Delhi’s pollution is making news headlines all over the world. Its air, water and land are highly polluted causing a lot of harm to millions of people living in and around the city. According to the World Health Organisation (WHO), the quality of air in Delhi is among the worst in 1650 world cities.
The millions of vehicles using petrol and diesel and releasing a colossal amount of poisonous gases, the road dust, the carbon particles and gases released during the burning of organic municipal waste and particularly stubble of adjacent agricultural lands have resulted in high air pollution. The air quality index (AQI) of Delhi particularly during October to December becomes very severe ranging from 400 – 500 and more.
This causes great harm to the people living in the city, damaging the lungs of more than 2.2 million people including children. It has been reported that the degree of pollution due to vehicular emission, dust and industries including power plants is 41%, 21.5% and 18% respectively.
For example, in November 2017, during the great smog of Delhi, the air pollution became far beyond the acceptable levels and the levels of particulate matter (PM) rose to 999 mg per cubic meter, whereas the safe limits are 60 and 100 respectively.
Besides the burning of stubble, the animals, and other agricultural activities in and around Delhi also contribute significantly to the air pollution of the city. Because of high atmospheric pollution, a large number of people in Delhi suffer from diseases like cancer, asthma etc. In view of this, health experts advise the residents to wear masks and stay indoors as long as possible as a general practice. However, the outdoor poor air quality also has an impact on indoor air quality.
The water bodies in and around Delhi are equally polluted. The river Yamuna is the main source of water in Delhi but is highly polluted and even has froth. About nineteen major drains in Delhi flow into the river contributing to 96% of its pollution.
It is estimated that 3260 million liters of wastewater is generated including 218 million liters per day (mld) from the industrial sector. Very small amounts of the total sewerage before discharging into the rivers is treated. The annual average discharge through drains into river Yamuna in 2003 was around 3267 mld and the average pollution load in terms of Biological Oxygen Demand (BOD) was 243 tons per day.
In view of this, the water quality in Delhi is questionable. It has been found that discharge of untreated sewage is the single most important source of pollution of ground as well as surface water. Polluted water in Delhi has become the main cause of various water-borne diseases like diarrhea, dysentery etc.
In addition to air and water pollution, land pollution is also very severe. Delhi generates about 8,700 tons of solid waste per day, including organic waste, construction waste, metal scraps, broken glasses, plastics etc. Most of this solid waste is dumped in open areas in and around Delhi. This waste is not segregated and it seems there are no notified municipal waste rules for proper segregation. It is reported that 50% of this waste is organic in nature, 30% is metal scraps, broken glasses, plastics etc. and the rest 20% is roads and building construction waste.
In view of the present situation of mismanagement of solid and liquid waste along with heavy air pollution, it is essential that the authorities should streamline management to make Delhi pollution-free.
To bring down the pollution level in the atmosphere, it is important to use renewable energy harnessed from sun, wind and biomass as well as hydropower. In the transport system, efforts should be made to utilise as much as possible, renewable energy converted to electrical energy and also CNG in place of the polluting diesel and petrol.
Further, biomass like organic waste, stubble etc can be utilised to produce bio energy. There are two well-known processes for conversion of biomass into biofuels – thermo- chemical and bio-chemical processes and both are techno economically viable. As solid organic municipal wastes, agricultural waste including stubble is available in large quantities, they can be subjected to either of the processes. The thermo-chemical process includes combustion, gasification and pyrolysis, whereas the bio-chemical process includes anaerobic digestion and fermentation. The municipal solid organic waste, sludge of sewerage water obtained after treatment and agricultural wastes are huge in quantity. These can produce large amounts of renewable energy. It may be mentioned here that, one ton of dry biomass can produce 85 kwh of electricity or 189 liters of bio-fuel.
In Delhi, the municipal solid wastes rules like segregation of waste at the source should be mandatory. If it is done properly, at least 50% of waste which is organic in nature can be used to produce renewable energy by the above processes, 30% of the wastes which are metal scraps, plastic, glasses, waste paper etc. can be sold for recycling to the respective industries and the rest 20% which is mostly the waste generated due to roads and building repair and constructions should be used for landfilling.
There are 30 sewerage treatment plants in Delhi with a total treatment capacity of 2030 million litres per day. However, it is reported that most of these do not perform satisfactorily due to various operational problems. All over the world, sewage treatment is carried out in three stages – activated sludge process, chlorination and filtration. Similar technology should be adopted in Delhi to treat sewage. After removing the solid materials from the sewage, the treated water can either be let out into river Yamuna or used for purposes like gardening, landscape development, road washing etc.
Heavy pollution of air, water and land in and around Delhi is causing a lot of harm to the people living in the city and surrounding areas. In view of this, the following programmes should be urgently carried out to keep the city environmentally clean and making it suitable for healthy living.
- It is essential to have a transport system run on electricity and biofuels as much as possible. The industries in and around the city should take measures to treat their fuel gases before letting these out and should dispose of solid wastes and wastewater after proper treatment.
- Efforts should be made to treat the city sewage water, remove the sludge from it for producing compost and biogas and let out the clean water to the river or utilise it for gardening, road washing etc.
- All municipal solid wastes should be processed at the source to separate organic waste, recyclable materials like metal scraps, broken glasses, plastics, etc. and the rest of the waste like rejects of building and roads construction. Organic material should be subjected to anaerobic digestion for producing methane gas and organic compost. Recyclable material can be sold to the respective industries and the rest of the solid wastes can be used for landfilling the low-lying areas.
- At suitable sites in the outskirts of Delhi the organic municipal solid wastes, the sludge of sewage and stubble and other agricultural wastes should be subjected to anaerobic digestion to produce large amounts of fuel gas and manure. The technology being simple large-scale units of these can be set up easily. One ton of dry organic waste can produce 800 cubic meters of fuel gas and 400 kg of organic manure. The authorities can earn a lot of money by selling these two essential items to the users in and around Delhi.
- Delhi and nearby areas should be kept green by planting a large number of trees like Neem, Karanj, mango, etc. in the vacant places and roadsides. The Aravali green ecological corridor along Aravali range from Gujarat to Delhi connecting Shivalik hill range as planned earlier should be made green by planting these trees which will help in combating air pollution to a great extent and also help to increase the groundwater resource.
These programmes should be planned scientifically and implemented seriously under the supervision of a high power expert committee as early as possible. This way, a clean national capital will be a model for all state capitals and other cities in the country.