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1.
Environ Res ; 237(Pt 2): 117014, 2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-37652216

RESUMO

In recent years, bioleaching has emerged as a cost-effective technology for enhancing the dewaterability of sludge. However, the lengthy treatment time involved in sludge bioleaching processes limits daily treatment capacity for sludge. Here, a novel approach was developed through a short time of sludge bioleaching with A. ferrooxidans LX5 (A. f) and A. thiooxidans TS6 (A. t) followed by polyferric sulfate (PFS) flocculation (A. f + A. t + PFS). After 12.5 h of the A. f + A. t + PFS treatment (30% A. f, 10% A. t, 40 mg/g DS S0, 60 mg/g DS FeSO4•7H2O, and 120 mg/g DS PFS), the reduction efficiency of specific resistance to filtration (SRF) and sludge cake moisture content reached 94.0% and 11.6%, respectively, which were comparable to the results achieved through 24 h of completed bioleaching treatment. In pilot-scale applications, the mechanical dewatering performance was notably improved following A. f + A. t + PFS treatment, with the low moisture content of the treated sludge cake (∼59.2%). This study provides new insights into the A. f + A. t + PFS process and holds potential for developing efficient and promising sludge dewatering strategies in engineering application.

2.
Brain Inj ; : 1-7, 2023 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-36625002

RESUMO

BACKGROUND: Cranioplasty is a common surgery in the neurosurgery for patients with skull defects following decompression craniectomy. Concomitant rare complications are increasingly reported, such as malignant cerebral edema after cranioplasty. CASE REPORT: A 45-year-old man underwent decompression craniectomy due to traumatic brain injury. At 3 months after the decompression craniectomy, the patient developed refractory subdural hydrogen and received ipsilateral refractory subdural effusion capsule resection, but no significant relief was seen. Therefore, the cranioplasty was decided to treat subdural hydrogen and restore the normal appearance of the skull. After the successful cranioplasty surgery and the expected anesthesia recovery period, the pupils of the patients were continued to be dilated and fixed, without light reflection and spontaneous breathing. The Computed Tomography of the patient 1 hour after surgery showed malignant cerebral edema. CONCLUSIONS: Malignant cerebral edema is a rare and lethal complication after cranioplasty. Negative pressure drainage and deregulation of cerebral blood flow at the end of cranioplasty may partially explain the malignant cerebral after cranioplasty. In addition, patients with epileptic seizures, no spontaneous breathing, dilated pupils without reflection, and hypotension within a short period after cranioplasty may show the occurrence of malignant cerebral.

3.
Chem Biodivers ; 20(8): e202300841, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37462846

RESUMO

Three undescribed glycoside constituents, macrophyllosides E-G and a pair of iridoid glycosides genticrasides A/B, together with eleven known glycoside compounds were isolated from the roots of Gentiana crassicaulis Duthie ex Burk. Their structures were identified by means of spectra analysis and data comparison with previous literatures. Interestingly, the glucose moieties in macrophylloside E and F possess free anomeric hydroxy groups. Genticrasides A/B, identified as a pair of iridoid originated lactones, have not been reported from Gentianaceae family up to now. The anti-inflammatory effects of selected compounds were also evaluated through the nitric oxide (NO) production inhibition in lipopolysaccharides (LPS)-induced RAW264.7 macrophage cells. In which, macrophyllosides G and D showed NO inhibitory activities with rates of 76.14±4.02 % and 52.44±8.29 % at 100 µg/mL.


Assuntos
Gentiana , Gentiana/química , Raízes de Plantas/química , Glicosídeos Iridoides/farmacologia , Iridoides/análise , Macrófagos , Óxido Nítrico
4.
J Environ Manage ; 327: 116901, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36481690

