RESUMO
AI thermal facial recognition (AITFR) has been rapidly applied globally in the fight against Coronavirus disease 2019 (COVID-19). However, AITFR has also been accompanied by a controversy regarding whether the public accepts it. Therefore, it is necessary to assess the acceptance of AITFR during the COVID-19 crisis. Drawing upon the theory of acceptable risk and Siegrist's causal model of public acceptance (PA), we built a combined psychological model that included the perceived severity of COVID-19 (PSC) to describe the influencing factors and pathways of AITFR acceptance. This model was verified through a survey conducted in Xi'an City, Shaanxi Province, China, which collected 754 valid questionnaires. The results show that (1) COVID-19 provides various application scenarios for AI-related technologies. However, the respondents' trust in AITFR was found to be very low. Additionally, the public appeared concerned about the privacy disclosure issue and the accuracy of the AITFR algorithm. (2) The PSC, social trust (ST), and perceived benefit (PB) were found to directly affect AITFR acceptance. (3) The PSC was found to have a significant positive effect on perceived risk (PR). PR was found to have no significant effect on PA, which is inconsistent with the findings of previous studies. (4) The PB were found to be a stronger mediator of the indirect effect of the PSC on ST induced by AITFR acceptance.
Assuntos
COVID-19 , Reconhecimento Facial , Humanos , Confiança , Modelos Psicológicos , Inteligência ArtificialRESUMO
In this study, a co-composting of rural organic solid waste (rural sewage sludge, kitchen waste and corn stalks) was conducted to analyze the variation of heavy metals (As, Cu, Cr, Ni, Pb, Hg, and Zn) and their major influencing factors. During composting, significant changes were observed in the total contents of heavy metals (p < 0.01): the total concentrations of As, Cu, Hg, Pb and Zn increased by 7.5%, 54.1%, 26.3%, 15.8%, and 34.2%, whereas that of Cr and Ni decreased by 71.3% and 33.4%, respectively. Heavy metals were mainly bound to the oxidizable and residual fractions. Spearman and Redundancy analysis (RDA) indicated that substances were significantly correlated with the changes in speciation of heavy metals, among all the factors, while pH and temperature were the dominating environmental influencing parameters. Several metal-resistant bacterial genera (Pseudomonas, Paenibacillus, Bacillus, Acinetobacter, Desulfovibrio, and Ochrobactrum, etc) were observed, with significant explanatory capacity for the changes in heavy metals. Composting showed a poor effect on heavy metal passivation, except for that of As. After composting, the heavy metal contents were consistent with the application standards. The evaluation of potential ecological risk showed a high cumulative ecological risk (336.9) of heavy metals. This study provides technical support and practical information for the disposal and safe recycling for rural organic solid waste.
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Compostagem , Metais Pesados , Metais Pesados/análise , Esgotos , Solo , Resíduos SólidosRESUMO
Landfill sites are regarded as prominent sources of bioaerosols for the surrounding atmosphere. The present study focused on the emission of airborne bacteria and fungi in four seasons of a sanitary landfill site. The main species found in bioaerosols were assayed using high-throughput sequencing. The SourceTracker method was utilized to identify the sources of the bioaerosols present at the boundary of the landfill site. Furthermore, the health consequences of the exposure to bioaerosols were evaluated based on the average daily dose rates. Results showed that the concentrations of airborne bacteria in the operation area (OPA) and the leakage treatment area (LTA) were in the range of (4684 ± 477)-(10883 ± 1395) CFU/m3 and (3179 ± 453)-(9051 ± 738) CFU/m3, respectively. The average emission levels of fungal aerosols were 4026 CFU/m3 for OPA and 1295 CFU/m3 for LTA. The landfill site received the maximum bioaerosol load during summer and the minimum during winter. Approximately 41.39%- 86.24% of the airborne bacteria had a particle size of 1.1 to 4.7 µm, whereas 48.27%- 66.45% of the airborne fungi had a particle size of more than 4.7 µm. Bacillus sp., Brevibacillus sp., and Paenibacillus sp. were abundant in the bacterial population, whereas Penicillium sp. and Aspergillus sp. dominated the fungal population. Bioaerosols released from the working area and treatment of leachate were the two main sources that emerged in the surrounding air of the landfill site boundary. The exposure risks during summer and autumn were higher than those in spring and winter.
