# Sensor-Based Solid Waste Handling Systems: A Survey
## 1 Introduction  
Everyday, the generation of waste increases and is paving the way for serious negative environmental impacts all over the world [1]. It is incontrovertible that all human activities end up generating a considerable quantity of waste in all forms of matter [2]. There is a huge impact on our environment due to undesigned modernization along with industrialization, which leads to a sudden increase in solid waste, nuclear waste, and other perilous wastes [3]. Waste management refers to the reduction in the amount of waste being produced and the disposal of the same products by using adequate measures [4, 5]. Waste may come in many shapes and forms, including solid waste being produced from domestic sources, infectious waste produced from hospitals, and radioactive waste produced by nuclear reactors [6, 7]. Waste management includes the collection, transportation, recycling or disposal, and analysis of waste materials, as shown in Figure 1. Moreover, waste management is relatively new as an industry, which is flourishing day-by-day because of its extreme impact on the ecosystem. Aunsingly, the rate of waste produced is linked to towering economic growth, and it is really an attribute of advanced countries. However, the quantity of waste generated depends on the region, season, and many other factors, which show the difficulty in proper waste disposal. The world bank statistics [8] on the projected regional waste production in millions of tonnes are shown in Figure 2.  
The management of waste is a complex multi-level process that involves government policy making, legal, financial, administrative, and research facilities [9]. The high cost associated with the safe and efficient management of waste makes investing in this industry difficult [10]. Therefore, a lot of research and development in this sector is required to establish efficient waste management systems [11]. The conventional waste management process begins with the disposal of waste in trash bins near the place of origination. At predetermined times, municipal or private enterprise vehicles pick up waste and move it to temporary collection units. However, these approaches may result in improper waste management due to the following circumstances. The collection of solid waste on a daily basis constitutes a loss of time, fuel, and labor in cases where trash bins are empty. Alternatively, the collection of solid waste once a week may lead to a risk of overflowing the trash bins. Consequently, solid waste spreads across the region, causing possible heath problems and environmental pollution. Moreover, when cities are large in size, an effective solid waste management system is of great importance. However, the technological developments in the field of sensors and wireless communications pave the way to automate solid waste management systems. Several automation techniques are available that begin with RFID technology relative to the latest Internet of Things (IoT)-based models. Nevertheless, for an efficient solid waste  
Figure 1: Process in solid waste management. Figure 2: Projected waste production by region (millions of tonnes/year). management system, a challenging task is to determine the appropriate mix of sensor and communication technologies with optimum solutions. Few surveys and study articles on solid waste management systems were reported previously. Most of them emphasized the trend at the time or on a wider range of sensor and communication technologies that aided the design of solid waste management systems. A survey on environmental informatics applied to solid waste management is presented in [12]. The limitations and drawbacks of various waste management models are highlighted in this work. Moreover, it presents a timeline of various technologies applied to the development of a solid waste management system. However, it does not discuss advanced communication technologies such as low power wide area networks (LPWAN), which is one of the enabling technologies of IoT.