RESUMO

Fungal mash derived from Aspergillus spp. is a green enzymatic additive for food waste (FW) valorization. In this study, the production of volatile fatty acids (VFAs) and the proportion of propionic acid (PA) in VFAs were increased by utilizing a complex enzyme (CE) obtained from Aspergillus oryzae. Results showed that CE addition significantly promoted SCOD concentration in the hydrolysis at a wide pH range from 4 to 9. In contrast, the production of VFAs was influenced by pH, and the highest yields of VFAs and PA were found at pH 7. At the CE dosage of 0.2 g/g VSS, the concentration of VFAs in the FW fermentation liquid reached 38.1 g COD/L with the PA proportion up to 42.7%, which increased by 107.9% and 63.7%, respectively, relative to that in the zero-dosage group. With CE continuing to be added, the C/N ratio declined, and the primary metabolic pathway was converted from acetic acid-type to PA-type. Further investigation of the dominant microbial communities and their metabolic capacities showed that the acrylate-mediated pathway was the potential metabolic reaction in PA-type fermentation. These results indicated that CE pretreatment was a feasible strategy to enhance the PA-rich fermentation of FW under neutral pH conditions.


Assuntos
Alimentos , Eliminação de Resíduos , Fermentação , Propionatos , Ácidos Graxos Voláteis , Ácidos , Concentração de Íons de Hidrogênio , Esgotos , Reatores Biológicos/microbiologia , Anaerobiose
5.
Environ Microbiol ; 24(10): 4946-4959, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36053866

RESUMO

Plastic pollution and antibiotic resistance are two emerging environmental and human health crises today. Although it was revealed that microplastics can serve as vectors for the dissemination of antibiotic resistance, it is still unclear how the nanoplastics influence the horizontal transfer of antibiotic resistance genes (ARGs). Herein, we firstly compared the effect of polystyrene (PS) micro/nanoplastics on the transformation of plasmid-borne ARG, using a transformation model consisting of plasmid pUC19 (ampR ) and Escherichia coli DH5α (recipient). Due to its size effect, PS nanoplastics (10-500 mg/L) significantly enhanced the transformation efficiency (2.8-5.4 folds) and frequency (3.2-8.4 folds) of exogenous ampR into E. coli, while PS microplastics exerted no influence. The detailed mechanisms were found that nanoplastics induced reactive oxygen species (ROS) overproduction, activated SOS response, increased cell membrane permeability and changed the secretion systems, thereby facilitating the uptake of exogenous DNA by bacteria. Moreover, the co-presences of nanoplastics with humic acid or Fe3+ relieved to some extent, but did not completely alleviate the promoting effect of nanoplastics on plasmid transformation. Our findings suggest that the risk of nanoplastics on promoting the dissemination of antibiotic resistance should not be neglected, and further studies are needed to investigate such risk in complex environments.


Assuntos
Escherichia coli , Microplásticos , Monofosfato de Adenosina , Ampicilina/farmacologia , Resistência a Ampicilina , Antibacterianos/farmacologia , Escherichia coli/genética , Humanos , Substâncias Húmicas , Plasmídeos/genética , Plásticos , Poliestirenos/farmacologia , Espécies Reativas de Oxigênio
6.
Environ Res ; 209: 112830, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35093307

RESUMO

The discharge of antibiotics evokes environmental health crisis, and is also a waste of organic energy. Currently, heterogeneous Fenton for antibiotics removal has attracted growing attentions due to wide pH range and no iron sludge production, however, it often suffers from a low formation rate of Fe(II), resulting in difficult application of heterogeneous Fenton technology in sewage treatment. To overcome this drawback, bamboo biochar (BB) is coupled with schwertmannite (Sch) through Acidithiobacillus ferrooxidans-mediated Fe(II) oxidation reaction to obtain a heterogeneous catalyst (Sch/BB) with high adsorption performance and Fenton activity. According to the analysis of experimental results, electrons around C (from BB) can easily transfer to Fe by Fe-O-C bonds to expedite ≡Fe(III)/≡Fe(II) cycle, while electrons of antibiotics adsorbed on Sch/BB surface are effectively utilized to maintain the efficient regeneration of ≡Fe(II) through BB electron shuttle or Fe-O-C bonds between Sch/BB and pollutants, further causing a superior Fenton activity (98% antibiotics removal) of Sch/BB. Moreover, due to its excellent adsorption performance, Sch/BB as filter materials can effectively remove dye pollutants in flow wastewater. These findings provided a high-activity and practical heterogeneous Fenton catalyst for pollutants degradation, while a new perspective for efficient utilization of the electrons of organic pollutants was given.


