Experimental study on the effects of used HEPA filters on water environment

In this paper, the commonly used High Efficiency Particulate Air filter (HEPA) material as the research object, through the design of indoor experiment, using pure water, groundwater, and rainwater solution to soak, analysis of unused and abandoned the mesh in different water chemical solution release/adsorption law of anion and metal components, in order to find out its potential impact on the water environment. Results showed that: (1) when the waste HEPA filters were soaked in water solutions, the maximum average release amounts $$(\overline {{Q_{max}}} )$$ of four anions were in a order as: $${\rm{SO}}_4^{2 - } > {\rm{NO}}_3^ - > {\rm{C}}{{\rm{l}}^ - } > {{\rm{F}}^ - }$$. Pure waters showed the highest $$(\overline {{Q_{max}}} )$$ of Cl- and $${\rm{NO}}_3^ -$$, which were 1.2120 and 0.3387 mg/g, respectively. Groundwater showed the highest $$(\overline {{Q_{max}}} )$$ of $${\rm{SO}}_4^{2 - } >$$ and F-, which were 6.7329 and 0.0348 mg/g. These indicated that $${\rm{SO}}_4^{2 - } >$$ was the major anion pollutant for waste HEPA filters soaked in water solutions, and groundwater and pure water were more susceptible to be contaminated by anions released from waste HEPA filters. (2) the $$(\overline {{Q_{max}}} )$$ of three metals released from waste HEPA filters were in a order as Zn> Pb> As, in which, groundwater showed the highest $$(\overline {{Q_{max}}} )$$ of Zn (2.21 μg/g), followed by rainwater and pure water. This meant that Zn is the major heavy metal pollutant released from waste HEPA filters into the water environment, and groundwater was more susceptible to be contaminated by metals released from waste HEPA filters. (3) None Zn, Pb, and As were released in these three different solutions for the unused filter, indicating that it has almost no contamination threat to the water environment. This study is expected to further improve the understanding of water environmental pollution prevention and management, and provide a theoretical basis for China’s ecological environment protection

Experimental platform for coal gangue sorting robot based on image detection

Currently, coal gangue pre-sorting is still mostly done manually, with high labor intensity, low sorting efficiency, and safety hazards. Using coal gangue sorting robots to replace manual coal gangue pre-sorting is an effective way to ensure the health and safety of workers and improve work efficiency. However, the existing coal gangue sorting robots have poor performance in situations such as low light intensity and coal gangue surface covered with coal powder. To solve the above problems, an experimental platform for coal gangue sorting robot based on image detection is proposed. This experimental platform collects coal gangue images through industrial cameras. The platform uses ResNet18-YOLOv3 deep learning algorithm to identify the coal gangue in the images. The platform uses TCP communication to provide the position information of the gangue to the coal gangue sorting module for trajectory planning, then controls the manipulator to clamp the gangue and completes the gangue sorting operation. The platform uses the Halcon calibration method for hand-eye calibration of the experimental platform, in order to achieve the conversion of camera pixel coordinates and manipulator spatial coordinates. The positioning error of the experimental platform is calibrated. For coal gangue samples with sizes above 50 mm, the positioning error should not exceed 9 mm. The experimental results show that the recognition accuracy of the experimental platform for coal gangue under strong lighting conditions is 99%. The recognition accuracy of coal gangue under weak lighting conditions is 95%. The recognition accuracy of coal gangue under pulverized coal adhesion conditions is not less than 82%. The accuracy of coal gangue sorting is 82%

On As(III) Adsorption Characteristics of Innovative Magnetite Graphene Oxide Chitosan Microsphere

