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1.
Bioresour Technol ; 302: 122583, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32014734

RESUMO

This study aimed to present a strategy that utilizing semi-continuous flow primary sludge fermentation liquor as carbon source for anaerobic- multistage anaerobic/oxic (A-MAO) process to treat low chemical oxygen demand (COD) and total nitrogen (TN) (C/N) ratio municipal wastewater. The results showed that adding fermentation liquor resulted in average TN and total phosphorus (TP) concentration in effluent decreased from 33 and 2.80 mg L-1 to 9.2 and 0.23 mg L-1, respectively, which met wastewater discharge standard. High-throughput sequencing results indicated that bacterial richness increased and diversity decreased with fermentation liquor adding, and the dominant genera varied from Methylophilaceae and Methylotenera to unclassified_f_Rhodocyclaceae, noran k_f__env.OPS_17, and Azospira. Meanwhile, the abundance of metabolism and organismal systems in A-MAO process rose from 48.42% and 0.74% to 49.52% and 0.78%. The improvement of nitrogen and phosphorus removal with fermentation adding was based on the increment of enzyme coding genes in nitrogen and phosphorus pathway.

2.
Artigo em Inglês | MEDLINE | ID: mdl-31919824

RESUMO

The influence of ultrasonication on membrane performance was investigated by two ultrasonication modes, direct and indirect ultrasonication as pretreatment, and simply improved PVDF-TiO2 membranes' performance was systematically compared. Ultrasound intensity of 100% and ultrasonication time ranged from 1 to 2 h positively affect membrane permeability. Characterization results manifested that membrane structure was eventually optimized with an even nano-TiO2 dispersion by direct ultrasonication. Analysis of surface roughness reflected that PVDF-TiO2 (MS-U2) surface morphological pattern was peak-valley structure that resisted fouling greatly. A good fitting of experimental result and Tansel's simulation illustrated that anti-fouling ability was realized direct ultrasonication modified membrane. PVDF-TiO2 (MS-U2) membrane showing the lowest |τ| reflecting the time required to reach a certain level of the fouling degree was the lowest. Relying upon modified Hermia's model analysis, protein blockage within the membrane pore was one major fouling mechanism; surface blockage degree of PVDF-TiO2 (MS-U2) was relative slight. Fouling mechanism analyzed by two models reflected that PVDF-TiO2 (MS-U2) membrane exhibited a higher anti-protein fouling ability during cross-flow filtration process.

3.
Emerg Microbes Infect ; 8(1): 367-376, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31851879

RESUMO

The dimorphic fungus Talaromyces marneffei (TM) is a common cause of HIV-associated opportunistic infections in Southeast Asia. Cotrimoxazole (CTX) inhibits folic acid synthesis which is important for the survival of many bacteria, protozoa, and fungi and has been used to prevent several opportunistic infections among HIV/AIDS patients. We question whether CTX is effective in preventing TM infection. To investigate this question, we conducted an 11-year (2005-2016) retrospective observational cohort study of all patients on the Chinese national antiretroviral therapy (ART) programme in Guangxi, a province with high HIV and TM burden in China. Survival analysis was conducted to investigate TM cumulative incidence, and Cox regression and propensity score matching (PSM) were used to evaluate the effect of CTX on TM incidence. Of the 3359 eligible individuals contributing 10,504.66 person-years of follow-up, 81.81% received CTX within 6 months after ART initiation, and 4.73% developed TM infection, contributing 15.14/1,000 person-year TM incidence rate. CTX patients had a significantly lower incidence of TM infection than non-CTX patients (4.11% vs. 7.53%; adjusted hazard ratio (aHR) = 0.50, 95% CI 0.35-0.73). CTX reduced TM incidence in all CD4+ cell subgroups (<50 cells/µL, 50-99 cells/µL, 100-199 cells/µL), with the highest reduction observed in patients with a baseline CD4+ cell count <50 cells/µL in both Cox regression and the PSM analyses. In conclusion, in addition to preventing other HIV-associated opportunistic infections, CTX prophylaxis has the potential to prevent TM infection in HIV/AIDS patients receiving ART.

