Author – Sumedh Mool
Enthusiastic students from across the various campuses of Indian Institutes of Technology (IIT) have developed environment-friendly projects that are both economic and easy to use. We had earlier showcased some path-breaking innovations that took their first steps at IIT campuses. In continuation, we are presenting a few more eco-friendly innovations emerging from the young minds of IITs – a novel water purification process that uses nanotechnology to provide affordable drinking water, a microbial fuel cell technology that generates power from sewage and a UNICEF-supported project for the development of zero disposable toilets,
Affordable Nano-particle Water Filter – IIT Madras
Water is a universal solvent that absorbs all kinds of materials including chemical contaminants such as metal ions, organic dyes, insecticides, pesticides, etc. Contaminated water contains dangerous impurities that are extremely small or even microscopic, and need molecular level or ultra-trace level purification processes in order to be removed. Considering this, a group of students led by Professor T Pradeep, from the Department of Chemistry at IIT Madras have used metal/metal oxide nanoparticles to design a filter for drinking water purification. This approach can help fight contaminants such as halogenated organics including pesticides, heavy metals such as arsenic, as well as microorganisms.
Currently, different techniques such as adsorption, membrane filtration, ion exchange etc., are available for water purification. However, nano-materials have proven to be extremely effective to purify a wide range of contaminants and relatively cheap adsorbents for water purification, due to large surface area, easy surface modification and selective catalytic activity.
The proposed technique involves a two-step purification process: the purifier first removes the microbial contaminants, through the help of the silver nanoparticles in the purifier (AgNps) release a very low concentration of silver ions (nearly 50 parts per billion) to kill microbes present in the water. Meanwhile, followed by chemical contaminants such as arsenic, lead, iron and others are selectively removed with the help of multiple combinations of metal nanoparticles. The water, thus obtained, is safe for consumption since the silver ion concentration is found to be lower than the permissible level of 100ppb.
This low cost water purifier costs just about INR500, while the replacement cartridge is priced at INR120 per annum. A larger version of the nanoparticle purifier has a capacity to purify around 18,000 litres of water per hour to cater to nearly 50,000 people. Prof. T Pradeep feels the filter has the potential to double the number of people who can avail safe drinking water over the long-run.
Microbial Fuel Cells to Treat Sewage – IIT Kharagpur
Microbial fuel cells are relatively new type of cells that use bacterial activity to generate electricity. Bacteria feeds on sewage water and in the process generates free electrons, which are harnessed to produce electricity. A lot of research is being done on microbial fuel cells given that it is a non-exhaustible source of energy. However, the electricity generated from a single fuel cell is meager. Understanding this, Manoj Kumar Mandelia, Prateek Kumar Jain and Mohan Yama of IIT Kharagpur have integrated this microbial fuel cell technology with sewage treatment systems to treat waste water and generate electricity simultaneously.
The project, named as LOCUS (Localized Operation Of Bio-Cells Using Sewage), can reduce the chemical oxygen demand (COD) in waste water by 60-80%. Microbial fuel cells are unique in their ability to utilize microorganisms, rather than an enzyme or inorganic molecule, as catalysts to convert chemical energy of feedstock directly into electricity. The LOCUS fuel cell has two compartments – one for the delivery and distribution of power and the other to take care of large, solid particles that enter the microbial fuel cell. The method could result in the generation of both fresh water and energy. The project is currently in the lab testing phase and on the verge of being commercialized with the help of Canopus India.
Zero Water Waste Toilets – IIT Kanpur
The Swacch Bharat Mission has placed the emphasis on having clean toilets across India, availability of water is a major issue. Professor Vinod Tare from IIT Kanpur and his students have come up with an idea to reduce water wastage in toilets. Generally, a single flush consumes 3-5 liters of water. In this regard, the concept of dry sanitation has come into picture, but not many people have come forward with any out-of-the-box innovations.
The IIT Kanpur team has innovated a mechanism where the vortex movement of water cleans the pan surface when the toilet is flushed and pushes the solid waste downwards into a tank located at the center. While the centrifugal force acting outward from a centre of rotation presses the water to the surface of the pan, the geometric design of the surface guides it through a circular path downward toward the separator. At the separator level, the water is guided into pipes across the sides and into another tank, which ensures close to 99% separation. The pipes are fitted with micro-filters made up of high-quality poly vinyl chloride to clean the liquid. Smell traps are fitted in pipes and tanks to ensure that the toilet does not stink.
The solid waste thus collected can be used for making compost, while the filtered water is sent to an overhead tank for storage purpose. In community toilets, the water can be sent to an overhead tank using a hand pump instead of electricity. However, it would be required to pump twice or thrice a day. These toilets are not only eco-friendly but also economic. The micro filters cost just INR100 and last for at least a year, while building a basic toilet would cost just around INR8000. This mechanism is being used by UNICEF on a trial basis in community toilets.