Assuntos
Carvão Vegetal , Sasa , Antibacterianos , Elétrons , Compostos Férricos , Compostos Ferrosos , Peróxido de Hidrogênio , Compostos de Ferro , Oxirredução
7.
J Environ Manage ; 310: 114802, 2022 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-35228166

RESUMO

Fecal contamination in wastewater treatment system may pose severe threats to human health, but the detailed contamination of fecal bacterial and viral pathogens in municipal sewage sludge remains unclear. In addition, it is also unclear how sludge conditioning treatments would impact the distribution of fecal markers in conditioned sewage sludge. Before addressing these two issues, the possible polymerase chain reaction (PCR) inhibition effect when determining the abundances of fecal markers in both sludge solids and sludge supernatants should be solved, and methods of effectively concentrating fecal markers from sludge supernatant should also be developed. In the present study, we found that the serial tenfold dilution effectively reduced the PCR inhibition effect when determining the abundances of fecal markers including cross-assembly phages (CrAssphage), JC polyomavirus (JCPyV), human-specific HF183 bacteroides (HF183), human BK polyomavirus (BKPyV), human adenovirus (HAdV) and Escherichia coli (EC), while the utilization of negatively charged HA membrane was effective to recover fecal markers from sludge supernatant. The results of a six-month monitoring revealed that gene markers of CrAssphage, JCPyV, HF183, BKPyV, HAdV, and EC can be detected in municipal sewage sludge collected from a local wastewater treatment plant. Among the investigated four chemical conditioning methods, i.e., chemical conditioning with polyacrylamide (PAM), Fe[III]/CaO, or Fenton's reagent, and chemical acidification conditioning, chemical conditioning with Fenton's reagent was much more effective than the other three conditioning methods to reduce the abundances of fecal markers in the supernatant and solid of conditioned sewage sludge. Furthermore, the investigated fecal markers in the conditioned sewage sludge can be simultaneously attenuated by employing suitable conditioning methods, consequently reducing the associated environmental risks.


Assuntos
Esgotos , Purificação da Água , Bactérias , Fezes/microbiologia , Humanos , Esgotos/química
8.
Environ Res ; 195: 110855, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33581092

RESUMO

Co-contamination of arsenic and polycyclic aromatic hydrocarbons (PAHs) in groundwater is frequently reported, and it is thus necessary to develop efficient techniques to tackle this problem. Here, we evaluated the feasibility of utilizing schwertmannite to co-adsorb As(III) and phenanthrene from water solution and regenerating spent schwertmannite via a heterogeneous Fenton-like reaction to degrade adsorbed phenanthrene and meanwhile oxidize adsorbed As(III). The results suggested that schwertmannite with a hedgehog-like morphology was superior to that with a smooth surface for the adsorption removal of As(III) or phenanthrene because of the much higher BET surface area and hydroxyl proportion of the former one, and schwertmannite formed at 72 h incubation effectively co-adsorbed As(III) and phenanthrene from water solution. The adsorption of As(III) and phenanthrene on schwertmannite did not interfere with each other, while the acidic initial solution pH delayed the adsorption of As(III) on schwertmannite but enhanced the adsorption capacity for phenanthrene. The adsorption of As(III) on schwertmannite mainly involved its exchange with SO42- (outer-sphere or inner-sphere) and its complexation with iron hydroxyl surface groups, and phenanthrene adsorption mainly occurred through cation-π bonding and OH-π interaction. During the adsorption-regeneration processes, schwertmannite adsorbed As(III) and phenanthrene firstly, and then it can be successfully regenerated via Fenton-like reaction catalyzed by itself to effectively degrade the adsorbed phenanthrene and meanwhile oxidize the adsorbed As(III) to As(V). Therefore, schwertmanite is an outstanding environmental adsorbent to decontaminate As(III) and phenanthrene co-existing in groundwater.


