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Radiographic films, increasingly less common today, pose a problem for the storage spaces of medical, industrial, and other institutions, becoming waste with negative economic value. Recycling these wastes by recovering silver and the polymeric substrate is a major concern in current research. Methods described in the literature include the use of NaOH or NH3 solutions, yielding variable silver recovery rates. The paper presents two technological variants tested in laboratory conditions, which combine leaching with NaOH with the use of ammonia, glucose, and formaldehyde. Additionally, the experimental procedure applied to the liquid residue of copper (II) and silver resulting from the filtration of the solid suspension, using copper cementation, is described. The obtained ted through laboratory analyses, including EDX and SEM determinations.

In the process of oilfield wastewater treatment, the polymer-modified materials with special wettability have been recognized by many scholars for their high filtration efficiency and good adsorption effect. In this paper, we used micro-computed tomography scanning and infrared scanning technology to further explore the internal structure and surface chemistry of polyurethane modified materials and then established an experimental platform for the filtration performance of polyurethane modified materials. The change of suspended solids concentration and oil content in the sewage was tested under different filtration rate, filter layer thickness, and water quality. The results showed that the porosity of the filter material and the oil-absorbing material was 65.85% and 56.03% respectively, and the difference in the number of oxygen-containing functional groups on the surface of these two materials indicated different adsorption force for sewage impurities. And the polyurethane modified materials had good filtration performance. Through these experiments, we demonstrated that the quality of water filtrated by the polyurethane modified materials met the requirements of the ‘National Comprehensive Wastewater Discharge Standards’, and the filtration efficiency for suspended particles and oils in oily sewage was higher than 80%. These materials have important practical significance for the harmless treatment of oily sewage.

Liu, J.; Peng, J.; Huang, F.; Liu, X., and Luo, Y., 2018. Influence of harbor cement production on the concentration of solid suspension in the surrounding atmosphere. In: Liu Z.L. and Mi C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 309–315. Coconut Creek (Florida), ISSN 0749-0208. At present, the production of harbor cement has a very serious negative impact on the surrounding air environment. Therefore, a method for studying the concentration of solid suspension in the atmosphere based on AERMOD model is proposed. According to the statistical data and monitoring data of pollutant emission amount of cement production, this kind pollutant is analyzed, and the relationship between pollutant emission intensity and the measured concentration of atmospheric environment is established; harbor cement production is simulated by using the AERMOD mode, to calculate the influence degree of harbor cement production on the suspended solids concentration in the atmosphere surrounding. Experiments show that when the discharge diameter is 2.458 µm, the mass concentration of particulate matter is the maximum of 2.353 mg/m. Based on the results, the distribution characteristics of pollutants in the harbor cement production enterprises can be grasped, to effectively improve the harbor cement production process from the source.

The rapid growth of population and industrialization have intensified the problem of water pollution globally. To meet the challenge of industrialization, the use of synthetic dyes in the textile industry, dyeing and printing industry, tannery and paint industry, paper and pulp industry, cosmetic and food industry, dye manufacturing industry, and pharmaceutical industry has increased exponentially. Among these industries, the textile industry is prominent for the water pollution due to the hefty consumption of water and discharge of coloring materials in the effluent. The discharge of this effluent into the aquatic reservoir affects its biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), and pH. The release of the effluents without any remedial treatment will generate a gigantic peril to the aquatic ecosystem and human health. The ecological-friendly treatment of the dye-containing wastewater to minimize the detrimental effect on human health and the environment is the need of the hour. The purpose of this review is to evaluate the catastrophic effects of textile dyes on human health and the environment. This review provides a comprehensive insight into the dyes and chemicals used in the textile industry, focusing on the typical treatment processes for their removal from industrial wastewaters, including chemical, biological, physical, and hybrid techniques.

This study provides a comprehensive review of the efforts utilized in the measurement of water quality parameters (WQPs) with a focus on total dissolved solids (TDS) and total suspended solids (TSS). The current method used in the measurement of TDS and TSS includes conventional field and gravimetric approaches. These methods are limited due to the associated cost and labor, and limited spatial coverages. Remote Sensing (RS) applications have, however, been used over the past few decades as an alternative to overcome these limitations. Although they also present underlying atmospheric interferences in images, radiometric and spectral resolution issues. Studies of these WQPs with RS, therefore, require the knowledge and utilization of the best mechanisms. The use of RS for retrieval of TDS, TSS, and their forms has been explored in many studies using images from airborne sensors onboard unmanned aerial vehicles (UAVs) and satellite sensors such as those onboard the Landsat, Sentinel-2, Aqua, and Terra platforms. The images and their spectral properties serve as inputs for deep learning analysis and statistical, and machine learning models. Methods used to retrieve these WQP measurements are dependent on the optical properties of the inland water bodies. While TSS is an optically active parameter, TDS is optically inactive with a low signal–noise ratio. The detection of TDS in the visible, near-infrared, and infrared bands is due to some process that (usually) co-occurs with changes in the TDS that is affecting a WQP that is optically active. This study revealed significant improvements in incorporating RS and conventional approaches in estimating WQPs. The findings reveal that improved spatiotemporal resolution has the potential to effectively detect changes in the WQPs. For effective monitoring of TDS and TSS using RS, we recommend employing atmospheric correction mechanisms to reduce image atmospheric interference, exploration of the fusion of optical and microwave bands, high-resolution hyperspectral images, utilization of ML and deep learning models, calibration and validation using observed data measured from conventional methods. Further studies could focus on the development of new technology and sensors using UAVs and satellite images to produce real-time in situ monitoring of TDS and TSS. The findings presented in this review aid in consolidating understanding and advancement of TDS and TSS measurements in a single repository thereby offering stakeholders, researchers, decision-makers, and regulatory bodies a go-to information resource to enhance their monitoring efforts and mitigation of water quality impairments.

