Abstract:The municipal solid waste landfill is the main place to hold the waste soil and slag.Due to the difference in the filling material and the compaction method, it is of practical significance to study the influence of initial seepage field on the calculation of rainfall infiltration characteristics and stability of the municipal solid waste landfill.Therefore, taking the municipal solid waste landfill in Bujiuwo, Shenzhen as the research object, a numerical calculation model was established based on the unsaturated seepage principle and unsaturated soil strength theory.The calculation schemes of different initial seepage conditions and rainfall intensities are designed. Then the seepage characteristics and the variation law of safety factor of the slope under rainfall are revealed. The results show that the initial seepage field and rainfall intensity have significant influence on the rainfall infiltration characteristics and therefore stability of the municipal solid waste landfill. The peak value of vertical velocity and the increase rate of pore water pressure are positively correlated with the initial matrix suction. When the rainfall intensity is 3.5 mm/h, the saturation time of monitoring point 1 is 10.9, 20.2, 25.5 h and the corresponding initial matrix suction equals to -25, -50, -75 kPa, respectively.Rainfall intensity,velocity of flow and volume water content are positively correlated with pore water pressure in vertical direction.When the initial matrix suction is -25 kPa and the rainfall intensity is 3.5 mm/h, the safety factor of the waste dump slope decreases obviously, and necessary engineering measures should be taken.

Abstract:Currently, the theoretical studies on pile foundation deformation induced by adjacent tunneling are generally based on one parameter Winkler foundation model or two parameters Pasternak foundation model,rare studies have been considering in three parameters Kerr foundation model with greater computational accuracy. Based on Kerr foundation model, the governing equation of horizontal deflection of passive pile is established. Combining with the horizontal additional stress imposed by shield excavation, the analytical expression of the mathematical matrix of tunneling on the adjacent pile foundation is obtained using the difference method, and then the semi-analytical solution of the horizontal displacement of the passive pile is obtained.Through verification of two engineering cases, the Kerr foundation model is more consistent with the measured data than the Winkler and Pasternak foundation model.The results of parameter analysis show that the horizontal displacement increases with the increase of tunnel diameter. With increase of the passive pile diameter,horizontal displacement of the passive pile decreases.Passive pile displacement decreases with the increase of the horizontal distance or vertical distance between the passive pile and tunneling for the tunnel excavation under the pile bottom.

Abstract:In view of the wide application of double row piles under complex surrounding environment and the complex mechanical behavior of double row piles, based on the principle of similar material model test, a laboratory test model for double row piles of deep foundation pit was built. The bearing characteristics of double-row piles under four kinds of working conditions, including inter-pile soil, passive zone at pile side, soil at pile end and un-reinforcement, were analyzed and studied. The results show that the maximum positive and negative bending moments of front row piles are 32.4% and 38.5% lower than those without reinforcement measures, while the maximum positive and negative bending moments of back row piles are 76.8% and 55.4% lower respectively, while the horizontal displacement of top piles is 57.5% lower. The bearing capacity of double-row piles can be effectively improved by soil reinforcement between piles, passive zone at pile side and soil reinforcement at pile end, but the effect of soil reinforcement between piles is the most significant. The main reason is that soil reinforcement between piles can significantly improve the deformation modulus of soil between piles, thereby enhancing the overall flexural rigidity of the cross-section of pile-soil composite bearing body, then improving the bearing capacity of double-row piles.

Abstract:Under the humidification condition, the strength parameters of the expansive soil will decrease and the expansion force will be generated. Under the combined action of the two, the stability of the surrounding rock of the expansive soil tunnel will be seriously reduced. Therefore, it is necessary to study the deformation and lining stress of the surrounding rock of expansive soil tunnel under the condition of humidification. In this paper, laboratory tests and numerical simulations are used to study the stability of the surrounding rock of the expansive soil tunnel. First, the shear experiment is carried out on the remolded expansive soil with different water contents, and the fitting relationship between friction angle and cohesion and water content is obtained. Then, the ABAQUS finite element software is used to simulate and analyze the excavation process of tunneling in the expansive soil.The temperature field module is used to simulate the humidification and expansion of the surrounding rock of the tunnel, and the stress and displacement of the tunnel before and after swelling were obtained. At the same time, the orthogonal experiment was designed to analyze the influence of various factors on the stability of the shallow buried tunnel in the expansive soil. Results show that after humidification, the stress value at the arch waist of the surrounding rock increases significantly, the stress value at the vault and arch bottom decreases.The longitudinal displacement value at the lining arch bottom increases, and the longitudinal displacement value at the arch top decreases. By designing orthogonal experiments and using range and variance analysis, the most influential factor on stability of the surrounding rock of the expansive soil shallow tunnel is the humidification strength, followed by the over-span ratio, the swelling thickness and the swelling coefficient.

