Development of a pre-treatment process of polymeric wastes (HDPE, LDPE/LLDPE, PP) for application in the qualification of selectors of recyclable materials

Recycling post-consumer packaging of high and linear/low-density polyethylene (HDPE, LDPE/LLDPE) and polypropylene (PP) (most representative in any plastic waste stream) is a viable alternative. However, these packages must be washed first, especially those with a high content of contaminants (such as yogurt-HDPE and margarine-PP). Therefore, this study aimed to develop a complete pre-treatment of polymeric wastes (HDPE, LDPE/LLDPE, PP) involving the steps of quantification, characterization, washing (pre-wash/ washing/rinsing), treatment of the generated effluent and the reuse of treated water in a closed circuit. Afterward, the qualification of recyclable material selectors was performed with associations/cooperatives of recyclable material in the Rio Grande do Sul, South region of Brazil. The results indicated that the subdivision in prewash/washing/rinsing utilizing sulfonic acid (1.16% v/v), lauryl (sodium lauryl ether sulfate) (0.53% v/v) and soda (0.31% v/v) was suitable for obtaining clean polymeric waste. Treatment of effluent using aluminum sulfate (4 g L-1) as a coagulant, followed by filtration, was efficient with removal values greater than 90%. These characteristics of treated water allowed its reutilization water of a safe way in closed circuit in the process of washing of the polymeric wastes. Finally, a total of sixty-four selectors of recyclable materials were trained and the theoretical-practical training was quite satisfactory for more than 95% of selectors. Therefore, it can be concluded that the great importance to transmitting the knowledge to society generated in this studies and thus provides best conditions for the development of these selectors of recyclable materials.

Automated summary

Recycling post-consumer packaging of HDPE, LDPE/LLDPE, and PP requires a thorough pre-treatment process to ensure cleanliness and reuse of water in a closed circuit. Effluent treatment using aluminum sulfate as a coagulant was found to be highly efficient, with removal rates exceeding 90%. Training recyclable material selectors was successful, with over 95% showing satisfaction and recognizing the importance of the training for their development in the field.