Choice of sewage sludge thermochemical disposal methods from multi‐ perspective analysis

Thermochemical conversion disposal methods for sewage sludge usually include incineration, gasification and pyrolysis. Incineration technology is relatively mature and the incineration ash can be potentially used for phosphorus (P) recovery. Gasification can be used to recover syngas which is convenient to be used for power & heat generation. While through pyrolysis, syngas of high quality, tar and char can be recovered. To make a proper choice from them, these techniques are compared from perspective of technology maturity, investment, operation cost, environmental impact and acceptability of the public. Technology maturity is evaluated by comparing industrial applications. Investment and operation cost are evaluated based on practical operation experiences; environmental impacts are evaluated based on life cycle assessment; and acceptability of the public is based on a questionnaire survey. Based on a scenario with capacity of 100 t/d in eastern China, investment are comparable for the three technologies within the range of 250,000-400,000 RMB yuan/(ton.d) with gasification close to the higher side; the operation cost varies in the range of 140 - 400 RMB yuan/ton with incineration the highest; pyrolysis corresponds to the lowest environmental impacts and the highest acceptability of the public, however the pyrolysis technology is not fully developed, especially the durable pyrolysis reactor and the application of pyrolysis char

Optimization of waste disposal method in urban functional zone based on multiple model evaluation: a case study of an urban sub‐domain planning

With the implements of urban and rural areas integration planning and new rural countryside construction, a new town planning is springing up in China. Planning of municipal solid waste (MSW) disposal is one of the most important contents. In the new town planning, MSW is considered as one kind of energy source instead of a trash stream, so how to choose a suitable method of waste to energy (WtE) and analyze the feasibility of the method combined with urban functional zone need to be considered. In this paper, by adopting the analytical hierarchy process (AHP) method which consists of life cycle analysis (LCA) model, cost benefit analysis (CBA) and questionnaire survey, the environmental benefits, economic benefits and social benefits are considered to decide the best WtE route for MSW in an urban functional zone. The functional unit is selected to be 1 ton of waste, and the system boundaries include the process of collection and transportation, disposal, and utilization of generation and treatment of residue. The alternatives include central incineration, in situ pyrolysis, central incineration of combustible MSW+ in situ anaerobic digestion of organic waste and in situ pyrolysis of combustible MSW + in situ anaerobic digestion of organic waste. The 4 alternatives are evaluated to determine the best suitable disposal method of MWS of a center business district (CBD) of a city in north China. The area of the CBD is 3150m×2100m, the generation rate of MSW is about 78t/d, of which the proportion of food waste is 50.84%. For small and moderate scale, tubular reactor can be competitive, so tubular reactor is selected in this study. The technical routes of the 4 alternatives are as followed: Collection (dry waste & wet waste) ®transportation (78t/d) ®central incineration (entire city: 836t/d) (energy generation efficiency: 25%; flue gas: purification; bottom ash: landfill; fly ash: solidification and landfill) Collection (dry waste & wet waste)®pyrolysis in transfer station (78t/d) ® pyrolysis gas into distributed energy station (pyrolysis gas: purification; residual char: landfill) Collection (dry waste)®transportation(38.3t/d)®central incineration(entire city: 836t/d) Collection(wet waste)®anaerobic digestion in transfer station(39.6t/d) ®biogas into distributed energy station (biogas: purification; digestion residue: landfill) Collection(dry waste)®pyrolysis in transfer station(38.3t/d)®pyrolysis gas into distributed energy station(pyrolysis gas: purification; residual char: landfill) Collection(wet waste)®anaerobic digestion in the transfer stations (39.6t/d) ®biogas to distributed energy station (biogas: purification; biogas residue: landfill) The evaluation result shows that the alternative 4 is the most suitable disposal method in urban functional zone

MSW derived syngas utilization in combination with distributed energy supply system: mode selection and evaluation

Syngas from MSW gasification and pyrolysis are characterized through a rotary kiln reactor followed by a gas scrubber, the components and energy & chemicals for cleaning the syngas were qualified. Then the syngas utilization modes in combination with distributed energy supply system are evaluated. For the separated MSW sample with dry-basis higher heat value (HHV) of 15.23MJ/kg, the HHV of pyrolysis syngas is higher than 15 MJ/kg. When combined with distributed energy supply system, the syngas is cleaned first to remove dust, tar and harmful components such as NH3 and H2S, then is used to supply power & heat. Based on a downtown district in a northern city in China, the syngas from pyrolysis of 43.34 ton/d separated MSW is assumed to generate power & heat through 4 routes, as shown in Fig.1: l burning in a gas engine (1); l burning in a gas turbine (2); l direct combustion in a furnace to generate steam followed by a steam turbine (3); l undergoing separation to obtain pure CH4 or H2 for industrial applications as avoidance of pure gas production or utilization in fuel cell (4). Please click Additional Files below to see the full abstract

An Optimized Classification Algorithm by Neural Network Ensemble Based on PLS and OLS

Using the neural network to classify the data which has higher dimension and fewer samples means overmuch feature inputs influence the structure design of neural network and fewer samples will generate incomplete or overfitting phenomenon during the neural network training. All of the above will restrict the recognition precision obviously. It is even better to use neural network to classify and, therefore, propose a neural network ensemble optimized classification algorithm based on PLS and OLS in this paper. The new algorithm takes some advantages of partial least squares (PLS) algorithm to reduce the feature dimension of small sample data, which obtains the low-dimensional and stronger illustrative data; using ordinary least squares (OLS) theory determines the weights of each neural network in ensemble learning system. Feature dimension reduction is applied to simplify the neural network’s structure and improve the operation efficiency; ensemble learning can compensate for the information loss caused by the dimension reduction; on the other hand, it improves the recognition precision of classification system. Finally, through the case analysis, the experiment results suggest that the operating efficiency and recognition precision of new algorithm are greatly improved, which is worthy of further promotion

