washing process
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Author(s):  
Hyunsoo Kim ◽  
Kanghee Cho ◽  
Oyunbileg Purev ◽  
Nagchoul Choi ◽  
Jaewon Lee

Based on the features of hydrodynamic cavitation, in this study, we developed a washing ejector that utilizes a high-pressure water jet. The cavitating flow was utilized to remove fine particles from contaminated soil. The volume of the contaminants and total metal concentration could be correlated to the fine-particle distribution in the contaminated soil. These particles can combine with a variety of pollutants. In this study, physical separation and soil washing as a two-step soil remediation strategy were performed to remediate contaminated soils from the smelter. A washing ejector was employed for physical separation, whereas phosphoric acid was used as the washing agent. The particles containing toxic heavy metals were composed of metal phase encapsulated in phyllosilicates, and metal phase weakly bound to phyllosilicate surfaces. The washing ejector involves the removal of fine particles bound to coarse particles and the dispersion of soil aggregates. From these results we determined that physical separation using a washing ejector was effective for the treatment of contaminated soil. Phosphoric acid (H3PO4) was effective in extracting arsenic from contaminated soil in which arsenic was associated with amorphous iron oxides. Thus, the obtained results can provide useful information and technical support for field soil washing for the remediation of soil contaminated by toxic heavy metals through emissions from the mining and ore processing industries.


2022 ◽  
Vol 14 (1) ◽  
pp. 451
Author(s):  
Abbas Solouki ◽  
Piergiorgio Tataranni ◽  
Cesare Sangiorgi

Most of the waste materials recycled for the production of new construction materials are by-products of various manufacturing processes, such as the aggregate washing process. Recycling such materials is of paramount importance since it could reduce the adverse environmental impacts resulting from landfilling. Various studies have attempted to recycle different types of waste materials and by-products into concrete paving blocks. However, the availability of literature on concrete paving blocks containing waste silt is quite scarce. Thus, the current paper focuses on mix design optimization and production of concrete paving blocks containing high amounts of waste silt resulting from the aggregate production process. Using the mixture Design of Experiments (DOE), 12 sets of concrete paving blocks with different aggregate blends were produced to optimize the mix design. Once the final mix design was achieved, the physical and mechanical properties of the concrete paving blocks were investigated following the EN 1338 standard. Shape and dimension measurements and various tests, including water absorption, tensile splitting strength, abrasion resistance, and slip/skid resistance were conducted on the experimental concrete paving samples. Overall, the produced concrete paving blocks showed promising properties for future applications in pedestrian walking paths.


Author(s):  
Noemi Belišová ◽  
Barbora Konečná ◽  
Nikoleta Bachratá ◽  
Jozef Ryba ◽  
Alena Potočárová ◽  
...  

The research aims at washing processes as possible sources of microplastics, specifical microfibers in wastewater, and the behavior of the virus particles SARS-CoV-2 in wastewater after the washing process as well as their ability to sorb to the surface of microfibers, released from washing processes. The conclusions of the research point to the ability of the virus to attach to possible solid impurities such as textile fibers (microfibers) occurring in the sewer and to the ability of wash water to influence their possible occurrence in the sewer. The highest efficiency (more than 99%) of removal virus particles was after washing process, using liquid washing powder, and washing soda. These findings may gradually contribute to a better understanding of the behavior of the virus particles in the sewer.


2021 ◽  
Vol 12 (1) ◽  
pp. 36
Author(s):  
Alessandra Diotti ◽  
Luca Cominoli ◽  
Giovanni Plizzari ◽  
Sabrina Sorlini

