Yao WangAlejandro Ruiz-AcevedoEemaan RameezVijaya Raghavan...
133-148页
查看更多>>摘要：Effective waste management is a major challenge for Small Island Developing States(SIDS)like Maldives due to limited land availability.Maldives exemplifies these issues as one of the most geographically dispersed countries,with a population unevenly distributed across numerous islands varying greatly in size and population density.This study provides an in-depth analysis of the unique waste management practices across different regions of Maldives in relation to its natural and socioeconomic context.Data shows Maldives has one of the highest population density and per capita waste generation among SIDS,despite its small land area and medium GDP per capita.Large disparities exist between the densely populated capital Male'with only 5.8 km2 area generating 63％of waste and the～194 scattered outer islands with ad hoc waste management practices.Given Male's dense population and high calorific waste,incineration could generate up to～30 GW/a energy and even increase Maldives'renewable energy supply by 200％.In contrast,decentralized anaerobic digestion presents an optimal solution for outer islands to reduce waste volume while providing over 40％-100％energy supply for daily cooking in local families.This timely study delivers valuable insights into designing context-specific waste-to-energy systems and integrated waste policies tailored to Maldives'distinct regions.The framework presented can also guide other SIDS facing similar challenges as Maldives in establishing sustainable,ecologically sound waste management strategies.
查看更多>>摘要：Substantial environmental and economic benefits can be achieved by recycling used lithium-ion batteries.Hydrometallurgy is often employed to recover waste LiNixCoyMnzO2 cathode materials.As Ni,Co and Mn are transition metals,they exhibit similar properties;therefore,separating them is difficult.Thus,most researchers have focused on leaching processes,while minimal attention has been devoted to the separation of valuable metals from waste LiNixCoyMnzO2 cathode materials.Herein,we propose an environment-friendly,gentle process involving the usage of pyrometallurgy and hydrometallurgy to gradually leach valuable metals and effectively separate them.Interestingly,Li is recovered through a reduction roasting and water leaching process using natural graphite powder,Ni and Co are recovered through ammonia leaching and extraction processes and Mn is recovered through acid leaching and evaporation-crystallization processes.Results show that～87％Li,97.01％Co,97.08％Ni and 99％Mn can be leached using water,ammonia and acid leaching processes.The result obtained using the response surface methodology shows that the concentration of(NH4)2SO3 is a notable factor affecting the leaching of transition metals.Under optimal conditions,～97.01％Co,97.08％Ni and 0.64％Mn can be leached out.The decomposition of LiNixCoyMnzO2 is a two-step process.This study provides valuable insights to develop an environment-friendly,gentle leaching process for efficiently recycling valuable metals,which is vital for the lithium-ion battery recycling industry.
查看更多>>摘要：The biocidal effects of free nitrous acid(FNA)have found applications in multiple units in an urban wastewater system,including sewer networks,wastewater treatment processes,and sludge treatment processes.However,these applications are associated with chemical costs as both nitrite and acid are needed to produce FNA at the required levels.The recent discovery of novel acid-tolerant ammonia oxidizers offers the possibility to produce FNA from domestic wastewater,enabling the development of next-generation FNA-based technologies capable of achieving self-sustaining FNA production.In this study,we focus on the concept of in situ FNA generation facilitated by acid-tolerant ammonia oxidizers and highlight the multiple benefits it creates,after a brief review of the historical development of FNA-based technologies.We will discuss how wastewater systems can be made more energy-efficient and sustainable by leveraging the potential of acid-tolerant ammonia oxidizers.
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