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Chemosphere Jun 2024Antimony contamination from textile industries has been a global environmental concern and the existing treatment technologies could not reduce Sb(V) to meet the...
Antimony contamination from textile industries has been a global environmental concern and the existing treatment technologies could not reduce Sb(V) to meet the discharge standards. To overcome this shortcoming, ferric flocs were introduced to expedite the biological process for enhanced Sb(V) removal in wastewater treatment plant (WWTP). For this purpose, a series of laboratorial-scale sequential batch reactor activated sludge processes (SBRs) were applied for Sb(V) removal with varied reactor conditions and the transformation of Fe and Sb in SBR system was investigated. Results showed a significant improvement in Sb(V) removal and the 20 mg L d iron ions dosage and iron loss rate was found to be only 15.2%. The influent Sb(V) concentration ranging 153-612 μg L was reduced to below 50 μg L, and the maximum Sb(V) removal rate of the enhanced system reached about 94.3%. Furthermore, it exhibited high stability of Sb(V) removal in the face of antimonate load, Fe strike and matrix change of wastewater. Sludge total Sb determination and capacity calculation revealed decreasing in Sb adsorption capacity and desorption without fresh Fe dosage. While sludge morphology analysis demonstrated the aging and crystallization of iron hydroxides. These results verify the distinct effects of fresh iron addition and iron aging on Sb(V) removal. High-throughput gene pyrosequencing results showed that the iron addition changed microbial mechanisms and effect Fe oxidized bacterial quantity, indicating Sb(V) immobilization achieved by microbial synergistic iron oxidation. The present study successfully established a simple and efficient method for Sb(V) removal during biological treatment, and the modification of biological process by iron supplement could provide insights for real textile wastewater treatment.
Topics: Wastewater; Waste Disposal, Fluid; Water Pollutants, Chemical; Sewage; Antimony; Iron; Adsorption; Textile Industry; Ferric Compounds; Bioreactors; Textiles; Biodegradation, Environmental; Aerobiosis
PubMed: 38636914
DOI: 10.1016/j.chemosphere.2024.141920 -
Chemosphere Jun 2024Aerobic denitrification has emerged as a promising and efficient method for nitrogen removal from wastewater. However, the direct application of aerobic denitrifying...
Aerobic denitrification has emerged as a promising and efficient method for nitrogen removal from wastewater. However, the direct application of aerobic denitrifying bacteria has faced challenges such as low nitrogen removal efficiency, bacterial loss, and poor stability. To address these issues, this study developed a novel microbial particle carrier using NaHCO-modified polyvinyl alcohol (PVA)/sodium alginate (SA) gel (NaHCO-PVA/SA). This carrier exhibits several advantageous properties, including excellent mass transfer efficiency, favorable biocompatibility, convenient film formation, abundant biomass, and exceptional pollutant treatment capacity. The carrier was modified with 0.3% NaHCO, 8.0% PVA, and 1.0% SA, resulting in a remarkable 3.4-fold increase in the average pore diameter and a 12.8% improvement in mass transfer efficiency. This carrier was utilized to immobilize the aerobic denitrifying bacterium Stutzerimonas stutzeri W-2 to enhance nitrogen removal (NaHCO-PVA/SA@W-2), resulting in a NO-N removal efficiency of 99.06%, which was 21.39% higher than that without modification. Compared with the non-immobilized W-2, the degradation efficiency was improved by 43.70%. After five reuses, the NO-N and TN removal rates remained at 99% and 93.01%, respectively. These results provide a solid foundation for the industrial application of the modified carrier as an effective tool for nitrogen removal in large-scale wastewater treatment processes.
Topics: Polyvinyl Alcohol; Alginates; Nitrogen; Denitrification; Wastewater; Waste Disposal, Fluid; Water Pollutants, Chemical; Aerobiosis; Pseudomonas stutzeri; Biodegradation, Environmental; Cells, Immobilized
PubMed: 38615964
DOI: 10.1016/j.chemosphere.2024.141954 -
Water Research Jun 2024Lingering inconsistencies in the global methane (CH) budget and ambiguity in CH sources and sinks triggered efforts to identify new CH formation pathways in natural...