Abstract:In order to study the influence of fiber content and fiber length on unconfined compressive strength characteristics of fiber reinforced cemented soil which was made of short-cut basalt fiber, cement and soil taken from Changchun, a series of unconfined compressive strength tests were carried out. The results show that the strength of basalt fiber reinforced cemented soil presents a generally convex curve with increase of fiber length, and the curve finally tends to be the strength of cemented soil without fiber under the same fiber contents. It shows that the fiber distribution uniformity and fiber distribution density have great influence on the strength. The strength of basalt fiber reinforced cemented soil presents a wavy curve with increase of fiber content under the same fiber length, the second wave peak value is less than the first wave peak value and the curve finally tends to a constant value. In practical engineering application, the fiber content of the first wave peak can be used in cemented soil reinforcement to achieve the expected reinforcement effect and reduce the project cost. Meanwhile, the impact of uneven mixing on the strength of cemented soil should be fully considered, and excessively long fibers should not be used. On the one hand, long fibers are easy to produce cluster phenomenon; on the other hand, they are easy to be attached to the stirring apparatus.

Abstract:Taking undisturbed loess as the research object, the effects of freeze-thaw cycles on the physical and mechanical properties of undisturbed loess were studied through plane strain tests. The results show that: as the freeze-thaw cycle increases, the surface damage of the soil sample becomes more severe; under the conditions of the same moisture content and consolidation confining pressure, the partial stress-axial strain of the undisturbed loess (σ₁-σ₃)-ε₁ curve gradually decreases with the increase of the number of freeze-thaw cycles, and the degradation of the original loess (σ₁-σ₃)-ε₁ curve by the freeze-thaw cycle increases with the increase of the water content and with the consolidation. As the confining pressure increases, it decreases. According to the Mohr-Coulomb strength criterion, it is concluded that both the cohesive force and the internal friction angle show a similar linear decrease with the increased water content, and the cohesive decreases exponentially with the increase of the freeze-thaw cycle, and the internal friction angle decreases slightly with the increase of the freeze-thaw cycle, but the fluctuation within 3°. Based on the rationality of the test data, a degradation model of the undisturbed loess along with the freeze-thaw cycle is fitted, which can be used to well describe the degradation law of the undisturbed loess with the freeze-thaw cycle after the test validation.

Abstract:The explicit dynamic FEM-based code AUTODYN was used to study the effect and law of barrier holes on blast-induced stress wave propagation and attenuation, as well as the dynamic responses of adjacent underground opening and ground. First of all, compared with the results of blasting model test, the effectiveness and accuracy of AUTODYN to simulate the process of underground opening explosion and stress wave propagation are verified. Then, the effects of different barrier hole parameters on peak particle velocity (PPV) of the adjacent chamber and ground, and the vibration-isolation rates of measuring points before and after barrier hole screen were analyzed through the numerical simulation method， and the pattem of varying barrier hole parameters on vibration reduction effect is revealed. The simulated results indicated that barrier hole diameter, hole spacing, the distance between hole and explosion center, and hole row have effects on PPVs of adjacent underground opening and ground and the vibration-isolation rates of measuring points before and after barrier hole screen. With increasing barrier hole diameter and barrier hole row, or decreasing barrier hole spacing and distance between barrier hole and explosion center, PPVs of the adjacent underground opening and ground show a decreasing trend and vibration-isolation rates of measuring points before and after barrier hole screen show a great increasing trend, that is, the vibration reduction effect of barrier hole is enhanced. In addition, with change of barrier hole parameters, the vibration-isolation rates of the measuring points before and after barrier hole and the measuring points before and after rock mass between barrier holes show significant differences. The former is obviously larger than the latter, and the difference between the two increases first and then decreases with increase of hole diameter, and decreases rapidly with increase of the distance between hole and explosion center. But it doesn't change significantly with the increase of barrier hole row. The change of barrier hole spacing could affect the relative position of the measuring point and the barrier hole, thus determining the vibration-isolation rate of the measuring point.

