Environmental and economic assessment of the construction, operation, and demolition of a decentralized composting facility.

Decentralized waste treatment facilities are recently highlighted for the treatment of solid waste in rural areas for being cheap, flexible, and reliable. Among them, decentralized composting is most commonly used. Many forms of decentralized composting facilities also develop and apply in developing countries, but the environmental and economical performances remain unknown. Therefore, this study analyzed the environmental impacts and cost of a decentralized composting facility through life cycle assessment and life cycle cost. The functional unit was the construction, operation, and demolition the composting facility. Contribution and sensitivity analysis were also performed to find out the most influential processes and parameters. The facility had a 10-year designed life span and could treat about 5840 t organic waste in its life cycle. The life cycle environmental impacts were 646,700 kg CO2-eq, 8980 kg SO2-eq, -28 kg P-eq, 7.09 × 10-3 CTUh, 0.13 CTUh, and 16,754 kg oil-eq for climate change, terrestrial acidification, freshwater eutrophication, human toxicity cancer effects, human toxicity non-cancer effects, and fossil resources scarce, respectively. The life cycle cost was 1080.925 k CNY. When scaling to treating 1 t organic waste, the environmental impacts were close to those of similar decentralized and centralized composting facilities and the cost was lower than those of centralized biological treatment plants when excluding revenues from compost. According to the contribution and sensitivity analysis, the operation stage had the largest environmental impacts. The composting and compost substitution processes in the operation stage were the most sensitive processes. This study proved quantitatively that the decentralized facility was feasible both environmentally and economically and enriched the study cases for decentralized composting facilities.

Life cycle assessment of waste management in rural areas in the transition period from mixed collection to source-separation.

Rural solid waste management is essential for fulfilling sustainable development goals, especially in developing countries. However, quantitative study on this aspect has been little and far behind the urban areas. In this study, the environmental impacts of four typical rural solid waste management systems were quantified using life cycle assessment based on data from field investigations of five towns across four seasons. Sensitivity analysis was used to determine the most influential parameters. The results showed that landfilling mixed waste contributed the highest environmental impacts. By substituting landfilling with incineration, the environmental impacts (i.e., global warming potential, terrestrial acidification potential, fossil resource scarcity, freshwater ecotoxicity potential) dropped about 110%-900%. When shifting collection schemes to source separation, the environmental impacts also decreased by approximately 50%-200%. However, the environmental impacts of applying source separation to the existing management systems with mixed collection and disposal facilities of landfill or waste-to-energy (WTE) incineration are unclear and depend on the performance of decentralized composting and anaerobic digestion facilities, which need further investigations. Compared with urban cases, the landfill in rural areas emits higher greenhouse gas (GHG), and WTE incineration plants in rural areas have similar GHG emissions to WTE in urban areas. Besides, energy recovery was the most influential process in WTE systems and a 1% improvement on that would bring over 10% progress on global warming potential impact category. These findings can be useful for improving and developing rural domestic waste treatment in China and other developing countries.