Abstract:With the development of urban construction in China, more and more applications of rectangular tunnel are emerging, but there are few theoretical studies on rectangular tunnels. In this paper, the elastic theoretical calculation model of the semi-infinite space rectangular tunnel was established. The coefficients of conformal mapping function were determined by the least squares iterative method. And the calculated area was mapped to a concentric ring on the complex plane. Afterwards, The Muskhelishvili complex function method was used to expand the stress function in the calculation area into the form of Laurant series, which gives the zero stress boundary on the ground surface and the radial displacement boundary of the rectangular hole. The stress field and displacement field of the rectangular tunnel in the semi-infinite space under the given displacement condition were also obtained by the method. In this paper, the influence of aspect ratios, Poisson's ratios, and buried depths on the displacement field and stress field was analyzed, and the general rules of the displacement field and stress field of rectangular tunnels has been summarized. The results show that a smaller aspect ratio, a larger Poisson's ratio, and a smaller buried depth will make the settlement curve no longer similar to a Gaussian curve. The variation of these parameters will also affect the size and distribution of the stress field and displacement field to varying degrees.

Abstract:In order to further reveal the process of rainfall infiltration and stability evolution of bedrock-type stepped high cutting slopes under rainfall cycling conditions, taking the bedrock-type stepped high cutting slope of a silty clay cover layer from Mabian to Zhaojue section of Lexi Expressway as the research object, a mathematical model for the deterioration of soil shear strength parameters was established through indoor dry-wet cycle tests; Geo-studio numerical simulation software was used to study the rainfall infiltration process of the high cutting slope under multi-case rainfall cycles, which reveals the internal seepage field and stability change rules of high cutting slopes under different rainfall cycle conditions and after rain. And the annual degradation equation of the stability coefficient of the rainfall-type high cutting slope has been established; Combining the results of indoor experiment and numerical simulation, a method for predicting the stability coefficient of this type of high cutting slope has been established. The research results show that the shape and position of the potential sliding surface of the high cutting slope does not change significantly during the process of rainfall infiltration, and it appears as a combined sliding surface of the circular surface and the bedrock water surface at the depth of the high cutting slope; In the same rainfall period, the depth of rainfall infiltration and the extent of stability degradation of high cutting slopes are positively correlated with rainfall intensity; The degree of stability degradation of high cutting slopes in a single rainfall cycle is negatively correlated with the number of rainfall cycles. The greater the depth of rainfall infiltration or the total rainfall infiltration of high cutting slopes, the smaller the recovery of the stability coefficient of high cutting slopes after rain; It is relatively safe and reasonable to use the average value of the degradation coefficient of the shear strength parameter of the soil for the degradation coefficient of the high cutting slope stability coefficient. And the prediction method for the stability coefficient of rainfall-type high cutting slope has high accuracy.

Abstract:Based on the deep foundation pit project of the utility tunnel of Yanjiang Avenue in Hangzhou, the HSS model was used for finite element numerical simulation to analyze the deformation of the foundation pit and adjacent pipelines under the dewatering excavation of the foundation pit. The simulation results are in good agreement with the monitoring results, which verifies the rationality of the finite element calculation and parameter selection. Based on the results, an optimized plan for dewatering of the partitioned foundation pit has been proposed, and the deformation response of the foundation pit and adjacent pipelines was studied when the penetration depth of the water-insulating curtain was different under steady-state seepage. The research results show that as the depth of the suspended waterproof curtain increases, the head difference of ground water between the inside and outside of the pit and the peak value of the lateral displacement of the retaining structure increases linearly, and the vertical displacement of the pipeline and the surface settlement outside the pit decrease linearly; Compared with the suspended waterproof curtain, the waterproof curtain has significant advantages in controlling the surface settlement outside the pit and the deformation of adjacent pipelines, however it is more unfavorable for the deformation control of the retaining structure.