This study provides an overview of the techniques, shortcomings, and strengths of remote sensing (RS) applications in the effective retrieval and monitoring of water quality parameters (WQPs) such as chlorophyll-a concentration, turbidity, total suspended solids, colored dissolved organic matter, total dissolved solids among others. To be effectively retrieved by RS, these WQPs are categorized as optically active or inactive based on their influence on the optical characteristics measured by RS sensors. RS applications offer the opportunity for decisionmakers to quantify and monitor WQPs on a spatiotemporal scale effectively. The use of RS for water quality monitoring has been explored in many studies using empirical, analytical, semi-empirical, and machine-learning algorithms. RS spectral signatures have been applied for the estimation of WQPs using two categories of RS, namely, microwave and optical sensors. Optical RS, which has been heavily applied in the estimation of WQPs, is further grouped as spaceborne and airborne sensors based on the platform they are on board. The choice of a particular sensor to be used in any RS application depends on various factors including cost, and spatial, spectral, and temporal resolutions of the images. Some of the known satellite sensors used in the literature and reviewed in this paper include the Multispectral Instrument aboard Sentinel-2A/B, Moderate Resolution Imaging Spectroradiometer, Landsat Thematic Mapper, Enhanced Thematic Mapper, and Operational Land Imager.

Slurry electrolysis (SE), as a hydrometallurgical process, has the characteristic of a multitank series connection, which leads to various stirring conditions and a complex solid suspension state. The computational fluid dynamics (CFD), which requires high computing resources, and a combination with machine learning was proposed to construct a rapid prediction model for the liquid flow and solid concentration fields in a SE tank. Through scientific selection of calculation samples via orthogonal experiments, a comprehensive dataset covering a wide range of conditions was established while effectively reducing the number of simulations and providing reasonable weights for each factor. Then, a prediction model of the SE tank was constructed using the K-nearest neighbor algorithm. The results show that with the increase in levels of orthogonal experiments, the prediction accuracy of the model improved remarkably. The model established with four factors and nine levels can accurately predict the flow and concentration fields, and the regression coefficients of average velocity and solid concentration were 0.926 and 0.937, respectively. Compared with traditional CFD, the response time of field information prediction in this model was reduced from 75 h to 20 s, which solves the problem of serious lag in CFD applied alone to actual production and meets real-time production control requirements.

The textile industry is one of the most intensive industries in chemical products whose wastewater contains hazardous dyes, pigments, dissolved/suspended solids, and heavy metals. Hence, it is important to effectively treat the wastewater generated by this industry before releasing it into the environment. Although the field of textile wastewater treatment has made tremendous progress, the developed treatment methods should be improved further to make them economically viable and friendly. In this review, characteristics of textile wastewater are introduced. We have primarily focused on the environmental impact and toxicity of textile wastewater. Toxic and harmful contaminants must be removed from textile wastewater to reduce the extent of environmental pollution caused when textile wastewater is released into rivers or reused. Hence, various techniques that are used to treat textile wastewater are discussed. Finally, the challenges faced, and prospects of the methods have been discussed in detail.

In order to solve the problem of non-uniform powder concentration in electrical discharge machining (EDM) working fluid, a mathematical model of powder particle movement in stirred tank was established, and the flow field and solid-liquid suspension uniformity were simulated in this paper. The factors of slot shape, depth-diameter ratio, blade angle, blade installation height, and solid particle volume fraction which affected flow field distribution, solid suspension particle uniformity, and power consumption were researched, and the stirred tank structure was optimized. When the ratio of spherical stirred tank depth to diameter is 0.8, the blade design angle is 45°, and the installation height of impeller blade is 120 mm, the suspension uniformity of solid particles is the best and the power consumption is the smallest. Under the conditions of Al powder concentration 4 g/L, pulse width 175 μs, and pulse interval 75 μs, the powder-mixed EDM experiment of SiC/Al functionally gradient material was carried out with this optimized stirring device. The results show that the material removal rate of powder-mixed EDM increased by 24.82% and the surface roughness decreased by 27.28% than that of the conventional EDM.

Computational fluid dynamics (CFDs) were adopted in order to investigate the solid suspending process in a dense solid–liquid system (with a solid volume fraction of 30%), agitated by a traditional dual axial impeller and a modified dual axial impeller, otherwise known as a dual triple blade impeller (DTBI) and a dual rigid-flexible triple blade impeller (DRFTBI), respectively. The effects of rotational speed, connection strap length/width, and off-bottom clearance on the solid distribution were investigated. The results show that the proportion of solid concentration larger than 0.4 in the DTBI system was 26.56 times of that in the DRFTBI system. This indicates that the DRFTBI system can strengthen the solid suspension and decrease the solid accumulation in the bottom of the tank. Furthermore, the velocity and turbulent kinetic energy in the DRFTBI system were promoted. In addition, for an optimal selection, the optimum length of connection strap was 1.2 H1, the optimum range of connection strap width was D/7–D/8, and the off-bottom clearance selected as T/4 was better.