Air pollution is one of the prime concerns for global warming and climate change around the world.
As per data published by World Health Organization (WHO), 30 Indian cities feature in the list of 100 most polluted global cities (in terms of particulate matter, PM10). According to a report on air quality recently published by Green Peace, out of 280 Indian cities with a population of 630 mn, 228 cities have not been complying with the annual permissible concentration of 60 µg/m³ – the limit prescribed by the Central Pollution Control Board (CPCB) under the National Ambient Air Quality Standards (NAAQS). In fact, none of the cities have been found to adhere to the standard – 20 µg/m³ – set by the WHO.
The alarming level of PM threatens the health of humans and other living beings in the planet. Supplementing the fact, layers of smog and haze that have been floating across northern India indicate that bad air is not confined to big cities alone. The urgency on deteriorating air quality should be dealt with priority as toxic air is engulfing spaces of urban and rural equally.
ADVERSE IMPACTS OF AIR POLLUTION
As per recent data from WHO, air pollution is linked to an estimated 7 mn premature deaths annually due to various diseases. The pollutants with the strongest evidence of health effects are particulate matter (PM), ozone (O3), nitrogen dioxide (NO2), sulphur dioxide (SO2) and carbon monoxide (CO). Out of all these pollutants, PM is inhalable and respirable particles that are composed of sulphate, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. Particles with a diameter of less than 10 microns (PM10), including fine particles less than 2.5 microns (PM2.5) pose the greatest risks to health, as they are capable of penetrating peoples’ lungs and entering their bloodstream. Sources of PM include combustion engines (both diesel and petrol), solid-fuel (coal, lignite, heavy oil and biomass) combustion for energy production, as well as other industrial activities (building, mining, manufacture of cement, ceramic and bricks, and smelting).
DIESEL SCENARIO IN INDIA
The chief source of pollution in automotive industry is diesel. India’s average monthly diesel consumption has increased from 6.4 mn tonne in 2016 to 6.6 mn tonne in 2017, indicating a 3.1 % growth year-on-year. The transport sector accounts for 70 % of total diesel sales, . Of this, cars, utility vehicles and three-wheelers consume the highest amount of diesel at 28.48 %, while trucks (HCV/ LCV) and buses account for 28.25 % and 9.55 % of diesel respectively. Railways, on the other hand, consume about 3.24 % of the total diesel in the transport sector. The 13 % share of diesel consumed by the agriculture sector includes tractors (7.4 %), pump-sets (2.9 %) and agriculture implements (2.7 %). Tractors have a higher consumption presumably because they are also used for non-agricultural purposes like transportation of construction material such as bricks, stones, mined sand, etc. and for transporting people in rural areas.
CONTROL SYSTEM FOR DIESEL ENGINE
To reduce pollutant emission from vehicles, several studies have been carried out for decades with focus on engine modifications, electronic controlled fuel injections systems, and improvement of fuel properties. However, these measures have failed to achieve emission reduction as per standards. The desired emission levels can be achieved only by means of emission control systems. Vehicles are equipped with emission control systems to meet the actual emissions standards. The emission control systems for present diesel engine are Diesel Oxidation Catalyst (DOC) to control CO, and HC emissions, Diesel Particulate Filter (DPF) to control PM emissions and Selective Catalytic Reduction (SCR) to control NOx emissions. Much iteration of changes in the designing is still on for achieving 100 % efficiency.
MEETING FUEL STANDARDS
The Government of India has laid the foundation towards introduction of stricter emission regulations in the country. The changeover to BS VI norms will require significant engine technology changes, including improvements in engine combustion and calibration, increased injection and cylinder pressures, NOx and PM aftertreatment solutions and transitioning to electronic controls.
Currently, BS IV norms are applicable in 13 major cities of the country, while BS III norms are applicable elsewhere. As per Auto Fuel Policy 2025, BS IV roll out was envisaged for the entire country by 2017, BS V by 2021 and BS VI by 2024. However, the government has put forth an ambitious target of transitioning from BS IV norms to BS VI, skipping BS V completely. This will bring down NOx emissions by 25 % in petrol engine vehicles, and by 68 % in diesel engine vehicles. PM emissions, a major component of outdoor air pollution, are also expected to come down drastically by over 80 % in diesel engine vehicles.
TECH START-UPs ADDRESSING PM
It is the need of the hour to develop new, clean and efficient technologies for this specific sector to check air pollution. Under the benefits reaped from the banner of “Make in India” and “Startup India”, two Indian start-ups – Graviky Labs and Chakr Innovation – are playing considerable role in developing world class clean technologies to address the issue related to PM emission, thus checking air pollution before it enters the atmosphere. They have developed unique efficient technologies to capture and process PM to the extent of 85-95 %, to produce eco-friendly inks, markers, sprays, and paints.