4.
J Environ Manage ; 255: 109849, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31760298

RESUMO

Phosphate removal through in-situ Fe2+ oxidation induced homogenous phosphate precipitation has shown its advantages in municipal wastewater treatment. Its feasibility and suitability for phosphate removal in industrial wastewater with wide-range pH variation like electro-plating wastewater were investigated in bench scale experiments using synthetic wastewater and continuous experiment using real wastewater. Bench scale experiments showed that different Fe2+ oxidation approaches worked well for phosphate removal at varied pH conditions. Sole dosing Fe2+ salt with aeration achieved sound phosphate removal at alkaline condition (pH ≥ 8). At neutral pH (6 < pH < 8), transition metallic ions catalytic oxidation is a suitable alternative. Cu2+ exhibited superior catalytic Fe2+ oxidization over Mn2+, Zn2+, and Ni2+. At acid pH (3.0 < pH ≤ 6.0), Fenton reaction oxidation (H2O2 = 5 mg/L) showed its efficiency. At their corresponding optimal pH conditions and with Fe2+/P ratio of 1.8, dosing sole Fe2+ salt, Cu2+ catalyzed Fe2+ oxidation, and Fe2+/H2O2 treatments can achieve the TP discharge limit of 0.5 mg/L. In a 30-day continuous experiment using real electro-plating wastewater (pH 4.9-5.5), in both direct Fe2+/H2O2 treatment and Cu2+ catalyzed Fe2+ oxidation treatment after wastewater pH being adjusted to 7 effluent TP met China's discharge requirement 0.5 mg/L.

5.
Artigo em Inglês | MEDLINE | ID: mdl-31505898

RESUMO

Currently, composting is one of the most effective methods for treating fecal waste on large-scale livestock and poultry farms, but the quality effects of different composting methods are different. In this study, we implemented four composting methods, including farmer compost (FC), anaerobic compost (AnC), mixed compost (MC), and aerobic compost (AC), to study the effects of different composting methods on nitrogen (N) losses while composting dairy manure. Our results showed that the germination indexes (GIs) of three of the composting treatments (AnC, MC, and AC) exceeded 80%, which met the maturity requirements for composted products. Ammonia (NH3) emissions were the main contributor to nitrogen losses, while accumulated nitrous oxide (N2O) emissions accounted for the lowest proportion of nitrogen losses. The cumulative N losses via the leachate of the AC treatment were the lowest and accounted for 0.38% of the initial total nitrogen (TN). The accumulated N losses of the AC, FC, AnC, and MC treatments accounted for 13.13% 15.98%, 15.08%, and 19.75%, respectively, of the initial TN. Overall, the AC method significantly reduced N losses via leachates, further reducing TN losses. This observation suggests that AC might be an appropriate method for highly efficient nitrogen management during dairy manure composting.


Assuntos
Compostagem/métodos , Indústria de Laticínios , Esterco/análise , Nitrogênio/análise , Amônia/análise , China , Óxido Nitroso/análise
6.
Eur J Med Chem ; 181: 111582, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31398615

