Long-term evolution of the climate change impacts of solid household waste management in Lappeenranta, Finland

Waste management processes have developed significantly in recent decades and will continue to change alongside the associated environmental impacts. This paper examines the climate change impacts of historical development in waste management, which has not received significant attention in the existing literature, while also exploring possible future developments. The city of Lappeenranta in Finland was selected as a case study, and the climate impacts of household waste (HW) management were calculated for the actual situations in 2009 and 2019 and the foreseen situation in 2029. Separately collected waste fractions of mixed residual waste (MRW), biowaste, cardboard, plastic, metal, and glass were included in the analysis. The results show that the net climate change impact decreased considerably from 945 kg_CO2-eq./t_HW in 2009 to -141 kg_CO2-eq./t_HW in 2019 mainly by directing the MRW to energy recovery instead of landfill. The emissions responsible for climate change could be further reduced in 2029 by directing biowaste to digestion instead of composting and by directing more fractions to recycling; e.g., plastic, the impact of which is affected by the demand for recycled plastic. For the year 2029, the net climate change impact was -181 kg_CO2-eq./t_HW when heat produced from MRW displaced natural gas and was as high as 142 kg_CO2-eq./t_HW if the heat substituted biomass heat. The findings reveal that as energy production mixes and materials become less fossil carbon intensive, they have a significant impact on the net climate impacts of waste management.