A magnetite graphene oxide chitosan (MGOCS) composite microsphere was specifically prepared to efficiently adsorb As(III) from aqueous solutions. The characterization analysis of BET, XRD, VSM, TG, FTIR, XPS, and SEM-EDS was used to identify the characteristics and adsorption mechanism. Batch experiments were carried out to determine the effects of the operational parameters and to evaluate the adsorption kinetic and equilibrium isotherm. The results show that the MGOCS composite microsphere with a particle size of about 1.5 mm can be prepared by a straightforward method of dropping FeCl2, graphene oxide (GO), and chitosan (CS) mixtures into NaOH solutions and then drying the mixed solutions at 45 °C. The produced MGOCS had a strong thermal stability with a mass loss of 2/g and 24.35 emu/g, respectively. The As(III) adsorption capacity (Qe) and removal efficiency (Re) was only 0.25 mg/g and 5.81% for GOCS, respectively. After 0.08 mol of Fe3O4 modification, more than 53% of As(III) was efficiently removed by the formed MGOCS from aqueous solutions over a wide pH range of 5–10, and this was almost unaffected by temperature. The coexisting ion of PO43− decreased Qe from 3.81 mg/g to 1.32 mg/g, but Mn2+ increased Qe from 3.50 mg/g to 4.19 mg/g. The As(III) adsorption fitted the best to the pseudo-second-order kinetic model, and the maximum Qe was 20.72 mg/g as fitted by the Sips model. After four times regeneration, the Re value of As(III) slightly decreased from 76.2% to 73.8%, and no secondary pollution of Fe happened. Chemisorption is the major mechanism for As(III) adsorption, and As(III) was adsorbed on the surface and interior of the MGOCS, while the adsorbed As(III) was partially oxidized to As(V) accompanied by the reduction of Fe(III) to Fe(II). The produced As(V) was further adsorbed through ligand exchange (by forming Fe–O–As complexes) and electrostatic attraction, enhancing the As(III) removal. As an easily prepared and environmental-friendly composite, MGOCS not only greatly adsorbs As(III) but also effectively removes Cr(VI) and As(V) (Re > 60%) and other metals, showing a great advantage in the treatment of heavy metal-contaminated water

Effects of S2- on arsenic adsorption to river sand and its mechanisms

Sulfur (S2-) is closely related to the migration and enrichment of arsenic (As) in the water environment, but its mechanism of action in different aqueous medium is still unclear. To determine the adsorption characteristics of As by river sand, a common aqueous medium in the hyporheic zone, under the action of S2-, the adsorption kinetics experiment of As on river sand and the adsorption experiment of As by river sand under the action of S2- are designed and carried out. Combined with simulation calculation by PHREEQC and characterization tests based on XRD, SEM-EDS, XPS and FTIR, the mechanism of action is further identified. The results show that the adsorption of As by river sand reaches adsorption equilibrium at approximately 200 h and the adsorption capacity of As(Ⅴ) is significantly higher than that of As(Ⅲ) at the solid-to-liquid ratio of 25 g/L; with increasing S2- concentration, the adsorption capacity of river sand to As decreases gradually. The simulation and characterization test results show that a small amount of As is adsorbed on the surface of river sandandis mainly combined with Fe and Al on its surface. The adsorption of As (Ⅲ) may also be related to SiS2 that is formed after the fracture of the Si-O bondwith S2-. The main influence mechanism of S2- on the adsorption of As by river sand is as follows: ① the addition of S2- increases the pH of the solution and decreases Eh, thus inhibiting the adsorption of As; ②under the condition of adding S2-, Fe and Al on the surface of river sand can form compounds such as AlAs, AlAsO4, FeS2 and Fe4As2O11 with S and As, which reduces the active sites of As adsorption on the surface of river sand

Sources and Eco-toxicological Effects of Ultrafine Particle Matters

Environmental air pollution has become an important threat to human health. As one of the major air pollutants, atmospheric particulates have received attention widely. In which, ultrafine particulate matters (UPM) with diameter below 0.1μm have become the main components of ambient air particulates, posing a serious threat to the health of the organism. Therefore, this paper investigated and summarized the research on ultrafine particles at home and abroad, systematically analysed the sources of UPM in ambient air, investigated its toxicological effects of ultrafine particles on the respiratory system, cardiovascular system, and central nervous system of organisms. This study will provide a theoretical reference for environmental air protection and pollution control in China

Calculation of Theoretical Travel Time and Automatic Picking of Actual Travel Time in Seismic Data