RESUMO

5-Aminolevulinic acid (5-ALA) and its two ester derivatives (5-ALA-OMe and 5-ALA-OHex) have been approved for photodiagnosis and photodynamic therapy (PDT) of tumors in the clinical. However, their pharmacological activities are limited by their instability under physiological conditions and lack of tumor selectivity. With the aim to overcome these shortcomings, a glutathione-responsive 5-ALA derivative (SA) was designed based on the fact that many types of tumor cells have higher intracellular glutathione level than normal cells. SA was synthesized by masking the 5-amion group of 5-ALA methyl ester (5-ALA-OMe) with a self-immolative disulfide linker. Compared with 5-ALA and 5-ALA-OMe, SA exhibited higher stability under physiological conditions, and it can efficiently release the parent compound 5-ALA-OMe in response to glutathione. In tumor cells, SA displayed excellent protoporphyrin IX (PpIX) production activity at low concentrations while 5-ALA and 5-ALA-OMe were ineffective at the same concentration. The SA-induced PpIX production was positively correlated with the intracellular glutathione level, and SA exhibited enhanced phototoxicity due to its excellent PpIX generation activity. This study indicates that modification of the amino group in 5-ALA derivatives with a self-immolative disulfide linker is an effective strategy to improve their chemical stability and pharmacological activities, and SA is a potential photosensitizer for photodiagnosis and PDT of tumors.


Assuntos
Ácidos Levulínicos/farmacologia , Neoplasias/tratamento farmacológico , Fármacos Fotossensibilizantes/farmacologia , Pró-Fármacos/farmacologia , Protoporfirinas/farmacologia , Linhagem Celular Tumoral , Glutationa/metabolismo , Humanos , Ácidos Levulínicos/metabolismo , Neoplasias/diagnóstico por imagem , Neoplasias/metabolismo , Imagem Óptica , Fotoquimioterapia , Fármacos Fotossensibilizantes/metabolismo , Pró-Fármacos/metabolismo , Protoporfirinas/metabolismo
7.
Chemosphere ; 235: 701-712, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31279120

RESUMO

This study systematically investigated the performance of ozonation on tetrabromobisphenol A (TBBPA) degradation under different ozone dosages (5.21-83.33 µmoL/L), initial solution pH (3.0-11.0) and temperatures (10-50 °C). At the same time, the generations of inorganic products (bromide ion and bromate) under different experimental conditions were evaluated and the organic products were also identified. Then, the possible mechanism was proposed and verified by the quantum chemical calculation. In addition, variations and controlling of the toxicity were also analyzed, including acute toxicity, chronic toxicity and genotoxicity. Ozonation was proved to be an efficient and promising technology for removing TBBPA from water. TBBPA of 1.84 µmoL/L could be completely degraded within 5 min under the ozone dosage of 41.67 µmoL/L in wide ranges of pH (3.0-11.0) and temperature (10-40 °C). During the degradation of TBBPA, over 65% of the average bromine ion was detected and nine products were identified. The proposed degradation pathways verified that TBBPA might undergo addition and stepwise oxidative debromination, the hydrogen extraction, and the deprotonation. The results of toxicity testing showed that ozonation could effectively control the acute and chronic toxicity of the water samples, although the toxicity increased in the initial reaction stage due to the accumulation of more toxic intermediates.


Assuntos
Ozônio/química , Bifenil Polibromatos/química , Poluentes Químicos da Água/química , Bromatos , Oxirredução , Bifenil Polibromatos/toxicidade , Testes de Toxicidade , Água , Poluentes Químicos da Água/toxicidade
8.
Chemosphere ; 235: 606-615, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31276873

RESUMO

Understanding the mechanism by which perfluorochemicals (PFCs) adsorbed on carbonaceous surface is eventually important to the design and process optimization of effective PFCs removal technologies. In this study, the possible binding mechanism of six different PFCs onto carbonaceous surface was investigated by means of first principles quantum mechanical methods based on density functional theory (DFT) calculation and wave function analysis. The adsorption process fitted well with pseudo-second-order kinetic indicated that chemical bonding could not be underestimated. The results indicate that there were monolayer adsorption, electrostatic and hydrophobic interactions existed in PFCs adsorption process. DFT results suggested that the adsorption of PFCs on carbonaceous surface was one chemisorption process that accompanied by Van der Waals interactions. As there was different head functional groups in PFOS and PFOA, their adsorption capacity mainly controlled by the availability of active sites that was occupied by PFCs. The variation of chain length of PFBS and PFOS also take a certain responsible for different adsorption paths, due mainly to their hydrophobic effect. The obtained results from wave function and DFT analysis give in-depth understanding of PFCs adsorption on carbonaceous surface and help to their effectively removal.