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Microbiologia do Ar , Monitoramento Ambiental , Aerossóis/análise , Fungos , Medição de Risco , Estações do Ano , Instalações de Eliminação de ResíduosRESUMO
The changes of protein secondary structures in the extracellular polymeric substances (EPS) extracted from activated sludge by four different methods were studied by analyzing the amide I region (1700-1600â¯cm-1) of the Fourier transform infrared spectra and model protein test. The results showed the molecular weight distribution of organic matter extracted by centrifugation, heating and cation exchange resin (CER) was similar, while the EPS extracted by centrifugation (Control) and CER had similar fluorescent organic matter. The protein secondary structures of extracted EPS by the four methods were different. The similarities of protein secondary structures between the EPS extracted by CER with the Control were the highest among the four extracted EPS. Although the EPS yield extracted by formaldehydeâ¯+â¯NaOH method were the highest, its protein secondary structures had the lowest similarity with those extracted by the Control. Additionally, the effects of centrifugation and CER extraction on the secondary structures of bovine serum albumin were also lower than that of other extraction processes. CER enables the second maximum extraction of EPS and maximum retention of the original secondary structure of proteins.
Assuntos
Proteínas de Bactérias/análise , Matriz Extracelular de Substâncias Poliméricas , Resinas de Troca de Cátion , Fracionamento Químico , PolímerosRESUMO
With rapid industrialization and urbanization in the nineteenth century, the activated sludge process (ASP) has experienced significant steps forward in the face of greater awareness of and sensitivity toward water-related environmental problems. Compared with conventional flocculent ASP, the major advantages of granular sludge are characterized by space saving and resource recovery, where the methane and hydrogen recovery in anaerobic granular and 50% more space saving, 30-50% of energy consumption reduction, 75% of footprint cutting, and even alginate recovery in aerobic granular. Numerous engineers and scientists have made great efforts to explore the superiority over the last 40 years. Therefore, a bibliometric analysis was desired to trace the global trends of granular sludge research from 1992 to 2016 indexed in the SCI-EXPANDED. Articles were published in 276 journals across 44 subject categories spanning 1420 institutes across 68 countries. Bioresource Technology (293, 11.9%), Water Research (235, 9.6%), and Applied Microbiology and Biotechnology (127, 5.2%) dominated in top three journals. The Engineering (991, 40.3%), China (906, 36.9%), and Harbin Inst Technol, China (114, 4.6%) were the most productive subject category, country, and institution, respectively. The hotspot is the emerging techniques depended on granular reactors in response to the desired removal requirements and bio-energy production (primarily in anaerobic granular sludge). In view of advanced and novel bio-analytical methods, the characteristics, functions, and mechanisms for microbial granular were further revealed in improving and innovating the granulation techniques. Therefore, a promising technique armed with strengthened treatment efficiency and efficient resource and bio-energy recovery can be achieved.
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Bibliometria , Pesquisa/estatística & dados numéricos , Esgotos , Reatores Biológicos , ChinaRESUMO
Lead (Pb2+) is a poisonous heavy metal that causes many pathophysiological effects in living systems. Its toxicological effects are well known as it causes apoptosis of several cell types and tissues. This study aimed to determine the criteria required for early diagnosis of Pb2+ poisoning in the Siberian tiger using a tiger population in China, to identify a safety Pb2+ concentration threshold, and to provide suggestions for preventing Pb2+ poisoning in Siberian tigers. We investigated the apoptotic effects of Pb2+ (0, 32, 64, and 125 µM) for 12-48 h on Siberian tiger fibroblasts in vitro. Typical apoptotic effects were observed after Pb2+ exposure. Pb2+ strongly blocked DNA synthesis in the G0/G1 phase and induced cell apoptosis in a dose- and time-dependent manner. Intracellular free calcium (Ca2+) levels, reactive oxygen species levels, and efflux of extracellular Ca2+ were increased. The mitochondrial membrane potential was lowered. Caspase-3, -8, and -9 activities were increased when fibroblasts were treated with 32, 64, and 125 µM Pb2+. The gene expression levels of Bax, caspase-3, -8, Fas, and p53 were increased, while that of Bcl-2 was decreased. Calcium homeostasis and mitochondrial function were disturbed. Ca2+ efflux, oxidative damage, activation of caspases, and regulation of Bax, Bcl-2, caspase-3, -8, Fas, and p53 gene expression played an important role in the apoptotic effects. The disorder of intracellular homeostasis was the trigger for apoptosis in Siberian tiger fibroblasts.
