Authors: Dr. Muhammad Nasrullah, Tiina Piira
Next time we come across any type of waste material, let’s think, could this be prevented or minimized in the first place? – if yes, how? Does it still contain any value? – if yes, how it can be recovered in the best possible efficient manner? What will be the effect of its disposing method on the environment and living beings?
Currently, about 5 % of global greenhouse gas (GHG) emissions are generated by the solid waste management sector.Kaza et al.
The estimated amount of municipal solid waste (MSW) generated globally in 2016 was 2.01 billion tonnes which is expected to grow to 3.40 billion tonnes in 2050. In South Asia, Sub-Saharan Africa, and the Middle East & North Africa of the total MSW generated in these Regions 75%, 69%, and 52.7%, respectively, ends up in open dumps. In Latin America & Caribbean, North America and East Asia & Pacific of the total MSW generated in these Regions 68.5%, 54.3%, and 46% respectively is transferred to landfills. Currently, about 5 % of global greenhouse gas (GHG) emissions are generated by the solid waste management sector . Open dumps of MSW are considered as a potential source of methane emissions into the atmosphere and deteriorating groundwater quality through contaminated leachate.
Waste Hierarchy and to shift from Linear Economy to Circular Economy are among the major approaches that need to be followed more effectively to achieve proper waste management and recovery of value from waste. Figure-1 shows both the mentioned approaches.
RDF/SRF is a mixture of waste components (paper, cardboard, plastic, textile, etc.) having a high calorific value which is used as fuel for incineration process (pyrolysis/gasification/combustion) producing energy (electricity, heat) or transportation fuel by integrating the incineration process with Fischer-Tropsch process.
Waste can potentially be considered as raw material and source of valuables such as energy (electricity, heat), fuel (transportation oil/compressed natural gas/liquefied natural gas), and recyclables (metal, glass, aggregates as construction material, biofertilizer, and other components). Mixed solid waste or un-sorted MSW generally consists of components such as biowaste (kitchen/yard waste), paper & cardboard, plastic, textile, metal (ferrous/non-ferrous), and inert (soil, concrete, stone, bricks, etc.).
For mixed waste or unsorted MSW, integrated mechanical-biological and incineration based solution is among the prime routes.
Circular Economy based Waste to Value solution provides a highly efficient and environmentally sound option for proper waste management by recovering the maximum value out of waste. For mixed waste or unsorted MSW, integrated mechanical-biological and incineration based solution is among the prime routes providing an option for proper waste management by recovering the maximum value out of it. In mechanical treatment/sorting operations, the input MSW is segregated into different streams of material like:
- Biowaste (kitchen waste with high moisture content)
- Combustible i.e. refuse-derived fuel (RDF)/solid recovered fuel (SRF)
- Recyclable (metal, glass, and other components)
- Inert fraction (soil, sand, stone, etc.)
- Reject material (hazardous/contaminated fraction)
The segregated streams of material are treated in their respective processes to get the maximum value out of these. In the mentioned Circular Economy based Waste to Value solution, biowaste stream is processed anaerobically in biogas (containing methane) production plant. Biogas is utilized for energy (electricity, heat) or transportation fuel (CNG/LNG) production. The digestate obtained after biogas production is transferred to biofertilizer. RDF/SRF is a mixture of waste components (paper, cardboard, plastic, textile, etc.) having a high calorific value which is used as fuel for incineration process (pyrolysis/gasification/combustion) producing energy (electricity, heat) or transportation fuel by integrating the incineration process with Fischer-Tropsch process.
Ash produced as a result of incineration of solid fuel can be utilized as a construction material with some specific/dedicated applications. Stream of recyclable material (metal, glass, or some other components) are recycled to their respective industries. Stream of the inert fraction (soil, sand, stone etc.) is processed (further sorting if needed, grinding/crushing and mixing/homogenizing) to be transformed as construction material with specific/dedicated applications. The reject material (hazardous/contaminated fraction) is disposed to properly managed landfill of respective material. A simplified diagram of Waste to Value transformation is shown in Figure 2.
Mindset change of society towards waste can be very relevant in achieving the goals of proper waste management set at National and International levels. At the same time, this provides an opportunity and option to recover the maximum possible value out of waste. There are multiple social benefits of proper waste management such as clean cities, clean environment (air and groundwater quality) socio-economic activities, alternative sources of energy, and reduction in greenhouse gases. Proper waste management may also affect positively to certain areas such as reducing the burden on the National healthcare system and improving tourism-related activities in society.
 Silpa Kaza, Lisa Yao, Perinaz Bhada-Tata, and Frank Van Woerden. What a Waste 2.0 A Global Snapshot of Solid Waste Management to 2050. World Bank Group. Available at: https://openknowledge.worldbank.org/handle/10986/30317.
 Directive 2012/18/EU of the European Parliament and of the Council of 4 July 2012 on the control of major-accident hazards involving dangerous substances, amending and subsequently repealing Council Directive 96/82/EC.
 Elisabeth Unterfrauner, Christian Voigt, Maria Schrammel and Massimo Menichinelli. The Maker Movement and the Disruption of the Producer-Consumer Relation. DOI: 10.1007/978-3-319-77547-0_9.