Lingering inconsistencies in the global methane (CH) budget and ambiguity in CH sources and sinks triggered efforts to identify new CH formation pathways in natural ecosystems. Herein, we reported a novel mechanism of light-induced generation of hydroxyl radicals (•OH) that drove the production of CH from aquatic dissolved organic matters (DOMs) under ambient conditions. A total of five DOM samples with different origins were applied to examine their potential in photo-methanification production under aerobic conditions, presenting a wide range of CH production rates from 3.57 × 10 to 5.90 × 10 nmol CH mg-C h. Experiments of •OH generator and scavenger indicated that the contribution of •OH to photo-methanificaiton among different DOM samples reached about 4∼42 %. In addition, Fourier transform infrared spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry showed that the carbohydrate- and lipid-like substances containing nitrogen-bonded methyl groups, methyl ester, acetyl groups, and ketones, were the potential precursors for light-induced CH production. Based on the experimental results and simulated calculations, the contribution of photo-methanification of aquatic DOMs to the diffusive CH flux across the water-air interface in a typical eutrophic shallow lake (e.g., Lake Chaohu) ranged from 0.1 % to 18.3 %. This study provides a new perspective on the pathways of CH formation in aquatic ecosystems and a deeper understanding on the sources and sinks of global CH.
Topics: Hydroxyl Radical; Methane; Aerobiosis
PubMed: 38615601
DOI: 10.1016/j.watres.2024.121609 -
Brazilian Oral Research 2024This study aimed to identify and characterize the antimicrobial susceptibility profile of bacteria found in primary endodontic infections in the teeth of patients...
This study aimed to identify and characterize the antimicrobial susceptibility profile of bacteria found in primary endodontic infections in the teeth of patients treated at the Dental Clinic of the University of Ribeirão Preto, São Paulo, Brazil. From September to December 2019, samples were obtained from 21 patients with primary endodontic infections. The collections were carried out in triplicate using paper cones placed close to the total length of the root canal. Bacterial isolation was performed in Brain Heart Infusion agar, Blood agar, and other selective culture media cultured at 37°C for up to 48 h under aerobiosis and microaerophilic conditions. The bacterial species were identified using the Vitek 2 automated system. The disk diffusion method on agar Müeller-Hinton was used to assess antimicrobial susceptibility with the recommended antimicrobials for each identified bacterial species. A total of 49 antibiotics were evaluated. Fifteen of the 21 samples collected showed bacterial growth, and 17 bacterial isolates were found. There were 10 different bacterial species identified: Enterococcus faecalis (four isolates), Streptococcus mitis/oralis (three isolates), Streptococcus anginosus (three isolates) being the most common, followed by Staphylococcus epidermidis, Enterococcus faecium, Streptococcus constellatus, Streptococcus alactolyticus, Enterobacter cloacae, Klebsiella variicola, and Providencia rettgeri (one isolate of each species). The analysis demonstrated significant susceptibility to most of the tested antibiotics. However, some Enterococcus isolates resisted the antibiotic's erythromycin, ciprofloxacin, and tetracycline. A Staphylococcus epidermidis isolate was characterized as multidrug-resistant. Five Streptococcus isolates were non-susceptible to all antibiotics tested.
Topics: Humans; Agar; Microbial Sensitivity Tests; Brazil; Anti-Bacterial Agents; Enterococcus faecium; Culture Media; Anti-Infective Agents
PubMed: 38597544
DOI: 10.1590/1807-3107bor-2024.vol38.0024 -
The Science of the Total Environment Jun 2024The enhanced biological phosphorus removal (EBPR) process requires alternate anaerobic and aerobic conditions, which are regulated respectively by aeration off and on....
The enhanced biological phosphorus removal (EBPR) process requires alternate anaerobic and aerobic conditions, which are regulated respectively by aeration off and on. Recently, in an ordinary EBPR reactor, an abnormal orthophosphate concentration (PO-P) decline in the anaerobic stage (namely non-aerated phosphorus uptake) aroused attention. It was not occasionally but occurred in each cycle and lasted for 101 d and shared about 16.63 % in the total P uptake amount. After excluding bio-mineralization and surface re-aeration, indoor light conditions (180 to 260 lx) inducing non-aerated P uptake were confirmed. High-throughput sequencing analysis revealed that cyanobacteria could produce oxygen via photosynthesis and were inhabited inside wall biofilm. The cyanobacteria (Pantalinema and Leptolyngbya ANT.L52.2) were incubated in a feeding transparent silicone hose, entered the reactor along with influent, and outcompeted Chlorophyta, which existed in the inoculum. Eventually, this work deciphered the reason for non-aerated phosphorus uptake and indicated its potential application in reducing CO emissions and energy consumption via the cooperation of microalgal-bacterial and biofilm-sludge.
