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Aiming at the problem that there is no GNSS signal in the coal mine, the state-of-the-art LiDAR SLAM algorithm is prone to degenerate due to insufficient feature constraints, a tight coupling SLAM algorithm of LiDAR and IMU for the coal mine environment is proposed. First, we design a dynamic feature point extraction method, by detecting whether there is degradation in the underground environment of coal mine to dynamically adjust the number of feature points extracted, build a rich and good feature information constraint matrix, improve the accuracy of pose estimation; then, the factor diagram optimization is used to realize the robust and accurate SLAM in the coal mine. Finally, a wide range of experimental analysis is carried out through the measured data in the coal mine. The results show that the proposed laser SLAM algorithm performs well, the pose estimation error is reduced by 50.93% in the horizontal direction and 42.13% in the vertical direction compared with LIO_SAM, it can provide technical reference for intelligent perception and safety inspection of coal mine robots.

The visual simultaneous localization and mapping (SLAM) algorithm based on the feature point method has certain applications in coal mines. However, due to factors such as uneven lighting, variable lighting, and alternating light and dark areas, the image quality is poor and texture information is lacking. This results in low precision of feature extraction and matching in the front end of visual SLAM. The problem of tracking loss is prone to occur, which affects the positioning precision and mapping effect of the visual SLAM algorithm. This study proposes a visual SLAM algorithm of coal mine underground considering image enhancement. The overall performance of visual SLAM is improved through image enhancement processing. Retinex algorithm based on improved bilateral filter is used to enhance the coal mine underground image. The original RGB image is converted to HSI color space, and the improved bilateral filter replaces the Gaussian filter of the traditional Retinex algorithm as the central surrounding function. After the image reflection component is estimated, it is converted to RGB color space to obtain the final enhanced image. Retinex algorithm based on improved bilateral filter is introduced into the classical ORB-SLAM2 algorithm framework for pose estimation and mapping. Based on the data collection platform of the wheeled mine-used robot, the visual SLAM algorithm considering image enhancement is tested in the roadway environment of coal mine underground. The results show that, compared with the traditional Retinex algorithm, the coal mine image enhanced by the Retinex algorithm based on improved bilateral filter does not show obvious whitening and halo, and the image quality is improved. Compared with the ORB-SLAM2 algorithm, the visual SLAM algorithm considering image enhancement improves the quality and quantity of feature matching. It has a higher degree of overlap between estimated trajectories and real trajectories. It reduces the mean absolute trajector error by 76.2%. It establishes a more realistic and accurate 3D dense point cloud map of underground roadway.

Water reclamation and ecological reuse is gradually becoming a popular solution to address the high pollutant loads and insufficient ecological flow of many urban rivers. However, emerging contaminants in water reuse system and associated human health and ecological risks need to be assessed. This study determined the occurrence and human health and ecological risk assessments of 35 emerging contaminants during one year, including 5 types of persistent organic pollutants (POPs), 5 pharmaceutical and personal care products (PPCPs), 7 endocrine disrupting chemicals (EDCs) and 18 disinfection by-products (DBPs), in a wastewater treatment plant (WWTP) and receiving rivers, as well as an unimpacted river for comparison. Results showed that most of PPCPs and EDCs, especially antibiotics, triclosan, estrogens and bisphenol A, occurred frequently at relatively high concentrations, and they were removed from 20.5% to 88.7% with a mean of 58.9% via WWTP. The highest potential noncarcinogenic and carcinogenic risks in different reuse scenarios were assessed using maximal detected concentrations, all below the acceptable risk limits, with the highest total combined risk value of 9.21 × 10-9 and 9.98 × 10-7, respectively. Ecological risk assessment was conducted using risk quotient (RQ) method and indicated that several PPCPs, EDCs and haloacetonitriles (HANs) pose high risk (RQ > 1) to aquatic ecology in the rivers, with the highest RQ up to 83.8. The study suggested that ecological risks need to be urgently addressed by updating and optimizing the process in WWTPs to strengthen the removal efficiencies of emerging contaminants. The study can serve as a reference for safer water reuse in the future, while further studies could be conducted on the health risk of specific groups of people, exposure parameters in water reuse, as well as more emerging contaminants.

