# Sensor-Based Solid Waste Handling Systems: A Survey
## 3 RFID Based Solid Waste Management Systems
### System Architecture  
A typical system architecture of the RFID-based solid waste handling system is shown in Figure 4. Communication technologies such as general packet radio service (GPRS), global positioning system (GPS), radio frequency identification (RFID), and geographic information system (GIS) including camera have been integrated for developing the system [27].  
Figure 3: Distribution of publications based on technologies.  
An RFID tag is attached to all the bins to provide unique identity. The truck, which is used to collect waste from the bins, is mounted with a data acquisition system comprising an RFID reader, camera, GPS, and GSM Module. Once the truck approaches the bin area, the RFID reader detects the RFID tag installed on the bin, the GPS module obtains the real-time location, and the camera captures images prior to and subsequent to waste collection in order to determine the waste in the bin and its surroundings. The data from the truck's data acquisition system are recorded and sent to a central monitoring station by using a GSM or GPRS network. The monitoring station comprises a receiver, GIS, database and a monitoring terminal for providing user interface. The GIS and database management systems are responsible for mapping of truck position and bin location to optimize truck routes according to waste estimation.  
RFID-Enabled Trash Bin Level Monitoring Systems  
Numerous trash bin level monitoring systems have been developed using RFID technology. Table 1 shows a summary of RFID enabled trash bin level monitoring system. The work presented in [27; 28] is a purely RFID-based system, which is not using any sensors for bin level measurement. The camera-equipped on the truck is capturing images of the trash bins, which will be sent to the central monitoring station for verifying the waste collection process. Moreover, the system is not using any routing methods to optimize waste collection. The system presented in [29] used an additional infrared sensor for measuring the trash bin's filled level. This system is not using any camera, since sensors are equipped to assess the emptiness of trash bins. In [30], a series of sensors was used to assess the unoccupied level and pressure of trash bins. A camera is also equipped in the system for the establishment of GIS for assisting the truck driver to execute optimized waste collection from the trash bins. In [31], an outdoor trash bin monitoring system based on RFID is presented. This system used a load-cell sensor to measure the weight of the trash bins. Threshold levels are set according to the filled and empty trash bin's weight.  
The RFID-based system presented in [32] is integrated with photoelectric and image sensors to obtain the filled status of the trash bins. A GPS module is also equipped to obtain the accurate locations of the bins to define optimized routing for the waste collection truck. An RFID-based smart trash bin is proposed in [33]. This system performs waste material classification with a web-based information system running on the remote server. The trash bins are equipped with RFID tags and each tag is mapped to particular waste  
Figure 4: A typical system architecture for RFID-based Solid Waste Handling System.  
material. This approach helps in waste material classification for proper and efficient recycling and disposal.  
From the study performed on the RFID enabled trash bin level monitoring systems, the following inferences are obtained:  
* RFID-based systems are unable to provide continuous real-time monitoring of the bin's filled level;
* Trash bins are monitored only when the truck is within the range of RFID tags;
* RFID tags are using to identify the bins uniquely and they do not provide any data on the filled levels of the bins;
* Additional infrastructure is required to obtain the filled levels of the trash bins.