DO/TAN) ratio control and free ammonia (FA) for inhibition of nitratation. Effluent from MBBR was directed to an integrated fixed-film activated sludge (IFAS) reactor where nitrogen was removed via anammox. MBBR achieved partial nitritation at 2.0 ±â€¯0.3 g-N m-2 d-1 and nitrogen removal in the IFAS reactor reached 0.45 ±â€¯0.1 g-N m-2 d-1 (55 g-N m-3 d-1). The process performed well at 19 ±â€¯3 °C with an average effluent total inorganic nitrogen (TIN) concentration of 11 ±â€¯4 mg L-1.


Assuntos
Biofilmes , Nitrogênio/metabolismo , Esgotos , Águas Residuárias/química , Amônia/metabolismo , Compostos de Amônio/metabolismo , Reatores Biológicos , Desnitrificação , Oxirredução , Oxigênio/metabolismo , Projetos Piloto
15.
Sci Total Environ ; 691: 1043-1050, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31326796

RESUMO

The reduction of greenhouse gases (GHG) emissions is important challenge in the wastewater treatment plants. In this way, the present study aimed to evaluate the GHG emissions and carbon dioxide fixation by duckweed ponds (DWP) applied to treat municipal wastewater in a polishing stage. Two pilot DWP (3000 L) were operated in a series with real wastewater receiving a flow rate of 200 L d-1 and organic load rate of 39 g COD ha-1 d-1. Beyond the standard physicochemical parameters for wastewater monitoring, the gases emissions from pond surface were measures by using a static flux chamber with infrared probes installed inside to detect CO2 and CH4 concentration. Operating the DWP with a load of 18.1 kg TN ha-1 d-1 and 2 kg TP ha-1 d-1, across 425 days of monitoring, higher COD and nutrient removal efficiency was identified (79%, 93% and 84% for COD, TN and TP, respectively). The CO2 emission rate ranged from 3048 to 6017 mg CO2 m-2 d-1 and the fixation rate ranged from 19,592 to 42,052 mg CO2 m-2 d-1. Methane emission was not detected (less than 0.1%). Moreover, low abundance of archaeal community was identified in both DWP. The results showed that in presented conditions, under low COD loading rate DWP could fix at least three times more CO2 than it emits, highlighting the sustainability of this natural technology.


Assuntos
Poluentes Atmosféricos/química , Gases de Efeito Estufa/análise , Eliminação de Resíduos Líquidos/métodos , Ciclo do Carbono , Sequestro de Carbono , Águas Residuárias/química
16.
Ecotoxicol Environ Saf ; 182: 109401, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31272024

RESUMO

Chronic impact will last from a sudden pollution accident, however, potential adverse effects of heavy metal(loid)s are overlooked when pollution decreased during years of equilibration. Here, we assessed the potential health risks of heavy metal(loid)s via intake of vegetables from fields affected by the smelting wastewater spill eight years later, basing on site-specific target hazard quotient (STHQ) and cancer risk (SCR) models. Results showed kohlrabi, lettuce and garlic had significant high concentrations of Sb (10.4 mg kg-1), Pb (21.0 mg kg-1), Cd (6.49 mg kg-1), and Zn (441 mg kg-1), and sweet potato and garlic enriched high levels of As (19.6 mg kg-1) and Cu (14.1 mg kg-1), respectively. Transfer factors of metal(loid)s from soil to plants were enhanced by high soluble metal(loid) concentrations, and Sb, As, Pb and Cd in most edible tissues exceeded the contamination limitations for food in China and FAO/WHO. Chinese cabbage had significant high STHQ of As (adult 9.31 and child 19.8) and Sb (adult 0.76 and child 1.61) (p < 0.05), and the highest STHQ of Cd (adult 1.41 and child 3.02) was in lettuce, whereas the highest STHQ of other elements from vegetables were below 1. However, the non-carcinogenic risks based on total STHQ values of these vegetables were several times higher than the acceptable level of 1. In addition, the total SCR values at 5% were hundreds times of safety level of 5.0 × 10-5 set by International Commission on Radiological Protection. Considering food frequency and metal(loid) levels, long-term consumption of local vegetables, especially lettuce and Chinese cabbage, are likely to increase non-carcinogenic and carcinogenic (e.g. As and Cd) health risks. Child's health risk of toxic elements was far greater than adult. This study might serve as a case study of long-term adverse impact for other pollutant incidents. People should pay attention to human health through food chain, and the government should solve the outstanding environmental problems that harm the health of the masses.


Assuntos
Exposição Dietética/estatística & dados numéricos , Monitoramento Ambiental , Metais Pesados/análise , Poluentes do Solo/análise , Verduras/química , Acidentes , Adulto , Vazamento de Resíduos Químicos , Criança , China , Poluentes Ambientais , Humanos , Metalurgia , Medição de Risco , Solo , Águas Residuárias/química
17.
Chemosphere ; 233: 946-953, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31340422

RESUMO

Scorodite is an important mineral not only for arsenic (As) removal from industrial wastewaters but also in the mobility and final fate of As in waste rocks, contaminated soils and sediments, and mine tailings. Because of the mineral's high As-loading capacity and stability, numerous studies have been done to understand its formation. Unfortunately, most of these studies were limited to elevated temperatures (>70 °C), so the processes involved in scorodite formation under ambient conditions remain unclear. This study provides evidence of the catalytic effects of hematite on the formation of scorodite at 25 °C in a pyrite-rich natural geologic material. Scorodite peaks were detected in the XRD patterns of the leaching residues with and without hematite, but those in the former were stronger and more pronounced than the latter. These results suggest that the formation of scorodite was catalysed by hematite, a generalisation that is further supported by strong characteristic IR absorption bands of scorodite at 819 cm-1 (As-O bending vibration), 785 and 725 cm-1 (As-O stretching vibrations), and 2990 cm-1 (OH-vibration) as well as the distinct XPS binding energies of Fe(III)-As (709.7 eV), As(V)-O (44.8, 44.31 and 43.7 eV), O2- (530.5 eV) and coordinated water (531.3 eV) in scorodite. This phenomenon could be attributed to three possible mechanisms: (1) more rapid precipitation promoted by the "seeding" effect of hematite particles, (2) additional supply of Fe3+ from hematite dissolution under acidic conditions, and (3) enhanced oxidations of Fe2+ to Fe3+ and As(III) to As(V) on the surface of hematite.