The failure of autonomous navigation, positioning and mapping of the mobile robot is caused by the shotcrete surface and symmetrical roadway in coal mine. In order to solve this problem, a real-time positioning and mapping method based on LiDAR and IMU fusion is proposed for the roadway environment in the coal mine. Firstly, the original point cloud is segmented. The IMU pre-integration pose is used to remove the nonlinear motion distortion of the original point cloud. The line and surface feature extraction is carried out on the obtained point cloud. Secondly, the line and surface features of adjacent frames are matched. The initial pose value obtained by IMU pre-integration is fused in the hierarchical pose estimation process. The calculation iteration times are reduced, the matching precision of feature points is improved, and the pose of the current frame is solved. Finally, the local map factor, IMU factor and key frame factor are inserted into the factor graph to optimize and constrain the pose. The key frame is matched with the local map, and the map construction is realized through an octree structure. In order to verify the positioning performance and mapping effect of the proposed method, the experimental platforms of Autolabor, VLP-16 LiDAR and Ellipse-N IMU are built. The qualitative and quantitative comparison between the proposed method and LeGO-LOAM and LIO-SAM methods is carried out. The results show the following points. ① In the coal mine roadway environment, the average and median of the absolute positioning error in the three axes direction of the real-time positioning and mapping method based on LiDAR and IMU fusion are less than 32 cm. The position and attitude estimation precision in the X-axis is the highest, with a cumulative error of 1.65 m and a position deviation of 2.97 m. The overall mapping effect is good, and the mapping track does not drift. The point cloud map constructed has excellent performance in integrity and geometric structure authenticity. The map can directly reflect the actual situation of the roadway environment, and has good robustness. This is because hierarchical pose estimation is performed after point cloud matching. The multi-factor optimization can effectively reduce the global cumulative error, which plays an important role in improving track precision and map consistency. ② In the corridor environment, the three-axis error of the real-time positioning and mapping method based on LiDAR and IMU fusion for the coal mine roadway environment is less than 1.01 m. The average error is 5~15 cm, with small error range and high precision. The accumulated position deviation is only 1.67 m. Integrity and environment matching have good performance. This is because by adding keyframe factors and inserting factor graphs to optimize the related variables of the newly added nodes, the drift of pose estimation is reduced. The positioning and mapping precision is relatively high.

The treatment and resource utilization of sludge from municipal sewage treatment plants is an important environmental issue. Cement kiln co-processing offers a promising solution, but challenges remain, particularly regarding sludge properties and feasibility in kiln systems. This study analyzes the characteristics of three pretreated sludges: mechanically dewatered sludge, deeply dewatered sludge, and lime-dried sludge. Using techniques such as thermogravimetric analysis (TGA) and X-ray diffraction (XRD), this study investigates their calorific values and raw material utilizability in co-processing. As the sludge moisture content decreases from interstitial to bound water, energy consumption per ton of evaporated water rises, particularly below 30%. At 10 °C/min heating, energy consumption for mechanically dewatered sludge at 80%, 30%, and 10% moisture was 3573, 8220, and 34,751 kJ/kg, respectively; for deeply dewatered sludge at 60%, 30%, and 10%, the values were 4398, 7550, and 11,504 kJ/kg. Keeping moisture content above 30% before kiln entry reduces energy use and enhances calorific value. Sludge utilizability as a raw material depends on its pretreatment. The ash composition of deeply and mechanically dewatered sludge resembles iron-rich raw materials, while lime-dried sludge aligns more with limestone. The utilizable ash content was 23.3%, 8.1%, and 46.3%, respectively, with lime-dried sludge showing the highest potential. This study provides insights into sludge properties and their co-processing potential in cement kilns, offering scientific and technical support for practical applications. [ABSTRACT FROM AUTHOR]

Combined sewer overflow (CSO) pollution is the main factor that plagues the water environment in the area with combined sewer system in most cities of China. This paper analyzed CSO pollution, and reviewed the measures to solve CSO pollution and the latest research progress. The problems of traditional river interception projects were analyzed, and optimization and improvement ideas were proposed. Finally, a combined optimization scheme of source reduction-process control-end storage was proposed to control CSO pollution, which could provide reference for urban CSO pollution control in China.

