Recycling Options for Household Organic Waste: A case study of Practicality Value Evaluation Fauziah S.H. and Agamuthu, P. Institute of Biological Sciences, Faculty of Science, University of Malaya, 060 Kuala Lumpur, Malaysia Abstract The presence of organic materials in the waste stream resulted with the generation of various landfill gases. Methane (CH ) in particular has been identified as one of the major greenhouse gas (GHG) that contributes to global warming. In order to reduce emissions from the disposal sites, it is very crucial that organic waste is diverted away from the MSW stream and landfill disposal. This placed recycling of organic waste as one of the most viable option in waste treatment hierarchy. Among the feasible recycling techniques to tackle household organic wastes are composting and anaerobic digestion. Anaerobic digestion is a sensitive procedure which requires utmost precautions in order to generate biogas for energy conversion. It also entails large capital where appropriate bioreactors are to be handled by skilled operators. On the other hand, composting is more straightforward and requires minimum cost of operation. The objective of this study was to identify the most practical and convenient waste recycling options for household organic waste in Malaysia. Also the options selected will be evaluated of its practicality by taking into consideration the ease of the operating techniques, equipments required, cost incurred and public acceptance. These values will be derived from the responses obtained from set of questionnaires distributed to various stakeholders in waste management in Malaysia. These values will be incorporated into formulated equations to determine the Practicality Value (PV) of each waste treatment option. The studies involved options such as anaerobic digestion, composting, and vermicomposting. PV obtained for vermicomposting was found to be the highest (.6) followed by conventional composting (0.), while RDF conversion presented the option with the lowest PV (-0.6). By taking into consideration the various issue such as cost incurred and operating technologies, vermicomposting was calculated to be the most practical option for household organic waste. Introduction Malaysia, a developing country with per capita income of USD 6,0 [], generates approximately 9,000 tonnes of municipal solid waste (MSW) daily. More than 90% of the total wastes received are disposed off into landfills since landfilling has been the most economical waste disposal option in the country. The indiscriminate disposal of the waste into 60 landfills throughout the nation has alarmed waste managers, as the country experienced % increase in waste generation annually. These landfills are filled up at a much faster rate than what has been planned. One contributing factor is the lack of resource recovery such as recycling and other treatment options in the country s waste management system. Improper waste management has been identified as one of the main issues contributing to environmental degradation in Malaysia. Besides becoming a pest breeding ground and contributing to surface and groundwater pollution, landfills also act as a bioreactor where natural degradation takes place.
Malaysian MSW is composed of 0% organic materials, which are sourced from domestic, industrial and commercial sectors. The presence of organic materials in the waste stream retains the high moisture level which creates an anaerobic condition when disposed off into the waste cells. Studies reported that Malaysian MSW has moisture content of 60-70% []. In the landfill, the degradation processes generate various landfill gases particularly methane (CH ). To make matters worst, since most of the disposal sites in Malaysia (approximately 9%) are non-sanitary landfills, landfill gases are passively released into the atmosphere. This will contribute to global warming. It is estimated that.7million m /day of landfill gas are generated from the disposal sites in Malaysia []. In order to reduce greenhouse gas (GHG) emissions from these disposal sites, it is very crucial that organic waste is diverted from MSW stream and its disposal into landfills reduced or controlled. This helps to reduce loss of nutrients but also lengthens the operation life of a landfill. Therefore, it is necessary to integrate various alternative treatment options into the waste management system in order to improve the current waste management into a more sustainable system. Sustainable waste management principles place recycling at a high priority after waste reduction. Recycling not only reduced environmental pollution but also reduced the need for virgin materials. Among the feasible recycling techniques to tackle household organic wastes are composting and anaerobic digestion. Anaerobic digestion is