# Modern Technologies for Waste Management: A Review
## 2 Overview of Technologies
### Smart Waste Bins  
Municipal waste plays a huge role in waste generation. In total, 530 kg of waste per capita were generated in the EU in 2021 [16], while, generally, 4.8 metric tons of waste were generated per EU inhabitant in 2020 [17]. That gives almost 10% of the contribution to the creation of waste. It is expected that the annual solid waste generation will reach around 3.4 billion tons by 2050, and that would lead to an approximate cost of $635.5 billion in the management of municipal waste management [18]. Designing a smart waste bin has a purpose to provide an easy solution to handle all of the waste bins in a city. It is equipped with various sensors and technologies to help manage waste more efficiently [19]. These sensors can detect a wide range of data such as the fill level of the bin, gas emissions produced by the waste, humidity, weight, and many more [20]. An effective method of controlling the waste material filling level is using an ultrasonic sensor which compares the current fill level by measuring the distance between the top and bottom of the bin [21]. Then, the microcontroller compares this value with waste bin fill capacity so that it can send a notification to the authorities. Humidity and flame sensors are used to predict an upcoming fire or harmful events [22; 23]. Due to smart bin sensors being an Internet of Things (IoT) device, they can communicate with other devices/systems, such as waste management workers' end-devices, to provide them with information about waste bin status. We should take into consideration that hardware is not everything, and that in order for smart bins to work properly, we need to take care of software that will handle all of this information. Storing data is also important for further analysis, so all of the data collected from various sensors need to be stored in a database. Smart waste bins can be standalone devices, or they can be retrofitted onto existing bins. They can also be powered by a vast range of technologies, including solar panels, batteries, or even kinetic energy generated by people throwing out waste. By monitoring the fill level of the bin, waste management companies can schedule pick-ups more effectively, reducing the number of trucks on the road and the associated emissions. In addition to smart waste bins, RFID tags [24] with RFID sensors that are cheap and consume little power [25], and GPS tracking [26; 27], are becoming a prevalent thing in waste management. RFID tags attached to waste bins or garbage trucks can transmit data about their location and status. There are several IoT technologies used to connect smart waste bins to a network. Some of the most commonly used include:  
1. MQTT (Message Queuing Telemetry Transport): A lightweight messaging protocol that is designed for low-power IoT applications. It uses the publish/subscribe model, where devices publish data to a broker, which then dispenses data to subscribers [28]. This protocol uses TCP/IP for data transmission and has very strong delivery guarantees. Each waste bin can be a client to the gateway which communicates with the cloud using an MQTT bridge [29]. 2. LoRaWAN (Low Power Wide Area Network): LoRaWAN is a wireless communication protocol that is being used for low-power, long-range IoT applications. It is a great choice for smart waste bins due to its long-distance data transmission and minimal power usage [30]. 3. Bluetooth: It is attached for short-range communication. It may not be suitable for large-scale applications due to its limited range [18]. It can be used by a worker for maintenance in case of system failure [25; 31]. 4. GSM (Global System for Mobile Communications): A cellular network technology that is commonly used for communication between smart bins. It provides high bandwidth and fast data-transfer rates [31]. It is also low-cost and easy to implement.