Graviky Labs Private Limited has developed a post tailpipe retrofit device called KAALINK™, which is a patent pending technology used to capture PM from vehicle emission, which is then processed to make proprietary ink AIR-INK. The device consists of filters, sensors and a capture unit. The capture technique is a fusion of electrostatic filtration, depth filtration and wall flow filtration. KAALINK™ is currently designed to fit into diesel generators, small chimney stacks, biogas burning chimneys, fleet of car and buses.
After capturing air-pollution through KAALINK™, it undergoes various proprietary processes to remove heavy metals and carcinogens. During the final stage, the carbon is taken through another chemical process, where heavy metals dealing with carcinogens are removed, and then optimised further for development of variety of inks and paints. The company claims 45 min of car emissions could produce 30 ml of ink.
The company aims to deliver the retrofit technology by collaborating with owners of diesel bus fleets – a primary source of pollution. They have received worldwide recognition for this novel innovation, and their proprietary ink is being used by artists and painters around the world. Graviky has created several grades of Air-Ink for different applications: markers with 2 mm and 15 mm round tips, 30 mm and 50 mm chisel tips, along with screen printing ink. Till date, the device is claimed to have captured and recycled 1.6 bn μg (microgram) of PM, equating to roughly 1.6 tn l of outdoor air.
Chakr Innovation Private Limited plays a major role in capturing air pollution generated from diesel generators, boilers, industrial furnaces and chimneys. Started by alumni of IIT Delhi, this start-up has developed a unique solution to address the problem. They have developed a patent pending solvent based technology by the name Chakr Shield, which captures air pollution i.e. the PM (soot) from DG generators before it enters the atmosphere.
The device designed by the company can be coupled with the exhausts of diesel engine generators and chimneys of industries, and can absorb more than 90 % of the PM that is being emitted by the generator. The device is composed of a heat exchanger, which reduces the temperature of the exhaust without consuming any energy. The cooled exhaust is passed through a chamber, where the PM is made to clot and is ultimately captured. This captured carbon is washed down by an engineered solvent, which holds the soot without chemically reacting with it. This soot containing solution is then processed as ink pigment. The device continues to collect PM, which is separated from the device once its concentration reaches a predefined value. The process of separation has also been patented by Chakr.
The separated PM can be used as a raw material in the ink industry (black pigment), textile industry (textile printing) and in the automobile tyre industry (pigment and reinforcing phase). Their proprietary ink name is Poink. Presently running at 35 different sites, Chakr Shield’s proprietary hardware technology has been able to capture more than 300 kg of PM till last year, which would have otherwise polluted 1,500 bn l of air.
WAY FORWARD – TRADE THE POLLUTANT & CREATE REVENUE
There are many Indian start-ups, who may play a significant role in reducing air pollution, if the technologies are recognised and utilised properly. Their innovative technologies for processing PM (soot) not only clean and filter the system but have created a unique business model and a competitive market for their ink products. Literally, these start-ups have generated revenue out of carbon particulate (pollutant) to produce some great inks and paints, which can add value to the society – thus cleaning the air we breathe. These start-ups, and their technologies, must be encouraged.
 Green Peace Report – Airpocalypse II (Assessment of Air Pollution in Indian Cities) Published on January 2018;
 WHO Air Pollution database;
 WHO Global Urban Ambient Air Pollution Database (update 2016);
 AUTO FUEL VISION AND POLICY 2025, REPORT OF THE EXPERT COMMITTEE (Ministry of Petroleum);
 Press release report on Estimates on Indoor and Outdoor Air Pollution by WHO;
 All India Study on Sectoral Demand of Diesel & Petrol ,Study conducted by M/s Nielsen (India) Pvt Ltd for Petroleum Planning and Analysis Cell (PPAC) of Petroleum Ministry;
 Measures to Control Air Pollution in Urban Centres of India: Policy and Institutional framework by TERI;
 The pollutant emissions from diesel-engine vehicles and exhaust after treatment systems (İbrahim Aslan Reşitoğlu, Kemal Altinişik Ali Keskin);
 Diesel emissions and their control (Khair MK, Majewski WA (2006));
SUJATHA RAMASAMY is Scientist B at TIFAC, an Autonomous body of the Department of Science and Technology, Government of India in New Delhi (India).
PULAK RANJAN BASAK is Scientist F at TIFAC, an Autonomous body of the Department of Science and Technology, Government of India in New Delhi (India).
SRIKANTA PRIYADARSHAN PATRA is Project Associate at TIFAC, an Autonomous body of the Department of Science and Technology, Government of India in New Delhi (India).