In recent years, there has been a sizable growth in Indian urbanization. The country had 377 million residents in urban areas in 2011. Since then, there has been continuous increase in the migration of rural population to major urban centres in search of jobs and better living conditions. The Economic Survey of the Government of India indicates the urban population will reach 600 million by 2030 [1]. Another estimate by the International Energy Agency (IEA) shows that the urban population would further increase to 760 million by 2040 [2].
A large influx of rural population to urban centres creates several economic and social challenges in terms of creating new physical infrastructure facilities such as housing, schools/colleges, hospitals, water supply and sanitation provisions, etc. for the new entrants to the urban areas. The local authorities and the state and the central governments are taking certain measures to meet these challenges. However, satisfactory progress is not being witnessed in tackling another challenge related to the effective management of the growing household waste created by the increasing population in urban areas. Most of the solid waste currently gets dumped mostly without primary treatment such as segregation and physical separation at nearby dumping sites. As a result, there has been a huge accumulation of solid waste at different dumping sites in India, which could be a potential health hazard, especially for people staying in the vicinity of these sites
A recent circular from the Ministry of Road Transport & Highways (MoRTH) reveals that nearly 10,000 hectares of land in the country is locked in dump sites [3]. The circular states that under the Swatch Bharat Mission Urban (SBM2.0), launched by the Ministry of Housing and Urban Affairs, solid waste sites and availability of waste material in the urban areas have been mapped and is available at their website https://sbmurban.org/swatch-bharat-mission-progress. The data from this website reveals that around 1,700 lakh tonnes (170 million tonnes) of solid waste was accumulated as on December 2023 across 2,304 dump sites in the country. A huge amount of waste indeed!
It is reported that the MoRTH undertook two pilot projects for the utilization of insert material from the solid waste in road embankment. The first pilot project was carried out at the Urban Extension road and DND Sohnaspur on Delhi-Mumbai expressway and the second on the Ahmedabad-Dholera expressway. In both projects, the use of inert material from solid waste proved successful.
Based on the experience gained in the two pilot projects, the MoRTH prepared guidelines for the use of inert solid waste in the embankment works under NHAI/MoRTH [3]. The guidelines mention that the responsibility of segregation and physical separation of the solid waste rests with the local municipal corporations. Further, the responsibility of carrying out the quality control (through accredited third-party labs) at the land-fill sites also rests with the local bodies.
While we heartily welcome the initiative of MoRTH to utilize inert solid waste in the construction embankments of National Highways, it would be appropriate to extend this initiative to the embankment construction on State Highways and Major District Roads in different states of India.
Incidentally, it is also high time that different municipal corporations and metropolitan authorities look into the issue of scientifically treating the solid waste and converting it into useful products. This issue needs urgent attention by local municipal/metropolitan authorities.
In this context, we would like to draw attention to a recent review paper that provides detailed information on different techniques used for conversion of municipal solid waste into useful products [4]. The author of the paper has divided the treatment of solid waste is into three broad categories, namely, thermal conversion, biological conversion and landfilling. (see Fig 1).
Fig 1 Different solid waste techniques and their products [4]
Three categories under the thermal conversion process can lead to the generation of energy/electricity, which is indeed an attractive by-product that will certainly go a long way in easing the energy demands of the rising population.
The first category under thermal conversion includes incineration which provides heat/steam, which in turn could be converted into energy/electricity. The second category includes gasification which can result in the production on Syngas (a mixture of hydrogen and carbon monoxide gases) which can be used as a clean alternative to fossil fuels in generating electricity or for the production of liquid fuels such as synthetic diesel, dimethyl ether, methanol, etc. The third category includes pyrolysis process, which can generate biofuel on the one hand and biochar on the other. Biofuels can be used as transportation fuels and also for heating and electricity generation. Biochar is a waste product from the pyrolysis process, which has a great potential to be used as a tool for carbon sequestration, either as a supplement for improvement of soil productivity or as an additive to cement/concrete. Considering the potential of biochar as a carbon sequestration tool, the use of biochar has recently attracted the attention of researchers and entrepreneurs.
Under the biological conversion process, two options are available – aerobic composting and anaerobic digestion. While aerobic conversion can produce compost that can be used as a nutrient for soil, the anaerobic digestion can produce biogas which could be used as a fuel for electrical energy.
Finally, whatever cannot be converted either through thermal and biological conversions, the same can then be sent for land filling.
From the above discussion, it is thus clear that solid municipal waste is not just a waste, but it has a potential to provide useful by-products. The “Waste to Energy” option is indeed attractive. We are aware that capital investments are essential for the conversion of solid waste into energy. However, considering the fact that the by-products of conversion can partly offset the initial investment costs, the conversion options may ultimately prove economically viable and socially desirable. Furthermore, carbon sequestration is an additional bonus!
References
- Economic Survey 2020-21: Volume 2. Department of Economic Affairs, Ministry of Finance, Government of India.
- India Energy Outlook 2021; International Energy Agency (IEA)
- Policy Guidelines on Use of Inert material in Construction of National Highways, Circular from Ministry of Road Transport & Highways, December 27, 2023
- Atul Kumar, S R Samadder, A review on technological options of waste to energy for effective management of municipal solid waste, Waste Management (2017),
http://dx.doi.org/10.1016/j.wasman.2017.08.046