In this paper, a new innovative technology for the treatment of returned concrete is proposed. This method is based on the application of physical–mechanical processes that allow to obtain new quality products: recycled aggregates, microfiltered water and cement sludge. Specifically, by means of a mechanical system equipped with buffer and Archimedes screws, fine (d < 5 mm) and coarse (d > 5 mm) aggregates are obtained. The water coming from the washing process is sent to a microfiltration process, where a filter membrane separates the liquid phase (microfiltered water) from the solid phase (cement sludge) and no type of potentially toxic additive is added. In this context, this paper investigates the feasibility of using all these components as new raw materials for sustainable concrete production. In particular, according to the requirements imposed by technical standards, an experimental program was developed, aimed at evaluating the physical, chemical, and mechanical properties of the analyzed materials. The results showed that both recycled aggregates, the microfiltered water and the cement sludge can be used to produce new structural concrete. In particular, it was proven that also the cement sludge, which generally represents the most critical component destined for disposal, can be reused as filler in the partial replacement of sand.


Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7781
Author(s):  
Mirjana Čurlin ◽  
Tanja Pušić ◽  
Branka Vojnović ◽  
Nino Dimitrov

The dominant type of polymer particles in water, sediment, and various organisms partly derives from natural and synthetic fibres released in the washing process. Pollution of aquatic recipients with these particles poses an interdisciplinary problem throughout the world. Wastewater from washing represents a dispersion system with different particle sizes that is also loaded with the source of the particles. Due to this complex system, the qualification and quantification of this type of pollution is difficult. In this paper, the laser diffraction technique was applied to characterize particles in effluents from washing and rinsing materials made of a mixture of cotton and polyester. The results obtained through the analysis prove that the laser diffraction technique is acceptable for the characterization of a composite effluent sample. The advanced statistical technique of multivariate analysis confirmed the interrelationship of the parameters of this complex dispersion system.


Author(s):  
Asep Bayu Dani Nandiyanto ◽  
◽  
Nissa Nur Azizah ◽  
Salma Rahmadianti ◽  
◽  
...  

The purpose of this study was to make carbon from banana stem waste and determine the isotherm adsorption characteristics of carbon from banana stem waste to methyl orange compounds. The process for making carbon from banana stem waste was done through the stages of preparation and carbonization at a temperature of 250°C for 1.5 h. Before being used as carbon, banana stem waste was cleaned, washed, dried, and mashed using a mill. The carbon then went through a washing process to remove impurities and tested for its absorbance ability into a solution containing a methyl orange compound under constant conditions of pH, temperature, and pressure. The experimental results showed that the appropriate sequence of adsorption models is the Langmuir, Temkin, Freundlich, and Dubinin-Radushkevich models. Adsorption occurs on the surface of a single layer (monolayer) and the interaction between the adsorbent and the adsorbate occurs physically. The value of maximum adsorption capacity (Qmax) is 37.5940 mg/g. The presence of banana stem carbon is expected to reduce the negative impacts, one of which is the disposal of industrial wastewater from textile factories.


2021 ◽  
Vol 6 (7) ◽  
pp. 77-81
Author(s):  
Abdullah Al Rakib Shikder ◽  
Jabed Hossen Emon ◽  
Md. Humayun Kabir Khan ◽  
Md. Mehedi Hasan ◽  
Md. Abu Bakar Siddiquee

The study was focused on investigating the impact of different washing processes (dark shade, medium shade, light shade) on various properties of denim fabric. Two different types of fabrics with twill and dobby weave constructions were produced from cotton, spandex, and polyester yarn, and different types of washing processes were applied. Dimensional stability, tensile strength, tearing strength, EPI and PPI, weight, colorfastness to rubbing, colorfastness to perspiration (acid and alkaline), and colorfastness to water was investigated and comparisons were made statistically between the before washed sample and after washed sample. It is found that the process result shows better tear and tensile strength in case of dark & medium shade wash than light shade wash. On the other hand, weight and EPI & PPI have shown better result for light wash than other wash. Colorfastness to rubbing, Colorfastness to water, and Colorfastness to perspiration (acid and alkaline medium) are similar. The shrinkage% is higher especially in the weft direction of the fabric for light wash than the dark wash.


Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1316
Author(s):  
Cindy Cindy ◽  
Ryotaro Sakai ◽  
Diego M. Mendoza ◽  
Kojo T. Konadu ◽  
Keiko Sasaki

Environmentally friendly pretreatment of double refractory gold ores (DRGO) to improve gold recovery without emitting pollutant gas is challenging. Sequential biotreatment, including iron-oxidizing microorganisms to decompose sulfides, followed by the enzymatic decomposition of carbonaceous matter, was recently developed. The effect of acid washing by 1 M HCl for 24 h between two bioprocesses was evaluated using a real double refractory gold ore from the Syama mines, Mali, which includes 24 g/t of Au and 5.27 wt % of carbon with a relatively higher graphitic degree. The addition of the acid washing process significantly improved gold recovery by cyanidation to yield to 84.9 ± 0.7% from 64.4 ± 9.2% (n = 2). The positive effects of acid washing can be explained by chemical alteration of carbonaceous matter to facilitate the accessibility for lignin peroxidase (LiP) and manganese peroxidase (MnP) in cell-free spent medium (CFSM), although the agglomeration was enhanced by an acid attack to structural Fe(III) in clay minerals. Sequential treatment of DRGO basically consists of the oxidative dissolution of sulfides and the degradation of carbonaceous matter prior to the extraction of gold; however, the details should be modified depending on the elemental and mineralogical compositions and the graphitic degree of carbonaceous matter.


Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2111
Author(s):  
Ziqi Zhu ◽  
Rihong Cong ◽  
Lingmei Zhou ◽  
Hao Zheng ◽  
Yanan Tu ◽  
...  

The kinetics during the pyrolysis process depend on both chemical structure and inherent mineral matters in coal, but normally, only one of these components is investigated in literature. In the present work, four low-rank coals were pyrolyzed in a thermogravimetric analyzer at a heating rate of 10 K/min in a constant nitrogen stream at a temperature up to 900 °C to study the pyrolysis behavior and kinetics. Two of the samples were raw coal (R-YL) and clean coal (C-YL) obtained through the washing process. The results showed that the coal-washing process mainly affected the inorganic part (mineral matters) and structure in coal, which did not largely change the chemical properties. The pyrolysis behavior in primary stage (before 550 °C) was mainly affected by the chemical properties of coal, while the pyrolysis behavior in higher temperature also depended on inherent mineral matters. The kinetics of four coals were obtained using the Coats–Redfern (CR) method with five theoretical models. The difference of E value was almost negligible for R-YL and C-YL, also showing that the coal-washing process did not largely change the chemical properties. The higher frequency factor A for clean coal C-YL showed a more porous structure due to the coal-washing process. The apparent activation energy E in the third stage was affected by the thermodynamic property of inherent minerals.


2021 ◽  
Vol 2079 (1) ◽  
pp. 012004
Author(s):  
Yongrong Qi ◽  
Yuan Gong ◽  
Haibin Wang ◽  
Li Peng ◽  
Liting Fan ◽  
...  

Abstract A large amount of spent pot lining (SPL) is produced by cryolite-alumina melting electrolysis process, and the fluoride content in the leaching solution is up to 6000 mg/L, which belongs to hazardous waste. If SPL is not handled effectively, it will cause great harm to the environment. Because the NaF rich in SPL is an important raw material for the synthesis of cryolite by carbonation, this paper uses SPL as the raw material to extract NaF. On the basis of exploring the process conditions of water washing leaching NaF, ultrasonic wave was introduced to enhance mass transfer and the effects of ultrasonic cavitation on water washing process was compared. The results show that ultrasonic waves can effectively shorten the time for water washing to reach equilibrium and further improve the efficiency of NaF leaching. Under the optimal process conditions determined by the experiment, when the ultrasonic power is 400 W, the time for washing to reach equilibrium is shortened from 50 min to 40 min, and the NaF leaching efficiency is increased from 67.25 % to 70.42 %. While improving the leaching efficiency, the water consumption is effectively reduced, and the purity of the recovered product NaF is 96.82 %. This research provides a technical reference for the harmless and low cost leaching of NaF from SPL in the aluminium electrolysis industry.


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