Assuntos
Fenantrenos , Adsorção , Concentração de Íons de Hidrogênio , Compostos de Ferro
9.
Appl Opt ; 60(36): 11058-11065, 2021 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-35201094

RESUMO

High-repetition-rate lunar laser ranging (LLR) has great prospects and significance. We have successfully obtained the effective echo signals of all five corner-cube reflectors (CCRs) on the lunar surface by using a 100 Hz repetition rate. This method can effectively improve the detection ability but has some defects: for example, the main wave and echo signals overlap. In this paper, the frequency selection and signal overlap are theoretically analyzed. The results show that the existing target prediction accuracy can meet the requirement of a 100 Hz repetition rate LLR. In the experiment, the use of a high-repetition-rate pulse laser allowed us to obtain detailed CCR information, such as the column number of CCRs, which will prove that the effective echo signals of LLR are reflected by the CCRs. Finally, we propose to use the resolved data to calculate the precision of inner coincidence and believe the accuracy can be within a millimeter.

10.
Gastroenterol Nurs ; 44(4): 227-232, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34176888

RESUMO

Fecal microbiota transplantation is an emerging treatment option that lacks a standardized nursing procedure. In our department, fecal microbiota transplantation has been undertaken to treat chronic hepatitis B and inflammatory bowel diseases since 2015. The fecal microbiota transplantation process involves various nursing measures that are critical for the successful completion of the procedures. In our center, a set of standardized nursing procedures has been established and has proved effective and operable. Standardized nursing procedures enhance the efficacy of fecal microbiota transplantation and alleviate the risk of treatment-related complications.


Assuntos
Transplante de Microbiota Fecal , Doenças Inflamatórias Intestinais , Fezes , Gastroscopia , Humanos , Resultado do Tratamento
11.
Appl Opt ; 59(30): 9558-9567, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-33104677

RESUMO

In this paper, an optical single-channel asymmetric cryptosystem based on the inverse discrete wavelet transform (IDWT) and chaotic standard map for multi-image in cyan-magenta-yellow-black (CMYK) mode is proposed. To the best of our knowledge, this is the first time that the color image in CMYK format is encoded into a real-valued two-dimensional (2D) format by the IDWT; thus, our scheme can be implemented in a single-channel step. In addition, we propose to generate the random phase mask based on the chaotic standard map. Due to the large key space and high efficiency of the chaotic standard map, the security level of the proposed scheme can be improved. The chaotic standard map is employed to generate the chaotic standard phase mask (CSPM). Then the encoded 2D image can be encrypted in the linear canonical transform domain based on the CSPM. Numerical simulation results are shown to verify the feasibility and effectiveness of our cryptosystem. In addition, our approach outperforms other relevant cryptosystems and can be extended to encrypt multiple color images directly.

12.
Appl Opt ; 59(7): 1854-1863, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32225701

RESUMO

In this paper, we propose an optical single-channel asymmetric cryptosystem for multi-image in cyan-magenta-yellow-black (CMYK) color space. To the best of our knowledge, this is the first time that multiple images in CMYK color space have been directly encrypted. The proposed optical asymmetric cryptosystem is based on the quick response (QR) encoding process and the designed Fresnel-linear canonical-fractional Fourier transform (FLFT) encryption process. Each FLFT encryption process consists of phase-truncated FLFT and random amplitude phase masks. The proposed cryptosystem without color space conversion can improve the quality of the decrypted images and avoid the loss of information. In addition, by utilizing the QR codes, the cross talk and quality-loss problems can be reduced efficiently. Numerical simulation results demonstrate that the proposed cryptosystem possesses high robustness against various types of attacks, high security for encrypting multiple color images, and fast encryption efficiency. Furthermore, the proposed cryptosystem outperforms the other relevant cryptosystems and can be extended to encrypt multiple color images in a straightforward way.

