Life cycle environmental assessment of industrial hazardous waste incineration and landfilling in China

Purpose

The improper handling of industrial hazardous waste (IHW), which comprises large amounts of toxic chemicals, heavy metals, or irradiation substances, is a considerable threat to human health and the environment. This study aims to quantify the life cycle environmental impacts of IHW landfilling and incineration in China, to identify its key factors, to improve its potential effects, and to establish a hazardous waste disposal inventory.

Methods

Life cycle assessment was conducted using the ReCiPe model to estimate the environmental impact of IHW landfilling and incineration. The characterization factors for the human toxicity and freshwater ecotoxicity categories shown in the ReCiPe were updated based on the geographies, population, food intake, and environmental conditions in China.

Results and discussion

The overall environmental burden was mainly attributed to the carcinogen category. The national carcinogen burden in 2014 at 37.8 CTUh was dominated by diesel consumption, cement and sodium hydroxide production, direct emission, transportation, and electricity generation stages caused by direct mercury and arsenic emissions, as well as indirect chromium emission. Although the atmospheric mercury emission directly caused by IHW incineration was comparative with the emission levels of developed countries, the annual direct mercury emission accounted for approximately 0.1% of the national mercury emission.

Conclusions

The key factors contributing to the reduction of the national environmental burden include the increasing diesel and electricity consumption efficiency, the reduction of cement and sodium hydroxide use, the development of air pollutant controlling systems, the reduction of transport distance between IHW disposers to suppliers, and the improvement of IHW recycling and reuse technologies.

     

Life cycle assessment of copper production: a case study in China

Purpose

China is the world’s largest producer and consumer of refined and reclaimed copper because of the rapid economic and industrial development of this country. However, only a few studies have analyzed the environmental impact of China’s copper industry. The current study analyzes the life cycle environmental impact of copper production in China.

Methods

A life cycle impact assessment using the ReCiPe method was conducted to estimate the environmental impact of refined and reclaimed copper production in China. Uncertainty analysis was also performed based on the Monte-Carlo simulation.

Results and discussion

The environmental impact of refined copper was higher than that of reclaimed copper in almost all categories except for human toxicity because of the direct atmospheric arsenic emission during the copper recycling stage. The overall environmental impact for the refined copper production was mainly attributed to metal depletion, freshwater ecotoxicity, marine ecotoxicity, and water depletion potential impact. By contrast, that for the reclaimed copper production was mainly caused by human toxicity impact.

Conclusions

Results show that the reclaimed copper scenario had approximately 59 to 99% more environmental benefits than those of the refined copper scenario in most key categories except for human toxicity, in which a similar environmental burden was observed between both scenarios. The key factors that reduce the overall environmental impact for China’s copper industry include decreasing direct heavy metal emissions in air and water, increasing the national recycling rate of copper, improving electricity consumption efficiency, replacing coal with clean energy sources for electricity production, and optimizing the efficiency of copper ore mining and consumption.

     

Comparative life cycle assessment of current and future electricity generation systems in the Czech Republic and Poland

Purpose

The purpose of the study was to perform a comparative life cycle assessment of current and future electricity generation systems in the Czech Republic and Poland. The paper also outlines the main sources of environmental impact for the different impact categories for the electricity generation technologies analyzed. The analyses covered the years 2000–2050, and were conducted within the framework of the international programme Interreg V-A Czech Republic-Poland, Microprojects Fund 2014–2020 in the Euroregion Silesia.

Methods

Environmental assessment was done using the life cycle assessment (LCA) and ReCiPe Midpoint and Endpoint methods, which allowed the presentation of different categories of environmental impact and damage. The LCA was based on ISO 14040 and ISO 14044, using SimaPro 8.2.3 software with the Ecoinvent 3.2 database. The analyses cover both the current electricity production structures in the Czech Republic and Poland, and the projected energy production.

Results and discussion

The LCA analyses performed for the energy systems under consideration in the Czech Republic and Poland enabled a comparative analysis of current and forecast energy systems in these countries, as well as identification of the main sources of environmental impact. Comparative analysis of the LCA results showed that current and future electricity generation systems in Poland caused higher environmental impact there, than in the Czech Republic.

