共查询到20条相似文献，搜索用时 15 毫秒
1.
The parameters characterizing and affecting anaerobic sludge digestion process in three Lithuanian cities are investigated. Results showed that digestion process was effective in all three objects: specific biogas production varied between 0.77 and 0.86 m3/kg volatile solids destroyed, methane content in the biogas varied between 64 and 67% and they complied with the values presented in the scientific references. The increase of VS loading (up to 2.6 kg VS/m3/day) led to the higher level of VS destruction which was up to 59%. The sludge retention time (hydraulic retention time) values must be in ranges of 20–25 days for the digestion process in order to get the design VS destruction, as well the biogas production. In a case of lack of raw materials, the application of wastes from food industry can help to reach the design parameters. The application of wastes from milk industry showed positive results in the digestion process. 相似文献
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Aparna Garg H. David Stensel Bob Bucher Pardi Sukapanpotharam Mari K. H. Winkler 《Water and Environment Journal》2021,35(1):381-389
In this study, waste activated sludge obtained from two full‐scale treatment plants with foaming issues was pretreated with acid/alkali treatment, acid‐phase fermentation, thermal treatment, ultrasonic treatment and metal salt treatment to investigate their effect on foam mitigation. Waste activated sludge was characterized for foaming index prior and after each pretreatment method. Among all pretreatment methods investigated, acid/alkali treatment and acid phase fermentation showed highest reduction of 53% in foaming and in inactivation of Gordonia amarae filaments. Pretreatment methods that resulted in sharp decrease in the foaming index concurred with higher amounts of dead foam formers as confirmed using live/dead staining and the PMA‐qPCR technique. Pretreating with iron(III)chloride gave good foaming reductions with 54% decrease in foaming potential at a concentration of 260 mg/L but did not result in a decline of foam formers as confirmed by live/dead staining. Ultrasonic treatment did not prove effective in lowering the foaming index or killing the G. amarae filaments. 相似文献
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城市污水处理厂剩余污泥厌氧消化试验研究 总被引：10，自引：4，他引：10
以北京市某污水处理厂的剩余污泥为研究对象，对该污泥的理论产气量进行了估算，考察了投加接种污泥和未投加接种污泥条件下污泥厌氧消化的产气情况，并分析了污泥消化前、后的泥质特点。结果表明：与未接种条件相比，污泥厌氧消化前采用投加接种污泥的方式可大大促进消化反应的进行，加快污泥的产气速率，使厌氧消化周期缩短近1／4，但对污泥的总产气量影响较小；在厌氧消化正常运行条件下，污泥产气量达到总产气量的90％时所需反应时间约为16d，可将其作为污泥厌氧消化工艺较为理想的消化周期；剩余污泥的消化性能差、产气率低、试验产气量占理论产气量的比例〈50％，在工程上单独的剩余污泥不宜采用厌氧消化工艺处理。 相似文献
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结合具体工程实例,对生态园区污水的特点进行了研究,分析了以生物转盘（RBC）为主的污水生物处理工艺,以及污泥在沼气池内进行常温厌氧消化的城市污水再生利用工程,得出了该处理设施出水水质已达到标准要求的结论,从而推广该污水处理工艺。 相似文献
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Criegee intermediates are formed in the ozonolysis of alkenes and play an important role in indoor chemistry, notably as a source of OH radicals. Recent studies have shown that these Criegee intermediates react very quickly with NO2, SO2, and carbonyls, and in this study, steady‐state calculations are used to inspect the potential impact of these data on indoor chemistry. It is shown that these reactions could accelerate NO3 formation and SO2 removal in the indoor environment significantly. In addition, reaction between Criegee intermediates and halogenated carbonyls could provide a significant loss process indoors, where currently one does not exist. 相似文献
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The aim of this study is to evaluate the use of Spirogyra sp. green algae for wastewater treatment process in sewer. The effects of light and carbon sources were investigated on growth of the algae Spirogyra sp, removal of nitrate, nitrite, phosphate, chemical oxygen demand (COD) and pH changes. Samples 1 & 4 were grown in autotroph form, while samples 2 & 5 and 3 & 6 were grown in media containing 100 and 200 mg/L of glucose, respectively. Samples 1 up to 3 were grown in cycling light but samples 4 up to 6 were grown in continuous light. Results indicated that algal growth, levels of nitrites and pH and removal of nitrate and phosphate were increased in continuous illumination and carbon sources availability (100 and 200 mg/L of glucose). It can be recommended to apply Spirogyra sp. for wastewater treatment proces s in sewer collection system. 相似文献
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D. U. Park M. C. Friesen H. S. Roh Y. Y. Choi J. J. Ahn H. K. Lim S. K. Kim D. H. Koh H. J. Jung J. H. Lee H. K. Cheong S. Y. Lim J. H. Leem Y. H. Kim D. M. Paek 《Indoor air》2015,25(6):631-640
