Abstract

This study evaluates the impact of introducing a curbside recycling collection service (CRCS) on plastic recycling, primarily PET bottles, when implemented alongside open-access street recycling bins. The analysis uses objective operational records from a 91-week non-randomized field experiment conducted in two middle-income neighborhoods in Osorno, Chile. The intervention included three stages: installation of street recycling bins in both neighborhoods, introduction of CRCS in the treatment area, and subsequent reinforcement through injunctive-normative appeal brochures. Results show that CRCS increased plastic collection by 3.5 kg per withdrawal and polygon, equivalent to a 74% increase relative to the control group. During the reinforcement stage, plastic collection increased by 1.3 kg, equivalent to a 31.1% increase, although this estimate cannot be interpreted as the isolated causal effect of messaging. Street-bin use did not decline after CRCS was introduced, providing suggestive evidence of complementarity between collection systems. Non-recyclable material increased modestly during the CRCS-only stage but decreased and became statistically insignificant during the reinforcement stage. By jointly examining material recovery, system interaction, and contamination using objective longitudinal field data, this study contributes to the literature on recycling system design in middle-income urban contexts. The findings suggest that curbside collection can improve plastic recovery, provided that monitoring and communication strategies are used to preserve material quality.