Assuntos
Apoptose/efeitos dos fármacos , Fibroblastos/efeitos dos fármacos , Intoxicação por Chumbo/etiologia , Compostos Organometálicos/toxicidade , Animais , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Cálcio/metabolismo , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular , Replicação do DNA/efeitos dos fármacos , Relação Dose-Resposta a Droga , Fibroblastos/metabolismo , Fibroblastos/ultraestrutura , Homeostase , Intoxicação por Chumbo/metabolismo , Intoxicação por Chumbo/patologia , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Espécies Reativas de Oxigênio/metabolismo , Medição de Risco , Transdução de Sinais/efeitos dos fármacos , Tigres , Fatores de TempoRESUMO
Disaster resettlement, as a mitigation and preparedness measure, entails significant economic, physical, and social impacts, which continue to challenge understanding of recovery from major events, especially regarding the extent of the context and environmental efforts to rebuild livelihoods. Based on a case study of Qinling Mountains, China, this research investigates the effects of disaster resettlement from a livelihoods perspective. Methodologically, it proposes a framework that combines the pressure-state-response framework and the sustainable livelihoods approach, and it employs a structural equation model to examine how specific factors affect disaster resettlement. The results indicate that conflicts may occur during and after resettlement owing to the difference or disparity between the concerns of resettled peasants and those of the government. Consequently, the risks related to livelihoods need to be taken seriously. Effective risk communication is critical to bridge the gap between different stakeholders. The paper concludes with some practical and policy recommendations.
Assuntos
Desastres , Ocupações/estatística & dados numéricos , Características de Residência/estatística & dados numéricos , China , Humanos , Fatores SocioeconômicosRESUMO
For the removal of phosphate (PO43-) from water, an adsorbent was prepared via carbonization of sewage sludge from a wastewater treatment plant: carbonized sludge adsorbent (CSA). The mechanism of phosphate removal was determined after studying the structure and chemical properties of the CSA and its influence on phosphate removal. The results demonstrate that phosphate adsorption by the CSA can be fitted with the pseudo second-order kinetics and Langmuir isotherm models, indicating that the adsorption is single molecular layer adsorption dominated by chemical reaction. The active sites binding phosphate on the surface are composed of mineral particles containing Si/Ca/Al/Fe. The mineral containing Ca, calcite, is the main factor responsible for phosphate removal. The phosphate removal mechanism is a complex process including crystallization via the interaction between Ca2+ and PO43-; formation of precipitates of Ca2+, Al3+, and PO43-; and adsorption of PO43- on some recalcitrant oxides composed of Si/Al/Fe.
Assuntos
Fosfatos/química , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Adsorção , Fosfatos/análise , Esgotos/química , Poluentes Químicos da Água/análiseRESUMO
An environmentally friendly chemical, tetrakis(hydroxymethyl)phosphonium sulfate (THPS), was used as a metabolic uncoupler to reduce sludge production in a pilot-scale anaerobic/anoxic/oxic process. The results show that the addition of THPS (1.08-1.86 mL/m(3) influent) in the sludge return section could reduce waste activated sludge by about 22.5 %, and decrease the sludge yield by about 14.7 % at the end of a run. At the same time, the addition of THPS slightly lowered the removal of chemical oxygen demand (COD), soluble COD and NH4 (+)-N, and slightly improved removal of total nitrogen. The effects of THPS addition on two characteristics of activated sludge in oxic tank are discussed in detail and the results suggest that the settleability of sludge was reduced by addition of THPS, while the specific oxygen uptake rate was increased. Molecular biology analysis shows that the addition of THPS had little effect on the microbial communities of sludge.