Abstract:The representative earth-rock embankment construction section in the reconstruction and expansion project of the National Highway Dana Highway from the provincial boundary (Hunchun) to Dongning was selected to study the deformation and compaction characteristics of the earth-rock embankment under different loose paving thicknesses and different rolling cycles. In particular, the differential settlement control index was used to determine compaction construction technique of earth-rock embankment with main packing filler of highly-weathered and medium-weathered tuff. Portable falling weight deflectometer (PFWD) was used to detect dynamic elastic modulus (E_vd) of earth-rock embankment. The E_vd value and differential settlement of earth-rock embankment after each rolling are linearly fitted. All correlation coefficients are above 0.86, which indicates that the E_vd value has a good linear correlation with the differential settlement. The finite element theory was used to establish a three-dimensional numerical model of the earth-rock embankment to analyze the dynamic response of the embankment under the action of vibration load. The compaction effect and influence depth of the vibratory roller on the roadbed was analyzed. It is found that the attenuation rate of the vertical dynamic stress along the depth direction tends to be initially fast and turns slow thereafter. The vibratory compaction process of a 32-ton roller can repeatedly strengthen and compact the lower compaction layer. Variance analysis indicates that the influence of roller vibration frequency on vibration compaction of earth-rock mixed embankment is greater than the amplitude excitation force.

Abstract:In this study, compared with the traditional train-track-subgrade integral coupling three-dimensional finite element model, an optimized method for handling train loads has been proposed. The train-track vertical coupling model was established based on the multi-body system dynamics theory, and the wheel-rail excitation load under the condition of random track irregularity was obtained through numerical calculation. Then the wheel-rail load was imported into the ballastless track-subgrade-natural foundation soil nonlinear numerical analysis three-dimensional finite element model by using the secondary development subroutine. On this basis, the dynamic stress distribution law of subgrade under high-speed moving load was studied and analyzed. The research results show that the vehicle load processing method used in this paper replaces the vehicle-irregular track-subgrade-foundation integrated vibration model under the premise of ensuring the calculation accuracy, reducing the modeling and calculation time cost, which has certain reference significance; The vertical dynamic stress distribution law along the transverse direction shows that the value is larger in the track structure, and the value in the subgrade bed is much smaller than that in the track structure. The surface layer of the subgrade bed and the bottom surface of the subgrade bed appears "saddle-shaped" distribution; The vertical dynamic stress distribution law along the vertical shows that as the depth increases, the vertical dynamic stress gradually decreases, and the attenuation rate in the surface layer of the subgrade bed is relatively large, even exceeding 50%; The vertical dynamic stress distribution law along the longitudinal direction shows that the number of stress peaks equal to the number of bogies is produced in each structural layer. The dynamic stress changes of the track and subgrade during train operation can be regarded as repeated loading and unloading processes; The moving speed of the train has an obvious effect on the dynamic response of the subgrade. When the speed increases from 200 km/h to 350 km/h, the dynamic stress amplitude of each structural layer increases by more than 30%.

Abstract:When the bucket foundation moves laterally or rotates, its sidewall may be separated from the soil to form a gap. The failure mechanism of the soil changes from "double-sided" to "single-sided", which reduces the bearing capacity. The three-dimensional finite element model was established to simulate the reaction between bucket foundation and cohesive soil. Two different types of contact types were set up, allowing separation or not allowing separation. The soil strength and aspect ratio of the bucket foundation were varied to determine the conditions when separation occurs. The effect of the separation on the bearing capacity of the bucket foundation under different conditions was studied, and the capacity formulas of uniaxial and combined loading have been proposed. The results show that the separation of the bucket foundation from the soil reduces the uniaxial and combined bearing capacity, and the reduction is more significant with the increase of soil strength, while the aspect ratio has little effect on the reduction of bearing capacity. For uniaxial bearing capacity, it is recommended to quantify the impact of separation through the reduction factor. For combined bearing capacity, the normalized envelope surface expression that is suitable for both separation and not separation situations has been proposed.

