Impacts of the Incineration of Municipal Solid Waste

Incineration of municipal solid waste

Introduction

As the growth of population in cities is constantly increasing, it causes the amount of waste generated to rise at a rapid rate as illustrated by figure 1 [1]. If the waste generated is not managed and treated appropriately and safely, it can have significant impacts on the environment and public health.  Municipal solid waste mainly consists waste obtained from households, hospitals, industries, businesses, educational institutions, construction and demolition sites [2]. Clothing, plastic, metals, furniture, paint, batteries and e-waste like old computers are examples of municipal solid waste [3]. Figure 2 shows how the composition of municipal solid waste has changed between 1960 and 2015. Plastic waste has increased by 12.7% and is the largest-scaling pollutant today [4]. Incineration is a waste treatment process used to dispose solid waste.

Figure 1: A graph showing increase of waste generation due to population growth from 2000 to 2030 [5].

Figure 2: A chart representing the composition of municipal solid waste between 1960 and 2015 [4].

The incineration process

An incinerator is a unit or facility used to burn waste material in the presence of oxygen at high temperatures between 750-1100°C [6]. It can also be referred as a thermal treatment. This temperature is used to ensure optimal combustion, complete removal of odours and protection of the walls of the incinerator [7].

Incineration is considered as the best alternative option for disposal of solid waste compared to any other disposal method [8].

An incinerator burns wastage and converts the wastage into ash, flue gas and heat [9]. During the process of incineration, the waste material is oxidised to produce ash and heat along with water vapour, nitrogen, carbon dioxide and oxygen [10]. In addition, other gases such as carbon monoxide, hydrogen chloride, sulphur dioxide and dioxins are also produced depending on the nature of waste and availability of oxygen [11]. At the end of incineration, bottom ash remains as the inorganic constituents of combustion. Incinerators are fitted with electrostatic precipitators to remove particulate matter in the flue gas [12] to reduce air pollution. Electrostatic precipitator is a highly efficient filtration device that is capable removing more than 99% small particles like smoke, mist and fly ash using force of an induced electrostatic attraction [13].  It charges the smoke particles inductively with an electric field causing the particles to become negatively charged. The negatively charged particulates are attracted to positively charged metal plates. The particles are collected by the collecting plates and then removed by a brushing mechanism in a process called rapping [14].

Figure 3: Annotated diagram of how an electrostatic precipitator works [15].

Conclusion

Although waste incineration increases CO2 emissions, even environmentalist agree waste incineration is safer for the environment than waste dumping that has been used for getting rid of garbage so far. **Change some words

Bibliography