CHAPTER 2: LITERATURE REVIEW
6. INSTITUTIONAL FRAMEWORK FOR WASTE MANAGEMENT AT MUNICIPALITIES IN SOUTH AFRICA . 145
6.6 Assessment of Waste Treatment Technologies
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Alternative 6, incineration, offers the best technology in terms of waste to energy options in respect of reducing methane gas emissions - it also provides an alternative energy source. The difficulty with this alternative is that waste practitioners are not familiar with this technology. Procurement to acquire it is a long and tedious process.
The Table 6- 1 below assesses the alternatives listed above and current practice in the case studies presented in earlier chapters.
Potential of Waste Technology
Waste Technology Deonar: Mumbai Current
Practice 5 4 3 2 1
YES NO
Alternative 1 Landfilling X
Alternative 2 MRF at the Landfill X X
Alternative 3 An MRF and Composting
Treatment X X
Alternative 4 An MRF and AD of the
Organic Waste X X
Alternative 5 MRF, MBT and RDF X X
Alternative 6 Incineration and WTE X X
Potential of Waste technology
Waste Technology Newcastle: South
Africa Current
Practice 5 4 3 2 1
YES NO
Alternative 1 Landfilling X
Alternative 2 MRF at the Landfill X X
Alternative 3 An MRF or Composting
Treatment X X
Alternative 4 An MRF and AD of the
Organic Waste X X
Alternative 5 MRF, MBT and RDF X X
Alternative 6 Incineration and WTE X X
The assessment outlines the various scenarios for waste management based on the case studies of Deonar in Mumbai and Newcastle South Africa as well as the literature review and key informant interviews. The MRFs, Anaerobic Digestion, Composting and Landfill Gas to Energy are the potential waste technologies that are mainly under consideration.
158 Table 6- 2 The four alternatives are unpacked in four scenarios:
Scenario Scenario Titles Brief Description
1 MRFs and Composting Waste recyclables are sorted, where most inorganic waste is removed from a clean or dirty MRF and the organic matter is composted e.g., garden waste, wood waste. It is impossible to obtain good recyclable material without separated collection at source will never produce an agronomic compost because too many impurities; the same for paper, it will never be of good quality to be recycled as secondary raw material to produce new paper.
2 MRF and Anaerobic
Digestion
Waste is sorted in organic and inorganic fractions. The inorganic fraction is diverted from landfill for recycling and the organic matter is anaerobically digested.
3 Landfilling and LFGTE All waste is sent to a landfill. Methane gas is extracted and converted as an energy source from the organic fraction of the MSW.
4 MRF and
Gasification/Pyrolysis
Waste such as metal and glass are removed from the waste stream, all other waste is placed into a waste bin, syngas is extracted and converted into electricity.
Scenario 1: MRF and Composting
Waste is either collected from households, through daily door to door collection which was the case in Mumbai. In South Africa, waste is collected once a week from the curbside of households and taken to a transfer station or a landfill. Depending on the distance, waste is transported to a MRF at a Waste Transfer Station or to a landfill site.
Recyclable material, such as plastic, paper and cardboard, glass and metals is diverted from the waste stream and sold to potential reclaimers for recycling or to make new products. The organic waste fraction is diverted for composting on the landfill site. There is mixed waste in the compost due to inefficiency in sorting and removing all inorganic waste from the waste stream.
159 Scenario 1:
Figure 6- 7 Schematic layout of Scenario 1
Scenario 2: Material Recovery Facility and Anaerobic Digestion
Waste is collected either from the curbside of households or through daily to-to door collection and transported to a transfer station then, to a MRF. The MRF will recover the recyclable inorganic fraction. The organic fraction is sent to the Anaerobic Digestion Plant site to generate methane gas for electricity production. The digestate will be utilized for fertilizer from the nutrient recovery.
Mumbai Newcastle
Daily door-to-door collection
Transfer station
Kerbside collection of Mixed Municipal Solid Waste
Material Recovery Facility
Inorganic/Recyclable Fraction of Municipal Solid Waste
Organic Fraction of Municipal Solid Waste
Residue Waste from the inorganic and non-recyclable waste
Plastic, Metal, Glass, Paper/Cardboard, for reprocessing - new product
Aerobic Composting
Compost
Landfill
160 Figure 6- 8 Schematic layout of Scenario 2
Scenario 3
Scenario 3 outlines waste management technologies that are implemented at Gorai Landfill site in Mumbai, India and at Marainnhill and Bisasar landfills in South Africa. Waste is collected and taken either to a transfer station or directly to a landfill site. The inorganic fraction of waste is not recovered. Waste in Gorai, Marainhill and Bisasar are landfilled. There is extraction of LFG to electricity.
Mumbai Newcastle
Daily door-to-door collection
Transfer station
Kerbside collection of Mixed Municipal Solid Waste
Material Recovery Facility
Inorganic/Recyclable Fraction of Municipal Solid Waste
Organic Fraction of Municipal Solid Waste
Residue Waste from the inorganic and non-recyclable waste
Plastic, Metal, Glass, Paper/Cardboard, for
reprocessing- new product Anaerobic Digestion
Landfill
Extraction of Biogas for Electricity Generation Digestrate - Fertiliser
161 Figure 6- 9 Schematic layout of Scenario 3
Scenario 4
In Scenario 4, waste is collected either from weekly curbside collection from households or daily door-to-door collection and transported to a waste transfer station and an MRF which is nearby or on a landfill site. Recyclable material such as plastic, glass, metal and paper is recovered. The rest of the waste which is organic, inert and some inorganic waste that cannot be recycled are fed into a gasification unit under anaerobic conditions. Energy is then recovered. Gasification is considered an expensive treatment process. It has environmental benefits and it an option for municipalities. It can be modified to handle waste streams according to the size and classification of the municipality. These technologies are usually funded to developing countries by funders from the developed countries. Some setbacks are tipping fees (often dollars and pounds) for receiving of waste as municipalities would usually landfill far exceeds the costs of collection and disposal of waste. The currencies of developing countries are usually weak and would not be able to sustain the tipping fees.
Mumbai Newcastle
Daily door-to-door collection
Transfer station
Curbside collection of Mixed Municipal Solid Waste
Land fill site
LFGTE
162 All other Municipal Solid Waste
Figure 6- 10 Schematic layout of Scenario 4
The scenario analysis clearly depicts the waste technologies and the current status quo of Mumbai, India and in South Africa. Scenarios 1 and 2 are referred to mechanical biological treatment, with a material recovery facility with mechanical sorting. They also provide for biological treatment such as composting and anaerobic digestion.
Scenarios 3 and 4 offer energy recovery opportunities. Scenarios 1-3 waste is still being landfilled, however with Scenario 4, there is no need for landfilling. Construction and demolition material can be pulverized and reused as subbase material for construction. The following section unpacks the process or roadmap for energy recovery projects.