Abstract:Calcareous clay is a kind of hydraulic reclamation coral foundation soil, whose permeability is of great significance for the construction of coral reef island projects. Based on the GDSPERM automatic environmental geotechnical permeability test system, a series of consolidation and permeability joint tests of calcareous clay of an reef island in the South China Sea were carried out, and the effects of void ratio, consolidation history, consolidation pressure, hydraulic gradient and pore fluid ion concentration on the permeability characteristics of calcareous clay were studied. The fitting analysis of the nonlinear relationship between the void ratio and the permeability coefficient of the calcareous clay was carried out, and a series of permeability laws of the calcareous clay have been summarized. The results show that the permeability coefficient of calcareous clay is about 10^-6 cm/s, and it does not change with the change of hydraulic gradient. There is an initial hydraulic gradient in its permeation; The consolidation history has a great influence on the permeability of calcareous clay. Under the same void ratio, unconsolidated soil samples show lower permeability; The permeability coefficient of calcareous clay decreases with the increase of consolidation pressure, and the decrease does not exceed an order of magnitude; As the void ratio increases, the permeability coefficient of the calcareous clay increases accordingly, and the relationship between the two is nonlinear. The "lg[k_v(1+e)]-lg e" model has a better fitting effect, which is considered to be the optimal nonlinear permeability model for calcareous clay; The permeability coefficient of calcareous clay decreases with the increase of NaCl concentration of pore solution.

Abstract:Based on the regional measured temperature, four common probability distribution models were proposed to fit the probability distribution of the daily temperature extremes in different seasons at the bridge location. The fitting of each model was evaluated through 5 performance indexes and the optimal probability distribution model was selected. Based on the optimal probability distribution model, the maximum and minimum temperature values with the return periods of 20 a, 50 a, and 100 a at the bridge location were calculated subsequently. The finite element model of a long-span steel box girder suspension bridge was established using ANSYS. Based on the established model, the effects of temperature variation of different structural components on the bridge's natural frequency and displacement was studied considering the extreme temperature. The influence of restraint systems such as central buckle, vertical supports and expansion joints on the temperature-induced effect of the bridge was further studied. The investigated results show that, except for the first-order symmetrical transverse bending frequency of the stiffening girder, the natural frequencies of the others are negatively correlated with the temperature of the full bridge; When the temperature of the pylons and stiffening girder of the suspension bridge rises or falls by 25℃ respectively, the changes in the natural frequency are all within 5%; When the temperature of the main cable of the suspension bridge is reduced by 12℃, the anti-symmetric vertical vibration frequency of the stiffening girder will increase significantly by about 12%; In addition, the vertical displacement response of the stiffening girder and the vertical and longitudinal displacement response of the bridge tower are linearly related to the temperature variation. And the longitudinal displacement of the stiffening girder is mainly affected by the temperature variation of the stiffening girder. The longitudinal displacement rate of Jianshui side and Yuanyang side are 4.7 mm/℃ and 3.3 mm/℃, respectively; The vertical displacement and rotation angle of the stiffening girder ends are mainly affected by the temperature variation of the main cable; The influence of the vertical support and the longitudinal limit device of the expansion joint on the temperature-induced displacement response of the bridge is negligible, but the central buckle will cause a sudden change in the internal force of the short suspender at the middle of the bridge.

Abstract:In order to study the influence of the yield strength f_y of the shear reinforcement and the concrete cover thickness h on the direct shear performance of the monolithically cast concrete interface, a push-out test of 12 Z-shaped specimens was carried out. Based on the experimental phenomenon and the measured load-slip curve of the interface, the interface shear force transfer mechanism was revealed. According to the test value of the bearing capacity of the specimens, the calculation formulas of the interface direct shear bearing capacity of the standard ACI, PCI and AASHTO were evaluated and analyzed. The results show that when f_y increases from 400 MPa to 600 MPa or h increases from 20 mm to 40 mm, the direct shear strength and stiffness of the interface do not change significantly, while the change of h will cause the different interface failure modes; The cohesive force of concrete has a great contribution to the direct shear bearing capacity of the interface; The three standard calculation formulas can be applied to engineering design, while the ACI and PCI calculation formulas are too conservative, and the AASHTO calculation formula is of great accuracy.