13.
J Environ Sci (China) ; 98: 186-195, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33097151

RESUMO

Here we reported an effective method to solve the rate-limiting steps, such as the reduction of Fe3+ to Fe2+ and an invalid decomposition of H2O2 in a conventional Fenton-like reaction. A magnetic heterogeneous photocatalyst, Fe3O4-schwertmannite (Fe3O4-sch) was successfully developed by adding Fe3O4 in the formation process of schwertmannite. Fe3O4-sch shows excellent electrons transfer ability and high utilization efficiency of H2O2 (98.5%). The catalytic activity of Fe3O4-sch was studied through the degradation of phenol in the heterogeneous photo-Fenton process. Phenol degradation at a wide pH (3 - 9) was up to 98% within 6 min under visible light illumination with the Fe3O4-sch as heterogeneous Fenton catalyst, which was higher than that using pure schwertmannite or Fe3O4. The excellent photocatalytic performance of Fe3O4-sch is ascribed to the effective recycling between Fe3+ and Fe2+ by the photo-generated electron, and also profit from the formation of the "Z-Scheme" system. According to the relevant data, photocatalytic mechanism of Fe3O4-sch for degrading phenol was proposed. This study not only provides an efficient way of enhancing heterogeneous Fenton reaction, but also gives potential application for iron oxyhydroxysulfate mineral.


Assuntos
Peróxido de Hidrogênio , Compostos de Ferro , Catálise , Ferro
14.
Ecotoxicol Environ Saf ; 163: 196-204, 2018 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-30055384

RESUMO

Conditioning is an indispensable step to improve mechanical dewatering of municipal sewage sludge. However, it is still unclear how sludge conditioning treatments impact the bioavailability of polycyclic aromatic hydrocarbons (PAHs) in sewage sludge that potentially influences the biodegradation of PAHs during the composting of dewatered sludge cake. In the present study, five sludge conditioning treatments, including chemical acidification, bioleaching driven by Acidithiobacillus ferrooxidans, chemical conditioning with Fe[III] and CaO, and chemical conditioning with either aluminum polychloride (PACl) or polyacrylamide (PAM), were investigated to reveal their respective impacts on the bioavailability of pyrene in sewage sludge. The bioavailability of pyrene in conditioned sludge was evaluated by using the n-butanol extraction method. The results showed that the bioavailable fraction of pyrene increased from 59.1% in raw sludge to 68.7% in chemically acidified sludge and 79.3% in bioleached sludge, while the other three conditioning approaches did not significantly change the bioavailability of pyrene. During chemical acidification or bioleaching of sludge, cellular membrane damage of sludge microbial cells induced changes in sludge chemical and physical properties. Ridge regression analysis revealed that during these two conditioning processes the contribution rates of the changes in sludge chemical properties and physical properties on the enhancement of pyrene bioavailability were 33.0% and 67.1%, respectively. Therefore, chemical acidification and bioleaching conditioning treatments can enhance the bioavailability of pyrene in sewage sludge, mainly through changing the relative hydrophobicity and particle size of sludge flocs.


Assuntos
Pirenos/análise , Esgotos/química , Eliminação de Resíduos Líquidos/métodos , Acidithiobacillus , Resinas Acrílicas/química , Agricultura , Cloreto de Alumínio , Compostos de Alumínio/química , Biodegradação Ambiental , Disponibilidade Biológica , Compostos de Cálcio/química , Cloretos/química , Compostagem , Ferro/química , Óxidos/química , Hidrocarbonetos Policíclicos Aromáticos/análise , Reciclagem
15.
Tumour Biol ; 39(7): 1010428317719273, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28718372

RESUMO

A growing body of evidence suggests that microRNA-592 is involved in tumor initiation and development in several types of human cancers. However, the biological functions and molecular mechanism of microRNA-592 in glioma remain unclear. In this study, we explored the potential role of microRNA-592 in glioma as well as the possible molecular mechanisms. Our results proved that microRNA-592 expression was significantly downregulated in glioma tissues and cell lines (p < 0.01). Functional assays revealed that overexpression of microRNA-592 dramatically reduced the cell proliferation, migration, and invasion and induced cell arrest at G1/G0 phase in vitro. Mechanistic investigations defined insulin-like growth factor binding protein 2 as a direct and functional downstream target of microRNA-592, which was involved in the microRNA-592-mediated tumor-suppressive effects in glioma cells. Moreover, the in vivo study showed that microRNA-592 overexpression produced the smaller tumor volume and weight in nude mice. In summary, these results elucidated the function of microRNA-592 in glioma progression and suggested a promising application of it in glioma treatment.