Abstract:In recent years, land subsidence and collapse accidents occur frequently in urban areas, and the leakage of pipelines is one of the main factors leading to such accidents. When the pipeline breaks and the fluid in the pipeline is of gravity flow, the soil around the pipeline will be eroded into the pipeline, which will eventually lead to settlement or ground collapse. To explore the migration process of soil under action of water flow during pipeline leakage, the authors propose a Fluent and PFC combined computational numerical simulation method based on computational fluid dynamics (CFD) and discrete element (DEM) theory. This method mainly uses particle flow program (PFC3D) to model the formation. The FLUENT module in the ANASYS is used to calculate the groundwater flow field, which will be imported into the PFC3D to conduct the joint computation. Using this flow-solid coupling method, this paper conducts a numerical modeling of the stratigraphic situation in the northern part of Shanghai, and this domain is the upper 1.5 m thick clay layer and the lower 2.5 m thick sandy soil layer. Then the influences of the crack size and the crack position of underground pipeline on the development of underground cavity area caused by pipeline leakage and the ground collapse are explored. The numerical simulation results show that the larger the crack size is, the greater the soil loss is, the wider the soil disturbance area is in sandy strata, and the surface settlement will not demonstrate large value due to the existence of the upper clay soil layer. The soil disturbance area starts from the crack location and continues to expand. The higher it extends, the larger the disturbance area is, and the disturbance area is much larger than the cavity area.

Abstract:In order to improve the accuracy of Portable Falling Weight Deflectometer (PFWD) in measuring the resilient modulus of high liquid limit soil subgrade, the influence of deformation lags effect on the back-calculation result was considered and a new method for back-calculation of the modulus was proposed based on Kelvin viscoelastic model and quasi-static dynamic analysis method. The effectiveness of the new method is verified by field tests. The results show that the measured modulus of the lower embankment filled with high liquid limit soil is lower and the peak vertical displacement of the top surface of the embankment obviously lags behind the peak value of the load under the impact load of PFWD. Furthermore, the load-displacement curve is significantly nonlinear. In addition, the conventional method based on linear elastic model makes the back-calculated modulus much larger than the measured modulus. The average relative error between back-calculated and the measured modulus reaches up to 52.5%. However, the new method can better reflect the deformation lag characteristics under impact load. The average relative error between them is only 9.2%. With increase of subgrade modulus, the lag effect of the deformation is not significant. The back-calculating results via conventional and new methods are similar, but the accuracy of the new method is higher.

Abstract:The uncertainty problem of geotechnical engineering is one of the research hotspots in recent years. The slope reliability analysis is a foundation.According to the principle of unscented transformation,the analysis methods and implementation steps of slope reliability are given.Based on the existing examples of the homogeneous slope and the layered slope, the rationality and applicability of slope reliability analysis method based on unscented transformation are discussed. The results show that the reliability analysis of slope based on the unscented transformation does not depend on the distribution types of variables,and this method is convenient in application and efficient in calculation. When the slope with higher reliabilityis analyzed,a large relative error is caused because the value of failure probability is small.Therefore, the method should be chosen carefully.But for the slope with lower reliability (higher failure probability,P_f>7%) is more concerned in the engineering,the method of slope reliability analysis has better applicability than the Monte Carlo method. Mean while,the relative error of this method is approximately within 5% and the error fluctuation caused by the change of variable correlation coefficient is small.

Abstract:Cold-formed thin-walled steel concrete composite floor is fabricated with profiled steel sheet-concrete composite slab at the top and cold formed steel built-up beam at the bottom.When fire occurs on the lower side of the floor, the cold-formed thin-walled steel beams and profiled steel sheets will be directly exposed to fire. In order to improve the fire resistance of the floor, a new type cold-formed thin-walled steel concrete composite floor is proposed by fixing fireproof board on the lower flange of cold-formed steel beams to form a fire protection layer. However, the temperature distribution, deflection and fire resistance time of the new floor will change after adding fire protection, so fire resistance performance of the new floor needs to be studied. A simplified three-dimensional finite element model is established to analyze the influence of concrete slab thickness, beam height, load ratio, fire protection on the fire resistance of the new floor. It is found that the temperature at the same height of the steel beam is basically similar along the span direction but not uniform along the height direction when the direction of the profiled steel sheet is vertical to the steel beam.Increasing the thickness of concrete slab appropriately has little effect on fire resistance.In addition,the critical temperature of the hot flange with different cross-section sizes under the load ratio of 0.2~0.5 and the time-temperature curves of the hot flange with different fire protection are obtained, which can be used to estimate the fire-resistance time of the new floor.

