Mitigation of global greenhouse gas emissions from waste: conclusions and strategies from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report. Working Group III (Mitigation)

Upcycling fruit waste into microalgae biotechnology: Perspective views and way forward

Fruit and vegetable wastes are linked to the depletion of natural resources and can pose serious health and environmental risks (e.g. eutrophication, water and soil pollution, and GHG emissions) if improperly managed. Current waste management practices often fail to recover high-value compounds from fruit wastes. Among emerging valorization methods, the utilization of fruit wastes as a feedstock for microalgal biorefineries is a promising approach for achieving net zero waste and sustainable development goals. This is due to the ability of microalgae to efficiently sequester carbon dioxide through photosynthesis, utilize nutrients in wastewater, grow in facilities located on non-arable land, and produce several commercially valuable compounds with applications in food, biofuels, bioplastics, cosmetics, nutraceuticals, pharmaceutics, and various other industries. However, the application of microalgal biotechnology towards upcycling fruit wastes has yet to be implemented on the industrial scale due to several economic, technical, operational, and regulatory challenges. Here, we identify sources of fruit waste along the food supply chain, evaluate current and emerging fruit waste management practices, describe value-added compounds in fruit wastes, and review current methods of microalgal cultivation using fruit wastes as a fermentation medium. We also propose some novel strategies for the practical implementation of industrial microalgal biorefineries for upcycling fruit waste in the future.

Nitrous oxide emissions and microbial communities variation in low dissolved oxygen and low carbon-to-nitrogen ratio anoxic-oxic wastewater treatment plant

Dissolved oxygen (DO) levels and carbon-to-nitrogen (C/N) ratio affect nitrous oxide (N2O) emissions by influencing the physiological and ecological dynamics of nitrifying and denitrifying microbial communities in activated sludge systems. For example, Nitrosomonas is a common N2O producing nitrifying bacteria in wastewater treatment plants (WWTPs), and DO conditions can affect the N2O production capacity. Previous studies have reported N2O emission characteristics under adequate DO and C/N conditions in A/O WWTPs. However, in actual operation, owing to economic and managerial factors, some WWTPs have a long-term state of low DO levels in oxic tanks and low influent C/N. Research on N2O emission characteristics in low DO-limited and low C/N ratio WWTPs is limited. This study investigated N2O emissions and the corresponding shifts in microorganisms within an anoxic-oxic (A/O) WWTP over 9-month. Quantitative PCR was used to assess the abundance of ten functional genes related to nitrification and denitrification processes, and high-throughput sequencing of the 16S rRNA gene was employed to determine the composition change of microorganisms. The findings revealed that 1) the average N2O emission factor was 1.07% in the studied WWTP; 2) the DO-limited oxic tank primarily contributed to N2O; 3) NO2-, TOC, and C/N ratios were key factors for dissolved N2O in the aerobic tank; and 4) Nitrosomonas and Terrimonas exhibited a robust correlation with N2O emissions. This research provides data references for estimating N2O emission factors and developing N2O reduction policies in WWTPs with DO-limited and low C/N ratios.

A critical review on global CO2 emission: where do industries stand?

Global CO2 emissions from different industries have been increasing at an alarming rate. This growth is outpacing the efforts, nations are putting in place to reduce their carbon footprints. In this topical review, we critically analyze the level of CO2 emissions on a global scale and across various industries and activities within them and the dominant anthropogenic forcing instability. The global CO2 emission from various economic sectors such as industries, transportation and variety of waste sources were traced globally and regionally. To contextualize our review, the sector wise CO2 emission trends data for a period more than a decade is reviewed which highlighted the main sources of emissions. The data shows the overall reduction of carbon footprints and its progress across various sectors is very limited. The governing factors for this continued global pattern can be ascribed to two main factors: high consumer demands, and poor efforts towards shifting low and zero carbon services across all sectors. Some efforts have been witnessed to shift towards clean fuels and renewables, particularly in Europe and North America. However, rapid growth in industrialization limits the shifting of fossil-based energy systems towards less harmful systems. In Asia, particularly in eastern, southern, and south-eastern regions, the carbon footprints were found to increased owing to a huge demand for materials production, travelling and energy services. Therefore, it is of utmost importance to identify, understand and tackle the most persistent and climate-harmful factors across all industries and drive such policies to substitute the fossil fuels with renewables.

Effects of Hydrophobic Biochar-Modified Landfill Soil Cover on Methane Oxidation

Landfill cover soils play an important role in mitigating landfill methane (CH4) emissions. Incorporating biochar into the soil has proven effective in reducing CH4 emissions. However, the role of hydrophobic biochar in this context remains underexplored. This study investigated the CH4 removal efficiency of a biochar-modified landfill soil cover column (RB) and hydrophobic biochar-modified landfill soil cover column (RH) under varying CH4 influx gas concentrations (25 and 35%), simulated CH4 inflow rates (10, 15, and 20 ml/min), and temperatures (20, 25, 30, 35, and 40 °C). RH consistently outperformed RB in terms of CH4 removal efficiency under these experimental conditions. The optimal conditions for CH4 degradation by both RB and RH were observed at a CH4 influx gas concentration of 35%, a simulated CH4 inflow rate of 10 ml/min, and a temperature of ~30 °C. RH achieved a CH4 removal rate of up to 99.96%. In summary, the addition of hydrophobic biochar enhanced the air permeability and hydrophobicity of landfill cover soils, providing a promising alternative to conventional cover soils for reducing CH4 emissions from landfills.

Impact of temperature on the performance of compost-based landfill biocovers

Methane (CH4) emissions from landfills are a major contributor to global greenhouse gas emissions. Compost-based biocovers offer a viable approach to reduce CH4 emissions from landfills; however, the effectiveness in climates with varying temperatures is not well understood. The methane removal performances of two compost-based biocover materials (food and yard waste compost) were examined under different temperature conditions using laboratory column experiments. A reactive transport model was used to simulate the experimental results to develop a better quantitative understanding of the effect of temperature on overall methane removal efficiency. As expected, experimental results indicated that the oxidation rate was influenced by temperature, as it was reduced when the temperature decreased from 22 °C to 8 °C. However, some oxidation was observed at a lower temperature, which was confirmed by CO2 concentrations above the initial level and the observed temperatures above the exposure temperature along the height of biocover column. Furthermore, results showed that when the compost-based materials were subjected to 8 °C and then increased to 22 °C, methane oxidation within the material recovered quickly and returned to similar oxidation rates as observed before the temperature was reduced, suggesting that compost-based biocovers may not be affected by cyclic temperature variations when used in colder climates. Methane oxidation capacity was limited by the maximum oxidation rate, the biocover porosity, and the gas saturation profile that affects residence time and overall methane oxidation in the columns. The model results show that the CH4 oxidation rate was reduced by one order of magnitude when the temperature decreased from 22 °C to 8 °C. Therefore, the calculated Q10 values were 4.19 and 5.18 for the food and yard waste compost, respectively. Overall, compost-based landfill biocovers, such as food and yard waste compost, are capable of mitigate CH4 emissions from old and small landfills under different temperature conditions.

Wastewater treatment by using microalgae: Insights into fate, transport, and associated challenges

The remediation of wastewater with microalgae is a new topic that concentrates on devising a cost-effective and environmentally beneficial method. Multiple microalgae and bacterial consortiums have recently been evaluated to determine if they can purify effluent from various sources. Critical to a system's efficacy is its ability to remove nutrients such as nitrogen (N) and phosphorus (P) and heavy metals such as arsenic (As), lead (Pb), and copper (Cu). This study compared traditional wastewater treatment systems to microalgae-based systems for treating different types of wastewater. The research investigates the potential for microalgae to cleanse wastewater. The research also evaluates wastewater parameters, methods, and scientific techniques for extracting nutrients and heavy metals from polluted water. According to the literature, Microalgae can remove between 98.7% and 100% of nitrogen (N), phosphorous (P), and heavy metals from various effluents. The paper concludes by discussing the difficulties of using microalgae to remediate wastewater. The elimination of nutrients from the effluent is influenced by biomass production, osmotic capacity, temperature, pH, and O2 concentration. Therefore, a "pilot" study is recommended to investigate contaminants.

