# IoT-Based Solid Waste Management Solutions: A Survey
## 7 Open Issues and Challenges
In Reference [124], a study is applied through dynamic multisimulation based on modeling agents applied to both urban space and individuals within a crowd. This dynamic becomes important within the concept of solid waste management to predict behavior when present in large clusters of people. Another important aspect that must be considered within a waste management system is the consumption of the battery generated by the use of the devices/sensors available in a solution. The IoT nodes used in solid waste management include ultrasonic sensors and load cell [125], GPS [126], actuators [36], microcontrollers [127], and transmission modules [128]. Some studies describe the use of renewable energy through photovoltaic panels for battery charge and avoid constant manual intervention for replacement. There are also aspects related to the network topology employed in the solution, such as point-to-point model topology, star model, hierarchical model, etc. Depending on the used topology model, nodes can consume more or less energy, just as the distance of node positioning should also be considered. Nodes closer to the base radio tend to spend less energy than nodes located at the periphery of the cell, bearing in mind that transmission modules are responsible for the higher energy consumption. The communication technology employed is also an aspect to be considered, whenever possible, to use low power technologies, such as 6 LoWPAN [60], BLE [109], etc., as well as to consider the aspects of sensing, such as whether it will occur periodically, continuously, reactively, or in real time. Based on the aspects mentioned above in Reference [119], a study was directed at the development of a sensor node for the real time monitoring of the level of filling of dumps based on the low energy consumption and the cost containment. They are retained not only to the sensor node more efficiently in terms of energy levels but also to the architecture of the solution, taking in account microcontrollers that can attend the computational capacity with low energy consumption and also to use policies that shut down the node or even part of it when idle. Another very favorable aspect that can help solid waste management systems is using data analysis to provide the capacity to forecast the generation of waste from a municipality in the short term. Based on data already collected within a specified period, an analysis will be applied, through which more efficient collection planning is enabled and even resources are estimated for a probable growth in the generation of waste that leads to higher investments in infrastructure. Some studies are based on the artificial neural network as presented in Reference [129] that uses input variables related to environmental issues, socioeconomic issues, changes in consumption patterns, and even population growth associated with migration. Through these analyses, it is possible to select the best results based on these performance indices applied for each criterion and thus improve municipal solid waste management implementations. Additionally, in Reference [130], a time series of autoregressive artificial neural networks is used to predict the monthly generation of residue since the characteristics of the solid waste generated are different in different places. The analysis of the related literature identified open issues that can be addressed in further research work. They can be considered as improvements for proposed systems and identified as follows:  
* A waste management platform focusing on citizens' perspective that can interact with the system through a mobile application that, through its location, finds the bins closest to their residence with the respective level of use. Knowing this information, the user can choose to discard the garbage at that moment in a container that has availability or even to retain it and wait until the collection system empties the deposit. In this way, the user will be contributing to the non-overflow of the containers and avoiding that their waste is exposed in the open.