Assuntos
Oxigênio/química , Esgotos , Amônia/isolamento & purificação , Sequência de Bases , Análise da Demanda Biológica de Oxigênio , Primers do DNA , Eletroforese em Gel de Gradiente Desnaturante , Microbiota , Nitrogênio/isolamento & purificação , Projetos Piloto , Reação em Cadeia da PolimeraseRESUMO
Bioaerosols from wastewater treatment processes are a significant subgroup of atmospheric aerosols. In the present study, airborne microorganisms generated from a wastewater treatment station (WWTS) that uses an oxidation ditch process were diminished by ventilation. Conventional sampling and detection methods combined with cloning/sequencing techniques were applied to determine the groups, concentrations, size distributions, and species diversity of airborne microorganisms before and after ventilation. There were 3021 ± 537 CFU/m³ of airborne bacteria and 926 ± 132 CFU/m³ of airborne fungi present in the WWTS bioaerosol. Results showed that the ventilation reduced airborne microorganisms significantly compared to the air in the WWTS. Over 60% of airborne bacteria and airborne fungi could be reduced after 4 hr of air exchange. The highest removal (92.1% for airborne bacteria and 89.1% for fungi) was achieved for 0.65-1.1 µm sized particles. The bioaerosol particles over 4.7 µm were also reduced effectively. Large particles tended to be lost by gravitational settling and small particles were generally carried away, which led to the relatively easy reduction of bioaerosol particles 0.65-1.1 µm and over 4.7 µm in size. An obvious variation occurred in the structure of the bacterial communities when ventilation was applied to control the airborne microorganisms in enclosed spaces.
Assuntos
Microbiologia do Ar , Bactérias/isolamento & purificação , Ventilação , Eliminação de Resíduos Líquidos/métodos , Aerossóis/química , Bactérias/classificação , Bactérias/genética , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Filogeografia , Fatores de Tempo , Instalações de Eliminação de ResíduosRESUMO
Hypertrophic scar (HS) is a fibrous proliferative disorder that occurs in the dermis after skin injury. Studies have confirmed that Botulinum toxin type A (BTA) is effective in scar prevention and treatment. However, the specific mechanism remains uncertain. Hypertrophic scar fibroblasts (HSFs) and normal skin fibroblasts (NSFs) from the skin tissues of HS patients were isolated and cultured. Western blot analysis was conducted to measure the expression of JAK2/STAT3 pathway-related proteins. HSFs were treated with the JAK2 inhibitor (AG490) or agonist (C-A1). The CCK-8 assay, EdU staining, scratch-wound assay and transwell assay were used to examine the biological properties of HSFs. Western blot, immunofluorescence, and Sirius red staining were used to assess the fibrosis of HSFs. Additionally, a mouse full-thickness wound model was constructed to investigate the role of BTA in wound healing. The results showed that the JAK2 and STAT3 phosphorylation levels were markedly increased in HS tissues and HSFs. AG490 treatment reduced cell viability, proliferation and migration capacity, and inhibited the fibrosis of HSFs, whereas C-A1 treatment had the opposite effect. BTA treatment inhibited the JAK2/STAT3 pathway. BTA reduced cell viability, proliferation and migration ability, and inhibited the fibrosis of HSFs, while C-A1 intervention weakened the impact of BTA. Meanwhile, BTA promoted wound healing and reduced collagen deposition in vivo. In conclusion, BTA inhibited the JAK2/STAT3 pathway, which in turn hindered the proliferation, migration and fibrosis of HSFs, and promoted wound healing in mice.
RESUMO
Pathogenic microorganisms can cause infection, sepsis, and other diseases in humans. Although municipal wastewater plants are important sources and sinks for potential pathogenic microorganisms, data on rural wastewater treatment processes are limited. The proximity of rural wastewater facilities to human settlements and the trend toward wastewater resourcing could pose risks to humans. Here, a typical village in southern China was selected to analyze potential pathogenic microorganisms in wastewater, sewage sludge, and aerosols during the collection, treatment, and discharge of domestic wastewater. The succession characteristics and concentration variations of potential pathogenic microorganisms throughout the wastewater treatment process were identified using high-throughput sequencing and culture methods. Bacteria-associated health risks in facility aerosols were estimated based on average daily dose rates from inhalation and dermal exposure. Lower amounts of pathogenic bacteria and pathogenic fungi were detected in the effluent of the 1-ton treatment scale and the 10-ton treatment scale facilities, compared to those in the influent. Pathogen effluent concentrations were significantly lower than influent concentrations after treatment in rural wastewater facilities. 16 and 29 potential pathogenic bacteria and fungi were detected in aerosols from wastewater treatment facilities, respectively. Furthermore, the potential pathogen concentrations were higher than those in the background air. Aerobic units are the main source of pathogen emissions from aerosols. There were 42 potential pathogenic bacteria and 34 potential pathogenic fungi in the sewage sludge. Biochemical units were the main source of potential pathogens in sewage sludge, and more potential airborne pathogens originated from wastewater. In rural wastewater resourcing processes with greater pollutant exposure, the effluent of rural wastewater treatment facilities (WWTFs), downstream rivers, and facility aerosols, could be important potential sources of microbial risk. Inhalation is the main pathway of human exposure to airborne bacteria. Therefore, more attention should be focused on microbiological risk in rural wastewater treatment processes.