Assuntos
Fluorcarbonetos/química , Poluentes Químicos da Água/química , Adsorção , Fluorcarbonetos/análise , Hidrocarbonetos Fluorados/análise , Interações Hidrofóbicas e Hidrofílicas , Cinética , Modelos Químicos , Modelos Teóricos , Poluentes Químicos da Água/análise
9.
Water Sci Technol ; 79(3): 580-588, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30924813

RESUMO

Fe-C micro-electrolysis was employed to the pretreatment of evaporated condensate generated during metal cutting process. The effect of the reaction conditions on the contaminant removal and degradation mechanism were studied. Through single-factor experiments, the effects of solid-liquid ratio, gas-liquid ratio and reaction time on the treatment of wastewater were preliminarily determined. The optimal reaction condition obtained was: 500 g/L solid-liquid ratio, 30:1 gas-liquid ratio with 4 h reaction time. Under the optimal condition, the chemical oxygen demand (COD) removal efficiency of micro-electrolysis could reach around 25%, and the biodegradability of wastewater increased from 0.12 to 0.32. According to the analysis results of gas chromatography-mass spectrometry (GC-MS) qualitative analysis, it was observed that the most organic contaminants in the influent were degraded or converted into simple structures under Fe-C micro-electrolysis, indicates that Fe-C micro-electrolysis pretreatment could improve the biodegradability of the evaporated condensate generated during metal cutting process and achieve certain degree removal of COD.


Assuntos
Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Eletrólise , Metais , Águas Residuárias
10.
Medicine (Baltimore) ; 98(13): e14867, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30921185

RESUMO

INTRODUCTION: Patients with chronic heart failure (HF) show many symptoms that worsen the quality of life (QoL). Collaborative care intervention (CCI) aims to improve the QoL and symptoms by integrating psychosocial and palliative strategies in chronic care. METHODS: The PubMed, EMBASE, and Cochrane library databases were searched from inception to September 2018. The included studies were used to determine pooled standard mean differences (SMDs) and associated 95% confidence intervals (CIs). The data were assessed by fixed- and random effects models, respectively. RESULTS: Twenty-one studies including 2999 patients with chronic heart failure were included. The results showed significantly improved QoL in the CCI group compared with the routine care group (SMD = 0.60, 95%CI 0.27-0.94, Pheterogeneity < .001, I = 94.1%). The patients who received face-to-face interventions experienced a significant improvement (SMD = 0.54, 95%CI 0.24-0.85, Pheterogeneity < .001, I = 88.7%) in terms of QoL compared with those administered only telephone interventions. Furthermore, significantly improved anxiety level (SMD = 0.33, 95%CI 0.12-0.55, Pheterogeneity = .612, I = 0%) and 6-min walk test (SMD = 0.46, 95%CI 0.29-0.64, Pheterogeneity = .458, I = 0%) were found in the CCI group compared with the routine care group. CONCLUSION: These findings confirmed that collaborative care intervention effectively improves the quality of life as well as psychological (anxiety) and physical (6-min walk test) functions in patients with chronic heart failure compared with routine care. Furthermore, face-to-face interventions show a greater improvement of QoL compared with telephone-only interventions.