Abstract:In prefabricated buildings, steel truss composite slabs are widely used as the main force-bearing components. However, the baseplate often cracks before installation on the site, which makes the composite slabs unusable. In this paper, a new type of two-way steel truss composite slab has been proposed, which installs additional transverse steel support on the traditional reinforced truss composite slab, thereby improving the flexural bearing capacity of the composite slab. In order to investigate the effect of the installed transverse steel truss on the cracking state and mechanical characteristics of the composite slab, static loading tests were carried out on the two-way steel truss composite slab baseplate and the ordinary one-way steel truss composite slab floor. The variation rules of the cracking moment, crack distribution, mid span deflection and strain with loads were obtained through the tests. The results show that, under the same load, compared with the traditional one-way steel truss composite slab, the cracking moment of the two-way steel truss composite slab baseplate is larger, the cracks develop more slowly, and the mid-span deflection and strain are smaller. The two-way steel truss can significantly improve the anti-cracking performance of the composite slab baseplate and effectively control the crack development.

Abstract:The use of topology optimization to assist in the completion of engineering design is a new method in recent years. The paper adopts the genetic bi-directional evolutionary structural optimization (GBESO) discrete model to obtain the optimal reinforcement topology based on the uniform stress distribution, which provides a new idea for solving the engineering reinforcement design problems of reinforced concrete deep beams and other two-dimensional components. With reference to the solution of the optimization algorithm and the empirical design method of deeply flexural members recommended by the Chinese code, a group of reinforced concrete simple-supported deep beam reinforcement designs have been completed and static comparison experiments were carried out. Results show that the component designed by GBESO has lower steel bars consumption, higher ultimate bearing capacity, stronger crack development capacity, and better energy dissipation capacity during the failure process. It proves that the reinforcement design method of the oblique section reinforced with oblique steel bars is more in line with the force mechanism and characteristics of the members. Ability of the GBESO discrete model in the design of deep beam reinforcement has been verified to a certain extent.

Abstract:Building facade information refers to the spatial distribution and attribute information of the contact surface between buildings and external space. How to extract building facade information from point cloud data is a hot and difficult problem in point cloud data processing. In order to solve the problems of single evaluation standard and weak adaptability of traditional grid density algorithm in building facade point cloud extraction, this paper analyzed the local and overall spatial characteristics such as elevation distribution, projection density and normal vector distribution of various typical surface feature point clouds in the construction area, and constructed a multi-level semantic feature descriptor composed of point cloud single point semantics, grid semantics and regional semantics. Based on this descriptor and the reasonable threshold which was set according to the semantic characteristics of building facade point cloud at different levels, a multi-level semantic feature extraction method was proposed to extract the building facade point cloud accurately layer by layer. The experimental results show that this algorithm can be used to quickly and accurately extract the building facades of low, high buildings and super high buildings from point clouds. Overall, this algorithm achieves a high precision, a high efficiency and a good adaptability.