Abstract:Due to the complexity of the experiment, the research on the dynamic mechanical properties of concrete under complex stress conditions after high temperature has been less, but in building fires and defense and military protection projects, concrete structures are mostly under the combined action of multiaxial stress and impact loads. In order to study the biaxial dynamic mechanical properties of concrete after high temperature under combined static and dynamic loads, a true triaxial static and dynamic comprehensive loading experimental system is used. A true triaxial test machine is used to apply biaxial axial pressure in advance, and the SHPB test device is used to apply dynamic load to concrete specimens after atmospheric temperature (25 ℃) and 200, 400, 600, 800 ℃ high-temperature, respectively, finding the regularity of the dynamic mechanical properties of concrete under the biaxial stress state after high temperature. The test results show that: temperature change is the main influencing factor of the biaxial dynamic mechanical properties of concrete after high temperature, and strain rate change is the secondary factor; when the temperature is higher than 400 ℃, the stress-strain relationship curve shows a yielding platform, and the concrete toughness is significantly improved than under low temperature. 200 ℃ is the transition temperature of biaxial dynamic compressive strength of concrete after high temperature. When the temperature continues to increase, the biaxial dynamic compressive strength decreases significantly.

Abstract:The special T-shaped composite columns with concrete-filled square steel tubulars have good mechanical properties. Taking the length, eccentricity and eccentricity direction of the specimen as the test parameters, nine specimens with different slenderness ratio are designed for eccentric compression test. By observing the failure mode of the specimen, the load-strain curve and load-deflection curve are obtained, and the influence of each parameter on the eccentric compression performance of the specimen is analyzed. The test results show that the strength of 600 mm long specimens is damaged. The specimens with lengths of 1 500, 1 800 mm are broken by bending instability; the longer the specimen length is, the more obvious the bending failure characteristics are; the larger the eccentricity is, the lower the eccentric bearing capacity is; the eccentricity direction has a relatively small impact on the eccentric compression performance. It is found that compared with the calculation results of relevant specifications, the results calculated by DBJ / T 13-51-2010 are in good agreement with the test results. The ductility of special T-shaped composite columns with concrete-filled square steel tubulars is well, the square steel tubes can work together, and the eccentric compression performance is good.

Abstract:The steel-basalt fiber composite bar (SFCB) has the advantages of the ductility of steel bar and the corrosion resistance of basalt fiber, and has significant secondary stiffness as well. However, SFCB's elasticity modulus is lower than that of the steel bar. The application of SFCBs as longitudinal reinforcement bars enables the flexural properties of concrete members to present secondary stiffness, but the shear capacity of the members will be reduced, compared with that of steel reinforced concrete beams. In this paper,four-point loading experiment of the beams longitudinal reinforced with SFCBs were carried out, taking the following variables of the specimens into consideration: the type of longitudinal reinforcement, and the shear span ratio. The influences of the above variables on the shear failure modes, the development of diabonal cracks, and shear force capacity of the above concrete beams were analyzed and summarized in detail.The research revealed the following three main results: the failure modes of the SFCB beam were mainly described as diagonal-compression failure,shear-compression failure and atypical shear-compression failure; the shear force capacity of SFCB beams was lower than that of steel reinforced beams; the diagonal cracks of SFCB reinforced beams were wider than those of steel reinforced beams. Based on the truss arch model, the shear force capacity formula of SFCB beams is derived.The calculating results of the formula agree well with the experimental ones with fairly applicability and safety.

Abstract:In order to improve the performance deficiency of cement-based materials such as low tensile strength, poor toughness and easy cracking, the basic mechanical properties of cement-based materials reinforced by micron grade CaCO₃ whisker and centimeter-grade short AR-glass fiber were studied by testing. The results show that the mechanical properties of reinforced cement-based material can be improved by the proper addition of CaCO₃ whisker and/or AR-glass fiber, and the improvement degree is related to the content and length of fibers. For the cement-based materials compound reinforced with CaCO₃ whisker and AR-glass fiber, the improvement of mechanical properties of the cement-based materials can be explained that the reinforcing roles of the two kinds of fibers can be played at the micro and macro structural levels respectively, and the flexural and tensile strength of reinforced cement-based materials can be increased by up to 60% and 80% compared with that of non-reinforced cement-based materials.

