Closing the loop: A case study on pathways for promoting sustainable waste management on university campuses.

The implementation of circular economy (CE) strategies has facilitated a comprehensive approach to waste management (WM) in university campuses. Composting food waste (FW) and biomass can mitigate negative environmental impacts and be part of a closed-loop economy. The compost can be used as a fertilizer, thereby closing the waste cycle. Implementing nudging strategies to promote effective waste segregation can help the campus move closer towards achieving neutrality and sustainability goals. The research was conducted at the Warsaw University of Life Sciences - WULS (SGGW). The University Campus is located in the south of Warsaw (Poland) and covers an area of 70 ha with 49 buildings. The SGGW campus generates selectively collected (glass, paper, plastic and metals, and biowaste) and mixed waste. Data were collected through a year-long report from the university administration. For the survey, waste data from 2019 to 2022 were obtained. The CE efficiency indicators of CE were measured. The indicators of CE efficiency for compost (Ic,ce) and plastic (I,) showed Ic,ce at 21.05 %, which means that 1/5th of the waste generated on the campus can be introduced into the CE paradigm through composting, and the resulting value I of 19.96 % indicates that this amount can be reintroduced into the CE paradigm through its reuse. The results of the seasonality study showed that there were no statistically significant differences in the generated biowaste between the separated periods of the year, and the Pearson correlation coefficient (r = 0.068) provided additional confirmation. The weak correlation between the amount of biowaste generated and the average for each year (r = 0.110) also indicates a stable biowaste generation system that does not require a reduction or increase in the efficiency of waste processing, such as composting. By implementing CE strategies, university campuses can improve WM practices and achieve sustainability goals.