Assuntos
Ansiedade/terapia , Insuficiência Cardíaca/psicologia , Insuficiência Cardíaca/terapia , Administração dos Cuidados ao Paciente/métodos , Idoso , Idoso de 80 Anos ou mais , Ansiedade/epidemiologia , Ansiedade/psicologia , Doença Crônica , Insuficiência Cardíaca/enfermagem , Humanos , Pessoa de Meia-Idade , Qualidade de Vida/psicologia , Ensaios Clínicos Controlados Aleatórios como Assunto , Teste de Caminhada/métodos
11.
J Photochem Photobiol B ; 190: 1-7, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30453160

RESUMO

Phthalocyanines (Pcs) are a kind of potential photosensitizers for fluorescence imaging and photodynamic therapy (PDT). However, the clinical application of Pcs is suffered from their poor solubility, high aggregation tendency and low tumor-specificity. To address these problems, two biotin moieties were linked to the axial positions of silicon(IV) phthalocyanine (SiPc) through hydrophilic polyethylene glycol (PEG) linkers to synthesize a new water-soluble and tumor-targeting photosensitizer (compound 1). The introduction of PEG linkers on SiPc markedly reduced the aggregation tendency of the conjugate. In vitro assays also proved that compound 1 could specifically accumulate in biotin receptor (BR) positive Hela cells through the BR-mediated internalization. Owing to the good characteristics of water-solubility and low aggregation, the bioactivity of compound 1 was examined in the xenograft tumor model. In vivo imaging and tissue distribution studies showed that compound 1 selectively accumulated in the tumor tissue, with tolerable signals found in other organs of the tumor-bearing mice. Furthermore, compound 1 could significantly depress tumor progression in vivo under irradiation. After 14 days of the treatment, the tumor volumes were even smaller than the beginning size. All these results reveal that compound 1 is a promising candidate, with low aggregation tendency, high tumor-specificity and water-solubility, for in vivo tumor diagnosis and PDT treatment.


Assuntos
Indóis/uso terapêutico , Neoplasias/diagnóstico por imagem , Neoplasias/terapia , Compostos de Organossilício/uso terapêutico , Fotoquimioterapia , Receptores de Fatores de Crescimento/metabolismo , Animais , Biotina/química , Reagentes para Ligações Cruzadas/química , Células HeLa , Xenoenxertos , Humanos , Indóis/metabolismo , Indóis/farmacocinética , Camundongos , Fármacos Fotossensibilizantes/farmacocinética , Fármacos Fotossensibilizantes/uso terapêutico , Polietilenoglicóis/química , Solubilidade , Distribuição Tecidual
12.
Bioresour Technol ; 270: 113-119, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30216920

RESUMO

Three ceramic MBRs (CMBR) installed with varied electrodes, i.e. Cu, Ti and Fe, were operated in parallel under the minute electric field to evaluate their suppression effect on membrane fouling, by comparison with control CMBR. Fe-CMBR released Fe2+ continuously to induce a higher organic removal efficiency and a smooth fouling rate. There was significant electric-flocculation effect in the Fe-CMBR, reflected by the increased sludge particle size and zeta potential, and to improve sludge filterability. Application of minute electric field could also affect the CMBR supernatant organic content and components, which was another reason for fouling mitigation. The formed membrane fouling layer was more easily to be detached by simple backwashing in all electric CMBRs, since that there were significant electric repulsive force to prevent foulants deposition.


Assuntos
Reatores Biológicos , Cerâmica , Eletricidade , Floculação , Tamanho da Partícula , Esgotos
13.
Environ Sci Pollut Res Int ; 25(25): 25227-25242, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29943255

RESUMO

Two hydrophilic poly-vinylidene fluoride (PVDF) ultrafiltration membranes were prepared via in situ embedment of nanoparticles (NP), i.e., TiO2 and Al2O3, respectively, and their anti-organic-fouling and anti-biofouling were comprehensively investigated. Characterization of modified PVDF-NP membranes by XRD and FTIR exhibited that nanoparticles were embedded successfully. Series of fast filtration tests demonstrated that in contrary to virgin PVDF membrane, PVDF-NP membranes have high permeability and anti-organic-fouling ability by decreasing the possibility of organic matters deposition and accumulation. Co-existed Ca2+ in feed solution deteriorated the organic fouling in virgin PVDF and PVDF-NP membranes, which was mainly caused by gelation of macromolecular foulants. PVDF-NP membranes were used to form MBR modules for domestic wastewater treatment, and the long-term monitoring evidenced that hydrophilic modified membranes achieved stably high COD and [Formula: see text] rejection efficiencies, and better organic rejection capability than mAO process. PVDF-NP membranes possessed consistently high anti-biofouling ability to maintain stable membrane permeability.


