The presence of particulate matter (PM) and fine particles is a source of distress for equally the industrial process and human health 1–5. PM is a complex mixture consisting of diverse particle types, much of which is likely to cause various adverse effects. For fine particles, there are three types that are used in the industry, i.e., dust capturing mechanisms, namely impaction, interception, and diffusion. By controlling, temperature and humidity could efficiently establish the cleaning process into a single unit. In which toxicity is larger when the lower particle size. Hence the fine particulate matter (PM) can produce substantial effects on human health acts both directly and indirectly as a carrier of hazardous materials 6–10. On the other hand, from the emitting sources, the very fine inhalable particles can travel long distances, but once inhaled, it may reach the deepest regions of the lungs and furthermore can enter the circulatory system 11–13. Also, PM could reduce visibility in cities and also can create large scale effects since it has a higher influence on atmospheric radioactive phenomena 14–16. Air pollutants are mainly due to hydrogen chloride (HCl), which is generated from natural chemical reactions and anthropological activities 17. Moreover, in a natural chemical reaction, NaCl particles can react with HNO3 and H2SO4 to form HCl 18.
In order to reduce NaCl, the device called wet scrubbers was developed in order to capture very fine particulate matter 19. Later on, developed a compact wet scrubber working in a self-priming mode that consists of several Venturi scrubbers. This compact wet Chandrasekara presented a model that estimates the memory effect of Pollution control using wet scrubbers. Bhave et al. (2008) introduced a wet scrubber suited for small-scale applications which have a wet packed bed scrubber-based producer gas cooling system and cleaning system. Chandrasekara Pillai et al. (2009) researched the possible settings for NOx and SO2 subtraction using a scrubber column which was packed with NO–SO2–air flue-gas mixtures. The results found that gaseous components were absorbed into the HNO3 electrolyte, and Ag (II) mediator acted as an oxidizing agent. It was also observed that remove the ready increase in the presence of SO2 and simultaneously gas/liquid and superficial liquid and gas velocity were compared to assess the flow rate effect. Daz-Somoano et al. (2007) evaluated mercury removal efficiency by the influence of different scrubber parameters using thermos-dynamical equilibrium data and laboratory test data. By modifying operational parameters such as pH and slurry can achieve the best results for converting flue gas desulphurization unit to a multi-pollutant control technology which also includes mercury level reduction. Lothgren and Van Bavel (2005) measured the dioxin levels after wet scrubbing systems which had PCDD/Fs on the plastic material and found the levels of dioxin decreased considerably. Perevezentsev et al. (2010) confirmed the high efficiency of the scrubber column for detritiation of air contaminated with tritiated water vapour and developed a simulation program that satisfactorily describes the operation of columns. Biard et al. (2009) investigated the removal of Dimethyl disulphide off columns in an original process compact scrubber which combined an advanced oxidation process. Dimethyl disulphide gas-liquid equilibrium was achieved at the end of the process leading to pollutant reduction. The flue gas cleaning system in the municipal waste incinerator temperature be subject to the absorption/desorption of the materials applied to the wet scrubbing systems. This gas can also be produced during industrial processes such as waste pyrolysis and incineration 20–22. Even though a major fraction of pollutants such as aerosols are generated by human activities originating from various industrial processes and combustion units, which pose major exposure threats for human beings. Moreover, the risk increases considerably for the habitants of urban areas due to domestic heating, diesel engines emissions and growth of industrial zones near the residential and commercial zones 23–25. Annular two-phase flow can have complications due to venture geometry which also can express as the flow of gas and water in a Venturi. The tube carries the liquid, which travels as a film laterally, to the wall and the remaining amount as gas droplets through the centre of the apparatus, which leads to a continuous exchange between the film and the droplets.
Over the years, numerous models have been proposed to achieve better results by knowing more about hydrodynamics in the scrubber, which may consist of simple correlation analysis or more complex studies such as Computational Fluid Dynamics (CFD) models 26–28. During the study, it was presumed that pressure drop across the scrubber is due to the change in the droplets momentum in the entry point of the scrubber and that there was no pressure spent due to the acceleration of the gas and friction between the wall and the core of the gas. Designing a more dynamic scrubber, for instance like flue-gas desulfurization (FGD) wet scrubber, needs an in-depth study and consideration of numerous essential factors, which may comprise the scrubber geometry, gas flow velocity of the tower, pressure changes, SO2 exclusion rate, and reagent slurry residue. The main drawback of a wet scrubber is the use of large power for operational needs which is determined by the change in pressure. It is evident from the innovative diagnostic methods like analysis of particle size and concentration in gas streams that the particulate matter produced by combustion sources are categorized as per the size of the particle, which may range from few nanometers up to several microns 29–32. From the existing emission treatment method 33, the disposal of the sludge’s and waste that comes out from the wet scrubber is more complicated. The water under the wet scrubber unit is recirculated to the scrubber continuously. So that the water gets polluted. There is a secondary pollutant formed in the water, which leads to the reduced performance of the wet scrubber. Different factors like throat diameter, its length and the pressure change in atomizers due to different cone angles were considered. Venturi connected to a holding vessel, which also acts as a phase separator, creates the whole structure for the wet scrubber. Later, Gamisans et al. (2004) studied the distribution of the liquid, geometrical effects, flow rates and the self- entrainment by a liquid jet in the ejector-venturi and suggested that similar studies should consider mass transfer theories to fully understand the liquid distribution.
Although many researchers have concentrated on addressing air pollution problems, only very few papers addressed foundry air pollution control using dust collectors 34, and it is evident that there was no sufficient contribution in addressing secondary pollution reduction in a wet scrubber. An attempt is made to reduce secondary pollution using sand filtering techniques. In practice, the disposal of water and sludge was carried out by a solar evaporation tank. The water gets vaporized by natural sunlight. After vaporization, the sludge deposited on the bottom of the solar evaporation tank were collected and disposed of safely. Since the evaporation process is possible only during daytime and hot summer periods, it is not possible to vaporize the water and collect the sludge during rainy seasons and nighttime. These problems were studied and would like to be implemented in our proposed method by replacing the solar evaporation tank with a sand filter, and a polluted water processing tank was introduced.
Section 2 validates the model of the proposed wet scrubber by introducing the concept of multi filtration zones along with porosity and zone height with different boundary conditions. Section 3 inspect the results and discuss the effectiveness of wet scrubber with proposed sand filtration tank using CFD modelling and efficiency by comparing the volume fraction. The last section summarizes all key points of the current research, its gaps, and prospective research objectives.