Global phenomenal expansion of industries and the inevitable increase in rate of urbanization due to the economic development has resulted in creation of enormous environmental challenges that have to be addressed by highly advanced scientifically based separation and filtration technologies. Recently, air and water pollution as the principle hazardous issues have raised public awareness at international scale. Thus, the implementation of rather tough legislations worldwide on control of air and water which has manifested in form of issues that has to be scientifically tackled if the human societies are to be safe guarded against consequences of the evitable industrialization and urbanization in a sustainable manner. Reduction or elimination of contaminants is involved with use of various types of filtration technologies. These vital technologies make use of filter media that are invariably fibrous such as nonwoven fabrics. Nonwoven fabrics simultaneously are soft, porous, and voluminous, with relatively high resistance to mechanical deformation. These fabrics due to their irregular internal structure are considered to be one the most effective means in general pollution control including air and water. In this study, the effect of needled nonwoven processing parameters including, needle punch density, needle penetration depth and auxiliary finishing operation i.e. thermal calendering on filtration function of needled nonwoven fabrics was investigated. In order to investigate the performance of filter media, filtration simulation apparatus was designed and the initial efficiency and pressure drop of needled media were analyzed. Moreover, 3D images of inner structure of filters were obtained using non-destructive X-ray micro-computed tomography. The effect of processing parameters on micro-structures of filter medium was evaluated. It was found that increase in needle punch density and conduct of thermal calendaring operation not only result in reduction of filter medium porosity, but also tends to increase structural uniformity of filter medium. It was established that, Nakagami distribution fits the medium most constricted pore size distribution. It was concluded that increase in the particle size enhances the initial efficiency of filter medium. Moreover, increase in fabric areal density led to higher initial filter efficiency and pressure drop. It was also found that initial efficiency of filter medium increases up to needle penetration depth of 9 mm but further increases in needle penetration beyond 9 mm tends to impair the filtration efficiency due to disintegration of the filter medium. It was observed that the thermal calendering operation results in considerable increase in initial filter efficiency.