Topics: Phosphorus; Cyanobacteria; Bioreactors; Anaerobiosis; Waste Disposal, Fluid; Biofilms; Aerobiosis
PubMed: 38593871
DOI: 10.1016/j.scitotenv.2024.172313 -
Bioresource Technology May 2024The ubiquitous use of volatile siloxanes in a myriad of product formulations has led to a widespread distribution of these persistent contaminants in both natural...
The ubiquitous use of volatile siloxanes in a myriad of product formulations has led to a widespread distribution of these persistent contaminants in both natural ecosystems and wastewater treatment plants. Microbial degradation under microaerobic conditions is a promising approach to mitigate D4 and D5 siloxanes while recovering energy in wastewater treatment plants. This study examined D4/D5 siloxanes biodegradation under both anaerobic and microaerobic conditions ( [Formula: see text] = 0, 1, 3 %) using wastewater sludge. Results show that the use of microaeration in an otherwise strictly anaerobic environment significantly enhances siloxane conversion to methane. 16S rRNA gene sequencing identified potential degraders, including Clostridium lituseburense, Clostridium bifermentans and Synergistales species. Furthermore, chemical analysis suggested a stepwise siloxane conversion preceding methanogenesis under microaerobic conditions. This study demonstrates the feasibility of microaerobic siloxane biodegradation, laying groundwork for scalable removal technologies in wastewater treatment plants, ultimately highlighting the importance of using bio-based approaches in tackling persistent pollutants.
Topics: Siloxanes; Methane; Biodegradation, Environmental; Sewage; RNA, Ribosomal, 16S; Aerobiosis; Wastewater; Volatilization
PubMed: 38583676
DOI: 10.1016/j.biortech.2024.130673 -
The Science of the Total Environment Jun 2024A mathematical model was developed to predict the formation of both the autotrophic and heterotrophic extracellular polymeric substances (EPS) in the aerobic membrane...
A mathematical model was developed to predict the formation of both the autotrophic and heterotrophic extracellular polymeric substances (EPS) in the aerobic membrane bioreactor (MBR). Batch experimental results and 45-day operation data on a pilot MBR at a sludge retention time (SRT) of 20 d were used to calibrate and validate the model. Simulated MBR setup results demonstrated the key role of the influent COD and NH-N in governing the composition of heterotrophic and autotrophic EPS in the MBR. These results also revealed that the autotrophic EPS process was non-ignorable in the system. According to the autotrophic EPS simulation in the MBR, the EPS yield increased with increasing influent COD/NH-N ratio towards a constant level. The EPS yield was significantly influenced by the SRT, attributed to the autotrophic process's impact on EPS. Simulation results revealed a slight increase in EPS yield with an SRT of up to 5 days, followed by a rapid decrease beyond that threshold.
Topics: Bioreactors; Autotrophic Processes; Waste Disposal, Fluid; Extracellular Polymeric Substance Matrix; Membranes, Artificial; Models, Theoretical; Aerobiosis; Sewage
PubMed: 38583621
DOI: 10.1016/j.scitotenv.2024.172207 -
The Science of the Total Environment Jun 2024The vertical distribution of 35 volatile organic compounds (VOCs) was investigated in soil columns from two obsolete industrial sites in Eastern China. The total...
The vertical distribution of 35 volatile organic compounds (VOCs) was investigated in soil columns from two obsolete industrial sites in Eastern China. The total concentrations of ΣVOCs in surface soils (0-20 cm) were 134-1664 ng g. Contamination of VOCs in surface soil exhibited remarkable variability, closely related to previous production activities at the sampling sites. Additionally, the concentrations of ΣVOCs varied with increasing soil depth from 0 to 10 m. Soils at depth of 2 m showed ΣVOCs concentrations of 127-47,389 ng g. Among the studied VOCs, xylene was the predominant contaminant in subsoils (2 m), with concentrations ranging from n.d. to 45,400 ng g. Chlorinated alkanes and olefins demonstrated a greater downward migration ability compared to monoaromatic hydrocarbons, likely due to their lower hydrophobicity. As a result, this vertical distribution of VOCs led to a high ecological risk in both the surface and deep soil. Notably, the risk quotient (RQ) of xylene in subsoil (2 m, RQ up to 319) was much higher than that in surface soil. Furthermore, distinct effects of VOCs on soil microbes were observed under aerobic and anaerobic conditions. Specifically, after the 30-d incubation of xylene-contaminated soil, Ilumatobacter was enriched under aerobic condition, whereas Anaerolineaceae was enriched under anaerobic condition. Moreover, xylene contamination significantly affected methylotrophy and methanol oxidation functions for aerobic soil (t-test, p < 0.05). However, aromatic compound degradation and ammonification were significantly enhanced by xylene in anaerobic soil (t-test, p < 0.05). These findings suggest that specific VOC compound has distinct microbial ecological effects under different oxygen content conditions in soil. Therefore, when conducting soil risk assessments of VOCs, it is crucial to consider their ecological effects at different soil depths.
