# IoT-Based Solid Waste Management Solutions: A Survey
## 2 Types and Methods of Waste Disposal  
The garbage generated by various segments of society can be classified according to its composition (physical characteristics) and destination. This classification is fundamental because it facilitates the selective collection, the recycling, and the definition of the most appropriate goal. These solid wastes discarded by urban municipalities represent a highly heterogeneous volume of matter, as well as a more homogeneous load of industrial and hospital waste [25]. Currently, a selective collection is the basis for proper waste management and the primary method adopted around the world when the goal is recycling. For a waste management system based on IoT, it is vital that classification is done previously, so specific containers for each waste type should be considered.  
As an example, the collection of solid waste, in London, is done according to the requirements of selective collection. It uses garbage bags or different colored containers, such as toxic waste in red; hospital waste in yellow; hospital waste after disinfection in blue; black household waste; glass bottles are divided into green, black, brown groups, according to their types and colors, and placed in different containers [26]. Then, the different types of considered waste are described as follows:  
* **Organic Waste.** It is the garbage derived from organic waste [27]. They are generated mainly in residences, restaurants, and commercial establishments that work with food. They must be separated from other types of waste since they are mostly destined to municipal landfills.
* **Recyclable Waste.** It is all the waste that can be used in the process of transformation to other elements or in the manufacture of raw materials [28]. It is generated in residences, companies, and industries, and must be separated so that the selective collection teams gather and then deliver to final processing in cooperatives and recycling companies.
* **Industrial Waste.** They are the residues, mainly solid, originating in the process of production at industries. It is usually composed by leftovers of raw materials destined for recycling or reuse in the industrial process [29].
* **Hospital Waste.** It is the waste originated in hospitals and medical clinics and can present contamination and transmit diseases to people that come into contact with it [30]. It should be treated according to established standards, with all possible care. This type of waste is intended for companies specializing in the treatment of such waste, where it is usually incinerated.
* **Commercial Waste.** It is the one produced by commercial establishments, such as clothing stores, toys, and appliances. This waste is almost entirely for recycling [31].
* **Green Waste.** It is the material that results, mainly, from the pruning of trees, branches, trunks, banks, and leaves that fall in the streets. Because it is organic matter, it could be used for composting and production of organic fertilizer [32].
* **Electronic Waste.** This is the waste generated by the disposal of consumer electronics products that no longer work or have become obsolete [33]. For disposal, there are appropriate places, such as companies and cooperatives that operate in the area of recycling. They send this waste in a way that does not cause damage to the environment.
* **Nuclear Waste.** It is the one that is generated, mainly, by nuclear plants. It is a highly dangerous waste because it is a radioactive element and should be treated according to strict safety standards [34].