Impact of leachate and landfill gas on the ecosystem and health: Research trends and the way forward towards sustainability

Globally, a whopping increase in solid waste (SW) generation and the risks posed by climate change are major concerns. A wide spread practice for disposal of municipal solid waste (MSW) is landfill, which swells with population and urbanization. Waste, if treated properly, can be used to produce renewable energy. The recent global event COP 27 mainly stressed on production of renewable energy to achieve the Net Zero target. The MSW landfill is the most significant anthropogenic source of methane (CH₄) emission. On one side, CH₄ is a greenhouse gas (GHG), and on the other it is a main component of biogas. Wastewater that collects due to rainwater percolation in landfills creates landfill leachate. There is a need to understand global landfill management practices thoroughly for implementation of better practices and policies related to this threat. This study critically reviews recent publications on leachate and landfill gas. The review discusses leachate treatment and landfill gas emissions, focusing on the possible reduction technology of CH₄ emission and its impact on the environment. Mixed leachate will benefit from the combinational therapy method because of its intricate combination. Implementation of circular material management, entrepreneurship ideas, blockchain, machine learning, LCA usage in waste management, and economic benefits from CH₄ production have been emphasized. Bibliometric analysis of 908 articles from the last 37 years revealed that industrialized nations dominate this research domain, with the United States having the highest number of citations.

The association between ambient temperature and antimicrobial resistance of Klebsiella pneumoniae in China: a difference-in-differences analysis

Introduction

Antimicrobial resistance (AMR) of Klebsiella pneumoniae (K. pneumoniae) poses a significant global public health threat and is responsible for a high prevalence of infections and mortality. However, knowledge about how ambient temperature influences the AMR of K. pneumoniae is limited in the context of global warming.

Methods

AMR data of 31 Chinese provinces was collected from the China Antimicrobial Resistance Surveillance System (CARSS) between 2014 and 2020. Socioeconomic and meteorological data were collected from the China Statistical Yearbook during the same period. A modified difference-in-differences (DID) approach was applied to estimate the association between ambient temperature and third-generation cephalosporin-resistant K. pneumoniae (3GCRKP) and carbapenem-resistant K. pneumoniae (CRKP). Furthermore, moderating effects of socioeconomic factors were also evaluated.

Results

Every 1°C increase in annual average temperature was associated with a 4.7% (relative risk (RR):1.047, 95% confidence intervals (CI): 1.031-1.082) increase in the detection rate of 3GCRKP, and a 10.7% (RR:1.107, 95% CI: 1.011-1.211) increase in the detection rate of CRKP. The relationships between ambient temperature and 3GCRKP and CRKP were found to be moderated by socioeconomic status (GDP per capita, income per capita, and consumption per capita; the interaction p-values <0.05), where higher economic status was found to strengthen the effects of temperature on the detection rate of 3GCRKP and weaken the effects on the detection rate of CRKP.

Discussion

Ambient temperature was found to be positively associated with AMR of K. pneumoniae, and this association was moderated by socioeconomic status. Policymakers should consider the impact of global warming and high temperatures on the spread of 3GCRKP and CRKP when developing strategies for the containment of AMR.

Exploring greenhouse gas emissions pathways and stakeholder perspectives: In search of circular economy policy innovation for waste paper management and carbon neutrality in Hong Kong

Waste paper disposed in landfills notably contributes to greenhouse gas (GHG) emissions and impedes more sustainable, circular alternatives, such as recycling. In Hong Kong, this unsustainable approach is currently dominant as 68% of waste paper products are treated in landfills in 2020. To contextualize the impact of local waste paper management and explore mitigation potentials of circular alternatives, this paper develops a quantitative assessment framework around GHG emissions development trajectories. Combining guidelines of the Intergovernmental Panel on Climate Change (IPCC), national GHG inventories, and local parameters from life cycle analysis, five GHG emissions projections were simulated along the Shared Socioeconomic Pathways (SSPs) until 2060. Most recent baselines indicate that Hong Kong's current waste paper treatment generated 638,360 tons CO₂-eq in 2020, comprising 1,821,040 tons CO₂-eq from landfill and 671,320 tons CO₂-eq from recycling, and -1,854,000 tons CO₂-eq from primary material replacement. Proceeding along a Business-as-Usual scenario under SSP5, GHG emissions will dramatically increase to a net 1,072,270 tons CO₂-eq by 2060, whereas a recycling-intensive scenario will lead to a net saving of -4,323,190 tons CO₂-eq. To complement the quantitative evidence on the benefits of waste paper recycling, field research was conducted to explore the feasibility of circular policy innovation from the perspective of recycling stakeholders. These empirical qualitative and quantitative findings from stakeholders' business routines and material transactions provide crucial indications for policy and institutional innovation: Essentially, for Hong Kong to improve waste paper recycling capacities and facilitate a circular economy (CE), local stakeholders require support via fiscal policy measures (financial subsidies or tax reductions) and infrastructure improvements (delivery access and material storage). In sum, this study employs a novel analytical framework combining original qualitative and quantitative evidence to provide policy innovation towards circular, GHG emission-saving waste paper management.

Socio-economic development drives solid waste management performance in cities: A global analysis using machine learning

Mismanaged municipal solid waste (MSW), the major source of plastics pollution and a key contributor to climate forcing, in Global South cities poses public health and environmental problems. This study analyses the first consistent and quality assured dataset available for cities distributed worldwide, featuring a comprehensive set of solid waste management performance indicators (Wasteaware Cities Benchmark Indicators - WABI). Machine learning (multivariate random forest) and univariate non-linear regression are applied, identifying best-fit converging models for a broad range of explanatory socioeconomic variables. These proxies describe in a variety of ways generic levels of progress, such as Gross Domestic Product - Purchasing Power per capita, Social Progress Index (SPI) and Corruption Perceptions Index. Specifically, the research tests and quantitatively confirms a long-standing, yet unverified, hypothesis: that variability in cities' performance on MSW can be accounted for by socioeconomic development indices. The results provide a baseline for measuring progress as cities report MSW performance for the sustainable development goal SDG11.6.1 indicator: median rates of controlled recovery and disposal are approximately at 45 % for cities in low-income countries, 75 % in lower-middle, and 100 % for both upper-middle and high-income. Casting light on aspects beyond the SDG metric, on the quality of MSW-related services, show that improvements in service quality often lag improvements in service coverage. Overall, the findings suggest that progress in collection coverage, and controlled recovery and disposal has already taken place in low- and middle-income cities. However, if cities aspire to perform better on MSW management than would have been anticipated by the average socioeconomic development in their country, they should identify ways to overcome systemic underlying failures associated with that socioeconomic level. Most alarmingly, 'business as usual' development would substantially increase their waste generation per capita unless new policies are found to promote decoupling.

"I Prefer to Stay Away": A Qualitative Study of Patients in an Opioid-Sparing Pain Management Protocol

OBJECTIVE

The aim of this study was to explore beliefs and behaviors of opioid pain medications among patients undergoing elective surgery.

BACKGROUND

Opioid dependence after surgery is a major contributor to the ongoing opioid epidemic. Recent efforts by surgeons and health systems have sought to improve the education patients receive regarding safe opioid use after surgery; however, little is known about patients' pre-existing beliefs surrounding opioids.