a sensitive procedure which requires utmost precautions in order to generate biogas for energy conversion. Various types of organic wastes can be utilized as sources for anaerobic digestion including paper, wood, sewage sludge, food leftover and others. The retention time required for the anaerobic digestion process differs with the types of waste utilized and the temperature applied. It also entails large capital where appropriate bioreactors are to be handled by skilled operators []. On the other hand, composting is more straightforward and requires lower operational cost. Process of composting involves biological decomposition of organic substances of plants or animal origin under controlled conditions to a state sufficiently stable for nuisance free storage and utilization. This process requires the degradation activities by decomposers including bacteria, fungi, actinomycetes and various protozoa, and under aerobic condition to produce a pathogen-free yield. Compost produced possesses similar characteristics as humus. The compost quality depends on the temperature, moisture content, nutrient content, ph, particle size, oxygen supply, and others [, ]. Good quality compost can be achieved when composting is conducted at an appropriate volume where temperature can be retained within the system, for example in a large composting plant. However, this is somewhat impractical if household waste is to be composted due to the small quantity of organic waste produced by individual households. The generation rate of Malaysian household organic waste averaged 0.9kg/day/family and rapid degradation is enhanced by the climatic factor. The alternative option to composting is vermicomposting which works efficiently in processing smaller quantity of organic matter. Vermicomposting is a process which involved the utilization of worms to digest and breakdown organic component including Eisenia foetida which was more adaptable under tropical conditions [6]. The process of vermicomposting is normally shorter than that of a conventional composting. It produces vermicast of higher quality with many additional benefits [7, 8, 9, 0].
Another option to recycle organic component is refuse-derived fuel conversion. Unlike composting and vermicomposting, this option processed and converted combustible component in waste including organic waste into pellets to be utilized in energy production. RDF processes involve the removal of non-combustible components as well as reduction in moisture content. This is essential to allow efficient burning and to harvest the heat for other utilization. However, this results in higher cost due to the requirement of energy for drying and other mechanical necessities. Economical aspect need to be considered in determining the efficiency of this process as compared to other waste treatment options. The objective of this study was to explore the possibility of conducting various recycling options for household organic waste in Malaysia, where the Practicality Value will be determined. It will take into consideration the ease of operating techniques, equipments required, costs incurred and public acceptance. Materials and Methods Determination of Practicality Value The economical aspects of the three options namely composting, vermicomposting and RDF conversion were evaluated by considering the following factors:. ease of the operating techniques (EOP);. utilization of equipments (UE),. cost incurred (CI) and. public acceptance (PA). Higher practicality value (PV) indicated higher practicality of the option. The lower the PV, the less practical the option is in Malaysia. PV was computed based on the following proposed formula: PV = PA - (CI + EOP + UE) (Equation ) The proposed value for each factor was based on the Likert scale indicated in Tables and. Table : Proposed numerical value based on Likert scale for factors contributing to PA and CI Numerica l value PA CI Public Public Government Capital cost Operational Participation (PP) Convenience (PC) Support (GS) (CAP) cost (OC) Very Highly High Very low Very low participative convenience Highly convenience Supportive Low Low participative Moderate participative Moderately convenience Moderate Moderate Moderate Low participative Low convenience Low support High High Against inconvenience Not Very high Very high
