The main objective of the present study was to provide a comprehensive LCI of medium scale composting of food waste
and yard waste at institutional level, based on substance flow analysis (SFA). A secondary objective was to present the
composition and assess the quality of the final compost product from composting of typical Asian organic waste (food
waste and yard waste). The experiments were designed to represent a batch situation in an institutional medium size
composting scenario with input material of food waste mixed with grass clippings and dried leaves. Two composting
runs were carried out with the intention to showcase the heterogeneity of organic waste and study the effect of windrow
size on the performance of the process. The input and output material were sampled and characterized in order to
quantify the substance balance of the process. SFA was performed by means of the mass balance model STAN 2.5 to
compute unknown parameters (gaseous emissions). SFAs have been performed for C, N, K, P, Cd, Cr, Cu, Ni and Pb. The
composting windrows were fed with 212.4 and 393 kg, respectively. VS content reduction is greater in composting pile
with larger size (Run 2). The loss of C during composting was recorded in the range of 0.146-0.166 kg/kg ww. The C
losses via leachate were insignificant (0.02% of the total input C). The total N loss during the process was 0.005-0.012
kg/kg ww. The leachate generation was measured as 0.012-0.013 kg/kg ww. The flows of selected heavy metals were
assessed. Heavy metals were of minor significance due to low concentrations in the inputs (food waste and yard waste).
Heavy metals were found to be released to the atmosphere. However, majority of heavy metals remain in the finished
compost. 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 and thus ready for application in gardening. The LCI
presented in the present study can be used as a starting point for making environmental assessments of medium-scale
co-composting of food waste and yard waste in tropical environment. No major environmental problems were identified
from the process, except for the emissions of GHGs.
In Malaysia, the greenhouse gases (GHGs) emissions reduction via composting of source-separated organic waste (SOW) in municipal solid waste (MSW) has not been assessed. Assessment of GHG emissions reduction via composting of SOW is important as environmental impacts from waste management are waste-specific and local-specific. The study presents the case study for potential carbon reduction via composting of SOW in University of Malaya (UM). In this study, a series of calculations were used to evaluate the GHG emission of different SOW management scenarios. The calculations based on IPCC calculation methods (AM0025) include GHGs emissions from landfilling, fuel consumption in transportation and SOW composting activity. The methods were applied to assess the GHG emissions from five alternative SOW management scenarios in UM. From the baseline scenario (S0), a total of 1,636.18 tCO2e was generated. In conjunction with target of 22% recycling rate, as shown in S1, 14% reduction in potential GHG emission can be achieved. The carbon reduction can be further enhanced by increasing the SOW composting capacity. The net GHG emission for S1, S2, S3 and S4 were 1,399.52, 1,161.29, 857.70 and 1,060.48 tCO2e, respectively. In general, waste diversion for composting proved a significant net GHG emission reduction as shown in S3 (47%), S4 (35%) and S2 (29%). Despite the emission due to direct on-site activity, the significant reduction in methane generation at landfill has reduced the net GHG emission. The emission source of each scenario was studied and analysed.
Technical benefit of incorporation of Palm Oil Clinker (POC) in cement-based applications has been proven in recent
studies. The aim of this work was to assess the heavy metal leaching behavior to ensure environmental safety of using
POC in cement-based applications. The chemical composition, morphology, total organic carbon (TOC) and mineralogy
were determined using XRF, FESEM, TOC analyzers and XRD to select appropriate chemical reagents for complete digestion.
HNO3
, HF and HClO4
were used for digestion of POC to measure heavy metal content using ICP-MS. The chemical reagents
CH3
COOH, NH2
OH-HCl, H2
O2
+CH3
COONH4
and HF+HNO3
+HCl were used for extraction of acid soluble, reducible,
oxidizable and residual fractions of heavy metals in POC, respectively. The leaching toxicity of the POC was investigated
by the USEPA 1311 TCLP method. The result showed the presence of Be, V, Cr, Ni, Cu, Zn, As, Se, Ag, Cd, Ba and Pb with
levels of 5.13, 11.02, 2.65, 1.93, 45.43, 11.84, 15.07, 0, 0, 81.97 and 1.76 mg/kg, respectively, in POC. The leaching value
in mg/L of As (4.56), Cu(1.05), Be (0.89), Zn(0.51), Ba(0.26), Ni (0.17), V(0.15), Cr(0.001) and Se (0.001) is found well
below the standard limit of risk. Risk assessment code (RAC) analysis confirms the safe incorporation of POC in cementbased
applications.