Assuntos
Proliferação de Células/genética , Glioma/genética , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/biossíntese , MicroRNAs/genética , Animais , Apoptose/genética , Pontos de Checagem do Ciclo Celular/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Genes Supressores de Tumor , Glioma/patologia , Humanos , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/genética , Masculino , Camundongos , Ensaios Antitumorais Modelo de Xenoenxerto
16.
Bioprocess Biosyst Eng ; 40(2): 319-330, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27796572

RESUMO

The effects of hydraulic retention time (20 and 15 days) and swine manure to rice straw ratios on distribution of sulfonamides (SAs) in liquid and solid anaerobic digestates were studied using bench-scale completely stirred tank reactors at (37 ± 1) °C. Results showed that anaerobic digestion (AD) treatment exhibited a good removal effect on sulfadiazine (SDZ), sulfadimidine (SM2) and sulfachloropyridazine (SCP), especially at HRT = 20 days and co-digestion with swine manure and rice straw. The removal rates of SDZ and SM2 were more than 90%, but only 72.8% for SCP. The residual SAs were mainly remained in solid digestates, with residual rates ranging from 28.8% to 71.3%, 40.6% to 88.0, and 82.7% to 97.0% for SDZ, SM2 and SCP, respectively. Due to lower pKa and higher log K ow of SCP, its residue in solid digestates was far more than SDZ and SM2. Higher HRT and co-digestion could improve the degradation of SAs, which can also be put down to the occurrence of cometabolism of SAs and COD.


Assuntos
Esterco/microbiologia , Oryza/química , Sulfonamidas/química , Anaerobiose , Animais , Suínos
17.
Environ Eng Sci ; 31(8): 447-452, 2014 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-25125941

RESUMO

Cu(II) catalytic reduction of Cr(VI) by tartaric acid under the irradiation of simulated solar light was investigated through batch experiments at pHs from 3 to 6 and at temperatures from 15°C to 35°C. Results demonstrated that introduction of Cu(II) could markedly improve reduction of Cr(VI) in comparison with tartaric acid alone. Optimal removal of Cr(VI) was achieved at pH 4. Reduction of Cr(VI) increased with increasing temperatures and initial concentrations of Cu(II) and tartaric acid. The catalytic role of Cu(II) in the reduction of Cr(VI) was ascribed to the formation of Cu(II)-tartaric acid complex, which generated active reductive intermediates, including Cu(I) and tartaric acid radicals through a pathway of metal-ligand-electron transfer with light. Cu(II) photocatalytic reduction of Cr(VI) by tartaric acid followed pseudo zero-order kinetics with regard to Cr(VI), and the activation energy was calculated to be 21.48 kJ/mol. To date, such a role of Cu(II) has not been reported. The results from the present study are helpful in fully understanding the photochemical reductive behavior of Cr(VI) in the presence of both tartaric acid and Cu(II) in soil and aquatic environments.

18.
Environ Technol ; 35(17-20): 2538-45, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25145209

RESUMO

It is well documented that bioleaching with the co-inoculation ofAcidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans can drastically enhance sludge dewaterability under ambient temperature condition, but little information on low temperature effect on bioleached sludge dewaterability is available. In this study, the optimum sludge retention time of bioleaching treatment and the mechanisms responsible for the dewaterability enhancement ofbioleached sludge were studied in two bioleaching systems conducted at a low temperature of 10 degrees C and a normal temperature of 28 degrees C, respectively. Results showed that Acidithiobacillus bacteria involved in the bioleaching were still active at 10 degrees C, and sludge capillary suction time (CST) decreased in the first 3 days of bioleaching. Nevertheless, the degree of sludge dewaterability enhancement by bioleaching was much lower at 10 degrees C than that at 28 degrees C. The only slight decreases in the sludge pH value and relative high contents of extracellular polymeric substances (EPS) and bound water at a low temperature were responsible for the relatively lower dewaterability enhancement of bioleached sludge compared to that at the normal temperature. Moreover, statistical results showed that sludge CST had significant positive correlations with the sludge pH value, and EPS and bound water contents in the optimum bioleaching process (from day 0 to day 3). Therefore, reducing medium pH, and/or removing EPS from bioleaching bacteria and bound water ofbioleached sludge through forced physical-chemical approaches prior to mechanical dewatering might be a good method to greatly improve sludge dewatering at a low temperature.