We conducted a comprehensive humidifier disinfectant exposure characterization for 374 subjects with lung disease who presumed their disease was related to humidifier disinfectant use (patient group) and for 303 of their family members (family group) for an ongoing epidemiological study. We visited the homes of the registered patients to investigate disinfectant use characteristics. Probability of exposure to disinfectants was determined from the questionnaire and supporting evidence from photographs demonstrating the use of humidifier disinfectant, disinfectant purchase receipts, any residual disinfectant, and the consistency of their statements. Exposure duration was estimated as cumulative disinfectant use hours from the questionnaire. Airborne disinfectant exposure intensity (μg/m3) was estimated based on the disinfectant volume (ml) and frequency added to the humidifier per day, disinfectant bulk level (μg/ml), the volume of the room (m3) with humidifier disinfectant, and the degree of ventilation. Overall, the distribution patterns of the intensity, duration, and cumulative exposure to humidifier disinfectants for the patient group were higher than those of the family group, especially for pregnant women and patients ≤6 years old. Further study is underway to evaluate the association between the disinfectant exposures estimated here with clinically diagnosed lung disease. 相似文献
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Cooking is recognized as an important source of particulate pollution in indoor and outdoor environments. We conducted more than 100 individual experiments to characterize the particulate and non‐methane organic gas emissions from various cooking processes, their reaction rates, and their secondary organic aerosol yields. We used this emission data to develop a box model, for simulating the cooking emission concentrations in a typical European home and the indoor gas‐phase reactions leading to secondary organic aerosol production. Our results suggest that about half of the indoor primary organic aerosol emission rates can be explained by cooking. Emission rates of larger and unsaturated aldehydes likely are dominated by cooking while the emission rates of terpenes are negligible. We found that cooking dominates the particulate and gas‐phase air pollution in non‐smoking European households exceeding 1000 μg m?3. While frying processes are the main driver of aldehyde emissions, terpenes are mostly emitted due to the use of condiments. The secondary aerosol production is negligible with around 2 μg m?3. Our results further show that ambient cooking organic aerosol concentrations can only be explained by super‐polluters like restaurants. The model offers a comprehensive framework for identifying the main parameters controlling indoor gas‐ and particle‐phase concentrations. 相似文献
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Qiyang He Aravindan Rajendran Jing Gan Hongjian Lin Craig A. Felt Bo Hu 《Water and Environment Journal》2019,33(4):508-517
Polyphosphate accumulating fungi was cultured to remove and recover the excessive phosphorus from dairy manure wastewater (DMW). The microbial treatment removed 83.9% of phosphorus in 20‐fold diluted DMW by the fungal biomass in 12 h. At the meantime, 33.6% of chemical oxygen demand, 46.5% of total nitrogen, and 89.4% of total ammonia nitrogen were removed as well. At seventh reuse batch, the cells could still remove 50.4% of phosphorus from the diluted wastewater. The average phosphorus removal efficiency in seven reuse batches was calculated as 62.1%, the nitrogen‐to‐phosphorus ratio in DMW increased from 3.6 : 1 to 6.3 : 1. With the treatment, DMW will be more suitable for farmland irrigation, with the better nutritional ratio to support crop growth, and it will help mitigate phosphorus pollution to water bodies caused by over‐applied phosphorus in the farmland. 相似文献
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《Structural Concrete》2018,19(2):483-488
The basic creep of concrete is the delayed deformation that occurs when concrete is subjected to loading without drying. This paper analyzes some findings from the literature. The derivatives of the compliance function J of basic creep tests with different loading ages t0 are compared. It has been observed that when dJ/dt is considered as a function of time t, the long‐term behavior is logarithmic with a uniform slope. This indicates that basic creep could be expressed as a logarithmic function in which the age of loading does not affect the final slope. In the recent fib Model Code 2010 (MC2010), basic creep is expressed exactly in this way. Using experimental data, the parameters of the model are calculated for each test and compared with the values proposed by MC2010. It is shown that MC2010 gives a fairly good set of values for the parameters whose accuracy could nevertheless be improved by adjusting these parameters to match experimental results. 相似文献
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Cumhur Avar 《Water and Environment Journal》2019,33(2):179-191
The Karasu River (Sinop, Turkey) was sampled for bacteriological analyses and investigation of antibiotic resistance at the bacterial isolates. In the study, the physical properties and numbers of total aerobic (TA), total coliform (TC), faecal coliform (FC), faecal Streptococci (FS) and Escherichia coli in water samples were investigated. E. coli strains were subjected to antibiotic susceptibility testing, antibiotic resistant genes, virulence genes and plasmid DNA analysis and fingerprinting techniques. The bacteriological analysis results showed that the difference between TA, TC, FC and FS numbers (p > 0.05) was not significant for a total of four stations. The Multiple Antibiotic Resistance Index (MARI) values of tested strains were found in range from 0.4 to 0.7. The antibiotic resistance genes of strains; tetA (33.9%), blacym‐2 (12.5%) and cat1 (16.7%) were screened by PCR method. Out of a total of 57 E. coli isolates, 11 E. coli strains were positive for the eae (19.6%) gene, representing atypical EPEC, whilst only one strain was positive for the eae and stx1 (1.7%) gene, representing STEC. Present study has shown that the aquatic environments can be reservoirs of pathogenic E. coli strains. The study also indicated that PCR‐based techniques might especially be helpful in the rapid identification of multidrug‐resistance analysis and virulence genes of strains. Karasu stream, which is important in Sinop province, Turkey, was investigated for the first time in this study in terms of a molecular microbiological perspective. 相似文献
