There is no sufficient information on the performance of India’s MSW composting facilities.
The composition of urban Muncipal Solid Waste in India is 51% organics, 17.5% recyclables (paper, plastic,
metal, and glass) and 31 % of inerts .The moisture content of urban MSW is 47% and
the average calorific value is 7.3 MJ/kg (1745 kcal/kg).important observation made during this study is that the compost yield from
mixed waste composting facilities (MBTs) is only 6-7% of the feed material. Up to 60% of the
input waste is discarded as composting rejects and landfilled (Figure 28); the rest consists of
water vapor and carbon dioxide generated during the composting processes.
The compost
product from mixed wastes was found to be of very low quality and contaminated by heavy
metals (Figure 30). The majority of the mixed waste compost samples fell below the quality
control standards for total potassium, total organic carbon, total phosphorus and moisture
content; and exceeded the quality control limits for heavy metals (lead, Pb, and chromium, Cr).
If all MSW generated in India in the next decade were to be composted as mixed waste and
used for agriculture, it would introduce 73,000 tons of heavy metals into agricultural soils .
Big cities collect about 70 - 90% of MSW generated, whereas smaller cities and towns collect
less than 50% of waste generated. More than 91% of the MSW collected formally is landfilled
on open lands and dumps .
MSW components Materials
Recycling and composting efficiency are greatly reduced due to the general absence of source separation. Absence of source separation also strikes centralized aerobic or anaerobic digestion processes off the list. Anaerobic digestion is highly sensitive to feed quality and any impurity can upset the entire plant. Aerobic digestion leads to heavy metals leaching into the final compost due to presence of impurities and makes it unfit for use on agricultural soils.
AEROBIC COMPOSTING:
source separated organic wastes can be composted and the compost obtained can be
used as an organic fertilizer on agricultural fields. Organic compost is rich in plant macro
nutrients like Nitrogen, Phosphorous and Potassium, and other essential micro
nutrients. Advantages of using organic manure in agriculture are well established and are a
part of public knowledge.
United Nations Environment Program (UNEP) defines composting as the biological decomposition of biodegradable solid waste underpredominantly aerobic conditions to a state that is sufficiently stable for nuisance-free storage and handling and is satisfactorily matured for safe use in agriculture. Composting can also be defined as human intervention into the natural process of decomposition as noted by Cornell Waste Management Institute. The biological decomposition accomplished by microbes during the process involves oxidation of carbon present in the organic waste. Energy released during oxidation is the cause for rise in temperatures in windrows during composting. Due to this energy loss, aerobic composting falls below anaerobic composting on the hierarchy of waste management.
ANAEROBIC DIGESTION:
The USEPA defines Anaerobic Digestion (AD) as a process where microorganisms break down organic materials, such as food scraps, manure and sewage sludge, in the absence of oxygen. In the context of SWM, anaerobic digestion (also called Anaerobic Composting or
Biomethanation) is a method to treat source separated organic waste to recover energy in the form of biogas, and compost in the form of a liquid residual. Biogas consists of methane and carbon dioxide and can be used as fuel or, by using a generator it can be converted to electricity on-site. The liquid slurry can be used as organic fertilizer. The ability to recover energy and compost from organics puts AD above aerobic composting on the hierarchy of waste management.
WASTE-TO-ENERGY COMBUSTION (WTE):
Waste-to-Energy combustion (WTE) is defined as a process of controlled combustion, using an enclosed device to thermally breakdown combustible solid waste to an ash residue that
contains little or no combustible material and that produces, electricity, steam or other energy as a result (24). Even though both WTE combustion and RDF combust MSW, the objective of WTE combustion is treating MSW to reduce its volume. Generating energy and electricity only adds value to this process.
The composition of urban Muncipal Solid Waste in India is 51% organics, 17.5% recyclables (paper, plastic,
metal, and glass) and 31 % of inerts .The moisture content of urban MSW is 47% and
the average calorific value is 7.3 MJ/kg (1745 kcal/kg).important observation made during this study is that the compost yield from
mixed waste composting facilities (MBTs) is only 6-7% of the feed material. Up to 60% of the
input waste is discarded as composting rejects and landfilled (Figure 28); the rest consists of
water vapor and carbon dioxide generated during the composting processes.
The compost
product from mixed wastes was found to be of very low quality and contaminated by heavy
metals (Figure 30). The majority of the mixed waste compost samples fell below the quality
control standards for total potassium, total organic carbon, total phosphorus and moisture
content; and exceeded the quality control limits for heavy metals (lead, Pb, and chromium, Cr).
If all MSW generated in India in the next decade were to be composted as mixed waste and
used for agriculture, it would introduce 73,000 tons of heavy metals into agricultural soils .
Big cities collect about 70 - 90% of MSW generated, whereas smaller cities and towns collect
less than 50% of waste generated. More than 91% of the MSW collected formally is landfilled
on open lands and dumps .
MSW components Materials
- Compostables ---Food waste, landscape and tree trimmings
- Recyclables---- Paper, Cardboard, Plastics, Glass, Metals
- Inerts ----Stones and silt, bones, and other inorganic materials
Recycling and composting efficiency are greatly reduced due to the general absence of source separation. Absence of source separation also strikes centralized aerobic or anaerobic digestion processes off the list. Anaerobic digestion is highly sensitive to feed quality and any impurity can upset the entire plant. Aerobic digestion leads to heavy metals leaching into the final compost due to presence of impurities and makes it unfit for use on agricultural soils.
AEROBIC COMPOSTING:
source separated organic wastes can be composted and the compost obtained can be
used as an organic fertilizer on agricultural fields. Organic compost is rich in plant macro
nutrients like Nitrogen, Phosphorous and Potassium, and other essential micro
nutrients. Advantages of using organic manure in agriculture are well established and are a
part of public knowledge.
United Nations Environment Program (UNEP) defines composting as the biological decomposition of biodegradable solid waste underpredominantly aerobic conditions to a state that is sufficiently stable for nuisance-free storage and handling and is satisfactorily matured for safe use in agriculture. Composting can also be defined as human intervention into the natural process of decomposition as noted by Cornell Waste Management Institute. The biological decomposition accomplished by microbes during the process involves oxidation of carbon present in the organic waste. Energy released during oxidation is the cause for rise in temperatures in windrows during composting. Due to this energy loss, aerobic composting falls below anaerobic composting on the hierarchy of waste management.
ANAEROBIC DIGESTION:
The USEPA defines Anaerobic Digestion (AD) as a process where microorganisms break down organic materials, such as food scraps, manure and sewage sludge, in the absence of oxygen. In the context of SWM, anaerobic digestion (also called Anaerobic Composting or
Biomethanation) is a method to treat source separated organic waste to recover energy in the form of biogas, and compost in the form of a liquid residual. Biogas consists of methane and carbon dioxide and can be used as fuel or, by using a generator it can be converted to electricity on-site. The liquid slurry can be used as organic fertilizer. The ability to recover energy and compost from organics puts AD above aerobic composting on the hierarchy of waste management.
WASTE-TO-ENERGY COMBUSTION (WTE):
Waste-to-Energy combustion (WTE) is defined as a process of controlled combustion, using an enclosed device to thermally breakdown combustible solid waste to an ash residue that
contains little or no combustible material and that produces, electricity, steam or other energy as a result (24). Even though both WTE combustion and RDF combust MSW, the objective of WTE combustion is treating MSW to reduce its volume. Generating energy and electricity only adds value to this process.
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