This paper presents the behavior of the bridge approach structure, which was repaired by using expended polystyrene foam as a replacement fill on Soft Bangkok Clay. The bridge approach began ...construction 20 years before a project. The settlement from consolidation and ground subsidence was high at 1.35 m at the end of the bearing unit before remedial measures. The settlement of the bridge approach structure before the project began and after completion was presented. After remedial measures, settlement rates tend to decrease after 100 days. The behavior of the bridge approach structure was modeled by using finite elements. The time-dependent strain of EPS geofoam can be predicted by an empirical equation by optimizing method. 3-dimensional finite element analysis can predict the overall behavior of bridge approach structure using EPS as fill material with time-dependent stiffness. The prediction before and after remedial measurement of the embankment was using similar model parameters. Important considerations to simulate EPS embankment behavior were long-term stiffness degradation of EPS block and ground subsidence.
Microbial extracellular polymeric substances (EPS) have been shown to alter soil moisture retention and to improve seedling survival and plant growth at the bulk scale. The mechanisms of EPS-mediated ...water retention include reversible swelling of the cross-linked polymer matrix and the promotion of an aggregated soil structure. However, the effects of EPS on water retention have never been directly observed at the pore scale. Here, emulated soil micromodels were developed to directly observe the effects of physical, chemical, and biological factors on pore-scale water retention. In this demonstration, a pseudo-2D pore structure was created to represent physical features of a fine sandy loam. Replicate micromodels were initially saturated with suspensions of different soil bacteria, and pore-scale air infiltration was directly imaged over time. External evaporativity was held constant through the use of a custom constant-humidity environmental chamber. Micromodels filled with suspensions of highly mucoid Sinorhizobium meliloti retained moisture about twice as long as physically identical micromodels filled with suspensions of non-mucoid S. meliloti. Relative drying rates in six replicate experiments ranged from 1.1 to 2.5 times slower for mucoid suspensions. Patterns of air infiltration were similar but not identical across replicates. The results suggest that pore fluid EPS and micromodel geometry act together to limit evaporation at pore throats. Advantages of the micromodel approach include direct observation of pore-scale dynamic process, and the ability to systematically replicate complex physical structures. These abilities will enable users to screen benefits from different structures and from microbial compositions, and build predictive understanding of the overall function of microbe-habitat systems.
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•Emulated soil micromodels allow dynamic visualization of pore-scale processes.•Physically-identical micromodels were filled with different bacterial suspensions.•Water evaporated more slowly from micromodels filled with EPS+ bacteria.•The ratio of drying rates for EPS+ and EPS-suspensions in emulated soil micromodels was 1:2.•EPS and soil structure have synergistic effects on soil water retention.
The EUMETSAT Polar System-Second Generation (EPS-SG) mission will be deployed in the 2019-2020 timeframe in order to ensure continuity of the EPS observation missions, currently realized with the ...MetOp satellite series, to support operational meteorology and oceanography; in particular, for numerical weather prediction (NWP), climate monitoring and to develop new environmental services. The scatterometer (SCA) is one of the high-priority payload instruments to provide vector surface wind observations over the ocean, which constitute an important input to NWP, as well as valuable information for tracking of extreme weather events. The EPS-SG SCA shall offer observations with higher spatial resolution than those provided by ASCAT on board MetOp, operating at C-band and with VV polarization. Furthermore, addition of HH or VH polarization is considered as an option. Phase 0 industrial studies, addressing the complete system design, have taken place from 2008 to 2009. Two study teams, constituted, respectively by Astrium SAS and Thales Alenia Space Italy, have performed comprehensive analyses of the system requirements, tradeoffs of various concepts, and preliminary design of the selected concepts, which included both the single and dual satellite configurations. Three distinct SCA concepts were initially considered for tradeoffs: 1) fixed fan-beam concept with six fixed antennas; 2) rotating fan-beam concept with a single rotating antenna; 3) rotating pencil-beam concept. The first two concepts were further elaborated during Phase 0, and the fixed fan-beam concept was selected as baseline after a final tradeoff. For supporting the above instrument concept elaboration by the industrial study teams during Phase 0, the Royal Dutch Meteorological Institute (KNMI) has developed retrieval algorithms tailored to those concepts, derived from the ASCAT operational algorithms, and specific metrics to characterize the associated retrieval performance. The metrics used for the present performance assessment were: 1) wind vector root-mean-square error; 2) ambiguity susceptibility; and 3) wind biases. The end-to-end performance evaluation makes use of an ensemble of wind fields as input having the mean climatology distribution, generates the output wind-fields which account for the measurement system imperfections and geophysical noise, and computes the performance metrics for comparisons. This paper describes the three SCA concepts as analysed in Phase 0 studies by the industrial study teams and summarizes the technical tradeoffs carried out. The performance metrics are described and applied to two of the concepts in order to compare their respective merits. It is shown that both concepts are able to meet the observation requirements of EPS-SG.