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Águas Residuárias , Purificação da Água , Humanos , Esgotos/microbiologia , Microbiologia do Ar , Medição de Risco , Bactérias , Aerossóis , FungosRESUMO
In the Orbal oxidation ditch, denitrification is primarily accomplished in the outer channel. However, the detailed characteristics of the flow field and dissolved oxygen (DO) distribution in the outer channel are not well understood. Therefore, in this study, the flow velocity and DO concentration in the outer channel of an Orbal oxidation ditch system in a wastewater treatment plant in Beijing (China) were monitored under actual operation conditions. The flow field and DO concentration distributions were analyzed by computed fluid dynamic modeling. In situ monitoring and modeling both showed that the flow velocity was heterogeneous in the outer channel. As a result, the DO was also heterogeneously distributed in the outer channel, with concentration gradients occurring along the flow direction as well as in the cross-section. This heterogeneous DO distribution created many anoxic and aerobic zones, which may have facilitated simultaneous nitrification-denitrification in the channel. These findings may provide supporting information for rational optimization of the performance of the Orbal oxidation ditch.
Assuntos
Simulação por Computador , Monitoramento Ambiental , Hidrodinâmica , Oxigênio/análise , Reologia , Purificação da Água/métodos , Modelos Químicos , Oxirredução , Solubilidade , Água/químicaRESUMO
This article reports an innovative integrated system utilizing solar energy as power for decentralized wastewater treatment, which consists of an oxidation ditch with double channels and a photovoltaic (PV) system without a storage battery. Because the system operates without a storage battery, which can reduce the cost of the PV system, the solar radiation intensity affects the amount of power output from the PV system. To ensure that the power output is sufficient in all different weather conditions, the solar radiation intensity of 78 W/m2 with 95% confidence interval was defined as a threshold of power output for the PV system according to the monitoring results in this study, and a step power output mode was used to utilize the solar energy as well as possible. The oxidation ditch driven by the PV system without storage battery ran during the day and stopped at night. Therefore, anaerobic, anoxic and aerobic conditions could periodically appear in the oxidation ditch, which was favorable to nitrogen and phosphate removal from the wastewater. The experimental results showed that the system was efficient, achieving average removal efficiencies of 88% COD, 98% NH4+-N, 70% TN and 83% TP, under the loading rates of 140 mg COD/(g MLSS x day), 32 mg NH4+-N/(g MLSS x day), 44 mg TN/(g MLSS x day) and 5 mg TP/(g MLSS x day).
Assuntos
Eliminação de Resíduos Líquidos/métodos , Reatores Biológicos/microbiologia , Nitrogênio/isolamento & purificação , Fosfatos/isolamento & purificaçãoRESUMO
Co-composting is an efficient strategy for collaborative disposal of multiple organic wastes in rural areas. In this study, we explored the co-composting of rural sewage sludge and other organic solid wastes (corn stalks and kitchen waste), with a focus on the variation of total petroleum hydrocarbons (TPH) during this process. 12% corn-derived biochar was applied in the composting (BC), with no additives applied as the control treatment (CK). The TPH contents of piles after composting ranged from 0.70 to 0.74 mg/g, with overall removal efficiencies of 35.6% and 61.1% for CK and BC, respectively. The results indicate that the addition of 12% biochar increased the rate of TPH degradation and accelerated the degradation process. 16s rDNA high-throughput sequencing was applied to investigate the biodiversity and bacterial community succession during the composting process. Diverse bacterial communities with TPH degradation functions were observed in the composting process, including Acinetobacter, Flavobacterium, Paenibacillus, Pseudomonas, and Bacillus spp. These functional bacteria synergistically degraded TPH, with cooperative behavior dominating during composting. Biochar amendment enhanced the microbial activity and effectively promoted the biodegradation of TPH. The physicochemical properties of the compost piles, including environmental factors (pH and temperature), nutrients (nitrogen, phosphorus, potassium), and humic substances produced in composting (humic acids and fulvic acids), directly and indirectly affected the variation in TPH contents. In conclusion, this work illustrates the variation in TPH content and associated influencing factors during co-composting of rural organic solid wastes, providing valuable guidance toward the further optimization of rural organic waste management.