Abstract:Since the Industrial Revolution, persistent organic compounds (POPs) in wastewater have been at the heart of water pollution control due to their complexity, stability, and high toxicity. Despite the rapid development of water treatment methods, there is no single method that can stand out from the crowd:advanced oxidation technology has significant advantages in the treatment of POPs, but it has the limitations of high cost, non-selective attack, and easy quenching and inactivation of active species; biological treatment is universal and has good impact resistance, but it has limitations in the treatment of difficult-to-degrade pollutants. Intimately coupled advanced oxidation and biodegradation (ICAB) technology organically combines the advantages of advanced oxidation and biodegradation, solves the limitation of their individual action, and has been proved to be effective in degrading many organic substances such as mineralized chlorophenols, antibiotics, dyestuffs, nitrobenzene, polycyclic aromatic hydrocarbons and so on. This paper reviews the concept and features, core components, advantages and current applications of the intimately coupled advanced oxidation and biodegradation technology, as well as its bottlenecks in terms of efficient quenching of carrier materials, active species quenching and high mass transfer reactor design, and looks forward to the future development of its application in practical water treatment. The aim of the paper is to promote the application and development of new ICAB technology in the field of treatment of non-degradable organic wastewater.

Abstract:Paper mill sludge is difficult to be treated with the high disposal cost, which limits the sustainable development of papermaking industry. The traditional disposal methods are mainly landfill and incineration, however, landfill and incineration will cause secondary pollution to the environment. Therefore, developing environmentally-friendly disposal methods is a key issue for paper mill sludge disposal. Many scholars focused on the comprehensive utilization of papermaking sludge, such as anaerobic fermentation, aerobic composting and production of building materials. Based on the rich biomass content in paper mill sludge, developing paper mill sludge-based functional materials by certain modification methods for water treatment can achieve the goal of "treating waste with waste". It not only conforms to the environmental protection concept of sustainable development, but also provides a new idea for the comprehensive utilization of paper mill sludge. This paper reviewed the sources, properties, disposal methods and comprehensive utilization of paper mill sludge, research status and prospect of the utilization of cellulosic substances in papermaking sludge. This paper aims to provide some theoretical support for the sustainable development of the paper industry.

Abstract:The resource utilization of protein in excess sludge is a research hotspot at home and abroad, and sludge pretreatment is an important way to realize protein release from sludge. In order to further improve the dissolution efficiency of protein in excess sludge, this paper selected thermal-alkali pretreatment, ultrasonic-alkali pretreatment and lysozyme pretreatment as the method of disintegration in sludge, and optimized the parameters with the protein extraction concentration as the main index. The isoelectric point method was also used to purify and recover crude protein. The results showed that the cellulolytic effect:thermal-alkali pretreatment (pH 13, temperature 140℃, time 1.5 h, 2 062.98 mg/L) > ultrasonic-alkali pretreatment (497.76 mg/L) > lysozyme pretreatment (269.95 mg/L), and the protein purification recovery of thermal-alkali pretreatment at pH 3 can reach 62.42%. It can be seen from the above test results that the thermal-alkali pretreatment has obvious advantages over the other two methods in terms of extraction effect, deserving of exploitation and utilization.

Abstract:Conventional activated sludge process and its derivative process have been regarded as a representative and valuable process for biological water treatment because of their simple operation and mature technology. Nevertheless, several drawbacks hinder their wider applicability, in which the high operating energy costs and poor microbial tolerance for toxic substances. Bacterial-algal symbiosis biofilm technology has been given increasing attentions since their high nutrients removal under the condition of less aeration and the excellent suffertibility of load and toxicity. The motivation of this study, therefore, to discuss the formation process of bacterial-algal biofilm and the mechanism of pollutants removal, to introduce the influence factors for the biofilm formation and advantage of the engineering application. We also summarize the insufficient and analysis the further prospects of the bacteria-algal biofilm to provide technical support for the popularization of bacterial-algal symbiotic biofilm.