Aerobic granular sludge membrane bioreactor (AGMBR) has been widely studied in recent years owing to its excellent wastewater treatment performance and antifouling property. However, the mechanisms ...of membrane fouling are lack of systematic and comprehensive elaboration. Here, the mechanisms of and distinctions between fouling of polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) membranes in an AGMBR were investigated. The nutrient-removal performances were excellent in both cases. Compared with the PVDF membrane, the PTFE membrane exhibited a better antifouling property, with a lower transmembrane-pressure growth rate (0.407 kPa/d). Moreover, the PTFE membrane had lower contents of extracellular polymeric substances (EPS) and soluble microbial products, probably owing to the lower relative abundance of the class Gammaproteobacteria, which is the producer of EPS. Additionally, a thermomechanical analysis revealed that the energy barrier of the PTFE membrane–foulant (71.20 kT) was higher than that of the PVDF membrane–foulant (51.77 kT), confirming that the PTFE membrane had better antifouling performance. Overall, this study enhances the understanding of mechanisms of membrane fouling in an AGMBR and is conducive motivate large-scale applications of AGMBR technology.
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•COD and nutrient removal were excellent for PTFE- and PVDF-based AGMBRs.•PTFE membrane exhibited superior antifouling property compared to PVDF membrane.•Protein in the fractions of EPS and SMP was a main contributor to membrane fouling.•Interactions of foulant-PVDF were stronger than the interactions of foulant-PTFE.•Membrane fouling mechanisms were proposed and future prospects were further assessed.
•We studied effect of expanded vermiculite and waste expanded polystyrene on mortar properties.•Both vermiculite and waste expanded polystyrene decreases mechanical properties of mortar.•Both ...vermiculite and waste expanded decreases thermal conductivity of mortar.•Vermiculite and polystyrene do not present a strong bond with cement paste.
Mortar is one of the most important component of cement based composites. Aggregates have also a significant effect on properties of mortars. Generally natural and crushed fine aggregates are used in mortar production for different applications and aims, one of which is energy conservation in buildings and facilities. Vermiculite and waste polystyrene as aggregates in mortar presents an opportunity to reduce the unit weight and the thermal conductivity coefficient that is important for thermal isolation. Five vermiculite+polystyrene/cement ratios, 3, 4, 5, 6 and 7, by volume were used to produce mortars. In each ratio, 100% vermiculite and 100% polystyrene by volume were studied in addition to their combination at 25%, 50% and 75%. Totally, 25 mortars with 4 × 4 × 16 cm were fabricated to investigate physical, mechanical and thermal properties. It was observed that the usage of vermiculite and polystyrene in mortar makes possible the production of mortars with unit weight between 393 and 946 kg/m3 due to very high porosity up to 67.2%. This is also very important in terms of thermal conductivity which decreases up to 0.09 W/mK. Compressive strength presents a variation between 0.57 and 5.89 MPa. Mortars with vermiculite and polystyrene can be used as a good insulation material where needed.