Assuntos
Incrustação Biológica/prevenção & controle , Membranas Artificiais , Nanopartículas/química , Polivinil/química , Análise da Demanda Biológica de Oxigênio , Interações Hidrofóbicas e Hidrofílicas , Permeabilidade , Ultrafiltração , Poluentes Químicos da Água/isolamento & purificação
14.
J Environ Manage ; 222: 37-43, 2018 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-29800863

RESUMO

Water supply was vital to people's life, especially inside Controlled Ecological Life Support System (CELSS) for long-term space exploration. A platform of 4-person-180-day integrated experiment inside a CELSS including 6 cabins called 'SPACEnter' was established in Shenzhen, China. Based on this platform, a Membrane Bio-Reactor (MBR) system configuring post advanced purification, including I-MBR, II-MBR, nanofiltration (NF), reverse osmosis (RO), ion-exchange (IE), polyiodide disinfection (PI) and mineralization (MC) stages, used as a Domestic Water Supply System (DWSS) to guarantee crew's daily life was constructed. The performance of DWSS to treat the real plant cabin's condensate water was examined during continuously 180-day experiment. The long-term operation results showed that, though the influent pollutant load changed as the experiment processing, the system exhibited stable performance on pollutants removal with average effluent TOC<0.5 mg/L, NH4+-N<0.02 mg/L, NO3--N<0.25 mg/L, NO2--N<0.001 mg/L, and displayed good capacity for controlling the trace metal ions and microorganism. The effluent through such modified MBR system was sufficiently allocated as hygiene water and potable water, and the average value was 39.69 and 10.93 L/d, respectively. The consumption of the modified MBR process was within the designed allowable scope. The outcomes of this study will be helpful for facilitating future applications of MBR as bio-based water supply technology in the CELSS.


Assuntos
Purificação da Água , Abastecimento de Água , Reatores Biológicos , China , Membranas Artificiais , Osmose , Eliminação de Resíduos Líquidos , Água
15.
Environ Sci Pollut Res Int ; 25(14): 13813-13822, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29508201

RESUMO

Adsorption is well accepted as an effective method for perfluorinated compounds' (PFCs) removal from water among various conventional methods. However, development of adsorbents that combine good performance of PFC removal and regenerability has not yet been realized. This work demonstrated the fabrication and application of an ammoniated magnetic adsorbent for efficient and economical PFOS and PFOA removal. Functional ammonium groups and γ-Fe2O3 were effectively incorporated in the particle with the proposed method. These fabricated magnetic particles presented superior adsorption performance for PFOS and PFOA with short equilibrium time of 120 min and high adsorption capacity. The isotherms revealed that the adsorption process belonged to multilayer sorption with their intricate interactions including anion exchange and hydrophobic interaction. The magnetic particle maintained its removal efficacy over a wide pH range of 3-9 or with coexisting substances. Moreover, the regeneration and reuse of the magnetic particle were successfully carried out with PFOS and PFOA removal efficiency sustained higher than 80% in 15 consecutive treatment cycles. Along with the efficient adsorption and easy separation of adsorbents, we expect that this ammoniated magnetic particle can serve as an excellent alternative for PFOS and PFOA removal from water.