Abstract:Aerobic sludge from the wastewater treatment plant was sampled as inoculation bacteria, and the effects of pH and initial Mn²⁺ concentration on the activation of manganese-oxidizing bacterium were studied. High-throughput sequencing technology was used to analyze the variation of microbial communities before and after activation. On this basis, the biogenic manganese oxides produced by manganese-oxidizing bacterium were characterized by X-ray diffraction. Besides, the effects of pH and biogenic manganese oxides dosage on the removal of EE2 by biogenic manganese oxides were analyzed. The results show that the best activation effect of manganese oxidizing bacterium is obtained when the initial Mn²⁺ concentration is 1 mmol/L at pH 7.0 and 83.3% Mn²⁺ is transformed into biogenic manganese oxides after 7 days under this condition. XRD results show that the biogenic manganese oxides produced mainly include MnO₂, Na₃Mn(PO₃)CO₃, and Mn₃O₄. According to the results of high-throughput sequencing, the abundance of Bacillus(0.75%), Acinetobacter(1.26%), Pseudomonas(1.36%), Sphingobacterium(1.81%), Flavobacterium(2.39%), Exiguobacterium(2.97%), Areomonas(7.35%) increases significantly, and the total relative abundance of typical manganese-oxidizing bacterium reaches 17.89%. When the biogenic manganese oxides dosage is 20 mg/L at pH 4.0, EE2 has the best removal efficiency. After 48 h, the removal rate of EE2 reaches 97.7%, in which 76.9% is removed by biogenic manganese oxides.

Abstract:Algae blooming in freshwater severely damages the aquatic ecosystem seriously, and nutrient level is the key environmental factor that results in the formation of algae blooming. For purpose of revealing the influence degrees of nutrient on the in situ growth of algae during the algae blooming, this study took the algae assemblages as the research object, and self designed devices were used in in situ experiments, which were carried out in the Pengxi River of the Three Gorges Reservoir. In this study, three different treatments including phosphorus, high nitrogen and low nitrogen treatments were introduced, and the conditions in the devices were consistent with that in the nature water body. During the phosphorus treatment as well as low nitrogen treatment, chlorophyll a showed a dramatic decreasing trend but did not manifest the same trend during the high nitrogen treatment. In order to elucidate the reason that caused the different chlorophyll a trend during different treatments, there were several methods conducted in this study to analyse and study the causes of different chlorophyll trends, such as chemometrics and correlation analysis, besides non-linear fitting. Finally, the results showed:(1) The optimal N:P for algae growth in the Pengxi River was 32.52, and the suitable phosphorus and nitrogen concentration for algae growth were 0.12 mg/L and 2.44 mg/L, respectively; (2) Both nutrient and water temperature were the key factors that resulted in the in situ algae growth. High nutrient concentration (the concentration of nitrogen was higher than 2.44 mg/L), low nutrient concentration (lower than the concentration that algae required for chemometrics), and low water temperature (lower than 20℃) might inhibit the algae growth. In contrast to the high nutrient concentration, the low nutrient concentration or the low water temperature could bring out higher inhibition for algae growth; (3) Algae blooming in the Pengxi River must meet two premises:Sufficient nutrient (higher than the lowest nutrient concentration that algae required for chemometrics) and appropriate suitable water temperature (higher than 20℃).

Abstract:A novel carbon fiber aerogel was prepared by one-step direct pyrolysis method using natural cotton as a precursor, and the electrolysis-ozone technology using CFA cathode (E-O₃-CFA) was established. The composition and structure of CFA were analyzed by SEM, BET and XPS. The removal of IBP and the main operational parameters (e.g., cathode materials、current intensity、ozone concentration and pH) were evaluated systematically. The pathway and mechanism of IBP removal were also investigated, and the energy consumption was calculated. The results showed that CFA is a porous interconnected three-dimensional network structure with developed pores, high specific surface area and abundant oxygen-containing functional groups on the surface. The removal rate of IBP by E-O₃-CFA process was 97.96% at ozone concentration of 16mg/L, current intensity of 300 mA, and without adjusting the initial pH. It was higher than the electrolysis-ozone technology with other cathode (steel cathode 83.11%、activated carbon fiber cathode 94.78%、graphite cathode 89.05%). The IBP was mainly removed by the free radical oxidation pathway by ·OH. Moreover, the specific energy consumption (SEC=2.49 kW·h/gTOC) of electrolysis-ozone technology for TOC removal was furtherly reduced by using CFA cathode.

