ABSTRACT
Pig breeding is moving toward more intensive development and is accompanied by the integrated generation of pig waste. This has disrupted the synergy between the original manure and sewage management mode and corresponding farmland at the household level. Centralized bio-energy mode is proposed to relieve environmental pressure, increase the resource recovery efficiency and rebuild the breeding and cropping. However, there is a lack of comprehensive information on a regional scale, particularly regarding evaluation, applicability and feasibility. Therefore, compared to the individual and traditional mode at the household level, this study was conducted using life cycle assessment and life cycle cost analysis, systematically assessed the environmental performance and economic viability of the centralized bio-energy mode at the regional scale, and further explored the adaptability of multi-subjects (various pig farms and biogas enterprise) and regional feasibility. Results revealed that the centralized bio-energy mode appeared to be a better alternative in terms of global warming, terrestrial acidification and marine eutrophication, with the significant reductions of 49.49 %, 6.8 % and 4.67 % respectively. Moreover, the study demonstrated a substantial profit of 48.5 CNY1 per ton of managed pig waste. Furthermore, both environmental and economic performance could be improved through scale expansion and transport optimization, with an optimal collection radius of less than 31.45 km. Conclusions clarified the potential of centralized bio-energy mode and provided valuable references for its implementation in various regions. Ultimately, further contributing to a more efficient, cost-effective, and regulated manner for resource recovery, culminating in the sustainability of pig farming and achieving environmental-friendly agriculture practices in regional contexts.
ABSTRACT
Urgent solutions are needed in Europe to deal with construction and demolition waste (CDW). EU policy has contributed to significantly reducing the amount of CDW going to landfill, but most of the effort has been put in downcycling practices. Therefore, further policies are needed to stimulate high-quality recycling of CDW. The present paper presents a combined life cycle assessment (LCA) and life cycle costing (LCC) methodologies to analyse the environmental and the economic drivers in four alternative CDW end-of-life scenarios in the region of Flanders, in Belgium. The four analysed alternatives are (i) landfilling, (ii) downcycling, (iii) advanced recycling and (iv) recycling after selective demolition. LCA results show that landiflling is the scenario having the highest environmental impacts in terms of person equivalent (PE), followed by downcycling and recycling (-36%) and recycling after selective demolition (-59%). The decrease in environmental impacts is mostly due to the avoided landfilling of CDW and the recovery of materials from selective demolition. LCC results indicate that landfilling is the scenario bearing the highest total economic costs. This is due to the high landfill tax in Flanders. The recycling after selective demolition bears the second highest cost. The increase of high-quality CDW recycling can significantly reduce the overall environmental impact of the system. Implementing a high landfill tax, increasing the gate fee to the recycling plant, and boosting the sales price of recycled aggregates are the most effective drivers to facilitate a transition towards a more sustainable CDW management system. The paper demonstrates that the combined LCA and LCC results can highlight the environmental and economic drivers in CDW management. The results of the combined analysis can help policymakers to promote the aspects contributing to sustainability and to limit the ones creating a barrier.