Assuntos
Compostagem , Petróleo , Esgotos , Resíduos Sólidos , Substâncias Húmicas , Hidrocarbonetos , Flavobacterium , SoloRESUMO
INTRODUCTION: The aim of the study was to investigate the effect of ultra-early intervention of nerve and motor development in infants at high risk of cerebral palsy. MATERIAL AND METHODS: One hundred and twenty cases of infants born in The Affiliated Hospital of Harbin Medical University from January 2017 to January 2019 and diagnosed with high risk of cerebral palsy were included in the observation group. In addition, 120 cases of infants at high risk of cerebral palsy (three to five months old) who were admitted to this hospital during the same period were included in the control group, and 120 healthy infants born in the same hospital were included in the healthy group. Intervention was performed on the observation group after diagnosis (within seven days of birth), mainly using neurodevelopmental therapy (NDT). Children in the control group underwent intervention after diagnosis (at three to five months old) using the same measures. The healthy group underwent no intervention. Changes in various indicators were compared among the observation group, healthy group, and control group. RESULTS: At baseline and at three months, the developmental quotient (DQ) at all functional areas, total DQ, and GESELL development scale (GDS) scores were significantly lower in the observation and control groups than in the healthy group ( p < 0.05). At six months, 12 months, 18 months, and 24 months, the DQ at all functional areas, total DQ, and GDS (adaptability, gross motor, fine motor, language, personal social interaction) scores in the observation and control groups were significantly lower than those in the healthy group ( p < 0.05). However, the observation group scores were significantly higher than the control group scores ( p < 0.05). In the observation group, the normalisation rate was higher than in the control group, and the incidence rate of cerebral palsy and full developmental delay was lower than in the control group ( p < 0.05). CONCLUSIONS: Ultra-early diagnosis and NDT intervention can significantly accelerate the motor development of infants at high risk of cerebral palsy. The earlier, the better. Ultra-early intervention can promote the normalisation of infants at high risk of cerebral palsy and significantly reduce the risk of progression to cerebral palsy.
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Paralisia Cerebral , Criança , Humanos , Lactente , Paralisia Cerebral/diagnóstico , Paralisia Cerebral/terapiaRESUMO
Current estimation schemes as decision support tools for the selection of wastewater treatment alternatives focus primarily on the treatment efficiency, effluent quality, and environmental consequences for receiving water bodies. However, these schemes generally do not quantify the potential to convert pollutants in wastewater to recoverable resources. This study proposes a refined evaluation scheme for choices of wastewater treatment processes that quantifies not only adverse environmental effects but also bioenergy and nutrient recovery indices. An original means of data processing was established and clear estimate indicators were consequently obtained to allow a smooth overall estimation. An array of wastewater treatment alternatives that meet three effluent limits were used as case studies to demonstrate how the present scheme works, simultaneously, to identify optimum choices. It is concluded in the overall estimation that the lower sustainability of wastewater treatment contributed by increasingly stringent discharge demands was offset and mitigated by the resource-recovery scenarios involved, and the scenario of recovering nutrients via excess-sludge composting was of more benefit. Thus, before tightening wastewater discharge requirements, one should bear in mind the situation of multiple sustainability by setting a goal to achieve not only the greatest reduction in environmental burden but also the maximum resource-recovery benefits.
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Conservação dos Recursos Naturais , Eliminação de Resíduos Líquidos , Purificação da Água/métodos , Projetos de PesquisaRESUMO
Seven different aeration modes, in which oxygen supply was changed by adjusting the number of aerators, were designed and applied in a full-scale municipal wastewater treatment plant with Orbal oxidation ditch to investigate the influence of dissolved oxygen (DO) on nitrogen removal performance. The full-scale experiment results of 574 days showed that nitrogen removal efficiency depended on the degree of nitrification and denitrification in the outer channel, which was the largest contributor for TN removal in the Orbal oxidation ditch. Appropriate aeration control in the outer channel was essential to balance nitrification and denitrification in the Orbal oxidation ditch. When DO was as low as about 0.2 mg/L in the outer channel, the highest TN removal efficiency of 75% was obtained. Microbial analysis confirmed that aerobic and anaerobic bacteria coexisted in the outer channel. The greater species diversity and more intensive activities of these bacteria in aeration Mode V may be responsible for the higher TN removal efficiency compared with Mode III. These results suggest that different aerated conditions in the Orbal oxidation ditch might have a significant effect on microbial community characteristics and nitrogen removal efficiencies.