Gut Microbiota Correlates With Clinical Responsiveness to Erythropoietin in Hemodialysis Patients With Anemia

The main treatment for renal anemia in end-stage renal disease (ESRD) patients on hemodialysis is erythropoiesis (EPO). EPO hyporesponsiveness (EH) in dialysis patients is a common clinical problem, which is poorly understood. Recent searches reported that gut microbiota was closely related to the occurrence and development of ESRD. This study aims to explore the changes in gut microbiota between ESRD patients with different responsiveness to EPO treatment. We compared the gut microbiota from 44 poor-response (PR) and 48 good-response (GR) hemodialysis patients treated with EPO using 16S rDNA sequencing analysis. The results showed that PR patients displayed a characteristic composition of the gut microbiome that clearly differed from that of GR patients. Nine genera (Neisseria, Streptococcus, Porphyromonas, Fusobacterium, Prevotella_7, Rothia, Leptotrichia, Prevotella, Actinomyces) we identified by Lasso regression and ROC curves could excellently predict EH. In contrast, five genera (Faecalibacterium, Citrobacter, Bifidobacterium, Escherichia–Shigella, Bacteroides) identified by the same means presented a protective effect against EH. Analyzing the correlation between these biomarkers and clinical indicators, we found that gut microbiota may affect response to EPO through nutritional status and parathyroid function. These findings suggest that gut microbiota is altered in hemodialysis patients with EH, giving new clues to the pathogenesis of renal anemia

Nicotine Dependence among Rural-Urban Migrants in China

<p>Abstract</p> <p>Background</p> <p>The complex mechanism of nicotine dependency makes it challenging to evaluate dependence or progress towards dependence. The aim of this study was to estimate nicotine dependence levels and identify determinants of dependence among Chinese rural-urban migrants.</p> <p>Methods</p> <p>Multi-stage systematic sampling was used to select 4,198 rural-urban migrants aged 18 years or older from three metropolises in China. A structured questionnaire was administered during face-to-face interviews. Nicotine dependence among participants was assessed by means of the six-item Mandarin Chinese Version of the Fagerström Test for Nicotine Dependence (CFTND). Determinants of dependence were analyzed using multivariate analysis of variance (MANOVA).</p> <p>Results</p> <p>Among 4,198 participants, estimated current, daily, and occasional smoking rates were 28.3%, 21.2%, and 7.1%, respectively. The CTFND score for the 894 daily smokers was 3.39(SD: 2.32). MANOVA showed that work type, age at first migration, length of migration, and number of cities ever lived were associated with nicotine dependence.</p> <p>Conclusion</p> <p>A migratory lifestyle is associated with nicotine dependence. Results could inform the design of tobacco control programs that target Chinese rural-urban migrant workers as a special at-risk population.</p

Single Endemic Genotype of Measles Virus Continuously Circulating in China for at Least 16 Years

The incidence of measles in China from 1991 to 2008 was reviewed, and the nucleotide sequences from 1507 measles viruses (MeV) isolated during 1993 to 2008 were phylogenetically analyzed. The results showed that measles epidemics peaked approximately every 3 to 5 years with the range of measles cases detected between 56,850 and 140,048 per year. The Chinese MeV strains represented three genotypes; 1501 H1, 1 H2 and 5 A. Genotype H1 was the predominant genotype throughout China continuously circulating for at least 16 years. Genotype H1 sequences could be divided into two distinct clusters, H1a and H1b. A 4.2% average nucleotide divergence was found between the H1a and H1b clusters, and the nucleotide sequence and predicted amino acid homologies of H1a viruses were 92.3%–100% and 84.7%–100%, H1b were 97.1%–100% and 95.3%–100%, respectively. Viruses from both clusters were distributed throughout China with no apparent geographic restriction and multiple co-circulating lineages were present in many provinces. Cluster H1a and H1b viruses were co-circulating during 1993 to 2005, while no H1b viruses were detected after 2005 and the transmission of that cluster has presumably been interrupted. Analysis of the nucleotide and predicted amino acid changes in the N proteins of H1a and H1b viruses showed no evidence of selective pressure. This study investigated the genotype and cluster distribution of MeV in China over a 16-year period to establish a genetic baseline before MeV elimination in Western Pacific Region (WPR). Continuous and extensive MeV surveillance and the ability to quickly identify imported cases of measles will become more critical as measles elimination goals are achieved in China in the near future. This is the first report that a single endemic genotype of measles virus has been found to be continuously circulating in one country for at least 16 years

The enormous repetitive Antarctic krill genome reveals environmental adaptations and population insights

Antarctic krill (Euphausia superba) is Earth’smost abundant wild animal, and its enormous biomass is vital to the Southern Ocean ecosystem. Here, we report a 48.01-Gb chromosome-level Antarctic krill genome, whose large genome size appears to have resulted from inter-genic transposable element expansions. Our assembly reveals the molecular architecture of the Antarctic krill circadian clock and uncovers expanded gene families associated with molting and energy metabolism, providing insights into adaptations to the cold and highly seasonal Antarctic environment. Population-level genome re-sequencing from four geographical sites around the Antarctic continent reveals no clear population structure but highlights natural selection associated with environmental variables. An apparent drastic reduction in krill population size 10 mya and a subsequent rebound 100 thousand years ago coincides with climate change events. Our findings uncover the genomic basis of Antarctic krill adaptations to the Southern Ocean and provide valuable resources for future Antarctic research

Bio-inspired geotechnical engineering: Principles, current work, opportunities and challenges

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