METHODS

Semistructured interviews were conducted with patients who underwent 1 of 4 common elective surgical procedures at 1 institution. Patients were specifically asked about their knowledge and beliefs about opioids before surgery and their opinions of opioid-sparing recovery after surgery. Coding was conducted through iterative steps, beginning with an initial cycle of rapid analysis, followed by focused coding, and thematic analysis.

RESULTS

Twenty-one patients were interviewed. Three major themes emerged regarding patient opinions about using opioids after surgery. First, there was widespread awareness among patients about opioid medications, and preoperatively, patients had specific intentions about using opioids, often informed by this awareness. Second, patients described a spectrum of opioid related behavior which both aligned and conflicted with preoperative intentions. Third, there was tension among patients about opioid-free postoperative recovery, with patients expressing support, opposition, and emphasis on tailoring recovery to patient needs.

CONCLUSIONS

Patients undergoing common surgical procedures often arrive at their surgical encounter with strong, pre-formed opinions about opioids. Eliciting these preexisting opinions may help surgeons better counsel patients about safe opioid use after surgery.

Revealing influencing factors on global waste distribution via deep-learning based dumpsite detection from satellite imagery

With the advancement of global civilisation, monitoring and managing dumpsites have become essential parts of environmental governance in various countries. Dumpsite locations are difficult to obtain in a timely manner by local government agencies and environmental groups. The World Bank shows that governments need to spend massive labour and economic costs to collect illegal dumpsites to implement management. Here we show that applying novel deep convolutional networks to high-resolution satellite images can provide an effective, efficient, and low-cost method to detect dumpsites. In sampled areas of 28 cities around the world, our model detects nearly 1000 dumpsites that appeared around 2021. This approach reduces the investigation time by more than 96.8% compared with the manual method. With this novel and powerful methodology, it is now capable of analysing the relationship between dumpsites and various social attributes on a global scale, temporally and spatially.

A full-scale black soldier fly larvae (Hermetia illucens) bioconversion system for domestic biodegradable wastes to resource

Domestic biodegradable wastes (DBW) pose a threat to environmental quality and human health. Bioconversion via black soldier fly larvae (BSFL; Hermitia illucens L.) is an expedient way for converting 'waste to resource' (insect protein and biofertilizer). Although researches abounded in laboratory-reared experiments and bioconversion mechanisms were pertinent, the void of data from actual and full-scale operation restricts the intensification of BSFL technology and its global adoption. Hence, a full-scale BSFL bioconversion system lasting 4 years in Hangzhou (China) was investigated, and the feasibility and efficiency of 15 tonnes of DBW per day were studied. Through continuous technical optimization, the average production of fresh larvae was increased from 8.5% in 2017 to 15.3% in 2020, along with bioconversion rate of final vermicompost decreased from 35.4% to 14.5%. The total biomass reduction rate in 2020 was 68.7 ± 17.4 kg/(m³ d), equivalent to 0.735 ± 0.215 kg/(kg d) in the form of fresh larvae. Crude fat in fresh larvae accounted for 13.4%, and crude protein accounted for 16.2% in which the determined amino acid profile bore a strong resemblance to fish meal only except histidine and tyrosine. Its economic benefits proved the feasibility of this technology, and the profit reached up to 35.9 US$ per tonne of DBW in 2019. In conclusion, BSFL bioconversion system under current 'insect-farm' operation was a promising solution for DBW treatment with value-added waste recycling.

Emerging nanotechnology based advanced techniques for wastewater treatment

The increasing trend of industrialization leads to tremendous release of industrial effluents. Waste water treatment is one of the important sectors to focus in order to overcome the most threatening issue of waste disposal and to ensure sustainability. Sustainable and energy efficient treatment methods are the attractive technologies for their current implementation of waste management. Even though the existing technologies are effective, unsustainability makes them unfit for their extended applications. Conventional and advanced technologies have been extensively implemented for the treatment of wide spectrum of effluents. Hybrid technologies including chemical and biological methods also emerging as promising technologies but secondary sludge generation is still unaddressed. Even though effectiveness of biochar varies over type of contaminants, cost-effectiveness and eco-friendly nature extended their applications in waste management. Nanotechnology and membrane technology are the promising and emerging areas of interest due to their widespread applications in waste water treatment. Carbon nano structures, nano filters, graphene, nano magnets modified with activated carbon are the potential candidates for the treatment. The present review demonstrates the emerging treatment technologies with special focus to nano based waste water treatment methods.

Dermatopathology Laboratory Green Initiatives

OBJECTIVES

Climate change and the accumulation of greenhouse gases pose challenges for humanity. The laboratory can reduce the environmental impact of routine operations.

METHODS

Our laboratory implemented several recycling initiatives in 2021, including shredding plastic and recycling 10% formalin, xylene, and reagent alcohols. Additional insulation has reduced electricity costs, and we have plans to derive 100% of our electricity from solar in 2022.

RESULTS

Recycling leads to decreases in reagent purchase by several hundred gallons. Our lab reduced its carbon footprint by a minimum of 68.52 tons, with an anticipated $43,000 savings in purchases and waste disposal during 2022.

CONCLUSIONS

Regardless of an individual's environmental consciousness, green initiatives have several tangible benefits. Recycling helps mitigate climate change and decrease the laboratory's carbon footprint. These measures also insulate the laboratory from supply shortages and lead to significant, tangible monetary savings.

Greenhouse gas emissions from municipal wastewater treatment facilities in China from 2006 to 2019

Wastewater treatment plants (WWTPs) alleviate water pollution but also induce resource consumption and environmental impacts especially greenhouse gas (GHG) emissions. Mitigating GHG emissions of WWTPs can contribute to achieving carbon neutrality in China. But there is still a lack of a high-resolution and time-series GHG emission inventories of WWTPs in China. In this study, we construct a firm-level emission inventory of WWTPs for CH4, N2O and CO2 emissions from different wastewater treatment processes, energy consumption and effluent discharge for the time-period from 2006 to 2019. We aim to develop a transparent, verifiable and comparable WWTP GHG emission inventory to support GHG mitigation of WWTPs in China.

Non-Fossil Methane Emissions Mitigation From Agricultural Sector and Its Impact on Sustainable Development Goals

The agriculture sector contributes to ∼40% of methane emissions globally. Methane is also 28 times (Assessment Report 5) more potent greenhouse gas than CO2. In this study, we assess the impact of measures for mitigating methane emissions from the agricultural sector on the achievement of all the 17 United Nations’ Sustainable Development Goals (SDGs). A keyword literature review was employed that focused on finding the synergies and trade-offs with non-fossil methane emissions from the agricultural sector and respective SDGs’ targets. The results were in broad consensus with the literature aimed at finding the relationship between SDGs and measures targeting climate change. There is a total of 88 synergies against eight trade-offs from the 126 SDGs’ targets that were assessed. It clearly shows that measures to mitigate methane emissions from the agricultural sector will significantly help in achieving the SDGs. Since agriculture is the primary occupation and the source of income in developing countries, it can further be inferred that methane mitigation measures in developing countries will play a larger role in achieving SDGs. Measures to mitigate methane emissions reduce poverty; diversify the source of income; promote health, equality, education, sanitation, and sustainable development while providing energy and resource security to the future generations.

