Life cycle assessment of bio-sludge for disposal with different alternative waste management scenarios: a case study of an olefin factory in Thailand

Bio-sludge generated from wastewater treatment plants is typically disposed of in landfills. Among the pressure of environmental problems, alternative options for bio-sludge disposal have been proposed. In addition to landfills, burning sludge in cement kilns and composting are new options for managing bio-sludge in Thailand. The objective of this study is to evaluate the environmental impact of alternative waste management practices for bio-sludge, including landfilling with landfill gas utilization systems, cement kilns, and composting, compared with conventional landfills. The environmental impact from each scenario was calculated at midpoints and damage levels using the IMPACT 2002+ method. The results indicate that landfilling with landfill gas utilization systems shows the greatest potential for greenhouse gas reduction compared with conventional landfills. The cement kiln option has the highest potential for aquatic acidification, terrestrial acidification and nitrification. While the fertilizer option has lowest potential for those impacts, the potential for aquatic eutrophication and terrestrial ecotoxicity is highest in this option. Finally, the endpoint analysis showed that the fertilizer option has a high performance in regard to human health and climate change, and it was recommended for selection as a first priority for bio-sludge disposal in Thailand.