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I. Bakolis J. Heinrich J. P. Zock D. Norbäck C. Svanes C. M. Chen S. Accordini G. Verlato M. Olivieri D. Jarvis 《Indoor air》2015,25(3):235-244
Exposure to house dust has been associated with asthma in adults, and this is commonly interpreted as a direct immunologic response to dust‐mite allergens in those who are IgE sensitized to house dust‐mite. Mattress house dust‐mite concentrations were measured in a population‐based sample of 2890 adults aged between 27 and 56 years living in 22 centers in 10 countries. Generalized linear mixed models were employed to explore the association of respiratory symptoms with house dust‐mite concentrations, adjusting for individual and household confounders. There was no overall association of respiratory outcomes with measured house dust‐mite concentrations, even in those who reported they had symptoms on exposure to dust and those who had physician‐diagnosed asthma. However, there was a positive association of high serum specific IgE levels to HDM (>3.5 kUA/l) with mattress house dust‐mite concentrations and a negative association of sensitization to cat with increasing house dust‐mite concentrations. In conclusion, there was no evidence that respiratory symptoms in adults were associated with exposure to house dust‐mite allergen in the mattress, but an association of house mite with strong sensitization was observed. 相似文献
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The aim of this study is to reduce the phosphate concentration in treated wastewater using a small amount of the reactive filter media, Filtralite P. Biologically treated wastewater was passed through a filter with 215 g of Filtralite P. In the laboratory, the phosphate removal efficiency was 51% at a flow speed of 0.87 m/h. Under real conditions, in an experimental stand filled with 0.5 m3 of Filtralite P, the phosphate removal efficiency was 85% and the removal efficiency of total suspended solids was 57% after a 5‐month period. The residual phosphate concentration in the filtrate from the experimental stand was 1 mg/L of PO4‐P after the 5‐month period. The experimental filtration plant was buried in the ground, and it did not freeze and worked well under winter conditions. The results of this study can be useful in the design and development of tertiary wastewater treatment plants in view of their sustainability potential. 相似文献
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《JAPAN ARCHITECTURAL REVIEW》2018,1(1):24-28
Project for a music school. Due to the superfluous consciousness of ambient noise and sound insulation, many music college facilities employ a style in which the exterior appears as a closed box and the lesson rooms are lined up along corridors in a jail‐cell‐like manner in the interior. In this project, we tried to break down such an image. By exposing the volume of the lesson rooms to the exterior, small, uneven, courtyard‐like spaces between neighboring rooms were created, and the volume of the building was broken down. As a result, the characteristic “porous” volume arrangement was born. For such adjustments, it was more appropriate to use a new computer‐based method of design that incorporates three‐dimensional feedback loops. The porous figures embed a sense of continuity and surprise, as if one were wandering around a village. This resulted in the creation of rich spaces and enhanced presence as a whole. 相似文献
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《JAPAN ARCHITECTURAL REVIEW》2018,1(1):96-108
There have been several studies on analyses using finely meshed finite‐element (FE) models to understand in detail the behaviors of buildings during severe earthquakes. The accuracy of such analyses is often validated by comparing the results to the corresponding full‐scale shaking‐table test. While this approach is highly successful in terms of accuracy, no studies have considered the effect of fractures of members. In this study, numerical analyses are conducted for a steel structure subjected to multiple series of excitations in a full‐scale shaking‐table test considering fractures. The structure is modeled with planar and solid finite elements, and the fracture is treated by the mandatory deletion of elements at the time at which the fracture is observed in the experiment. The results show that by considering the fracture of steel members with the deletion of elements, the history of input excitations, and the resulting damages, the behaviors can be simulated analytically with a much higher accuracy. 相似文献