The reclaimed water produced by sewage treatment plants can be reused for many purposes, which has gradually been paid great attention. However, its pricing mechanism has not been well established especially in China, which has brought certain restrictions on the wide application of reclaimed water. Therefore, this paper attempts to analyze the current situation of domestic reclaimed water pricing, combined with the research and analysis of reclaimed water production costs and related industry profits, and gives the recommended reclaimed water pricing. Taking the reclaimed water reuse project in Ningbo, China as an example, the cost and profit are analyzed by season. The recommended price in non-winter is 0.3833 yuan/ton, and the recommended price in winter is 0.4283 yuan/ton. This study may provide some reference for the improvement of the pricing mechanism of reclaimed water, thus contributing to the wide application of reclaimed water.

Biological co-metabolism is an economical and efficient technique for treating refractory organic matter, and in recent years, it has been widely used in the treatment of chlorophenol-containing wastewater. It has been found that many conditions affect the bio co-metabolism efficiency, such as the carbon source type, carbon source content, microorganism types, and environmental factors. The carbon source concentration experiment showed that when the dosage ratio of sodium acetate to black aniline powder was 1:2, the degradation rate of black aniline powder was 82%, and the removal rate was 92.9%. When tetrachlorophenol increased from 210 mg/L to 2100 mg/L, the tetrachlorophenol was increased in the effluent, and the microorganism's activity was inhibited. Besides, the sedimentation performance of activated sludge was also damaged. The temperature test showed that the removed 4-chlorophenol was as high as 2100 mg/L at 35 °C, and the apparent 4-chlorophenol residue in the effluent could be detected at 20 °C. Therefore, by appropriately controlling the external operating conditions of the reactor, the co-metabolism of refractory organic such as chlorophenols can be achieved.

Iron release from water supply network affects water quality safety. To investigate the change of microbial community structure and its effect on iron release in water supply pipes under leakage condition, the research was carried out based on the pilot platform used in actual water supply system. Microbial community structure was analyzed using high-throughput sequencing and the total iron index was measured by atomic flame absorption spectroscopy. The results showed that Proteobacteria had a large competitive advantage in the laminar flow rate, the average relative content increased more than 60%. At the level of class, the relative content of Alphaproteobacteria, Gammaproteobacteria, Betaproteobacteria increased larger than others. When the velocity was close to the critical flow rate, the microbial community was gradually stabilized. The total iron concentration decreased with the increase of flow rates, when the flow rate was 40% of the critical flow rate, the total iron concentration tended to be stable, and the promotion of total iron release was mainly iron-oxidizing bacteria and sulfate reducing bacteria, and the inhibition effect was mainly nitrate reducing bacteria. It has important reference significance for further controlling the microbial community and iron release in the water at the end of the pipe network.

Emerging contaminants in water have attracted more and more attention from scholars and the public. Various technologies have been gradually studied and applied to remove emerging contaminants in water, including adsorption technology based on carbon materials, membrane separation technology, advanced oxidation technology and constructed wetland. In this paper, the research progress of these technologies is reviewed, especially for photocatalysis, a promising technology, which is analyzed in detail. Immobilization is an important means for photocatalytic technology to be applied in engineering. In this paper, four existing immobilization methods of photocatalytic materials are analyzed, and the existing research is prospected. More in-depth research is urgently needed, and exploratory research aimed at application is encouraged. This study can provide some ideas and reference for the treatment of emerging contaminants in water.

Chlorophenol wastewater belongs to highly toxic industrial wastewater, which can cause serious harm to the environment and human health if not treated effectively. The current treatment methods for chlorophenol wastewater are divided into physical, chemical, and biological methods. The physical adsorption experiment found that the monodisperse magnetic nano-column was prepared by the solvothermal method, which could remove 91.5% of pentachlorophenol within 30 mins. More than 90% of chlorophenol can be extracted using an ionic liquid as an extractant. When the chlorophenol reaches 15 g/L, the extraction rate only slightly decreases. CaO and SiO2 can achieve 99.0% 2,4,6-trichlorophenol in 6 hours as ball milling materials by physical and chemical methods. The electrochemical reduction test found that using Pd/Py SDBS/Ti as the cathode, 2-chlorophenol, 4-chlorophenol, and 3-chlorophenol could be reduced and dechlorinated, in which 100 mg/L of 2-chlorophenol could be completely degraded within 60 minutes. The biochemical index BOD5/COD of wastewater is less than 0.3 if the biological treatment technology based on co-metabolism is adopted to realize the chlorophenol treatment. In treating chlorophenol wastewater, the application scenario should be fully considered to achieve the best treatment effect of chlorophenol wastewater.