Activated sludge (AS) process has been widely utilized for municipal sewage and industrial wastewater treatment. Zoolgoea and its related floc-forming bacteria are required for formation of AS flocs ...which is the key to gravitational effluent-and-sludge separation and AS recycling. However, little is known about the genetics, biochemistry and physiology of Zoogloea and its related bacteria. This report deals with the comparative genomic analyses on two Zoogloea resiniphila draft genomes and the closely related proteobacterial species commonly found in AS. In particular, the metabolic processes involved in removal of organic matters, nitrogen and phosphorus were analyzed. Furthermore, it is revealed that a large gene cluster, encoding eight glycosyltransferases and other proteins involved in biosynthesis and export of extracellular polysaccharides (EPS), was required for floc formation. One of the two asparagine synthase paralogues, associated with this EPS biosynthesis gene cluster, was required for floc formation in Zoogloea. Similar EPS biosynthesis gene cluster(s) were identified in the genome of other AS proteobacteria including polyphosphate-accumulating Candidatus Accumulibacter phosphatis (CAP) and nitrifying Nitrosopira and Nitrosomonas bacteria, but the gene composition varies interspecifically and intraspecifically. Our results indicate that floc formation of desired AS bacteria, including CAP strains, facilitate their recruitment into AS and gradual enrichment via repeated AS settling and recycling processes.
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•Analyses of two Zoogloea resiniphila genomes revealed the nitrogen and phosphorus metabolisms.•A large gene cluster required for floc formation was experimentally identified.•Two asparagine synthase paralogues within this gene cluster were required for floc formation.•Similar gene cluster(s) were found in other crucial activated sludge bacteria.•The exopolysaccharide biosynthesis genes vary intraspecifically and interspecifically.
•Five typical CRB were isolated from RO membranes in pilot and full-scale systems.•Fouling potential of all the strains increased monotonically with chlorine resistance.•EPS was decisive factor to ...chlorine resistance and fouling potential of CRB.•CFD simulation demonstrated the contribution of EPS to filtration resistance.•Membrane adhesion potential and fouling potential of CRB were relatively independent.
Chlorine disinfection is often used as a pretreatment technology to control biofouling of reverse osmosis (RO) membranes. However, previous studies showed that biofouling of the RO system was aggravated after chlorine disinfection. Chlorine-resistant bacteria (CRB) were presumed to be closely related to the aggravation of fouling caused by chlorine disinfection. In order to analyze the membrane fouling mechanisms of CRB, 5 CRB strains were isolated from the surface of fouled RO membranes for wastewater reclamation, and 3 reference bacterial strains, Sphingopyxis soli BM1–1, Pseudomonas aeruginosa PAO1 and Escherichia coli CGMCC1.3373, were selected for comparative study. The chlorine resistance, membrane fouling potential, secretion and adhesion characteristics of these strains were evaluated. Among these isolated strains, 3 strains showed much higher chlorine resistance than PAO1 under the condition of 0.5, 2, 5 mg/L-Cl2, especially Bacillus CR19 and Bacillus CR2. Furthermore, a significant positive correlation was found between membrane fouling potential and chlorine resistance of all the strains in this study. The membrane fouling potential of the above 8 strains increased monotonically with the increase of chlorine resistance (under the condition of 0.5 mg/L-Cl2). Serious fouling caused by extracellular substances was observed in biofouling layers of the strains with high chlorine resistance, which lead to more severe flux decline. Extracellular polymeric substances (EPS) amount per cell was found to be the main factor related to the chlorine resistance as well as the fouling potential. Computational fluid dynamics (CFD) simulation was used to demonstrate the filtration resistance induced by the secretion of EPS. However, CRB with higher EPS amount may not show higher membrane adhesion potential, and thus may not be the dominant strain on the RO membranes before chlorine disinfection. These CRB with high fouling potential but low membrane adhesion potential, such as Bacillus CR19 and Bacillus CR2, may become the dominant bacteria on the membrane surface after chlorine disinfection and thus aggravate membrane fouling significantly.