The Evolution of the Spatial-Temporal Differences of Municipal Solid Waste Carbon Emission Efficiency in China

Municipal solid waste (MSW) treatment is one of the major contributors to carbon emissions. The improvement in MSW treatment carbon emission efficiency is crucial for China to achieve its CO2 emission targets. Firstly, this study used the super-efficiency SBM-DEA model to calculate the MSW treatment carbon emission efficiency in 31 provinces in China from 2010 to 2019. The results show that the MSW treatment carbon emission efficiency in all provinces except Shanghai and Jiangsu is less than 1, and the provinces with high efficiency are mainly located in eastern China. Secondly, the spatial auto correlation model and spatial Markov chain are used to test the regional differences and the spatial spillover effect of efficiency. The results show that the national average efficiency shows a fluctuating downward trend, and only the western region achieves a gradual increase. The regional differences in China’s MSW processing efficiency of carbon emissions show a fluctuating upward trend, and the regional background affects the spatiotemporal evolution pattern of the efficiency. Finally, the special error model was used to analyze the factors and influence paths that affect the efficiency, and to find that the degree of government intervention as an influencing factor that restricts the improvement of efficiency. Based on the research results, we put forward countermeasures and suggestions to improve the MSW treatment carbon emission efficiency in each province and the country as a whole.

Sustainable Upcycling of Fisheries and Aquaculture Wastes Using Fish-Derived Cold-Adapted Proteases

The fisheries and aquaculture industries are some of the major economic sectors in the world. However, these industries generate significant amounts of wastes that need to be properly managed to avoid serious health and environmental issues. Recent advances in marine waste valorization indicate that fish waste biomass represents an abundant source of high-value biomolecules including enzymes, functional proteins, bioactive peptides, and omega-3 rich oils. Enzyme-assisted processes, for the recovery of these value-added biomolecules, have gained interest over chemical-based processes due to their cost-effectiveness as well as their green and eco-friendly aspects. Currently, the majority of commercially available proteases that are used to recover value-added compounds from fisheries and aquaculture wastes are mesophilic and/or thermophilic that require significant energy input and can lead to unfavorable reactions (i.e., oxidation). Cold-adapted proteases extracted from cold-water fish species, on the other hand, are active at low temperatures but unstable at higher temperatures which makes them interesting from both environmental and economic points of view by upcycling fish waste as well as by offering substantial energy savings. This review provides a general overview of cold-adapted proteolytic enzymes from cold-water fish species and highlights the opportunities they offer in the valorization of fisheries and aquaculture wastes.

Differences in responses of ammonia volatilization and greenhouse gas emissions to straw return and paddy-upland rotations

Paddy-upland rotation and/or straw return could improve soil structure and soil nutrient availability. Different previous crops (wheat and/or oilseed rape) and straw return methods (straw mulching and/or returning) might increase soil organic carbon (C) and total nitrogen (N) content, and further affected the ammonia (NH₃) volatilization, nitrous oxide (N₂O), and methane (CH₄) emissions. A comparison study was carried out in a located field experiment started from 2014 in Central China, aiming to exam seasonal and annual NH₃, N₂O, and CH₄ emissions under the wheat-rice (WR) and oilseed rape-rice (OR) rotations. Three treatments were chosen, i.e., (i) no chemical N fertilizer application (PK), (ii) chemical nitrogen-phosphorus-potassium combination (NPK), and (iii) chemical NPK with straw returning (NPK+St). We found that after 3 years of cultivation, treatment with straw return increased soil total N content and organic C by 15.57% and 17.11% on average as compared with the NPK treatment, respectively. Straw return did not generate additional NH₃ and N₂O losses during the rice season after improving soil fertility. However, CH₄ emissions increased by 45.35% on average after straw return in summer. In winter, straw return increased NH₃, N₂O, and CH₄ emissions by 70.12-85.23%, 16.93-22.97%, and 7.18-9.17%, respectively. The stimulation of NH₃ volatilization mainly occurred in the topdressing stage. Compared with WR rotation, OR rotation had no significant effect on NH₃ and CH₄ emissions, and the change of N₂O emission might be related to the increase of soil C and N pools. The retention of residues in the process of straw decomposition may be the main factor leading to the difference of gas emission between the paddy-upland rotation and straw return.

Life Cycle Assessment of Existing and Alternative Options for Municipal Solid Waste Management in Saint Petersburg and the Leningrad Region, Russia

A waste reform was recently introduced in Russia to divert waste from landfills. To help advance the reform, this paper presents a life cycle assessment of the municipal solid waste management system in Russia’s second largest city—Saint Petersburg—and its neighboring Leningrad region. Five scenarios were evaluated: the current state of the system (S0), its expected post-reform state in 2024 (S1), and its state improved by increased landfill gas collection (S2), by increased waste incineration (S3), and by separate collection of waste (S4). The environmental impact was assessed in terms of climate change, acidification, eutrophication, and abiotic resource depletion (fossil fuels). The results showed an overall reduction in the environmental impact of the waste management system across all impact categories and all scenarios studied. The largest reduction in all impact categories (except abiotic resource depletion) was achieved through source separation of municipal solid waste. Particularly, global warming potential was reduced from 0.328 kg CO2-eq./kg waste generated in S0 to 0.010 kg CO2-eq./kg waste in S4. Regarding abiotic resource depletion potential (fossil fuels), the incineration scenario is the most beneficial, since it reduces the impact by 573%.

Progress and challenges of contaminate removal from wastewater using microalgae biomass

The utilization of microalgae in treating wastewater has been an emerging topic focussed on finding an economically sustainable and environmentally friendly approach to treating wastewater. Over the last several years, different types of con microalgae and bacteria consortia have been experimented with to explore their potential in effectively treating wastewater from different sources. The basic features considered while determining efficiency is their capacity to remove nutrients including nitrogen (N) and phosphorus (P) and heavy metals like arsenic (As), lead (Pb), and copper (Cu). This paper reviews the efficiency of microalgae as an approach to treating wastewater from different sources and compares conventional and microalgae-based treatment systems. The paper also discusses the characteristics of wastewater, conventional methods of wastewater treatment that have been used so far, and the technological mechanisms for removing nutrients and heavy metals from contaminated water. Microalgae can successfully eliminate the suspended nutrients and have been reported to successfully remove N, P, and heavy metals by up to 99.6 %, 100 %, and 13%-100 % from different types of wastewater. However, although a microalgae-based wastewater treatment system offers some benefits, it also presents some challenges as outlined in the last section of this paper. Performance in eliminating nutrients from wastewater is affected by different parameters such as temperature, biomass productivity, osmotic ability, pH, O₂ concentration. Therefore, the conducting of pilot-scale studies and exploration of the complexities of contaminants under complex environmental conditions is recommended.

Gaseous Emissions from the Composting Process: Controlling Parameters and Strategies of Mitigation

Organic waste generation, collection, and management have become a crucial problem in modern and developing societies. Among the technologies proposed in a circular economy and sustainability framework, composting has reached a strong relevance in terms of clean technology that permits reintroducing organic matter to the systems. However, composting has also negative environmental impacts, some of them of social concern. This is the case of composting atmospheric emissions, especially in the case of greenhouse gases (GHG) and certain families of volatile organic compounds (VOC). They should be taken into account in any environmental assessment of composting as organic waste management technology. This review presents the relationship between composting operation and composting gaseous emissions, in addition to typical emission values for the main organic wastes that are being composted. Some novel mitigation technologies to reduce gaseous emissions from composting are also presented (use of biochar), although it is evident that a unique solution does not exist, given the variability of exhaust gases from composting.

