## 5 Discussion
### Research Limitations  
One notable limitation encountered during prototype development is related to the load cell used for weighing the recycled items. The scale could not be placed on the sorting flap because it could not return to a perfectly horizontal position. As the load cell operates at gram-level precision, any misalignment could lead to measurement inaccuracies. This potential measurement error may affect the trust level calculations and the overall effectiveness of the recycling process. Currently, the load cell measures the entire system, with a limitation of 20 kg.  
The second limitation concerns the Internet connection, as the system must be connected to the network to send requests to Azure for image analysis and data retrieval. This dependency on Internet access poses a limitation, especially in environments where connectivity may be intermittent or unreliable. In such cases, the performance of the Azure Custom Vision service could be compromised, leading to delays in processing and the potential misclassification of PET bottles. Therefore, implementing a local processing solution could improve the prototype's resilience against connectivity issues.  
Another limitation is that users must create an account to recycle PET bottles. This requirement may deter potential users who prefer a more straightforward, hassle-free recycling process. To improve accessibility, future iterations of the system could consider implementing a solution that allows users to print a voucher or receipt, enabling those without an account to participate in recycling activities.  
The tests conducted in this experiment were carried out under natural daylight conditions, simulating a scenario in which a waste bin system is installed in the yard of a residential complex. The choice is justified by considering the real usage context. On the other hand, expanding the number of test cases requires an increase in the volume of images needed for each scenario. Therefore, the tests were not conducted in low light conditions or in the presence of strong direct light, such as backlighting from the sun. For use in such conditions, future iterations will propose the addition of a white-light LED, automatically activated by the PIR sensor, or the use of cameras with increased infrared sensitivity. Adapting the system to various lighting conditions represents a future development direction.  
Additionally, the current system does not permit manual entry of the client code, which can limit usability for individuals who may not have immediate access to their QR code or face difficulties with scanning. Allowing for manual input could improve the user experience and enable more individuals to participate in the recycling process.  
The following studies [64; 65; 66] demonstrate the possibility of integrating Self-Sovereign Identity (SSI) architectures into public services without compromising user security measures. In practice, these architectures anonymize access to the system without compromising the reward or penalty function. For this reason, a future research direction will be the use of the SSI system in the management of recyclable waste. In a subsequent iteration, the expansion of the PRS will include an SSI-based ecosystem to build a transparent circular economy.  
While there are areas for improvement and challenges to address, the PRS prototype represents a step forward in utilizing technology for sustainable waste management. Future iterations of the system can benefit from addressing these limitations to optimize its performance, improve the user experience, and ensure that the project continues to make a positive contribution to recycling efforts and environmental sustainability.