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Pavement structures constructed on the expansive soil subgrade experience a higher upward pressure compared to any other subgrade material. The upward pressure is caused due to high swelling and ...shrinkage characteristics of expansive clay soil. The present study has investigated and identified the mechanisms by which a remolded expansive soil can be modified to reduce the upward pressure and swelling (heave). To achieve this, a lightweight, environmentally friendly, and high pressure resistive expanded polystyrene (EPS) granules have been used with expansive soil s from three different locations of Madhya Pradesh state, India. The study has been performed to understand the swelling and strength characteristics of soil with and without the use of EPS (density = 21.6 kg/m3) as per ASTM specifications. The chemical and microstructural components of the expansive soil were investigated using autotuned total reflectance Fourier transform infrared (ATR-FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). Several laboratory experiments, including optimum moisture content, maximum dry unit weight, grain-size distribution, liquid limit, plastic limit, shrinkage limit, free swell index, unconfined compressive strength, and pressure swelling tests were carried out on the statically compacted expansive clay soil specimen with and without EPS (0.25%, 0.50%, 1.00%). The maximum addition of EPS was considered as 1% as the very high expansion was observed, and beyond this, further addition of EPS was not feasible. The results show that the swelling pressure, expansion percentage, and time rate of swell decrease, whereas the unconfined compressive strength (UCS) increases with the addition of EPS. The inclusion of EPS in expansive clay soil exponentially reduced the heave and the upward pressure, whereas the maximum UCS was observed at 0.5%.
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•COD removal rate could reach 92.1% with initial COD concentration of 960 mg/L.•Acclimation of the microorganism led to high removal efficiency of nitrogen.•AMS activity and protein ...content in EPS could be fit by quadratic function model.•A peak was identified as active substances in 3-D EEM diagram.•SDBS inhibited the transport and metabolisms of amino acids, carbohydrate and lipids.
Sequential vertical flow trickling filter and horizontal flow multi-soil-layering bioreactor were investigated for the treatment of decentralized domestic wastewater at various concentrations of sodium dodecyl benzene sulfonate (SDBS). Results have shown that the removal rate of COD could reach 92.1% at initial COD concentration of 960 mg/L (800 mg/L was provided by SDBS). NH4+-N concentration could be reduced from 52.4 to 9.71 mg/L without aeration. Besides, a quadratic function model was fit to describe the relationship between the relative activity of amylase and the protein content in extracellular polymer substance. SDBS could inhibit the transport and metabolisms of amino acids, lipids and carbohydrates in biofilms. The analysis of three-dimensional fluorescence diagram indicated that the peak in excitation/emission wavelengths = 310–340/370–430 nm was the characteristic peaks of some active substances such as some enzymes in EPS. Only Microbacterium could totally offset the toxicity of SDBS degradation products.
Disease-suppressive soils are ecosystems in which plants suffer less from root infections due to the activities of specific microbial consortia. The characteristics of soils suppressive to specific ...fungal root pathogens are comparable to those of adaptive immunity in animals, as reported by Raaijmakers and Mazzola (Science 352:1392-3, 2016), but the mechanisms and microbial species involved in the soil suppressiveness are largely unknown. Previous taxonomic and metatranscriptome analyses of a soil suppressive to the fungal root pathogen Rhizoctonia solani revealed that members of the Burkholderiaceae family were more abundant and more active in suppressive than in non-suppressive soils. Here, isolation, phylogeny, and soil bioassays revealed a significant disease-suppressive activity for representative isolates of Burkholderia pyrrocinia, Paraburkholderia caledonica, P. graminis, P. hospita, and P. terricola. In vitro antifungal activity was only observed for P. graminis. Comparative genomics and metabolite profiling further showed that the antifungal activity of P. graminis PHS1 was associated with the production of sulfurous volatile compounds encoded by genes not found in the other four genera. Site-directed mutagenesis of two of these genes, encoding a dimethyl sulfoxide reductase and a cysteine desulfurase, resulted in a loss of antifungal activity both in vitro and in situ. These results indicate that specific members of the Burkholderiaceae family contribute to soil suppressiveness via the production of sulfurous volatile compounds.
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