NATIONAL MISSION ON HIMALAYAN STUDIES CURRENT SCIENCE, VOL. 120, NO. 5, 10 MARCH 2021 809 *For correspondence. (e-mail: jaspreet@iitmandi.ac.in) Water purification and biomineralization using nanofibres-based membrane technology Manish Kumar, Siddhant Kumar, Samar Agnihotri, Bharat Singh Rajpurohit and Jaspreet Kaur Randhawa* Indian Institute of Technology Mandi, Mandi 175 005, India Population of world and industrialization are increas- ing rapidly due to which the amount of fresh water is decreasing. There is a need to promote a novel cost- effective technique to purify the contaminated water. Nanotechnology provides extraordinary nanomaterials with unique properties which can be used to purify the water. In this article the use of polymeric hybrid membranes is discussed. A novel high flux filtration hybrid membrane system, consisting of a three-layer composite with hierarchical structures, i.e. highly porous hydrophilic material coated top layer, an elec- trospun nanofibrous barrier layer in the middle; for support the bottom layer is made of nonwoven fibrous web to provide high tensile strength up to 40 MPa, more durability and high retention ratio. Keywords: Hybrid membrane, electrospinning tech- nique, nanomaterials, porous nanofibres. Introduction ACCORDING to the WHO report 1 , there are about 2.2 bil- lion people (one in three people of the world) in the world who do not have access to safe drinking water and 4.2 billion people who have lack of appropriate sanitation services. The contribution of the developing countries is more. The world is facing challenges to meet the rising demands of consumable water as the available supply of freshwater is limited as the population is increasing rapidly and distribution of water is limited for use (Figure 1). In the past two decades, excessive increase in indu- strialization has further made this situation worse. Devel- oping countries are more affected by the shortage of drinkable water because of a lack of infrastructure and an increase in population. In countries like India, whose 70% of the population live in villages, the above situation is noticeable. Lack of developed infrastructure and the poor economy are the prime reasons for this. The village areas do not have safe drinking water, electrical power, communication, sanitation and hence these issues are im- portant. In Indian villages, water is drawn from the near by river or lake for daily use such as drinking, cooking and cleaning. Heavy metals, dyes and drug pollutions present in water bodies severely affect the human body upon consumption. Also, the toxic nature of heavy metals and drugs causes damage to human and animal body or- gans. Limits of heavy metals, metalloids and transition metals in drinking water and their toxic symptoms are shown in Table 1. It is necessary to provide safe drinking water at low cost with high reliability in these areas. There is a need for the development of innovative new techniques and materials to address challenges related to safe potable water. Though new techniques are continually being examined, these need to be cost effective, highly durable and more effective than current options for the removal of contaminants from water. Nanotechnology is progressively being distinguished as a region of science and innovation that could assume a job in tending to a portion of short-comings of conven- tional purpose of-use (POU) devices. The comparison of POU water filtration techniques is shown in Table 2. Na- notechnology encompasses the creation and utilization of materials, devices and systems at the level of atoms and molecules, cutting across disciplines such as chemistry, physics, biology, engineering, and materials science. Na- nomaterials and nanostructures have nanoscale dimen- sions that range from 1 to 100 nm, and often exhibit novel and significantly changed physical, chemical and biologi- cal properties. These have a result of their structure, larger surface area per unit volume and quantum effects that occur at the nanoscale. Proponents propose that nanotechnology-based materials could prompt less expensive, more durable, and more effective water treat- ment advances that address the issues of developing countries. A few water treatment techniques and devices that incorporate nanoscale materials are as of now eco- nomically accessible, and others are being developed. These nanotechnology-based items incorporate water filters, filtration hybrid membranes, catalysts, and nano- particles for groundwater remediation. More efficient water treatment techniques are required because prevention of water pollution is not possible. Legislation also supports the use of more efficient water treatment techniques, which can lead to better purifica- tion results of waste water and the recovery of valuable compounds (minerals) from wastewaters. One filtration