Worldometers.info (2017) estimated that the world population is expected to increase from 7.5 billion in 2017 to 9.7 billion in 2050, where Asian countries contributed almost 60 percent of the current world population. This immense figure gives a stress situation to every country across the world especially in managing Municipal Solid Waste (MSW) generation. According to EPA (2016), MSW also can be called trash or garbage consisting of everyday items that generated from domestic, industrial and commercial, and services institutions such as hospitals and schools.
The amount of MSW generation across the world is caused by the growth of population and urbanization together with the improvement of the individual living quality of life. On average, the developed countries typically generated 521.95-759.2 kg per person per year and 109.5-525.6 kg per person per year typically generated by the developing countries (Karak et al., 2012). A recent study by Karak et al. (2012) estimated that the world MSW generation exceeds 2 billion tons per year, which will rise to approximately 27 billion tons in the year 2050. This significant number will surely give environmental impacts if the waste is not treated properly.
Current waste disposal and treatment have been proved that generated waste can be extracted into unconventional energy as well as can reduce the emission of greenhouse gases and environmental impacts. It also saves land usage for waste disposal since waste is treated in one big container. Waste-To-Energy (WTE) technology is widely implemented especially in developed nations where treated waste is converted into electricity or heat (Conserve Energy Future, 2016). By using this developing technology, waste can be disposed and compressed, as well as attempting the energy generated from them and reduce environmental impacts.
Penang is one of the most urbanized states in Malaysia. Its strategic situation at the Northern part of Peninsular Malaysia together with many industrial and commercial activities has attracted people to migrate into Penang. It is also connected with good road, highway, and railway, together with airport and seaport facilities has even escalated connection between Penang and the neighbouring states. Penang also has many business and trading activities which offer many employment opportunities and has become a preferable place to work and live.
The exponential growth of Penang population has also increased the amount of MSW generation in Penang. To date, Penang waste generation rate is 1.5 to 1.8 kg per person per day which is expected to rise to 1.1 million metric tons in 2020 (PPCC, 2016). This number increased by 15 percent of the amount MSW generated in 2011. Even though the amount of recycling waste able to recover is also increased, but there is still a huge amount of waste disposal being dump into landfill (PGC, 2011).
Currently, Penang has one operating transfer station, one Construction and Demolition (C&D), Green, and Bulky Waste landfill, and one sanitary landfill to accommodate MSW disposal. This sanitary landfill has used 33 acres (0.134 [km.sup.2]) and can be used up to the year 2028 to operate before reaching its maximum capacity of 66 acres (0.267 [km.sup.2]) (Kamaruddin et al., 2016). The increasing amount of MSW in Penang will shorten the lifespan of the current landfill which will force local authorities to locate new MSW landfill. However, limited land available in Penang would give difficulties to local authorities to develop new landfill site for Penang. Thus, this paper aims to explore available WtE technology and discussed a strategic approach to implement feasible WtE technology for Penang state in handling MSW.
PENANG MUNICIPAL SOLID WASTE
Based on the Satang Report in 2003, MSW generation consists of more than 50 percent of organic waste per day as shown in Table 1 (Gok, 2007). There are four major types of organic waste generated from Penang state; food and kitchen waste, green waste (garden & yard trimmings), animal waste (manure), and bulky waste (organic portion of furniture and household hold fittings) (Omran et al., 2009). Due to Penang MSW characteristics, Penang state...