Conclusions

The assessment of the life cycle of electricity sources showed that the main determinant of the negative impact on the environment of energy systems in both Poland and the Czech Republic was the consumption of solid fuels, and in particular, the consumption of lignite. It is important to highlight that this is the first attempt of a comparative LCA of electricity production in the Czech Republic and Poland. This is also the first approach that contains analyses of the life cycle assessment of both present and future energy systems. The economic assessment and eco-efficiency of current and future electricity generation systems in European Union countries will be addressed in future research.

     

Life cycle inventories of electricity generation and power supply in version 3 of the ecoinvent database—part II: electricity markets

Purpose

Representative, consistent and up-to-date life cycle inventories (LCI) of electricity supply are key elements of ecoinvent as an LCI background database since these are often among the determining factors with regard to life cycle assessment (LCA) results. ecoinvent version 3 (ev3) offers new LCI data of power supply (electricity markets) in 71 geographies. This article gives an overview of these electricity markets and discusses new ecoinvent features in the context of power supply.

Methods

The annual geography- and technology-specific electricity production for the year 2008 specifies the technology shares on the high-, medium- and low-voltage level electricity markets. Data are based on IEA statistics. Different voltage levels are linked by transformation activities. Region-specific electricity losses due to power transmission and voltage transformation are considered in the market and transformation activities. The majority of the 71 power markets are defined by national boundaries. The attributional ecoinvent system model in ev3 with linking to average current suppliers results in electricity markets supplied by all geography-specific power generation technologies and electricity imports, while the consequential system model generates markets only linked to unconstrained suppliers.

Results and discussion

The availability of LCI data for 71 electricity markets in ev3 covering 50 countries reduces the “Rest-of-the-World” electricity supply not covered by country- or region-specific inventories to 17 % for the year 2008. Specific power supply activities for all countries contributing more than 1 % to global electricity production are available. The electricity markets show large variations concerning contributions from specific technologies and energy carriers. Imports can substantially change the national/regional power mix, especially in small markets. Large differences can also be observed between the electricity markets in the attributional and the consequential database calculation. Region-specific total power losses between production on the high voltage level and consumer on the low voltage level are on the order of 2.5–23 %.

Conclusions

Electricity supply mixes (electricity markets) in the ecoinvent database have been updated and substantially extended for v3. Inventories for electricity supply in all globally important economies are available with geography-specific technology and market datasets which will contribute to increasing quality and reducing uncertainties in LCA studies worldwide and to allow more accurate estimation of environmental burdens from global production chains. Future work should focus on improving the details of country-specific data, implementation of more countries into the database, splitting of large countries into smaller regions and on developing a more sophisticated approach specifying country-specific electricity mixes in consequential system models.

     

Environmental impact assessment of centralized municipal wastewater management in Thailand

Purpose

Urbanization and industrial development intensify water utilization and wastewater generation. The efficiency of wastewater treatment systems varies and depends on system design and wastewater condition. The research aims to examine seven existing centralized municipal wastewater treatment plants (WWTPs) in Bangkok to discover which system configuration yields the best environmental and economic performance. The degree of environmental impact and operational costs from different system designs were investigated to help select future wastewater treatment systems.

Methods

Life cycle assessment (LCA) has been conducted to evaluate environmental impacts from centralized municipal wastewater treatment systems. Life cycle impact assessment method based on endpoint modeling (LIME) was applied, with three major potential environmental impact categories including eutrophication, global warming, and acidification. All seven centralized municipal WWTPs in Bangkok were investigated as case studies. The system configurations are classified into five types of activated sludge (AS) systems. The contribution of impacts from individual processes in each type of AS system was analyzed. The methodology covered major on-site and off-site operational processes excluding construction and maintenance phases. Average annual data were calculated to develop an inventory dataset. JEMAI-Pro software was utilized in this study to analyze the life cycle impact of the systems.

Results and discussion

The level of environmental impact from a WWTP depends on the configuration of the AS system. The highest potential environmental impact from a municipal WWTP is eutrophication, which is obviously affected by ammonium and phosphorous discharges into water bodies. The vertical loop reactor activated sludge (VLRAS) system yielded the best treatment performance among the five AS sub-systems. The consumption of electricity used to operate the system contributed significantly to global warming potential and correlated considerably with operating costs. Comparing among three system sizes, the large-scale WWTP revealed inefficient electricity consumption, whereas the medium plant provided better performance in chemical use and operating costs.