Exploring the environmental traits and applications of Klebsiella variicola

Klebsiella variicola has been found in various natural niches, alone or in association with other bacteria, and causes diseases in animals and plants with important economic and environmental impacts. K. variicola has the capacity to fix nitrogen in the rhizosphere and soil; produces indole acetic acid, acetoin, and ammonia; and dissolves phosphorus and potassium, which play an important role in plant growth promotion and nutrition. Some members of K. variicola have properties such as halotolerance and alkalotolerance, conferring an evolutionary advantage. In the environmental protection, K. variicola can be used in the wastewater treatment, biodegradation, and bioremediation of polluted soil, either alone or in association with other organisms. In addition, it has the potential to carry out industrial processes in the food and pharmaceutical industries, like the production of maltose and glucose by the catalysis of debranching unmodified oligosaccharides by the pullulanase enzyme. Finally, this bacterium has the ability to transform chemical energy into electrical energy, such as a biocatalyst, which could be useful in the near future. These properties show that K. variicola should be considered an eco-friendly bacterium with hopeful technological promise. In this review, we explore the most significant aspects of K. variicola and highlight its potential applications in environmental and biotechnological processes.

An Assessment of Air Quality within Facilities of Municipal Solid Waste Management (MSWM) Sites in Lahore, Pakistan

The pollutants emission during the process of municipal solid waste management (MSWM) is of great concern due to its hazardous effect on the environment and living organisms. An assessment of the air quality of MSWM sites was made after having 16 repetitive visits at solid waste disposal sites and transfer stations of Lahore during wet and dry seasons. Pollution parameters such as fine particulate matter (PM2.5) and greenhouse gases (GHG) were measured along with meteorological parameters. PM2.5 measurement was made by using particle counter Dylos and TSI’s Dust Trak. Both of these instruments were positioned simultaneously at the source site and downwind (50 m). CH4 and meteorological parameters were measured by Aeroqual 500 series, while the Extech CO220 monitor was used to measure CO2 concentration. An assessment of air quality showed the levels of their mean values as CH4 and CO2 ranged between 1.5–13.7 ppm and 443.4–515.7 ppm, respectively. The PM2.5 ranged between 127.1 and 307.1 µg/m3 at sources and 172.3 and 403.8 µg/m3 downwind (50 m). GHG showed lower levels than the proposed limit value, which could not cause any health issues, while PM2.5 was 6–10 times higher than the Pak-EPA established standards. Higher pollutant concentration was recorded in the dry season than the wet season. Regression analysis was performed to predict correlation of PM2.5 with GHG and meteorological parameters. GHG as well as meteorological parameters also exhibited a correlation with PM2.5. It was estimated that the ambient air of such sites is not safe for public health. So, it is necessary to use safe practices for MSWM and its emission control to prevent nearby communities and the environment.

Potential Applications of 5G Network Technology for Climate Change Control: A Scoping Review of Singapore

Climate change is one of the most challenging problems that humanity has ever faced. With the rapid development in technology, a key feature of 5G networks is the increased level of connectivity between everyday objects, facilitated by faster internet speeds with smart facilities indicative of the forthcoming 5G-driven revolution in Internet of Things (IoT). This study revisited the benefits of 5G network technologies to enhance the efficiency of the smart city and minimize climate change impacts in Singapore, thus creating a clean environment for healthy living. Results revealed that the smart management of energy, wastes, water resources, agricultures, risk factors, and the economy adopted in Singapore can remarkably contribute to reducing climate change, thus attaining the sustainability goals. Hence, future studies on cost-effective design and implementation are essential to increase the focus on the smart city concept globally.

Life cycle assessment applied to waste management in Italy: A mini-review of characteristics and methodological perspectives for local assessment

Life cycle assessment (LCA) and related tools are commonly used to evaluate the potential environmental impacts of waste treatment scenarios. This manuscript presents a mini-review of studies published over the last 10 years in Italy and aims to investigate how life cycle thinking tools are applied to assess the environmental sustainability of local-level waste policies. Results reveal that different waste flows, technologies and policies have been investigated independently and in varying detail. Review suggests that boundary selection significantly affects LCA results; integration of different waste systems is therefore crucial to avoid spatial or temporal shifts of environmental impacts. Moreover, the description of methodological characteristics, limitations and transversal aspects of Italian waste management studies allows various stakeholders to assess the reliability of past and future research for waste policy planning and rebound effects prevention. This review also highlights the need to define minimum requirements of transparency and ease of reporting of the studies to private and public stakeholders. Finally, the paper investigates whether using both the organisational LCA and the life cycle sustainability approach for the overall waste management process may be useful to develop a standard method to address multi-functionalities and multiple sites.

A ridge regression approach to estimate the relationship between landfill taxation and waste collection and disposal in England

The production of household waste is characterised by externalities and market failure, where the decision to consume does not consider the environmental impact of consequent waste generated. Policy interventions in the UK have focused primarily on pricing the disposal of waste through a landfill tax. This article tests the effectiveness of landfill taxation on household waste collection and disposal. Using a ridge regression with correction for fixed effects on a panel dataset of English local authorities, we estimate the landfill tax elasticity of waste for a range of waste disposal and collection streams. Results indicate that the landfill tax is elastic at disposal and effective in shifting waste from landfills to incineration. The tax is inelastic at collection, and encourages recycling. Our results indicate that landfill taxation is an important tool to change how waste is disposed by households and local authorities.

Mitigation of methane and trace gas emissions through a large-scale active biofilter system at Glatved landfill, Denmark

Biocover systems are a cost-effective technology utilised to mitigate methane (CH₄) and trace gas emissions from landfills. A full-scale biofilter system was constructed at Glatved landfill, Denmark, consisting of three biofilters with a total area of 3950 m². Landfill gas collected mainly from shredder waste cells was mixed with ambient air and fed actively into the biofilter, resulting in an average load of 60-75 g m^-2 d^-1 for CH₄ and 0.15-0.21 g m^-2 d^-1 for trace gases (e.g., aromatics, chlorofluorocarbons (CFCs), aliphatic hydrocarbons). The initial CH₄ surface screening showed uneven gas distribution into the system, and elevated surface concentrations were observed close to the gas inlet. Both positive and negative CH₄ fluxes, ranging from -0.36 to 4.25 g m^-2 d^-1, were measured across the surface of the biofilter. Total trace gas emissions were between -0.005 and 0.042 g m^-2 d^-1, and the emission flux of individual compounds were generally small (10^-8 to 10^-3 g m^-2 d^-1). Vertical gas concentration profiles showed that the oxidation of CH₄ and easily degradable trace compounds such as aromatics and aliphatic hydrocarbons happened in the aerobic zones, while CFCs were degraded in the anaerobic zone inside the compost layer. In addition, oxidation/degradation of CH₄ and trace gases also occurred in the gas distribution layer, which contributed significantly to the overall mitigation efficiency of the biofilter system. Overall, the biofilter system showed mitigation efficiencies of nearly 100% for both CH₄ and trace gases, and it might have the potential to work under higher loads.

Township recycling performance assessment based on fuzzy TOPSIS model: An empirical investigation using the artificial intelligence-based VIKOR approach

The problem of waste reduction is particularly emphasized the sources of environmental income i.e. tax and unit-pricing, instead of stimulus recycling administrative in the published literatures. A long-term rebate policy for recycling fund allowance was implemented in different metropolitan districts. However, evaluating the recycling performance at the local level does not include examining its rationality and efficiency in detail. To understand the uncertainty of role in decision making for substitute ranking, analysis based on decision making using fuzzy interval for performance assessment. This article redefines the criteria for evaluating recycling performance at the township level with assistance of artificial intelligence, and illustrates the results. We used a simple and swift evaluation process, namely, the VIKOR method, in place of the traditional public hearing or the Delphi method. The conclusion derived from the results can be used to analyze the effectiveness of the rebate policy for recycling at the township level.

