An assessment of higher-value recyclable wastes in Mexico City households using a novel waste collector citizen science approach.

The ability to accurately characterize and collect data on household waste generation and composition is essential for promoting recycling and developing city management plans. However, traditional data collection approaches in developing countries are hampered by jurisdictional and budgetary constraints. Here, we explore whether citizen science projects that collaborate with waste collectors can solve this problem and be a viable tool for addressing household waste generation across temporal and geographic boundaries. In this regard, this first study evaluated recyclable household waste generation by engaging waste collectors both door-to-door individuals and trucks as citizen scientists daily in an urbanized colony (5797 inhabitants and 1747 houses) in Mexico City between September and October 2022. To understand their distribution and consumption patterns on a regional basis, we stratified the colony's households into 2 distinct non-overlapping sub zones and one Wednesday market based on waste collectors' routine using a Geographical Information System. Results show that for seven weeks, household waste constitutes up to 12.19 t of recyclables, ranging from 99.5 to 480.8 kg/day, with 35 % cardboard, 23 % PET plastics, 21 % hard plastics, 17 % glass, and 4 % aluminum. The average amount of recyclable waste produced was 54 g/person/day, resulting in an annual recycling generation of 114 t. Statistical analysis revealed that recyclable waste generation varied by day and subzone. Furthermore, informal centers rather than municipal waste disposal facilities are in charge of the final disposition of the collected recyclables, suggesting that a substantial waste proportion may go unaccounted for in the local government's annual MSW report and calling for the implementation of formal recycling sectors. Overall, this study show how effective waste collector engagement in science can be and imply that the proposed citizen science approach is vital for future waste projects and the generation of transparent datasets in developing cities.