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Accumulation of volatile organic compounds (VOCs) that migrate inside buildings from underlying contaminated soils and groundwater poses human health risks. VOCs intrusion into buildings driven only by diffusion was reproduced by a laboratory‐scale experiment. Effective diffusion coefficients and fluxes of a group of selected chlorinated solvents and BTEX through two types of isolation material – that is, concrete (anhydrite screed) and geo‐membrane – were estimated. The laboratory experiment indicated that the diffusive transfer of pollutants through sediments into indoor air of buildings cannot be prevented by building sealing material, but it could be attenuated to a certain degree by concrete and up to non‐detectable levels by the geo‐membrane. Effective diffusion coefficients through concrete and geo‐membrane ranged from 3.17 × 10?2 to 5.90 × 10?5 cm2/s and from 5.47 × 10?6 to 5.50 × 10?8 cm2/s, respectively. 相似文献
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This intervention study evaluated the effect of moisture‐damage repairs on the exposure and on the upper airway inflammatory responses of the occupants. The airborne microbial exposure was followed by quantitative PCR analyses of 13 microbial species in repeated long‐term indoor air samples before (N = 26) and after (N = 28) repairs of the school building. Airborne particulate matter was collected similarly from the same premises (before N = 25, after N = 34) for determination of nitric oxide (NO), tumor necrosis factor α (TNFα), and interleukin‐6 (IL‐6), measured in the cell culture medium of mouse macrophages. NO, TNFα, IL‐6, and IL‐4 were also analyzed in the nasal lavage (NAL) samples of the occupants (N = 13) to characterize their upper airway inflammatory responses during the exposure and after its cessation. After the repairs, concentrations of the measured airborne microbes decreased, the difference being significant for six of 13 species. After renovation, airborne particulate matter also caused significantly lower production of IL‐6 and TNF‐α in mouse macrophages than the material collected before the renovation. The concentration of IL‐4 in the NAL samples was significantly lower after the renovation. These results show that the inflammatory potential of the airborne material decreases after intensive repair of the moisture damage. 相似文献
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J. Rosbach E. Krop M. Vonk J. van Ginkel C. Meliefste S. de Wind U. Gehring B. Brunekreef 《Indoor air》2016,26(4):538-545
Inadequate ventilation of classrooms may lead to increased concentrations of pollutants generated indoors in schools. The FRESH study, on the effects of increased classroom ventilation on indoor air quality, was performed in 18 naturally ventilated classrooms of 17 primary schools in the Netherlands during the heating seasons of 2010–2012. In 12 classrooms, ventilation was increased to targeted CO2 concentrations of 800 or 1200 ppm, using a temporary CO2 controlled mechanical ventilation system. Six classrooms were included as controls. In each classroom, data on endotoxin, β(1,3)‐glucans, and particles with diameters of <10 μm (PM10) and <2.5 μm (PM2.5) and nitrogen dioxide (NO2) were collected during three consecutive weeks. Associations between the intervention and these measured indoor air pollution levels were assessed using mixed models, with random classroom effects. The intervention lowered endotoxin and β(1,3)‐glucan levels and PM10 concentrations significantly. PM10 for instance was reduced by 25 μg/m³ (95% confidence interval 13–38 μg/m³) from 54 μg/m³ at maximum ventilation rate. No significant differences were found between the two ventilation settings. Concentrations of PM2.5 and NO2 were not affected by the intervention. Our results provide evidence that increasing classroom ventilation is effective in decreasing the concentrations of some indoor‐generated pollutants. 相似文献
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This work uses an in situ filter test method to measure the size‐resolved removal efficiency of indoor‐generated ultrafine particles (approximately 7–100 nm) for six new commercially available filters installed in a recirculating heating, ventilating, and air‐conditioning (HVAC) system in an unoccupied test house. The fibrous HVAC filters were previously rated by the manufacturers according to ASHRAE Standard 52.2 and ranged from shallow (2.5 cm) fiberglass panel filters (MERV 4) to deep‐bed (12.7 cm) electrostatically charged synthetic media filters (MERV 16). Measured removal efficiency ranged from 0 to 10% for most ultrafine particles (UFP) sizes with the lowest rated filters (MERV 4 and 6) to 60–80% for most UFP sizes with the highest rated filter (MERV 16). The deeper bed filters generally achieved higher removal efficiencies than the panel filters, while maintaining a low pressure drop and higher airflow rate in the operating HVAC system. Assuming constant efficiency, a modeling effort using these measured values for new filters and other inputs from real buildings shows that MERV 13–16 filters could reduce the indoor proportion of outdoor UFPs (in the absence of indoor sources) by as much as a factor of 2–3 in a typical single‐family residence relative to the lowest efficiency filters, depending in part on particle size. 相似文献