Abstract:Due to the high technicality of the multi-axial test equipment, the dynamic research of concrete under complex stress condition is relatively less. In order to study the dynamic compressive properties of concrete under biaxial compression, the impact compression tests of concrete cube specimens under five types of biaxial compression conditions were carried out by using the true triaxial static and dynamic comprehensive loading test system. The effects of biaxial compression on the dynamic response of concrete are analyzed from the aspects of stress-strain curve characteristics, strength characteristics and deformation characteristics. The results show that: under biaxial compression, the concrete exhibits typical brittle failure when subjected to impact load, and there is no obvious compaction stage in the initial stage of the stress-strain curve; when the spindle pressure ratio is fixed, with the increase of the unilateral pressure ratio, the dynamic compressive strength of concrete shows a trend of first increasing and then decreasing, and the peak strain and average strain rate show a trend of first decreasing and then increasing; biaxial compression has the effect of reinforcement and restraint on concrete, which improves its dynamic compressive strength and deformation resistance. When the ratio of spindle pressure ratio to unilateral pressure ratio is 0.4∶0.4, the effect is the best.

Abstract:The effects of nano-C—S—H/PCE on the setting time, early hydration and compressive strength of Portland-Sulphoaluminate composite cement were studied. XRD, TG, pH meter and SEM were used to characterize the early hydration products and liquid alkalinity. The enhancement mechanism of nano-C—S—H/PCE on Portland-Sulphoaluminate composite cement was studied. The results showed that the addition of nano-C—S—H/PCE could effectively shorten both the initial setting time and final setting time of fresh composite cement paste. When the C—S—H content was more than 1.0%, the initial time difference of the composite cement was obviously shortened. The nano-C—S—H/PCE accelerated the hydration heat releasing rate of the composite cement, and increased the total hydration heat. The early-age hydration products were increased obviously, however, it had no effect on the type of cement hydration products. The compressive strength of the composite cement mortars at 8 h, 12 h and 16 h were significantly increased.

Abstract:In order to solve the problem of distortion of thermal parameters of mass concrete in bridge engineering, an inverse analysis method of thermal parameters of mass concrete based on uniform design theory and BP neural network was proposed. This method uses BP neural network to establish the non-linear relationship between the temperature field and thermal parameters of large-volume concrete; training samples of BP neural network are determined by uniform design method; during the training phase of BP neural network, additional momentum method is used to optimize the network structure; The error curve before and after optimization and the analysis results of multiple training processes show that the additional momentum method can significantly shorten the network training time, and the average absolute percentage error value and root mean square error value of the multiple training processes are stable. The adiabatic temperature rise, reaction rate constant, and thermal conductivity were inverted during the construction of the bulk concrete of the supporting platform of the saddle pier of the Taihong Yangtze River Bridge. The calculated temperature based on the inversion value agrees well with the actual measured value, and the maximum temperature peak error is only 1.1 ℃. Therefore, the inverse analysis method for thermal parameters of large-volume concrete based on uniform design theory and BP neural network is feasible and the inversion process is stable and convergent, and the inversion accuracy is high. It can be used to guide the temperature-controlled construction to reduce the risk of large-scale concrete cracking.

Abstract:Microplastics are a new type of pollutants that are difficult to degrade and are widely distributed in the ocean, fresh water, soil and wetland systems. Wetlands are an important part of the ecological environment. They are rich in animal, plant and microbial resources and play an important role in maintaining biodiversity. Therefore, the presence of microplastics may pose a threat to the diversity of wetland species. This article introduces the distribution characteristics and existing forms of microplastics in the wetland system, analyzes the toxicological effects of microplastics on the animals, plants and microorganisms of the wetland system. On the basis of previous research, it summarizes the analysis and detection method of microplastics in the wetland environmental water bodies, sediments and organisms, the detection process of microplastics in different components of the wetland environment is proposed, and the future research focus of microplastics in wetland systems is prospected. By analyzing the distribution of microplastics in the wetland and the impact of ecotoxicology, it can provide a theoretical basis for clarifying the status of microplastics in the wetland environment and provide new ideas for future research on microplastics in the wetland environment.