Quantification of methane emissions from UK biogas plants

The rising number of operational biogas plants in the UK brings a new emissions category to consider for methane monitoring, quantification and reduction. Minimising methane losses from biogas plants to the atmosphere is critical not only because of their contribution of methane to global warming but also with respect to the sustainability of renewable energy production. Mobile greenhouse gas surveys were conducted to detect plumes of methane emissions from the biogas plants in southern England that varied in their size, waste feed input materials and biogas utilization. Gaussian plume modelling was used to estimate total emissions of methane from ten biogas plants based on repeat passes through the plumes. Methane emission rates ranged from 0.1 to 58.7 kg CH₄ hr^-1, and the percentage of losses relative to the calculated production rate varied between 0.02 and 8.1%. The average emission rate was 15.9 kg CH₄ hr^-1, and the average loss was 3.7%. In general, methane emission rates from smaller farm biogas plants were higher than from larger food waste biogas plants. We also suggest that biogas methane emissions may account for between 0.4 and 3.8%, with an average being 1.9% of the total methane emissions in the UK excluding the sewage sludge biogas plants.

Environmental implications of stored cattle slurry treatment with sulphuric acid and biochar: A life cycle assessment approach

With the increase of animal slurry produced from livestock production, the monitoring and mitigation of greenhouse gas (GHG) and ammonia (NH₃) emissions represent a major issue. Life cycle assessment (LCA) has been used to evaluate the long-term environmental effects of applied strategies and technologies on cattle slurry management for mitigation of environmental harmful gases. This study was carried on two main aims: first, the effect of the addition of sulphuric acid (SA), biochar (SBi) or A + Bi to liquid cattle-slurry (treated systems) on gas emissions during storage compared to the untreated system (S) was investigated in a laboratory-controlled experiment; second, the environmental implications of each treated or untreated system were assessed through a LCA approach according to ISO 14040/44. Five CML 2001 impact categories were used: eutrophication potential (EP), acidification potential (AP), global warming potential (GWP), human toxicity potential (HTP) and Ozone Layer Depletion Potential (ODP). Comparisons were based on 1 ton fresh dairy cattle slurry. The environmental profile of untreated system showed lower efficiency in mitigation of total GHG and NH₃ emissions (0.0312 and 0.0001 kg CO₂-eq respectively), during storage period and greater impact on GWP and HTP categories. The electricity consumption in mechanical separation dominated the environmental impacts. From the three proposed treated systems, SA showed the highest efficiency on mitigation of gas emissions compared to the other treatments, reducing NH₃, CH₄ and CO₂ emissions respectively in 61%, 98% and 15%, when compared to the SBi system. In all categories, acidified slurry also showed the lowest environmental impact relative to other treated systems and the benefit was more evident when the impacts were expressed per kilogram of nitrogen in the slurry. Therefore, LCA methodology was of great importance to assess the environmental implications of the treatments and acidification can be considered as an effective technique on the mitigation of environmental implications of livestock production and cattle-effluent valorization. Optimization and uniformity of performed studies are essential to validate new strategies to improve the sustainability of this sector in the management of animal wastewater.

Spatial and temporal distribution of methane emissions from a covered landfill equipped with a gas recollection system

A previously developed surface probe method, which allows for instantaneous methane (CH₄) flux measurement, was used to establish CH₄ emission maps of a municipal landfill with a final clay cover and equipped with a gas recollection system. In addition to spatial variations, the method was applied at 7 different times over a total timeframe of 65 h and under similar weather conditions to determine the intrinsic temporal variations of CH₄ emissions; i.e., the temporal variation related to the dynamic of the landfill rather than the one driven by external factors. Furthermore, continuous CH₄ fluxes, with a data acquisition frequency of 1 Hz, were measured during 12 h at a single position, and for one hour at 22 locations of the landfill, spanning a large range of CH₄ emission magnitudes. A simple model for the numerical characterization of spatiotemporal variability of the landfill emission was used and allowed us to separately quantify the temporal and spatial variability. This model showed that, in the landfill tested, the temporal distribution of CH₄ emissions resulted more homogeneous than the spatial distribution. Other attributes of the temporal and spatial distributions of CH₄ emissions were also established including the anisotropic nature of the spatial distribution and, contrastingly, the stochastic temporal variability of such emissions.

Waste generation, wealth and GHG emissions from the waste sector: Is Denmark on the path towards circular economy?

Municipal solid waste (MSW) is one of the most urgent issues associated with economic growth and urban population. When untreated, it generates harmful and toxic substances spreading out into the soils. When treated, they produce an important amount of Greenhouse Gas (GHG) emissions directly contributing to global warming. With its promising path to sustainability, the Danish case is of high interest since estimated results are thought to bring useful information for policy purposes. Here, we exploit the most recent and available data period (1994-2017) and investigate the causal relationship between MSW generation per capita, income level, urbanization, and GHG emissions from the waste sector in Denmark. We use an experiment based on Artificial Neural Networks and the Breitung-Candelon Spectral Granger-causality test to understand how the variables, object of the study, manage to interact within a complex ecosystem such as the environment and waste. Through numerous tests in Machine Learning, we arrive at results that imply how economic growth, identifiable by changes in per capita GDP, affects the acceleration and the velocity of the neural signal with waste emissions. We observe a periodical shift from the traditional linear economy to a circular economy that has important policy implications.

Climate Change Impacts of Electricity Generated at a Waste-to-Energy Facility

Waste-to-energy (WTE) facilities combust both biogenic and nonbiogenic materials comprising municipal solid waste (MSW) in addition to managing waste, leading to a lack of clarity on the life cycle climate change impact (LCCCI) as an electricity generator. In order to investigate the LCCCI of this resource, a cradle-to-gate life cycle assessment (LCA) of a WTE facility in Jamesville, NY, was performed utilizing system expansion to account for avoided landfilling emissions, additional metals recycling, and the loss of potential electricity generation from landfill gas. The LCCCI of electricity from this WTE facility ranges from 0.664 to 0.951 kg CO_2eq/kWh before system expansion, which reduced the impact to -0.280 to 0.593 kg CO_2eq/kWh when accounting for avoided waste management emissions. Combustion is the leading contributor of GHG emissions from cradle-to-gate, and sensitivity analysis indicates that the nonbiogenic fraction of the waste most significantly influences the LCCCI before including cobenefits. The fraction of methane from landfills that is not captured is the most influential variable under system expansion. Before system expansion, the LCCCI of this system is comparable to that of electricity from fossil fuels. With system expansion, the LCCCI ranges from below that of renewable energy to comparable to natural gas based electricity. These results disagree with claims in the reviewed literature that WTE can avoid GHG emissions overall, although avoided emissions reduce the magnitude of its impact.

Integrating micro-algae into wastewater treatment: A review

Improving the ecological status of water sources is a growing focus for many developed and developing nations, in particular with reducing nitrogen and phosphorus in wastewater effluent. In recent years, mixotrophic micro-algae have received increased interest in implementing them as part of wastewater treatment. This is based on their ability to utilise organic and inorganic carbon, as well as inorganic nitrogen (N) and phosphorous (P) in wastewater for their growth, with the desired results of a reduction in the concentration of these substances in the water. The aim of this review is to provide a critical account of micro-algae as an important step in wastewater treatment for enhancing the reduction of N, P and the chemical oxygen demand (COD) in wastewater, whilst utilising a fraction of the energy demand of conventional biological treatment systems. Here, we begin with an overview of the various steps in the treatment process, followed by a review of the cellular and metabolic mechanisms that micro-algae use to reduce N, P and COD of wastewater with identification of when the process may potentially be most effective. We also describe the various abiotic and biotic factors influencing micro-algae wastewater treatment, together with a review of bioreactor configuration and design. Furthermore, a detailed overview is provided of the current state-of-the-art in the use of micro-algae in wastewater treatment.

