| Résumé: | Organic Municipal Solid Waste (OMSW) generation in Malaysia is overwhelming and
most of the waste generated ended up in the waste stream to be disposed in landfills.
However, there has been minimal research on the comprehensive evaluation of the
Malaysian OMSW management system from environmental perspective despite priority
being given to increase recycling rate and composting of OMSW by the Malaysian
government. The main aim of the thesis is to study the environmental benefits of
OMSW management. The objectives include: (1) to determine the characteristics and
elemental composition of OMSW generated in Malaysia; (2) to provide a
comprehensive Life Cycle Inventory (LCI) of medium scale co-composting of OMSW;
(3) to evaluate environmental impacts and benefits associated with alternative OMSW
management system; and (4) to quantify the total CO2 equivalent reduction potential
from OMSW recycling via composting as compared to landfilling (Business-as-Usual)
in Peninsular Malaysia. A comprehensive Life Cycle Inventory (LCI) of medium scale
co-composting of OMSW was carried out based on comprehensive field studies.
Substance Flow Analysis of C, N, P, K, Cd, Cr, Cu, Ni and Pb were carried out by using
STAN 2.5 software. The inputs and outputs of OMSW composting process were also
recorded. The life cycle environmental impacts from alternative OMSW management
system were evaluated based on ISO 14000 series. The total CO2 equivalent reduction
potential from OMSW recycling via composting as compared to landfilling was
assessed through scenarios comparison in accordance to Malaysian municipal solid
waste management strategic plan. The LCI of medium-scale co-composting of OMSW
in tropical environment was presented. The C/N reduction during the process was in the
range of 10-23%. In general, the compost composition was considered to be within the
ranges previously reported in literature. Heavy metals were found to remain in the
finished compost where the release of heavy metal to atmosphere is insignificant. No
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major environmental problems were identified from the OMSE composting process,
except for the emissions of GHGs. LCA studies revealed that anaerobic digestion is the
most environmentally sound management for OMSW with net environmental gain
whereas disposal of OMSW at landfill are generally less environmental favourable. This
study also highlights the importance of decomposition emissions control during OMSW
composting, particularly CH4, N2O and NH3. OMSW diversion from disposal created
significant climate change benefits in term of net GHG emissions reduction. The current
study reveals that an additional of 21% GHG emissions reduction including the
recycling of OMSW via composting in all sectors, on top of 25.5% GHG emission
reduction from Malaysia waste by increasing the recycling rate to 22% as reported by
previous study. A knowledge-based goal-oriented OMSW management study is
necessary to analyse the state-of-art of OMSW management in Malaysia and direct it
towards fulfilling the main goals of waste management. The results provide information
of all significant inputs and outputs in the form of elementary flow to and from the
environment from OMSW management involved. Based on the experience of SFA in
the present study, the emissions quantified are likely to be in agreement with that from
previous studies. Hence, author agrees and advocates that SFA is able to be integrated
with LCI and eventually LCIA studies upon OMSW management sector in Malaysia.
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