Resources, Conservation and Recycling: X最新文献

This study explores the motivations, opportunities, and abilities that consumers have for reducing food waste in everyday contexts that involve competing (food-related) goals. The framework of motivations, opportunities, and abilities is used to disentangle the complex array of factors that contribute to food waste. Results from 24 focus groups conducted in four European countries reveal that household food waste is the unintended result of balancing multiple competing goals. The results also indicate that abilities and opportunities influence the ease with which consumers can reduce food waste and act upon other goals (to which they assign greater value). These insights imply that, in addition to strengthening the importance that consumers attach to reducing food waste, interventions should focus on providing opportunities and abilities that will enable consumers to comply with multiple goals, including food-waste reduction.

The existing building stock represents a huge accumulation of physical resources: a material ‘reserve’ that could be mined in the future to improve resource efficiency. However, in the absence of systematically collected information about materials deposited in the built environment, the ability to manage and exploit them is limited. An approach to quantification of material stocks based on the use of secondary data from external research bodies, national statistics and a housing stock management database is used to estimate the timber stock in residential buildings constructed in the London Borough of Tower Hamlets before 1992. Results show a total timber accumulation of almost 67,000 tonnes across 68,000 dwellings, with a material intensity for timber between 20−34 kg/m² of building floorspace (6.8–11.2 kg/m³ of gross building volume) for terraced houses and 5.4−11 kg/m² (1.8–3.6 kg/m³) for flats and maisonettes. Generally, there is more timber in floors and roofs, and in older buildings. This method appears to be robust, as it results in comparable timber intensities to those determined using other methods in previous studies. It can be used for other materials and may be useful in other contexts where data is available (i.e., other scales, building types and materials), and capable of contributing to the growing understand of existing buildings as material banks.

One innovation developed to tackle food waste in professional catering units is different versions of smart scales and softwares designed to simplify food waste quantification. The intention with this is to managing meal production more efficiently based on previous outcomes. However, quantification can be performed in different ways and having a catering unit quantify its food waste does not necessarily guarantee a reduction. Therefore this study sought to identify factors that could make food waste quantification more efficient in terms of waste reduction, and to determine the waste reduction payoff from more ambitious quantification set-ups. Data on 735 hotels, restaurants, and canteens in Europe, especially Sweden and Norway, that use a spreadsheet, a dedicated scale, or an internet-based service to track food waste were analyzed and parameters describing initial waste, number of guests and length, resolution, and completeness of quantification were determined. These parameters were then compared against the waste reduction achieved, in order to test their influence. It was found that 61% of the catering units studied had reduced their waste and that initial mass of waste per guest was the most influential factor for waste reduction. Catering units using more automated quantification tools recorded more data and reduced their food waste by slightly more, but also had a higher level of initial waste and therefore a greater opportunity for reduction. From this, it can be concluded that prioritizing catering units with the greatest waste volume could be an efficient strategy to reduce overall food waste in the most cost-efficient way.

The large variety and amounts of plastic waste produced worldwide requires to better organize the industrial network devoted to the exploitation of this material by including different processes that allow to recover the “material” as main target. This paper presents the results of the feasibility study developed for an integrated system for plastic waste management designed in such a way to deal with the real market and provide for reliable targets in term of material recovery yields, energy efficiency and waste minimization. The system under study is a combination of mechanical sorting, thermochemical processes and conversion into materials and energy. The quantified block diagrams are used to represent the mass and feedstock energy balances by allowing the calculation of yields of given products. The equipment list for each sub-system is provided together with the installed power for the main component and/or auxiliary; these data allowed to perform the energy balance and to obtain the net energy production by the integrated system. The energy balance demonstrated that the integrated system is feasible while, on the contrary, the single processes are not energetic self-sustainable.

The long-term supply sustainability of copper, zinc and lead was assessed. Copper will not run into physcal scarcity in the future, but increased demand and decreased resource quality will cause significant price increases. The copper price is suggested to increase significantly in the coming decades. A similar situation applies for zinc and lead with soft scarcity and increased prices for zinc. The total supply of copper reaches a maximum 2030–2045, zinc 2030–2050 and lead 2025-2030. The copper supply per person and year and decline after 2130, and the copper stock-in-use reaches a maximum in 2050 and decline afterwards. The zinc supply per person per year reach a maximum in 2100 and decline after 2100, and the zinc stock-in use shows a similar pattern. The lead supply per person reach a plateau in 1985, and decline after 2070, whereas the lead stock-in-use reach a plateau in 2080 and decline after 2100. For copper, zinc and lead, scarcity will mainly be manifested as increased metal price, with feedbacks on demand. The predicted price increase will cause recycling to increase in the future. The supply situation for copper would be much improved if the recycling of copper could be strongly promoted through policy means, as well as it would work well to limit the price increases predicted under business-as-usual. Considering the importance of these metals for society, it is essential to set adequate policies for resource efficiency and resource conservation for society.

