a b s t r a c tPlastics have been the most consumed materials of human societies in recent decades and, in the mean time, one of the major products obtained from landfill mining. Characteristics of the landfill mined plastic wastes and their recovery potential were the key points to determine the feasibility of landfill mining projects. We collected municipal solid waste samples of different storage years from the landfill and did mechanical screening and manual separating to sort out plastic wastes, and a typical old landfill, which is of 24 storage years and located in central China, was taken as our studied case. According to our research, plastic wastes accounted for 10.62 ± 5.12% of the total stored wastes in the old landfill, among which, 69.13% was plastic bags (white PE plastic bags accounted for 11.34%; colored PE plastic bags 29.77%; other plastic bags 28.02%), and 30.87% was other plastics (incl. PP, PVC, PS, etc.). The average moisture content in the plastic waste was 19.96 ± 4.65% and the average impurities content was 71.02 ± 6.31% before manual washing and cleaning. The VS, ash, fixed carbon and calorific value of manually cleaned plastic wastes were 87.09 ± 0.55%, 10.84 ± 1.19%, 2.07 ± 0.85% and 43.18 ± 1.49 MJ kg À1 , respectively. Elements testing (C, N, O, S, Cl, Si, Al) and surface images analysis under scanning electron microscope showed that normal cleaning techniques had a difficulty in thoroughly getting rid of all the impurities on the surface of plastic bags excavated from old landfill, which will impede plastic wastes from being mechanical recycled as renewable materials or being chemically recycled by either pyrolysis, gasification, hydrogenation. Incineration or treating as residue derived fuels (RDFs) for recovering energy was the most practical way to process landfill mining plastic wastes under the normal cleaning techniques.

No abstract

No abstract

a b s t r a c tLandfill mining is an environmentally-friendly technology that combines the concepts of material recycling and sustainable waste management, and it has received a great deal of worldwide attention because of its significant environmental and economic potential in material recycling, energy recovery, land reclamation and pollution prevention. This work applied a cost-benefit analysis model for assessing the economic feasibility, which is important for promoting landfill mining. The model includes eight indicators of costs and nine indicators of benefits. Four landfill mining scenarios were designed and analyzed based on field data. The economic feasibility of landfill mining was then evaluated by the indicator of net present value (NPV). According to our case study of a typical old landfill mining project in China (Yingchun landfill), rental of excavation and hauling equipment, waste processing and material transportation were the top three costs of landfill mining, accounting for 88.2% of the total cost, and the average cost per unit of stored waste was 12.7 USD ton À1 . The top three benefits of landfill mining were electricity generation by incineration, land reclamation and recycling soil-like materials. The NPV analysis of the four different scenarios indicated that the Yingchun landfill mining project could obtain a net positive benefit varying from 1.92 million USD to 16.63 million USD. However, the NPV was sensitive to the mode of land reuse, the availability of energy recovery facilities and the possibility of obtaining financial support by avoiding post-closure care.

The sharp increase in global urban population and rapid expansion of impervious urban surfaces is raising concerns over more than just the quality of human life; researchers are also worried about ecosystem services and the stability and security of urban ecosystems and the infrastructures. In this paper, we define "urban ecological infrastructure" and propose an integrated framework in which the infrastructure network provides ecosystem services and sustainable urban systems despite changing landscapes and climate. We define the urban ecological infrastructure (UEI) as an organic integration of blue (water-based), green (vegetated), and grey (non-living) landscapes, combined with exits (outflows, treatment, or recycling) and arteries (corridors), at an ecosystem scale. The UEI framework represents the biotic and abiotic interactions within an ecosystem, and stresses an integrated relationship between artificial and natural systems. It links the grey, blue, and green infrastructures, and integrates them via both exits and arteries. Its insights can help to improve the circulation and reuse of resources throughout the urban ecosystem. This comprehensive conceptual framework can facilitate more rational urban development, and can improve urban ecosystem services and regional sustainability. Although understanding the form and function of UEIs is an important first step, innovative strategies are needed to address challenging obstacles such as rigid thinking, institutional fragmentation and inflexible policies. New thinking and innovative ways of acting will be required to provide a more resilient, stable, and sustainable urban system.

Municipal solid waste (MSW) landfills are the most prevalent waste disposal method and constitute one of the largest sources of anthropogenic methane emissions in the world. Microbial activities in disposed waste play a crucial role in greenhouse gas emissions; however, only a few studies have examined metagenomic microbial profiles in landfills. Here, the MiSeq high-throughput sequencing method was applied for the first time to examine microbial diversity of the cover soil and stored waste located at different depths (0-150cm) in a typical MSW landfill in Yangzhou City, East China. The abundance of microorganisms in the cover soil (0-30cm) was the lowest among all samples, whereas that in stored waste decreased from the top to the middle layer (30-90cm) and then increased from the middle to the bottom layer (90-150cm). In total, 14 phyla and 18 genera were found in the landfill. A microbial diversity analysis showed that Firmicutes, Proteobacteria, and Bacteroidetes were the dominant phyla, whereas Halanaerobium, Methylohalobius, Syntrophomonas, Fastidiosipila, and Spirochaeta were the dominant genera. Methylohalobius (methanotrophs) was more abundant in the cover layers of soil than in stored waste, whereas Syntrophomonas and Fastidiosipila, which affect methane production, were more abundant in the middle to bottom layers (90-150cm) in stored waste. A canonical correlation analysis showed that microbial diversity in the landfill was most strongly correlated with the conductivity, organic matter, and moisture content of the stored waste.

To ascertain the most discriminant variables for three pumpkin species principal component analysis (PCA) was performed. Twenty-four parameters (pH, conductivity, sucrose, glucose, total soluble solids, ,, , individual weight, edible rate, firmness, citric acid, fumaric acid, l-ascorbic acid, malic acid, PPO activity, POD activity, total flavonoids, vitamin E, total phenolics, DPPH, FRAP, β-carotene, and aroma) were considered. The studied pumpkin species were, , and. Three pumpkin species were classified by PCA based on aroma, physicochemical and antioxidant properties because the sum of PC1 and PC2 were both greater than 85% (85.06 and 93.64% respectively). Results were validated by the PCA and showed that PPO activity, total flavonoid, sucrose, glucose, TSS, , pH, malic acid, vitamin E, DPPH, FRAP and β-carotene, and aroma are highly useful parameters to classify pumpkin species.

No abstract