supportive PA is the level of acceptance by public and governmental support which is computed according to the proposed formula: PA = (PC + PP + GS) (Equation ) where PC = public convenience PP = public participation GS = government support The likert scales ranged from (very positive responses) to (very negative responses). Numeric EOP UE al value Costs incurred (CI) by the options include all costs borne by the process including capital (CAP) and operational costs (OC). It is calculated with the following proposed formula: CI = (CAP + OC)/ (Equation ) EOP is the value of the ease of operating techniques which involved skill (SR), training procedures (TP), faulty consequences (Fr) and possibility of failure (Fp). It can be obtained by calculating the numerical value of EOP as proposed; EOP =/ n [SR + TP + Fr +Fp] (Equation ) where n = number of stages involved. Utilization of equipments (UE) includes the availability and the necessity of equipments in order to allow the process to completion. The determination of UE is accomplished using the following formula: UE = /n n (AE + NECEQ) (Equation ) where n = number of equipment required. The proposed numerical values of the related factors in determining EOP and UE are detailed in Table. Table : The proposed numerical value based on Likert scale for factors contributing to EOP and UE
Skill requireme nt (SR) Possibility of failure (Fp) Training procedures (TP) Risk of faulty consequences (Fr) Availability of equipments (AE) Necessity of equipments (NECEQ) Unnecessary No skill None Unnecessary Never Highly available Little Low Optional Seldom Available Optional skill Moderate Moderate Moderately Sometimes Moderately Moderately skill required available required High High Important Usually Low Important skill availability Very Very Very Always Unavailable Very high high crucial crucial skill Practicality of the Options Evaluated The three recycling options were found to be feasible in diverting organic components from the household waste. However, in order to determine its practicality the economical and technology aspects were evaluated. Table illustrates the calculation in determining the practicality of composting the household organic waste. Table : Factors of practicality in household organic waste conversion via composting Table a: Value for PA PA PC PP GS PC + PP + GS = 9
Table b: Value for CI CI CAP OC (CAP + OC) / = 7/ =. Table c: Value for EOP EOP N SR TP Fr Fp. waste sorting. mixing. moisture monitoring. temperature. quality control Total 9 9 /n n [SR + TP + Fr +Fp] = / 0 ( + + 9 + 9) = Table c: Value for UE UE N AE NECEQ. collection bin. mixer. turner. packaging. quality control Total 7 /n n (AE + NECEQ) = /n (+7) =. Since the practicality value, PV = PA - (EOP + UE + CI); the calculated value for composting option at a composting plant is: PV composting = PA - (EOP + UE + CI) = 9 - ( +. +.) = 9 8.7 = 0. The determination of PV for vermicomposting is indicated in Table 6. Table 6: Factors of practicality in household organic waste conversion via vermicomposting Table 6a: Value for PA PA PC PP GS PC + PP + GS = 8 Table 6b: Value for CI CI CAP OC
(CAP + OC) / = / =. Table 6c: Value for EOP EOP. waste sorting. setting up. mixing. moisture monitoring n SR TP Fr Fp Total 6 7 /n n [SR + TP + Fr +Fp] = / 6 (6 + + 7 + ) =.8 Table 6d: Value for UE UE n AE NECEQ. vermicomposting bin Total /n n (AE + NECEQ) = ½ () =. The calculated PV for household vermicomposting is: PV vermiomposting = PA - (EOP + UE + CI) = 8 - (.8 +. +.) = 8.8 =.6 The calculation of the value of RDF conversion is indicated in Table 7. Table 7: Factors of practicality in household organic waste conversion to RDF Table 7a: Value for PA PA PC PP GS PC + PP + GS = 0 Table 7b: Value for CI CI CAP OC (CAP + OC) / = 8/ = Table 7c: Value for EOP n SR TP Fr Fp EOP. waste sorting. shredding
. palletizing. marketing. pretreatment/ moisture removal Total 0 /n n [SR + TP + Fr +Fp] = / 0 ( 9) =.9 Table 7d: Value for UE UE n AE NECEQ. collection bin. shredding. palletizing. packaging. drying Total 6 /n n (AE + NECEQ) = /0 (7) =.7 The practicality value for the RDF conversion can be calculated as: PV RDF conversion = PA - (EOP + UE + CI) = 0 - (.9 +.7 + ) = 0-0.6 = -0.6 Table 8 depicts the summary of PV values of the three options namely composting, vermicomposting and RDF conversion. Table 8: The PV values for three different recycling option for household organic waste. Options Composting Vermicomposting RDF conversion PV 0..6-0.6 PV for vermicomposting is the highest as compared to composting and RDF conversion. Therefore, it is the most practical option to manage the organic component from household. Conclusions By taking into consideration various issues such as costs incurred and operating technologies, vermicomposting is the most practical option for household organic waste management in Malaysia. References. World Bank (008) World Development Indicators database. (http://siteresources.worldbank.org/datastatistics/resources/gnipc.pdf). Fauziah, S.H., Simon, C. and Agamuthu, P. 00. Municipal solid waste management in Malaysia- Possibility of improvement?. Malaysian Journal of Science. (): 6-70. Agamuthu, P. (00) Solid Waste: Principle and Management. University of Malaya Press. pp 9 7.
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