We used the ray tracing technique based on the IASP91 Earth model to calculate the travel times in order to identify the phases. This technique can calculate the travel times for the seismic phases in the conventional travel time tables. The waveform data received from the stations in the Guangxi area are selected for analysis and discussion. The outcomes of the numerical modeling and its use demonstrate that there is good agreement in terms of the absolute differences between the calculated and theoretical travel times from the ISAP91 tables. The relative residuals are determined directly from the actual arrival times picking during the correlation analysis, and the validity of the travel time method for picking seismic phases by correlation analysis can be demonstrated

Simulation Study on the Environmental Impact of Rare Earth Ore Development on Groundwater in Hilly Areas: A Case Study in Nuodong, China

Mineral extraction can significantly affect the groundwater flow and hydrochemical environment. However, for hilly areas, significant ground elevation changes and complex geological conditions make it difficult to accurately analyze and predict the impact of mineral mining. This study takes the Nuodong rare earth mining area as an example. Based on field investigations and experiments, GOCAD software (version 2022) was used to establish a geological model in combination with GMS numerical simulation software, which was used to build a groundwater flow model and a solute transport model. The flow model in the hilly area indicated that the absolute error between the simulated and measured water levels of each observation well is 0.554 m. The solute-transport model showed that the maximum pollutant concentration of ammonia-nitrogen (NH3-N) in the liquid injection area, stream area, and village area monitoring wells reaches 139.15, 27.9, and 3-N, which threatens the safety of the water for mine area residents. To control pollutant transport, two stages of pumping were adopted to reduce NH3-N concentrations in groundwater. After adopting the first stage, the peak concentration of the stream area monitoring wells decreased significantly, with the maximum peak concentration decreasing from 27.9 mg/L to 5.51 mg/L. Based on the results of the first stage of the pump-out treatment, a second stage was adopted. The model results showed that the peak concentration of NH3-N pollutants discharged into the stream is less than 0.5 mg/L. The results provide a theoretical basis and reference for groundwater monitoring and pollution control after mining in this area

Near Surface Velocity Estimation Using GPR Data: Investigations by Numerical Simulation, and Experimental Approach with AVO Response

The velocity of near-surface materials is one of the most important for Ground-Penetrating Radar (GPR). In the study, we evaluate the options for determining the GPR velocity to measure the accuracy of velocity approximations from the acquired GPR data at an experimental site in Hangzhou, China. A vertical profile of interval velocities can be estimated from each common mid-point (CMP) gather using velocity spectrum analysis. Firstly, GPR data are acquired and analyzed using the popular method of hyperbola fitting which generated surprisingly high subsurface signal velocity estimates while, for the same profile, the Amplitude variation with offset (AVO) analysis of the GPR data (using the same hyperbola fitting method) generate a more reasonable subsurface signal velocity estimate. Several necessary processing steps are applied both for CMP and AVO analysis. Furthermore, experimental analysis is conducted on the same test site to get velocities of samples based on dielectric constant measurement during the drilling process. Synthetic velocities generated by AVO analysis are validated by the experimental velocities which confirmed the suitability of velocity interpretations

Rupture Behavior of the Litang Fault within the Sichuan-Yunnan Active Block, Southeastern Tibetan Plateau

AbstractIn mainland China, approximately 86% of M≥7 earthquakes have occurred in the block boundary zone, which has been well explained by active block theory. However, a few large earthquakes have occurred within the active block, which provides us with an opportunity to better study the deformation of the Tibetan Plateau. The Litang Fault (LTF) is a strike-slip fault within the Sichuan-Yunnan Active Block and produced the 1948 Litang M7.3 earthquake. We presented the Holocene rupture behavior of the LTF based on detailed field investigations, paleoearthquake trenching, and radiocarbon dating. Specifically, we revealed 13 Holocene paleoearthquake events at four trenching sites and divided these events into 3 rupture cycles at the whole-fault scale. The seismic rupture behavior of the LTF is characterized by recurrent southeastward migration, and since the Holocene, the period of each rupture cycle has decreased rapidly from 8000 years to 500 years. Our results may provide geologic evidence for understanding the intrablock stress patterns and material transfer of the southeastern region of the Tibetan Plateau. The rapidly enhanced fault activity of the LTF since the late Holocene indicates that the LTF may have played an important role in accommodating the deformation of the southeastern region of the Tibetan Plateau