Abstract:Using coal gangue as raw material, high-efficiency inorganic polymer flocculant polymeric aluminum ferric calcium chloride (PAFCC) was prepared through high-temperature roasting, acid precipitation, polymerization, and maturation. The effects of PAFCC preparation conditions on turbidity, COD and UV₂₅₄ removal rate were studied by single factor experiments. The results showed that the optimum polymerization conditions of PAFCC were pH 2, polymerization temperature 60℃, polymerization time 5 h, and curing at 40℃ for 28 h. The coagulation results showed that the prepared PAFCC had excellent removal effect on turbidity, reaching 95.70%, and had a certain removal effect on COD and UV₂₅₄, and the removal rates reached 47.51% and 45.98%, respectively. The coagulation results of the refining wastewater showed that PAFCC had a good removal effect on turbidity and total phosphorus, while it had a certain removal effect on COD and ammonia nitrogen, and the effect was significantly better than traditional PAC.

Abstract:The remediation of petroleum hydrocarbon contaminated soil was studied by using activated carbon enhanced microwave thermal effect technology in a petrochemical plant. Under the best condition of microwave treatment, the treatment effect of petroleum hydrocarbon contaminated soil was investigated in the site. The components and removal characteristics of petroleum pollutants were analyzed by 3D-EEM (three-dimensional fluorescence) and GC (gas chromatography), and the deep biodegradation test of the repaired soil was carried out by the bacterial strengthening method. The results showed that the activated carbon enhanced microwave thermal remediation technology had a better removal effect on petroleum hydrocarbon contaminated soil. Under the experimental conditions of microwave power of 700 W, irradiation for 15min, soil moisture content of 10% and addition of 5% activated carbon, the content of petroleum hydrocarbon in the soil could be reduced from 5 700 mg/kg to 2 800 mg/kg, and the removal rate reached 50.9%; GC analysis showed that the main pollutants in the soil were TPH (C₆-C₉), TPH (C₁₅-C₂₈) and TPH (C₂₉-C₃₆), and after the microwave thermal remediation, the removal rate of TPH (C₁₅-C₂₈) in the soil was higher, reaching 70.4%; Based on 3D-EEM analysis, the results showed that the microwave thermal remediation had a better effect on removing tricyclic aromatic compounds and their homologues in the soil. The deep biodegradation of the engineered bacterial agent was carried out on the soil after microwave thermal remediation, the results showed that after 14 days of degradation, the content of petroleum hydrocarbon in the contaminated soil decreased to 716.8 mg/kg, and the removal rate increased to 74.4%, which reached the first class of land selection value in standard for Soil Environmental Quality Standards for Soil Pollution Risk Control of Construction Land (Trial) (GB 36600-2018).

Abstract:This study investigated factors influencing a sequencing batch reactor (SBR) enhanced biological phosphorus removal (EBPR) granular sludge system, in order to provide technical support for the practical application of EBPR. The start-up, the phosphorus removal performance of the EBPR granular sludge system and the sludge granulation were studied in a SBR system with a working volume of 12L, where sodium acetate was used as the carbon source and KH₂PO₄ was used as the phosphorus source. Results showed that when the carbon to phosphorus ratio of influent was too low (C:P=200:15), the phosphorus removal efficiencies were at a low level. Compared with 25℃, the EPS content of sludge increased at 15℃. Moreover, the increase of protein (PN) content was more obvious at 15℃, which was conducive to sludge granulation and resulted in an obvious increase of sludge particle size. Compared with 25℃, the lower temperature of 15℃ was more favorable for the growth of Rhodocyclus, which is mainly responsible for biological phosphorus removal in traditional EBPR systems. This resulted in Rhodocyclus becoming the dominant bacteria in the system and improved the phosphorus removal efficiencies.