Urban runoff pollution has become one of the important limiting factors hindering the continuous improvement of water environment. In the process of drainage system reconstruction, the evaluation of interception pipeline for the collection and storage efficiency of initial rainwater is an important work. Therefore, this study uses the analytic hierarchy process to establish an evaluation system and method containing 4 first-level indicators and 10 second-level indicators to evaluate the comprehensive efficiency of the interception pipeline for initial rainwater collection and storage. Taking the interception pipeline in a drainage system in Shanghai as a case study, the established evaluation method was adopted to evaluate it, and the comprehensive indexes under the rainfall return periods of 0.5 year, 1 year, 3 years and 5 years were calculated. The results indicated that the evaluation method could be well applied to the effectiveness evaluation of intercepting pipelines in drainage systems, and could provide technical support for the planning and design of urban runoff pollution control projects in the future.

The rapid industrialization process has brought about explosive growth in the types of chemicals and the widespread and extensive usage of chemicals. These chemicals enter into the aquatic environment with their application in industry and daily life, posing a security threat to natural water bodies and public health. It is necessary and urgent to carry out risk assessment of these new pollutants or micro-pollutants in water. Therefore, this paper reviewed the research progress and development direction of health risk assessment and ecological risk assessment of emerging contaminants in aquatic environment, and prospected the research and application in China. This paper proposes that it is necessary to deeply study the public health effects, environmental effects and migration and transformation characteristics of these emerging contaminants in water, and to understand their toxicological effects, so as to establish a sound risk assessment benchmark and method as soon as possible to help water resources management and water security.

Currently, the treatment of point source pollution has been basically com-pleted, and the development of non-point source pollution(NPP) has become a new threat to natural water. Unlike point source pollution, NPP is much more complex than point source pollution in terms of treatment difficulty and treatment measures. Therefore, NPP has gradually become the focus of researchers’ attention. This paper mainly reviews the current research status on the governance of NPP, precisely urban source and agricultural source pollution governance. In addition, the article reviews the treatment measures of NPP at the present stage, from source treatment, process blocking and end-of-pipe treatment. This thesis provides a more comprehensive overview of NPP treatment measures, which can provide a reference for further research and development of engineering practices on NPP.

The Yangtze River protection is an important environmental protection strategy for China, and the quality and efficiency of the sewage system is also one of the environmental protection actions that China is working hard to implement in recent years. As the first batch of pilot cities for the protection of the Yangtze River, Wuhu City has significantly improved its sewage system through a series of comprehensive sewage system improvement engineering measures. This paper briefly described the general situation and measures of the sewage system renovation project in the CD area of Wuhu City, and based on the systematic thinking of “source-network-plant-river”, the performance of improving the quality and efficiency of the sewage system was evaluated. With the implementation of the sewage system remediation project, the water quality at the source and discharge outlet as well as the water quantity of sewage collected had been greatly improved. The sewage collection volume had been increased from 10,000 m3/d to 42,000 m3/d and the COD concentration of the influent has increased significantly. The introduction and analysis of this project may provide some reference for other similar sewage system remediation projects in China and other countries and regions.

Objective: Unicystic ameloblastomas are a variant of ameloblastoma with a definite recurrence rate because of the biological behaviours of the tumour. The risk factors associated with disease recurrence were analysed in this retrospective study. Methods: A total of 132 patients with primary unicystic ameloblastoma reported in a tertiary hospital from 2005 to 2015 were analysed to identify the clinic‐pathological and radiological factors associated with recurrence using univariate and multivariate Cox regression analyses. Results: The mean volume was 30.54cm3 ± 12.55 cm3, and this value differed significantly according to recurrence (p < 0.001). Root resorption and bone cortex/soft tissue invasion were also significantly associated with recurrence among unicystic ameloblastoma patients (p = 0.017 vs. p < 0.001, respectively). A new stage classification system was developed to predict disease recurrence of patients. The multivariate Cox regression analysis revealed that the new stage classification system was the only predictor of disease recurrence in unicystic ameloblastoma patients (p < 0.001), regardless of root resorption, position and site characteristics. Conclusions: Volume, root resorption and bone cortex/soft tissue invasion were risk factors for disease recurrence among unicystic ameloblastoma patients. The new stage classification was an independent predictor of disease recurrence in patients with unicystic ameloblastoma. [ABSTRACT FROM AUTHOR]