Abstract:With the implementation of stricter ammonia nitrogen wastewater discharge standards, the problem that the effluent of most urban sewage treatment plants in China is difficult to meet the standards is becoming increasingly prominent, in which the lack of carbon source becomes a limiting factor of denitrification. For low carbon nitrogen ratio wastewater, additional carbon source should be added to enhance denitrification. Based on the research results on denitrification and external carbon sources, this paper summarizes the traditional carbon sources mainly composed of small molecular organics and carbohydrates, the new type of solid carbon source mainly based on natural cellulose materials, synthetic polymers, and skeleton composite slow-release carbon sources, and the new type of liquid carbon source mainly based on industrial wastewater, sludge and kitchen waste hydrolysate, and analyzes the problems and challenges in the current research and practical application of external carbon sources. The results show that the hybrid carbon sources based on traditional carbon sources are more suitable for commercial promotion at present, while most of the new carbon sources still have various problems in practical application, but they are worth further study due to their low cost, high environmental protection and wide application.

Abstract:In order to explore the adsorption characteristics of Pb (Ⅱ) and mechanism, polyacrylonitrile was selected as the matrix to be chemically modified with diethylenetriamine (DETA),preferred as an amination reagent,and a kind of polyamine chelating nanofiber (D-PAN) has been successfully prepared. The physical and chemical structure analysis by SEM, BET,FTIR and XPS was performed, and the effects of initial pH value, contact time, temperature, inorganic salt and other factors on the adsorption process of D-PAN were studied.The results show that: amine groups was successfully introduced into three-dimensional network of D-PAN, and multi channel structure is conducive to improve the adsorption properties of D-PAN for Pb (Ⅱ). It had the best static adsorption property at pH 5.0. The maximum adsorption capacity was 1.73 mmol/g obtained by fitting with Langmuir model, and the quasi-first-order kinetic rate constant is up to 0.06 min^-1. Moreover, D-PAN had a significant “salt-promoting” effect, and the adsorption amount of Pb (Ⅱ) in the salt-containing system could be nearly doubled.Combining the results of XPS and DFT, it was found that Pb(Ⅱ) could be removed by chelating with N atoms in polyamine groups to form bidentate and tridentate complexes.Furthermore, D-PAN exhibited excellent structural stability after multiple regeneration. In summary, D-PAN has the advantages of fast adsorption, large capacity and easy regeneration, and has broad application prospects.

Abstract:In this study, six decentralized rural sewage treatment facilities in Luoyang Town, Wujin District, Changzhou City were used as the research objects. The total inlet water, total outflow water and wetland soils from six dispersed rural sewage treatment facilities were sampled. And the mass concentrations of 11 PFCAs (perfluorohydroxyl acid substances, C₄-C₁₄), 4 PFSAs (perfluorosulfonic acid substances, C₄, C₆, C₈, and C₁₀),MeFOSA (n-methyl perfluorooctyl sulfonamide), EtFOSA (n-ethyl perfluorooctyl sulfonamide), MeFOSE (n-methyl perfluorooctyl sulfonamide)and other PFOS(perfluorooctane sulfonic acid)precursors were detected in these samples. The results showed that the detection rates of 6 PFCAs and 3 PFSAs in the influent water of 6 sewage treatment facilities were over 83.33%. In PFSAs, PFOS (perfluorooctane sulfonic acid) had the highest concentration, and the concentration range was from N.D. to 79.89 ng/L. In PFCAs, PFOA (perfluorooctanoic acid) had the highest concentration, and the concentration range was from 3.87 to 8.60 ng/L. The concentration characteristics of perfluorinated and polyfluorinated compounds (PFASs) in three different wastewater collection methods was: rainwater and sewage confluence and enterprise drainage > rain and sewage diversion > rainwater and sewage confluence. In the process of A/O contact oxidation and the multistage A/O process, the total concentration of PFASs in the outlet water was higher than that in the inlet water. So these two processes had no removal effect on PFASs. But A/O-MBR process had good removal effect on the medium-chain PFASs, and the removal rate was 81.27%.The removal of PFOS was the most obvious,the concentration of PFOS decreased from 64.45 to 15.41 ng/L, and the removal rate was about 74.90%. However, the process had no obvious removal on the short-chain PFASs. Constructed wetlands also had good removal effect on the medium-chain PFASs. And PFOS in outlet water of wetlands could be reduced from 15.41 ng/L to below the detection limit. The short-chain PFASs had low adsorption potential and hydrophobicity, which made it easier to exist in the liquid phase rather than in the solid phase,so that several processes have no obvious removal effect on them, even the concentration of effluent water is higher than that of inflow water.

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