Assuntos
Nitrogênio/isolamento & purificação , Oxigênio/química , Águas Residuárias , Bactérias/isolamento & purificação , Sequência de Bases , Primers do DNA , Eletroforese em Gel de Ágar , Oxirredução , Reação em Cadeia da PolimeraseRESUMO
Concentrations of six endocrine-disrupting compounds (EDCs), bisphenol A (BPA), estrone (E(1)), 17ß-estradiol (E(2)), estriol (E(3)), 17α-ethynylestradiol (EE(2)) and diethylstilbestrol (DES), were assessed in influents, effluents and excess sludge in ten municipal wastewater treatment plants (WWTPs) in the Three Gorges Reservoir (TGR) area, Chongqing, China. Three types of activated sludge treatment processes, oxidation ditch (OD), reversed anaerobic-anoxic-oxic (rA(2)/O) technology and sequential batch reactor (SBR), were used in the surveyed WWTPs. These WWTPs were all combined landfill leachate-sewage treatment plants. All analytes were extracted by solid-phase extraction (SPE) in the dissolved phase and by accelerated solvent-based extraction (ASE) in sludge. Gas chromatography-mass spectrometry (GC-MS) was employed for the analysis of EDCs. Among these EDCs, BPA was the most frequently detected and abundant compound (100.0-10566.7 ng L(-1), 15.5-1210.7 ng L(-1) and 85.0-2470.4 ng g(-1) with respect to the influents, effluents and excess sludge samples). The greatest levels of steroidal estrogens in municipal influents were observed in E(3) which were all >100 ng L(-1), followed by E(1) (42.2-110.7 ng L(-1)) and E(2) (7.4-32.7 ng L(-1)), and in the effluents and sludge were E(1) > E(3) > E(2) which were all <31 ng L(-1) and 105 ng g(-1), respectively. Regarding synthetic estrogens, EE(2) was frequently detected in the influents, occurring below 50 ng L(-1), while DES was not detected at all. A high correlation coefficient was observed between the leachate-sludge ratio and concentrations of influent EDCs, and it was statistically significant (i.e., R > 0.65, P < 0.05), but removal efficiency of the EDCs did not show significant differences with OD, rA(2)/O and SBR processes. Furthermore, modification of treatment technology as well as operational parameters, such as hydraulic retention time (HRT), sludge retention time (SRT) and disinfection process (DP), were recommended to further eliminate the residual EDCs.
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Disruptores Endócrinos/análise , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Compostos Benzidrílicos , China , Dietilestilbestrol/análise , Monitoramento Ambiental , Estradiol/análise , Estriol/análise , Estrona/análise , Etinilestradiol/análise , Cromatografia Gasosa-Espectrometria de Massas , Fenóis/análise , Poluição Química da Água/estatística & dados numéricosRESUMO
The livelihood recovery strategy is utilized for peasants during the COVID-19 pandemic. This strategy serves a salient role to help them recover from the relevant hazardous impacts. Disaster risk has been a major concern among hazards for the increasing likelihood of exposure and vulnerability, especially in the process of poverty alleviation in China. However, few studies have discussed the factors and mechanisms that influence peasants to adopt livelihood recovery strategies in the context of the COVID-19 pandemic in China. Based on a case study of Ningqiang County, China, this study explores the mechanisms that catalyze the proactive recovery of peasants from the COVID-19 pandemic from a livelihood perspective. Methodologically, the study proposes a framework that integrates the modified pressure-state-response (PSR) framework and the sustainable livelihoods approach (SLA), and it employs structure equation modeling (SEM) approach to examine how specific factors affect peasants to proactively adopt livelihood strategies to recover from the COVID-19 pandemic. The results indicate that the COVID-19 pressure significantly increases the risk perception of peasants and decreases their livelihood capital. Further, the decreased livelihood capital, the improvement of risk perception and supportive policy will promote peasants to adopt livelihood recovery strategies. Moreover, the results specify that risk perception and supportive policy mediate the relation between livelihood capital and recovery strategy. The findings will be beneficial for policymakers and researchers to understand the mechanisms that peasants adopt livelihood strategies to recover from disasters, and can serve as references for formulating disaster risk reduction and resilience policies.