Assuntos
Ácidos Alcanossulfônicos/isolamento & purificação , Compostos de Amônio/química , Caprilatos/isolamento & purificação , Compostos Férricos/química , Fluorcarbonetos/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Ácidos Alcanossulfônicos/química , Caprilatos/química , Fluorcarbonetos/química , Interações Hidrofóbicas e Hidrofílicas , Troca Iônica , Nanopartículas de Magnetita/análise , Nanopartículas de Magnetita/química , Poluentes Químicos da Água/química
16.
Crit Rev Biotechnol ; 38(6): 902-917, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29510650

RESUMO

Utilization of microbial oil for biodiesel production has gained growing interest due to the increase in prices and the shortage of the oils and fats traditionally used in biodiesel production. However, it is still in the laboratory study stage due to the high cost of production. Employing organic wastes as raw materials to grow heterotrophic oleaginous microorganisms for further lipid production to produce biodiesel has been predicted to be a promising method for reducing costs. However, there are many obstacles including the low biodegradability of organic wastes, low lipid accumulation capacity of heterotrophic oleaginous microorganisms while using organic wastes, a great dependence on a high-energy consumption approach for biomass harvesting, utilization of toxic organic solvents for lipid extraction, and large amount of methanol required in trans-esterification and in-situ trans-esterifications. Ultra-sonication as a green technology has been extensively utilized to enhance bio-product production from organic wastes. In this article, ultra-sonication applications in biodiesel production steps with heterotrophic oleaginous microorganisms have been reviewed, and its impact, potential, and limitations on the process have been discussed.


Assuntos
Biocombustíveis , Microbiologia Industrial/métodos , Sonicação , Esterificação , Lipídeos
17.
Chemosphere ; 202: 238-245, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29571144

RESUMO

Treatment of Ni-EDTA in industrial nickel plating effluents was investigated by integrated application of Fenton and ozone-based oxidation processes. Determination of integrated sequence found that Fenton oxidation presented higher apparent kinetic rate constant of Ni-EDTA oxidation and capacity for contamination load than ozone-based oxidation process, the latter, however, was favorable to guarantee the further mineralization of organic substances, especially at a low concentration. Serial-connection mode of two oxidation processes was appraised, Fenton effluent after treated by hydroxide precipitation and filtration negatively affected the overall performance of the sequential system, as evidenced by the removal efficiencies of Ni2+ and TOC dropping from 99.8% to 98.7%, and from 74.8% to 66.6%, respectively. As a comparison, O3/Fe2+ oxidation process was proved to be more effective than other processes (e.g. O3-Fe2+, O3/H2O2/Fe2+, O3/H2O2-Fe2+), and the final effluent Ni2+ concentration could satisfied the discharge standard (<0.1 mg L-1, China) under the optimal conditions (H2O2 dosage of 1.0 mL L-1, Fe2+: H2O2 mole ratio of 1.46, and reaction time of 10 min for Fenton reaction, initial influent pH of 3.0, O3 dosage of 252 mg L-1, Fe2+ of 150 mg L-1, and reaction time of 30 min for O3/Fe2+ oxidation). Furthermore, pilot-scale test was carried out to study the practical treatability towards the real nickel plating effluent, revealing the effective removal of some other co-existence contaminations. And Fenton reaction has contributed most, with the percentage ranging from 72.41% to 93.76%. The economic cost advantage made it a promising alternative to the continuous Fenton oxidation.


Assuntos
Ácido Edético/análise , Peróxido de Hidrogênio/química , Ferro/química , Níquel/análise , Ozônio/química , Poluentes Químicos da Água/análise , Ácido Edético/química , Níquel/química , Oxirredução , Poluentes Químicos da Água/química
18.
J Hazard Mater ; 350: 128-135, 2018 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-29466779