Conclusions

Centralized municipal WWTPs with capacities ranging from 10 to 350?×?10³ m³/day were evaluated with respect to environmental performance and costs during the operating phase. Among all case studies, a medium-scale WWTP with a VLRAS system offered the best operating performance in terms of low environmental impact, resource consumption, and cost. To enhance WWTP management, it is vital to improve the efficiency of electricity consumption in primary and secondary treatment processes and increase wastewater collection efficiency to maximize the plant operating capacity and minimize overall environmental impacts.

     

Blue mussel (<Emphasis Type="Italic">Mytilus edulis</Emphasis>) bouchot culture in Mont-St Michel Bay: potential mitigation effects on climate change and eutrophication

Purpose

Bivalve production is an important aquaculture activity worldwide, but few environmental assessments have focused on it. In particular, bivalves’ ability to extract nutrients from the environment by intensely filtering water and producing a shell must be considered in the environmental assessment.

Methods

LCA of blue mussel bouchot culture (grown out on wood pilings) in Mont Saint-Michel Bay (France) was performed to identify its impact hotspots. The chemical composition of mussel flesh and shell was analyzed to accurately identify potential positive effects on eutrophication and climate change. The fate of mussel shells after consumption was also considered.

Results and discussion

Its potential as a carbon-sink is influenced by assumptions made about the carbon sequestration in wooden bouchots and in the mussel shell. The fate of the shells which depends on management of discarded mussels and household waste plays also an important role. Its carbon-sink potential barely compensates the climate change impact induced by the use of fuel used for on-site transportation. The export of N and P in mussel flesh slightly decreases potential eutrophication. Environmental impacts of blue mussel culture are determined by the location of production and mussel yields, which are influenced by marine currents and the distance to on-shore technical base.

Conclusions

Bouchot mussel culture has low environmental impacts compared to livestock systems, but the overall environmental performances depend on farming practices and the amount of fuel used. Changes to the surrounding ecosystem induced by high mussel density must be considered in future LCA studies.

     

Electric car life cycle assessment based on real-world mileage and the electric conversion scenario

Purpose

While almost all life cycle assessment (LCA) studies published so far are based on generic vehicles, type approval energy consumption as well as emission data, and application scenarios related to standardized laboratory-based driving cycles, this projects aims at quantifying the LCA based on a real-world vehicle composition and energy consumption data measured before and after the electric conversion of a mini class car. Furthermore, consequences of a second life of a vehicle’s glider on the environmental impact were investigated.

Methods

After having driven 100,000 km, a Smart was converted from combustion to electric in a laboratory project. The inventory was developed grounded upon materials data from laboratory measurements during the conversion process as well as on real-world energy consumption data prior and after the conversion. Three base models are compared in this life cycle impact assessment: a conventional new Smart (combustion engine), a new electric Smart, and a Smart converted from combustion engine to electric. Together with two sensitivity analyses (four different electricity mixes as well as urban vs. mixed driving conditions) and two EOL treatments, 36 scenarios have been quantified. The inventory is based on Ecoinvent database v 2.2 as a background system and includes raw material extraction.

Results and discussion

In urban use, the modeled battery electric vehicle has a favorable environmental impact compared to the ICEV even when charged with the German electricity mix of the year 2013. The advantage in summed up endpoints of the converted Smart is 23 % vs. the new electric Smart on average for the mixed driving conditions and 26 % for the urban driving conditions, respectively. Over a variety of impact categories, electricity consumption during battery cell production in China as well as impacts due to microelectronic components dominated the life cycle. Results for 18 midpoint categories, endpoints for damages to human health, to resource quality and to ecosystem quality as well as the Single score endpoints are reported.

Conclusions

This investigation points out that real-world treatments in inventory development can more specifically outline the environmental advantages of the electric car. The electric conversion of a used combustion engine vehicle can save an additional 16 % (CO₂-eq) and 19 % (single score endpoints) of the environmental impact over a lifetime, respectively, when compared with the new BEV.

     

Functional unit and product functionality—addressing increase in consumption and demand for functionality in sustainability assessment with LCA

Purpose

The static functional unit definition in the current LCA framework has limitations in addressing the changing product functionality and associated environmental impact of constantly evolving product technologies. As a result, it overlooks the changes in consumer behaviour of increased consumption of products in provided services as well as in growing volumes. This article aims to present a new framework in defining a dynamic functional unit of product technologies that caters for changes in consumer behaviour and growing market.

Methods

A new approach to defining the functional unit is proposed that caters for changes in consumer behaviour and the use of technology from a technical performance perspective. A dynamic approach to definition of the functional unit is proposed that is based on Kano’s model of product function and satisfaction.