Topics: Volatile Organic Compounds; Soil Pollutants; Soil Microbiology; China; Anaerobiosis; Environmental Monitoring; Soil; Aerobiosis
PubMed: 38583613
DOI: 10.1016/j.scitotenv.2024.172256 -
Journal of Hazardous Materials May 2024Tetrabromobisphenol A (TBBPA), a common brominated flame retardant and a notorious pollutant in anaerobic environments, resists aerobic degradation but can undergo...
Tetrabromobisphenol A (TBBPA), a common brominated flame retardant and a notorious pollutant in anaerobic environments, resists aerobic degradation but can undergo reductive dehalogenation to produce bisphenol A (BPA), an endocrine disruptor. Conversely, BPA is resistant to anaerobic biodegradation but susceptible to aerobic degradation. Microbial degradation of TBBPA via anoxic/oxic processes is scarcely documented. We established an anaerobic microcosm for TBBPA dehalogenation to BPA facilitated by humin. Dehalobacter species increased with a growth yield of 1.5 × 10 cells per μmol Br released, suggesting their role in TBBPA dehalogenation. We innovatively achieved complete and sustainable biodegradation of TBBPA in sand/soil columns columns, synergizing TBBPA reductive dehalogenation by anaerobic functional microbiota and BPA aerobic oxidation by Sphingomonas sp. strain TTNP3. Over 42 days, 95.11 % of the injected TBBPA in three batches was debrominated to BPA. Following injection of strain TTNP3 cells, 85.57 % of BPA was aerobically degraded. Aerobic BPA degradation column experiments also indicated that aeration and cell colonization significantly increased degradation rates. This treatment strategy provides valuable technical insights for complete TBBPA biodegradation and analogous contaminants.
Topics: Biodegradation, Environmental; Polybrominated Biphenyls; Anaerobiosis; Oxidation-Reduction; Aerobiosis; Phenols; Flame Retardants; Benzhydryl Compounds; Sphingomonas; Halogenation; Soil Pollutants
PubMed: 38583197
DOI: 10.1016/j.jhazmat.2024.134217 -
Waste Management (New York, N.Y.) May 2024The main disposal method for municipal solid waste (MSW), including the growing worldwide volumes of kitchen waste, involves transport to landfills. Because kitchen...
The main disposal method for municipal solid waste (MSW), including the growing worldwide volumes of kitchen waste, involves transport to landfills. Because kitchen waste is mainly composed of organic matter and has a high moisture content, large amounts of leachate and landfill gas are generated when it is sent to landfills. Therefore, rapid waste stabilization is essential. In this study, four semi-aerobic bioreactors (named NS, SS, MS, and LS) were established with void fractions of 33.76%, 39.84%, 44.62%, and 41.31%, respectively. The results showed that the void fractions of landfill directly affected the gas flow path. When the landfill void fraction was small (e.g., NS), most airflow traveled directly through the pipeline and minimal airflow entered the waste layer. When the landfill void fraction was large (e.g., MS), air easily entered the waste layer and some air flowed into the gas vent with the landfill gas. As the reaction proceeded, the void fraction gradually decreased due to gravity-induced sedimentation. During the water addition experiment, the voids were occupied by water, leading to formation of an anaerobic area. Among the four bioreactors, only MS had negligible formation of an anaerobic zone in the center. Methane (CH) generation was detected only at the connection between the gas vent and the leachate collection pipe. A larger void fraction led to formation of a smaller anaerobic zone. The ratio of air flowing in pipeline was lowest in MS. These results indicated that a large void fraction promotes the decomposition of organic matter.
Topics: Bioreactors; Waste Disposal Facilities; Refuse Disposal; Aerobiosis; Solid Waste
PubMed: 38581750
DOI: 10.1016/j.wasman.2024.03.027