RESUMO

This research explored the application of electro-Fenton (E-Fenton) technique for the simultaneous decomplexation in blended Cu(II)/Ni(II)-EDTA systems by using iron sacrificing electrodes. Standard discharge (0.3 mg L-1 for Cu and 0.1 mg L-1 for Ni in China) could be achieved after 30 min reaction under the optimum conditions (i.e. initial solution pH of 2.0, H2O2 dosage of 6 mL L-1 h-1, current density of 20 mA/cm2, inter-electrode distance of 2 cm, and sulfate electrolyte concentration of 2000 mg L-1). The distinct differences in apparent kinetic rate constants (kapp) and intermediate removal efficiencies corresponding to mere and blended systems indicated the mutual promotion effect toward the decomplexation between Cu(II) and Ni(II). Massive accumulation of Fe(Ⅲ) favored the further removal of Cu(II) and Ni(II) by metal ion substitution. Species distribution results demonstrated that the decomplexation of metal-EDTA in E-Fenton process was mainly contributed to the combination of various reactions, including Fenton reaction together with the anodic oxidation, electro-coagulation (E-coagulation) and electrodeposition. Unlike hypophosphite and citrate, the presence of chlorine ion displayed favorable effects on the removal efficiencies of Cu(II) and Ni(II) at low dosage, but facilitated the ammonia nitrogen (NH4+-N) removal only at high dosage.

19.
Chemosphere ; 198: 92-102, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29421765

RESUMO

This study systematically investigated the degradation of tetrabromobisphenol A (TBBPA) by ferrate (VI) oxidation. The reaction kinetics between ferrate (VI) with TBBPA were studied under pseudo-first-order conditions in the pH range 5.5-10.5. Then, a series of batch experiments were carried out to investigate other factors, including the ferrate (VI) dosage, temperature and interfering ions. Additionally, the generation of inorganic products (bromide ion and bromate) was evaluated. The organic intermediates were identified, and possible pathways were proposed. In addition, the toxicity variation was analyzed with marine luminous bacteria (V. fischeri). Degradation of TBBPA by ferrate (VI) oxidation was confirmed to be an effective and environmentally friendly technique. The reaction was fitted with a second-order rate model. With a ferrate (VI) dosage of 25.25 µmol/L, TBBPA concentration of 1.84 µmol/L, an initial pH of 7.0, and a temperature of 25 °C, a 99.06% TBBPA removal was achieved within 30 min. The evaluation of inorganic products showed that the capacity of ferrate (VI) oxidation to yield bromide ions was relatively strong and could prevent the formation of bromate compared to photocatalytic and mechanochemical techniques. Eleven intermediates were identified, and the proposed degradation pathway indicated that TBBPA might undergo debromination, beta scission, substitution, deprotonation and oxidation. The results of toxicity testing showed that ferrate (VI) could effectively control the toxicity of the treated samples, although the toxicity increased in the initial reaction stage due to the accumulation and destruction of more toxic intermediates.


Assuntos
Ferro/química , Bifenil Polibromatos/análise , Bifenil Polibromatos/toxicidade , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Aliivibrio fischeri/efeitos dos fármacos , Bromatos/análise , Brometos/análise , Cinética , Oxirredução , Testes de Toxicidade
20.
Bioresour Technol ; 249: 943-952, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29145121

RESUMO

This study aimed to investigate the effect of acid- or alkali-treatment on volatile fatty acids (VFAs) production and microbiological mechanism during primary sludge anaerobic fermentation. Seven fermentation experiments were conducted at different pH (3-12). Results showed that the optimal pH was 10 for accumulation of VFAs. High-throughput sequencing results indicated that acid and alkali treatment could inhibit Erysipelotrichaceae_UCG-004 and norank_p_Aminicenantes, instead of promoting Pseudomonas and Tissierella at acidic and alkaline condition, respectively. Besides, molecular ecological networks (MENs) analysis and multivariate canonical correspondence analysis (CCA) revealed that the microbial community interactions are significant different between acid and alkali treatment groups, and acetic acid was the most vital factor in the distinct bacterial community assemblages. Predictive functional profiling using marker gene sequences found that amino acid transport and metabolism was the most abundant metabolic type with 8.43-9.41%, and acid- and alkali-treatment did not benefit Stickland reaction.


Assuntos
Reatores Biológicos , Esgotos , Álcalis , Ácidos Graxos Voláteis , Fermentação , Concentração de Íons de Hidrogênio
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