Results and discussion

The new approach is demonstrated on a case study in which the analysis of historical data for two TV product technologies—CRT and LCD—is used to show how the total environmental impact is increasing due to the increased functionality which triggers an increase in the volume of the market. Despite the efforts of improving product life cycle design, the society is still faced with increasing environmental impact from the product type overall.

Conclusions

This article presents the challenges of using a static, single functional unit definition in an industrial culture with constant evolution of products that influences usage behaviour and demonstrates the vicious circle of improving product efficiency that leads to further consumption and environmental impact. To address this problem, a new framework of dynamic functional unit definition is put forward for performing comparative LCA to manage the development of product life cycle design that helps keep the total environmental impact of the company’s product portfolio within absolute boundaries.

     

Do green wooden composites using lignin-based binder have environmentally benign alternatives? A preliminary LCA case study in China

Purpose

Nowadays, formaldehyde emissions from petroleum-based adhesives contribute considerably to environmental problems and are a constraint to the development of forest-based industries. Although many efforts are being made to develop new lignin-based adhesives for panels, very few studies were carried out via life cycle assessment (LCA). This study aims to assess the life cycle of green wooden composites by using hybrid-modified ammonium lignosulfonate (HMAL) as the binder and investigate the possibility of lignin-based binder to be a good alternative.

Methods

This study is a step further of the previous work conducted on HMAL as an alternative binder for medium-density fiberboard (MDF) or, in other words, the wooden composite made from HMAL and wood fiber (WF). LCA was carried out to assess the environmental impacts during the life cycle of the new manufacturing process of HMAL/WF production using ReCiPe 1.08 Endpoint and IPCC global warming potential (GWP) method built into the GaBi version 6.0 software. The production system involved two subsystems: raw material supply and board manufacture. Meanwhile, a comparative LCA of conventional MDF, with three main damage categories and GWP, was also carried out.

Results and discussion

The hydrogen peroxide (H₂O₂) production, electricity, and the HMAL/WF manufacturing stages had the greatest environmental impact. The comparative results pointed out that HMAL/WF production is environmentally superior to conventional MDF in general. Due to the environmental impacts associated with the HMAL binder, a sensitivity analysis was carried out. Suggestions were made for a cleaner production, in which the H₂O₂ dose was reduced to 24 wt%.

Conclusions

H₂O₂ use, energy, and electricity consumption are main contributors to most impact categories, which help us to find the potential improvements of sustainability, choose the appropriate HMAL technology, and optimize the HMAL/WF system. Feasible production processes and life cycle costs are factors that still need to be studied.

     

Conventional and exergetic life cycle assessment of organic rankine cycle implementation to municipal waste management: the case study of Mae Hong Son (Thailand)

Purpose

The critical issue of waste management in Thailand has been rapidly increasing in almost all of the cities due to the economic growth and rising population that could double the amount of solid waste in landfill area. The alternative ways of waste treatment that have more efficiency and effectiveness in terms of energy, ecology, and resources become the key issue for each municipality to replace the old fashioned technology and be able to enhance the ability of solid waste problem management. Waste to energy is one of the favorable approaches to diminish the amount of waste to landfill and utilize waste for electricity. The aim of this study is to identify and quantify the life cycle impacts of the municipal solid waste (MSW) of Mae Hong Son municipality (MHSM), and the case study is the selected waste treatment technology of the Refuse-Derived Fuel (RDF) hybrid with 20 kW of Organic Rankine Cycle (ORC).

Methods

The functional unit is defined as 1 t of MSW. The energy, environment, and resource impacts were evaluated by using Life Cycle Assessment (LCA); ReCipe and Net Energy Consumption were referred to calculate the environmental impacts and the benefits of energy recovery of WtE technology. Exergetic LCA was used to analyze the resource consumption, especially land use change.

Results and discussion

The results indicated that the environmental impacts were comparatively high at the operation stage of RDF combustion. On the other hand, the production stage of RDF illustrated the highest energy consumption. The ORC power generation mainly consumed resources from material and energy used. The ORC system demonstrated better results in terms of energy and resource consumption when applied to waste management, especially the land required for landfill. Substitution of electricity production from ORC system was the contributor to the reduction of both energy and resource consumption. Installation of spray dry and fabric filter unit to RDF burner can reduce heavy metals and some pollutants leading to the reduction of most of the impacts such as climate change, human toxicity, and fossil depletion which are much lower than the conventional landfill.