Assuntos
Biodegradação Ambiental , Espaço Extracelular/química , Polímeros/química , Esgotos , Acidithiobacillus/metabolismo , Temperatura Baixa , Espaço Extracelular/metabolismo , Concentração de Íons de Hidrogênio , Ferro/química , Ferro/metabolismo , Polímeros/metabolismo , Enxofre/química , Enxofre/metabolismo
19.
PLoS One ; 19(5): e0302311, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38814929

RESUMO

This study aimed to enhance sludge dewatering through sequential bioleaching, employing the filamentous fungus Mucor sp. ZG-3 and the iron-oxidizing bacterium Acidithiobacillus ferrooxidans LX5. The mechanism by which Mucor sp. ZG-3 alleviates sludge dissolved organic matter (DOM) inhibition of A. ferrooxidans LX5 was investigated, and the optimal addition of energy source for enhanced sludge dewaterability during sequential bioleaching was determined. Sludge dissolved organic carbon (DOC) decreased to 272 mg/L with a 65.2% reduction by Mucor sp. ZG-3 in 3 days, and the degraded fraction of sludge DOM was mainly low-molecular-weight DOM (L-DOM) which inhibited the oxidization of Fe2+ by A. ferrooxidans LX5. By degrading significant inhibitory low-molecular-weight organic acids, Mucor sp. ZG-3 alleviated DOM inhibition of A. ferrooxidans LX5. In the sequential bioleaching process, the optimal concentration of FeSO4·7H2O for A. ferrooxidans LX5 was 4 g/L, resulting in the minimum specific resistance to filtration (SRF) of 2.60×1011 m/kg, 40.0% lower than that in the conventional bioleaching process with 10 g/L energy source. Moreover, the sequential bioleaching process increased the sludge zeta potential (from -31.8 to -9.47 mV) and median particle size (d50) of the sludge particle (from 17.90 to 27.44 µm), contributing to enhanced sludge dewaterability. Inoculation of Mucor sp. ZG-3 during the bioleaching process reduced the demand for energy sources by A. ferrooxidans LX5 while improving sludge dewaterability performance.


Assuntos
Mucor , Esgotos , Mucor/metabolismo , Esgotos/microbiologia , Biodegradação Ambiental , Água/química , Água/metabolismo , Compostos Orgânicos/metabolismo
20.
Environ Pollut ; 350: 124005, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38648965

RESUMO

Simultaneously stabilizing of arsenic (As) and cadmium (Cd) in co-contaminated soil presents substantial challenges due to their contrasting chemical properties. Schwertmannite (Sch) is recognized as a potent adsorbent for As pollution, with alkali modification showing promising results in the simultaneous immobilization of both As and Cd. This study systematically investigated the long-term stabilization efficacy of alkali-modified Sch in Cd-As co-contaminated farmland soil over a 200-day flooding-drying period. The results revealed that As showed significant mobility in flooded conditions, whereas Cd exhibited increased soil availability under drying phases. The addition of Sch did not affect the trends in soil pH and Eh fluctuations; nonetheless, it led to an augmentation in the levels of amorphous iron oxides and SO42- concentration in soil pore water. At a dosage of 0.5% Sch, there was a notable decrease in the mobility and soil availability of As and Cd under both flooding (34.5% and 53.6% at Day 50) and drying conditions (27.0% and 29.4% at Day 130), primarily promoting the transformation of labile metal(loid) fraction into amorphous iron oxide-bound forms. Throughout the flooding-drying treatment period, Sch maintained stable mineral morphology and mineralogical phase, highlighting its long-term stabilization effect. The findings of this study emphasize the promising application of Sch-based soil remediation agents in mitigating the challenges arising from As-Cd co-contamination. Further research is warranted to explore their application in real farmland settings and their impact on the uptake of toxic metal(loid)s by plants.


Assuntos
Arsênio , Cádmio , Recuperação e Remediação Ambiental , Inundações , Poluentes do Solo , Solo , Arsênio/análise , Cádmio/análise , Solo/química , Recuperação e Remediação Ambiental/métodos , Compostos de Ferro/química , Fazendas , Adsorção
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