# Sensor-Based Solid Waste Handling Systems: A Survey
## 6 Comparison and Discussion  
A comparative study is performed in this article to investigate how technological advancements in communication and sensor design revolutionize the solid waste management sector. The study has emphasized three major approaches via RFID, WSN, and IoT in solid waste management. This section presents an overall comparison of the aforementioned approaches on the basis of the study performed in this work. RFID-based solid waste management systems are enabled with GPRS and GIS for remote monitoring and route planning respectively. The RFID tags shall be considered as one of the best methods for identifying trash bins uniquely. Moreover, these approaches are mostly truck-oriented, in which significant computing loads are on the infrastructure deployed on the truck. In [27; 28], trash bin surveillance is performed only by using a camera equipped on the truck. The aforementioned systems did not use any sensors while the bin status is captured before and after waste collection with the camera-equipped on the trucks. These approaches are not completely automated since the truck driver is responsible for adjusting the camera manually for accurate image capturing. Furthermore, the adoption of GIS makes a perfect fit for route optimization and the allocation of new bins. However, the requirement of a larger database and heavy processing power for image storage and image processing, respectively, makes the deployment expensive. In most of the works, a GPS sensor is incorporated to obtain the geolocation of trash bins. Since trash bins are stationary, the GPS sensor can be avoided in the node design and the same functionality can be obtained by mapping the RFID of every trash bin to the geolocation. The possibilities of the ghost tags and proximity between the truck and the trash bins for accurate tag reading are some of the challenges in these approaches. Moreover, none of the RFID-based systems studied in this work were able to provide real-time surveillance of the trash bins. WSN-based solid waste management systems shall be considered as a breakthrough in the waste management industry. In contrast to RFID-based systems, real-time surveillance of the trash bins is established through WSNs. The adoption of wireless technologies such as Zigbee, SimpliciTi, etc., has reduced the power consumption of the sensor nodes, which will ultimately result in the improved lifetime of the batteries. Meanwhile, Wi-Fi is identified as one of the preferred communication technologies in many works studied in this survey even though its power consumption is relatively high when compared with similar communication protocols. This may be due to the fact that Wi-Fi is a popular communication technology and people are used to this technology due to the usage of smart devices or gadgets. Moreover, energy harvesting methods are adopted to enable self-powering to the sensor node. The works presented in [35; 38; 39] designed sensor nodes equipped with solar panels to extract energy from sunlight to charge the batteries. Nevertheless, a complete design of the charging circuit for energy harvesting is not presented in the aforementioned works. Most WSN-based approaches considered in this study are designed with GUIs to provide the remote monitoring of trash bins. Particularly in [39], progressive bars are represented to indicate the real-time unfilled level of the trash bins. Most of the WSN based solid waste management systems require a personal computer to send data to remote servers. The wide-area deployment of the trash bins is possible only through repeaters and other associated additional infrastructures. Consequently, all these lead to the increment of the overall cost for system implementation and complex designs. Furthermore, these approaches lag interoperability with other communication protocols. The technological advances in sensor design and lightweight communication protocols pave the way for another trend in solid waste management.