Sustainable solid waste management challenges in hill cities of developing Countries: Insights from eastern Himalayan smart cities of Sikkim, India

Rapid urbanization and the growing tourism industry in the Himalayan region have raised significant concerns about the sustainable handling and management of solid waste in the area. This concern is particularly pronounced in the unique and vulnerable ecosystem of cities nestled in the eastern Indian Himalayas, where geography, ecology, and socio-economic factors converge to create distinctive challenges. This study undertakes a thorough investigation of solid waste management practices and challenges in two smart cities nestled in the eastern Himalayan region of India, specifically Gangtok and Namchi. The primary objective was to unveil the complex challenges confronting these cities by conducting an in-depth exploration of waste management practices. This comprehensive investigation was achieved through the collection of samples, conducting surveys within each ward of the cities, and performing physicochemical characterization analyses. The study also proposes a solution-oriented approach leveraging life cycle analysis. Despite the Himalayan backdrop, waste generation varies significantly, with Gangtok producing substantially more waste (50 tons per day (TPD)) compared to Namchi (4.6 TPD). Both cities excel in waste collection, but Gangtok leads in proactive treatment, with 22% (11 TPD) undergoing composting and recycling. However, shared challenges at riverside disposal sites, including overfilled dumpsites and leachate contamination, pose potential environmental hazards amid the Himalayan allure. Organic waste predominates at 40.9% and 40.01% in both cities, indicating composting potential. Plastic closely at 22.25% (Namchi) and 22.65% (Gangtok) was way above the global (12 %) and national (8.4 %) average respectively, emphasizing the urgency of plastic waste reduction strategy. The 16.95% cardboard in Gangtok highlights potential commerce-related waste. The study also highlights the importance of comprehensive policies for informal sector well-being. The lifecycle assessment of Namchi and Gangtok reveals significant methane emissions (99%) from waste anaerobic decomposition potentially due to poor source segregation. Implementing a futuristic waste strategy reduces emissions by 38% in Namchi and 40% in Gangtok, through biogas utilization and renewable energy adoption. The findings advocate for citizen engagement, improved collection, targeted campaigns, and circular economy principles. To ensure sustainability and resilience in waste management within mountain regions, tailored strategies such as material recycling facilities, community engagement initiatives, and landfill diversion mandates should integrate ecological, socioeconomic, and logistical considerations, fostering awareness and participation among communities.