Assuntos
Arsênico/química , Arsenicais/síntese química , Compostos Férricos/química , Águas Residuárias/química , Purificação da Água/métodos , Catálise , Ferro/química , Oxirredução , Poluentes do Solo/análise , Sulfetos/química , Poluentes Químicos da Água/análise
18.
Chemosphere ; 233: 405-413, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31176904

RESUMO

Water-stable PVA/PAA nanofibers were fabricated through electrospinning and evaluated for their performance in lead (Pb(II)) and cadmium (Cd(II)) removal from water in a batch experiment. The adsorption mechanism of Pb(II) was explored using the extended X-ray absorption fine structure (EXAFS) spectroscopic analysis. The PVA/PAA nanofibers showed a pH-dependent behavior for heavy metal removal, and its adsorption capacities for Pb(II) and Cd(II) could reach as high as 159 and 102 mg/g, respectively. The calcium ion (Ca(II)) had no effect on Pb(II) removal at pH 5.0 whereas it significantly reduced Cd(II) removal at pH 7.0. The adsorption of Pb(II) and Cd(II) was spontaneous and exothermic in nature with a decrease in randomness. The saturated PVA/PAA nanofibers could be regenerated using acidic solutions for reuse. The Fourier-transform infrared (FTIR) spectroscopic analysis indicated the formation of surface complexes between adsorbed Pb(II) and Cd(II) and carboxyl groups on PVA/PAA nanofibers. Moreover, EXAFS analysis suggested that a Pb(II) cation was chelated with three carboxyl groups on the nanofibers. This molecular-level adsorption structure was successfully implemented into a surface complexation model for the prediction of the macroscopic Pb(II) and Cd(II) adsorption behaviors. The results gained from this study provided complementary information on heavy metal removal by a new generation of adsorbents and improved the fundamental understanding for the removal process.


Assuntos
Resinas Acrílicas/química , Metais Pesados/análise , Modelos Teóricos , Nanofibras/química , Álcool de Polivinil/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Cádmio/análise , Concentração de Íons de Hidrogênio , Cinética , Chumbo/análise , Águas Residuárias/química
19.
Chemosphere ; 233: 431-439, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31176907

RESUMO

The transformation of roxarsone (ROX) during UV disinfection with Fe(III) has been investigated. Fe(OH)2+, as the main Fe(III) species at pH = 3, produces HO under UV irradiation leading to the oxidation of ROX. Dissolved oxygen plays a very important role in the continuous conversion of generated Fe2+ to Fe3+, which ensures a Fe(III)-Fe(II) cycle in the system. The presence of Cl-/HCO3-/NO3- has little influence on the ROX transformation, whereas PO43- achieves an obvious inhibitory effect. The transformation of ROX leads to the formation of inorganic arsenic consisting of a much higher amount of As(V) than As(III). LC-MS analysis shows that phenol, o-nitrophenol and arsenic acid were the main transformation products. Both the radical scavenger experiment and electron spin resonance data confirm that the HO is responsible for ROX transformation. The toxic transformation products are found to have potential environmental risks for the natural environment, organisms and human beings.


Assuntos
Desinfecção/métodos , Compostos Férricos/química , Roxarsona , Raios Ultravioleta , Poluentes Químicos da Água , Purificação da Água/métodos , Íons , Oxirredução , Processos Fotoquímicos , Roxarsona/química , Roxarsona/efeitos da radiação , Águas Residuárias/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/efeitos da radiação
20.
Chemosphere ; 233: 462-471, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31181493

RESUMO

This study investigated the effect of granular activated carbon (GAC) on the digestion of blackwater collected from different collection systems, by monitoring the biochemical methane production (BMP), adsorption of molecules to GAC and their impacts on the microbial community. Without GAC-amendment, BMP reached 35.6, 42.6 and 50.4% in 1L, 5L and 9L water-flushed blackwater, respectively. When 33.3 gL-1 GAC was added to the cultures, methane potential increased up to 53.1% in 1L water-flushed blackwater, while in 5L and 9L water-flushed conditions the BMP drastically decreased to 16.1 and 9.6%, respectively. The concentration of volatile fatty acids (VFA) in 5L and 9L water-flushed blackwater with GAC-amended cultures was not enhanced, in contrast with 1L water-flushed blackwater. Further tests showed 29.8% (±1.9%) of VFA and 86.0% of soluble chemical oxygen demand were removed by GAC adsorption in 9L water-flushed blackwater. A decrease in biomass density in 5L and 9L GAC-amended cultures was also observed, corroborated by a significant decrease in gene copy numbers of methanogenic archaeal communities. This study gives an insight on the effect of GAC on different strengths of blackwater, which is of relevance for further tests of long-time and full-scale application.


Assuntos
Carvão Vegetal/química , Metano/biossíntese , Esgotos/microbiologia , Águas Residuárias/microbiologia , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Anaerobiose , Análise da Demanda Biológica de Oxigênio , Biomassa , Ácidos Graxos Voláteis/análise , Esgotos/química , Águas Residuárias/química
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