Onsite (a.k.a. decentralized) water reuse can reduce overall potable water demand and aid in meeting water reduction goals. In spite of clear benefits, onsite non-potable water systems (ONWS), specifically non-blackwater commercial systems, face many challenges that are preventing growth and expansion in California. This study utilized a technical advisory committee and a survey to identify the most significant challenges facing onsite water reuse systems, how these challenges affect ONWS stakeholders, and potential solutions at the state level. The given methods found that the most prevalent challenges hindering the growth of ONWS appeared to be the absence of a local regulatory program, system cost, poor access to training for regulators, and limited public education about alternate water sources. Survey results revealed several possible drivers for the existence of these challenges including that informational and training resources are not adequately disseminated to target groups. The study concluded that the creation of trainings for regulators, the development of an organization dedicated to onsite systems, expanded technology certifications, policy changes, and highlighting existing systems might help overcome the challenges hindering growth and allow for greater expansion of onsite non-potable water systems throughout California.

The cement industry in China has been conducting overcapacity elimination through technology upgrading in the past years. Most of the overcapacity elimination policies are in the form of administrative and regulative approaches. However, the cost of overcapacity elimination by implementing command-and-control policies will be increasingly higher, at the same time, the orientation of such technology upgrading remains unknown. Such contradiction creates the necessities to reveal the impact of other policy instruments on the technology upgrading in the cement industry, as well as to clarify the optimal output allocation among all alternative technology choices. In this paper, an LCA-RCOT model (Life Cycle Assessment and Rectangular Choices Of Technologies) is established to provide such optimal technology combination with the constraints from a projected emission trading scheme (ETS). The results show that under an ETS cap with a target of 5% reduction of emission, 10% of subsidy allowances, and one-way linking with another ETS with higher average market price, the optimal solution suggest that 114.5 billion USD of total output in the cement sector should be produced by small dry kilns, while 102.5 billion USD by large dry kilns. In all feasible solutions, the optimal technology combination may shift to fewer shaft kilns and more dry kilns. In the long run, the climate policy instrument, ETS, may promote the upgrading of production technology by decomposing the total emission mitigation costs to the factor inputs of each cement producer.

Increased awareness in the United Kingdom around the issues of dealing with plastic waste, particularly non-recyclable plastics, has created political pressure to find new ways to manage this waste stream. As a result, the UK government recently convened consultations around adapting the national plastic waste management strategy in light of curtailed overseas plastic recycling. In this work, we consider the potential role that chemical recycling, such as gasification and pyrolysis, may have to play in the context of plastic waste valorization, and assess the policies and market conditions that would be required to make chemical recycling a feasible means by which to manage difficult to recycle plastic waste in the UK.

To reduce environmental issues resulting from excess nutrients, conserve valuable resources and safeguard future food security, natural nutrient cycles in agro-food-waste systems need to be restored. To this end, nutrient stock and flow analyses of the agro-food-waste system can be undertaken. There is currently no standardized method for the systematic analysis of nutrient stocks and flows to support nutrient circularity of those systems at a local scale. This review of 57 studies summarizes the current knowledge on nutrient stock and flow analysis of agro-food-waste systems in local areas and proposes a six-step framework. About a third of the reviewed studies analyzed the complete agro-food-waste system, including crop production, animal production, food and feed processing industry, consumption and waste management. Furthermore, the main focus tends to be on phosphorus (P), and to a lesser extent on nitrogen (N), potassium (K) and (organic) carbon (C). Only a few studies combined the analyses of different nutrients, even though nutrient use efficiency relies on obtaining the optimal stoichiometric balance. The proposed framework for nutrient stock and flow analyses encompasses the inclusion of the complete agro-food-waste system and simultaneous analysis of N, P, K and C to facilitate assessment of the full potential to restore local nutrient circularity. Moreover, the local study area needs to be sufficiently large to include all the subsystems and sufficiently small to facilitate transportation of nutrients. Following this six-step framework, analyses will be able to identify hotspots, based on which effective measures to restore local nutrient circularity can be developed.