Learning from microorganisms: using new insights in microbial physiology for sustainable nitrogen management

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To reduce nitrate to N₂ distinct nitrogen-oxide-reducing microorganisms function together.

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Detecting nirS, nirK or narG genes cannot be directly linked to NO and N₂O emission.

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Nitrogen-oxide-reducing specialists can be exploited to reduce NO and N₂O emission from wwtp.

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Aerobic methanotrophs and methane stripping must be considered for the application of N-DAMO.

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Ammonium recovery could be a more sustainable alternative to nitrogen removal.

Diverse nitrogen-transforming microorganisms with a wide variety of physiological properties are employed for biological nitrogen removal from wastewater. There are many technologies that achieve the required nitrogen discharge standards; however, greenhouse gas emissions and energy consumption constitute the bulk of the environmental footprint of wastewater treatment plants. In this review, we highlight current and proposed approaches aiming to achieve more energy-efficient and environment-friendly biological nitrogen removal, discuss whether new discoveries in microbial physiology of nitrogen-transforming microorganisms could be used to reduce greenhouse gas emissions, and summarize recent advances in ammonium recovery from wastewater.

Rethinking organic wastes bioconversion: Evaluating the potential of the black soldier fly (Hermetia illucens (L.)) (Diptera: Stratiomyidae) (BSF)

Population growth and unprecedented economic growth and urbanization, especially in low- and middle-income countries, coupled with extreme weather patterns, the high-environmental footprint of agricultural practices, and disposal-oriented waste management practices, require significant changes in the ways we produce food, feed and fuel, and manage enormous amounts of organic wastes. Farming insects such as the black soldier fly (BSF) (Hermetia illucens) on diverse organic wastes provides an opportunity for producing nutrient-rich animal feed, fuel, organic fertilizer, and biobased products with concurrent valorization of wastes. Inclusion of BSF larvae/pupae in the diets of poultry, fish, and swine has shown promise as a potential substitute of conventional feed ingredients such as soybean meal and fish meal. Moreover, the bioactive compounds such as antimicrobial peptides, medium chain fatty acids, and chitin and its derivatives present in BSF larvae/pupae, could also add values to the animal diets. However, to realize the full potential of BSF-based biorefining, more research and development efforts are necessary for scaling up the production and processing of BSF biomass using more mechanized and automated systems. More studies are also needed to ensure the safety of the BSF biomass grown on various organic wastes for animal feed (also food) and legalizing the feed application of BSF biomass to wider categories of animals. This critical review presents the current status of the BSF technology, identifies the research gaps, highlights the challenges towards industrial scale production, and provides future perspectives.

Biochar and gypsum amendment of agro-industrial waste for enhanced black soldier fly larval biomass and quality frass fertilizer

Black soldier fly (BSF) (Hermetia illucens L.) is one of the most efficient bio-waste recyclers. Although, waste substrate amendments with biochar or gypsum during composting process are known to enhance nutrient retention, their impact on agro-industrial waste have not been documented. Hence, this study focuses on a comparative effect of agro-industrial waste amended with biochar and gypsum on BSF larval performance, waste degradation, and nitrogen (N) and potassium retention in frass fertilizer. Brewery spent grain was amended with biochar or gypsum at 0, 5, 10, 15 and 20% to determine the most effective rates of inclusion. Amending feedstock with 20% biochar significantly increased wet (89%) and dried (86%) larval yields than the control (unamended feedstock). However, amendment with 15% gypsum caused decrease in wet (34%) and dried (30%) larval yields but conserved the highest amount of N in frass. Furthermore, the inclusion of 20% biochar recorded the highest frass fertilizer yield and gave a 21% increase in N retention in frass fertilizer, while biomass conversion rate was increased by 195% compared to the control. Feedstock amendment with 5% biochar had the highest waste degradation efficiency. Potassium content in frass fertilizer was also significantly enhanced with biochar amendment. At maturity, frass compost with more than 10% inclusion rate of biochar had the highest cabbage seed germination indices (>100%). The findings of this study revealed that initial composting of biochar amended feedstocks using BSF larvae can significantly shorten compost maturity time to 5 weeks with enhanced nutrient recycling compared to the conventional composting methods.

Driving Municipal Recycling by Connecting Digital Value Endpoints in Smart Cities

Uncontrolled global economic growth at any cost is having palpable and general consequences for SC (smart cities) environments and sustainability worldwide. The current economic growth model is, according to experts, decidedly unsustainable, and if urgent measures are not taken, the quality of life for future citizens will decline. In the search for solutions that would make cities sustainable, the deployment of the ICT factor is playing a decisive role. However, in its role as a driver, the ICT factor needs to increase the numbers of value endpoint connectors by incorporating citizens, corporations and institutions into city decision-making, thereby becoming a real integrative tool that achieves sustainability and is more than merely a tech flag. In this sense, the present paper proposes that the digital and programmable economy as an ecosystem should become a sustainability city driver because it facilitates the integration of different value endpoints in order to work in the same purpose, allowing, for example, increased sustainability levels in cities such as improving municipal recycling. This paper will apply ICT and digital concepts, the environment-social-economy model and fuzzy logic methodology.

Multidecadal records of intrinsic water-use efficiency in the desert shrub Encelia farinosa reveal strong responses to climate change

While tree rings have enabled interannual examination of the influence of climate on trees, this is not possible for most shrubs. Here, we leverage a multidecadal record of annual foliar carbon isotope ratio collections coupled with 39 y of survey data from two populations of the drought-deciduous desert shrub Encelia farinosa to provide insight into water-use dynamics and climate. This carbon isotope record provides a unique opportunity to examine the response of desert shrubs to increasing temperature and water stress in a region where climate is changing rapidly. Population mean carbon isotope ratios fluctuated predictably in response to interannual variations in temperature, vapor pressure deficit, and precipitation, and responses were similar among individuals. We leveraged the well-established relationships between leaf carbon isotope ratios and the ratio of intracellular to ambient CO2 concentrations to calculate intrinsic water-use efficiency (iWUE) of the plants and to quantify plant responses to long-term environmental change. The population mean iWUE value increased by 53 to 58% over the study period, much more than the 20 to 30% increase that has been measured in forests [J. Peñuelas, J. G. Canadell, R. Ogaya, Glob. Ecol. Biogeogr. 20, 597-608 (2011)]. Changes were associated with both increased CO2 concentration and increased water stress. Individuals whose lifetimes spanned the entire study period exhibited increases in iWUE that were very similar to the population mean, suggesting that there was significant plasticity within individuals rather than selection at the population scale.

The relationship between municipal solid waste and greenhouse gas emissions: Evidence from Switzerland

Municipal solid waste generation is becoming a prominent issue in the environmental arena. The aim of this paper is to investigate the relationship among municipal waste generation, greenhouse gas emissions, and GDP in Switzerland over the period 1990-2017. We apply both time series procedures (stationarity and causality tests) and a Machine Learning approach. Empirical findings underline a bidirectional causal relationship between municipal solid waste generation and GDP, indicating that the Environmental Kuznets Curve hypothesis holds for Switzerland. Moreover, we found that waste recovery (recycling and composting) is a key driver in mitigating greenhouse gas emissions. In fact, in the Tree Model, the probability that a change in the waste recovery variable could lead to a reduction in the greenhouse gas emissions registered a value of 87%.

Towards Urban Mining—Estimating the Potential Environmental Benefits by Applying an Alternative Construction Practice. A Case Study from Switzerland

Modern cities emerged as the main accumulator for primary and waste materials. Recovery of both types from buildings after demolition/disassembly creates a secondary material stream that could relieve pressure from primary resources. Urban mining represents this circular approach, and its application depends on redefining current construction practice. Through the life cycle assessment (LCA) methodology and assuming primary resources as step zero of urban mining, this study estimates the impacts and benefits of conventional versus a circular construction practice applied to various buildings with different parameters and the country-level environmental potential savings that could be achieved through this switch in construction practice—using the increase of the residential building stock in Switzerland between 2012 and 2016 as a case study and key values from the experimental unit “Urban Mining and Recycling”, designed by Werner Sobek with Dirk E. Hebel and Felix Heisel and installed inside the NEST (Next Evolution in Sustainable Building Technologies) research building on the Empa campus in Switzerland. The results exhibit lower total impacts (at least 16% in each examined impact category) at building level and resulting benefits (i.e., 68–117 kt CO2-Eq) at country level over five years, which can be further reduced/increased respectively by using existing or recycled components, instead of virgin materials.

Performance of a compacted loess/gravel cover as a capillary barrier and landfill gas emissions controller in Northwest China

Loess is widely distributed in Northwest China where the rainy season coincides with the warm and vegetation growth period. The use of loess as a capillary barrier cover (CBC) material is promising. However, how the loess/gravel CBC perform as a capillary barrier and landfill gas emissions controller remains elusive. In this study, the performance of a designed CBC comprised 1.3 m-thick compacted loess underlain by 0.3 m-thick gravel in extremely wet and dry years of Xi'an city from 1950 to 2000 was analyzed using numerical modeling. An instrumented CBC test section comprised 0.9 m-thick compacted loess underlain by 0.3 m-thick gravel was constructed to show the hydraulic responses in real conditions from January 2015 to January 2017. The numerical results indicated that the designed CBC performed well as a capillary barrier as no percolation occurred during the extremely wet periods. Despite adopting a CBC of 0.4 m thinner than the designed one, the test section produced only 16.16 mm percolation during the two-year monitoring period, and that can meet the recommended limit of 30 mm/yr. The effect of the capillary break on increasing the water storage within the CBC was observed at the test section in fall. The increased water storage can significantly decrease the gas permeability, and thus improve the performance of the CBC as a LFG emissions controller. Furthermore, the LFG emissions can be controlled to meet the limit set by the Australian guideline by decreasing the bottom gas pressure and artificial watering. Finally, a procedure was proposed to enhance the performance of CBCs.

Investigation of fugitive methane and gas collection efficiency in Halton landfill in Ontario, Canada

Methane gas is one of the significant contributors to global warming. A large portion of methane emissions comes from landfills. Developing reliable measurement methods for methane emissions from landfill sites has become very important. In this paper, the surface emissions of methane gas are quantified using a portable probe having a flame ionization detector (FID), a method proven to be successful in landfill gas measurement. Surface methane emissions from two closed cells in the Halton landfill in Ontario, Canada, were measured using the FID method. By analyzing the emissions within the perimeter of the landfill, hotspots of gas leakage were identified. The closed cells in the Halton landfill are equipped with gas extraction system for flaring and energy recovery and a clay topsoil cover. Emission concentrations of fugitive methane were found to range from 0.1 to 63 ppm. The largest emissions were detected in locations next to the leachate extraction manholes and malfunctioning gas extraction wells. The landfill gas balance showed that the landfill gas recovery efficiency was 44%, resulting in an average amount of fugitive methane from the landfill of 6124 m³/day. The results of the study were used to determine the methane generation potential (L_o) for municipal solid waste to further calibrate the USEPA LandGEM model for Ontario landfills. The model was calibrated by actual methane emission measurement and recovery data. The calibrated L_o was found to be 70 m³/t, which is lower than the estimated values in previous studies.

A simple and rapid in situ method for measuring landfill gas emissions and methane oxidation rates in landfill covers

A newly developed static chamber method with a laser methane detector and a biogas analyser was proposed to measure the landfill gas emissions and methane (CH₄) oxidation rates in landfill covers. The method relied on a laser methane detector for measuring CH₄ concentration, avoiding gas samplings during test and hence the potential interference of gas compositions inside the chamber. All the measurements could be obtained on site. The method was applied to determine the landfill gas emissions and CH₄ oxidation rates in a full-scale loess gravel capillary barrier cover constructed in landfill. Both laboratory calibration and in-situ tests demonstrated that fast (i.e. <20 min) and accurate measurements could be obtained by the proposed method. The method is capable of capturing the significant spatial and temporal variations of the landfill gas emissions and CH₄ oxidation rates in landfill site.

Is the reusable tableware the best option? Analysis of the aviation catering sector with a life cycle approach

Annually, around 7.7 billion passengers travel by plane. The menus served during the flight are quite similar between different airlines and are composed of the food itself, packaging (paper envelopes, film, etc.) and tableware (mainly trays, plates, glasses, cups and cutlery). In 2016, 1522 tonnes of tourist class menus were served in Iberia aircrafts landing at Madrid Barajas airport in Spain. From this amount, 51% by weight was packaging and tableware, and the remaining 49% food. As changes in the food has little room for maneuver, since the same amount would be delivered regardless how it is served, this study focus on the possibilities of packaging and tableware to reduce GHG emissions. The assessment has been done using life cycle assessment methodology (LCA) in order to identify the hotspots along the whole life cycle of packaging and tableware items. The case study chosen was the catering service of Iberia, the national airline of Spain. The functional unit used was "the service of 1,000 tourist class menus on Iberia flights that landed in Madrid in 2016". The results show that the impacts of reusable and single use items take place at different stages of their life cycles. For reusable ones, 76% of the impact is produced during the flight phase, meanwhile, for single use ones, 53% of the impact comes from the production stage. Variables such as material, weight and the number of reuses can greatly influence greenhouse gas (GHG) emissions. From the results of the analysis some eco-design strategies has been proposed and analysed. The paper reveals that the lighter single-use packaging and tableware for airline catering are less harmful under a life cycle perspective become.

Sustainable Thermal Energy Generation at Universities by Using Loquat Seeds as Biofuel

Global energy consumption has increased the emission of greenhouse gases (GHG), these being the main cause of global warming. Within renewable energies, bioenergy has undergone a great development in recent years. This is due to its carbon neutral balance and the fact that bioenergy can be obtained from a range of biomass resources, including residues from forestry, agricultural or livestock industries, the rapid rotation of forest plantations, the development of energy crops, organic matter from urban solid waste, and other sources of organic waste from agro-food industries. Processing factories that use loquats to make products such as liqueurs and jams generate large amounts of waste mainly in the form of skin and stones or seeds. These wastes are disposed of and sent to landfills without making environmentally sustainable use of them. The University of Almeria Sports Centre is made up of indoor spaces in which different sports can be practiced: sports centre pavilion (central court and two lateral courts), rocodrome, fitness room, cycle inner room, and indoor swimming pool. At present, the indoor swimming pool of the University of Almeria (UAL) has two fuel oil boilers, with a nominal power of 267 kW. The main objective of this study is to propose an energetic analysis to determine, on the one hand, the energetic properties of the loquat seed and, on the other hand, to evaluate its suitability to be used as a solid biofuel to feed the boilers of the heated swimming pool of the University of Almeria (Spain), highlighting the significant energy and environmental savings obtained. Results show that the higher calorific value of loquat seed (17.205 MJ/kg), is like other industrial wastes such as wheat straw, or pistachio shell, which demonstrates the energy potential of this residual biomass. In addition, the change of the fuel oil boiler to a biomass (loquat seed) boiler in the UAL’s indoor swimming pool means a reduction of 147,973.8 kg of CO2 in emissions into the atmosphere and an annual saving of 35,739.5 €, which means a saving of 72.78% with respect to the previous fuel oil installation. A sensitivity analysis shows that fuel cost of base case is the variable with the most sensitivity changing the initial cost and net present value (NPV).