Conclusions

LCA results revealed that the environmental impacts and energy consumption can be reduced by applying the RDF and ORC systems. The exergetic LCA is one of the appropriate tools used to evaluate the resource consumption of MSW. It is obviously proven that landfill contributed to higher impacts than WtE for waste management.

     

Development of an electricity system model allowing dynamic and marginal approaches in LCA—tested in the French context of space heating in buildings

Purpose

This study aims at accounting for the variation in electricity production, processes and related impacts depending on season (heating, cooling), day of the week (tertiary building) and hour of the day. In this context, this paper suggests two alternative methods to integrate grid-building interaction in life cycle assessment of buildings and districts.

Methods

An attributional dynamic method (AD) and a marginal dynamic method (MD) are compared with an annual average method (AA), representative of standard practice, using electric space heating as an illustrative case. The different methods are based on a dispatch model simulating electricity supply on an hourly basis, averaging historically observed climatic and economic variability. The meteorological inputs of the model are identical to those of the building energy simulation. Therefore, the environmental benefits from smart buildings and onsite renewable energy production are more accurately evaluated.

Results and discussion

Using electricity production (or supply) data for a specific past year is a common practice in building LCA. This practice is sensitive to economic and meteorological hazards. The suggested methodology is based on a proposed reference year mitigating these hazards and thus could be seen as more representative of average impacts. Depending on the chosen approach (average or marginal) to evaluate electricity supply related impacts, the carbon footprint of the electric space heating option for the studied low-energy house in France is evaluated to 61.4 to 84.9 g CO₂eq kWh^?1 (AA), 78.8 to 110.2 g CO₂eq kWh^?1 (AD) and 765.1 to 928.7 g CO₂eq kWh^?1 (MD). Compared to wood and gas boiler, 22–107 and 218–284 g CO₂eq kWh^?1 respectively, the ranking between the different technical options depends on the chosen approach. Uncertainty analysis does not undermine the interpretation of the results.

Conclusions

The proposed electricity system model allows a more precise and representative evaluation of electricity supply related impacts in LCA compared to standard practices. Two alternative methods are suggested corresponding to attributional and consequential LCA. The approach has to be chosen in line with the assessment objectives (e.g. certification, ecodesign). Prospective assessment integrating long-term evolution of the electric system and influence of global warming on buildings behaviour are identified as relevant future research subjects.

     

Environmental profile of Spanish porcelain stoneware tiles

Purpose

Porcelain stoneware tile (PST) is currently the ceramic tile of greatest commercial and innovation interest. An environmental life cycle assessment of different varieties of PST was undertaken to enable hotspots to be identified, strategies to be defined, differences between PST varieties to be evaluated and guidance for PST manufacturers to be provided in choosing the Environmental Product Declaration (EPD) programme that best suited their needs according to grouping criteria.

Methods

Analysis of previous information allowed three main parameters (thickness, glaze content and mechanical treatment) to be identified in order to encompass all PST variations. Fifteen varieties of PST were thus studied. The coverage of 1 m² of household floor surface with the different PST varieties for 50 years was defined as functional unit. The study sets out environmental data whose traceability was verified by independent third parties for obtaining 14 EPDs of PST under Spanish EPD programmes.

Results and discussion

The study presents PST inventory analysis and environmental impact over the entire life cycle of the studied PST varieties. The natural gas consumed in the manufacturing stage accounted for more than 70% abiotic depletion–fossil fuels and global warming; electricity consumption accounted for more than 60% ozone layer depletion, while the electricity generated by the cogeneration systems avoided significant environmental impacts in the Spanish power grid mix. The variations in PST thickness, amount of glaze and mechanical treatments were evaluated. The PST variety with the lowest environmental impact was the one with the lowest thickness, was unglazed and had no mechanical treatments. Similarly, the PST variety with the highest environmental impact was the one with the greatest thickness, was glazed and had been mechanically treated.

Conclusions

The PST life cycle stage with the highest environmental impact was the manufacturing stage. The main hotspots found were production and consumption of energy and raw materials extraction. Variation in thickness was a key factor that proportionally influenced almost all studied impact categories; the quantity of glaze strongly modified abiotic depletion–elements and eutrophication, while the mechanical treatments contributed mainly to ozone depletion. The study of all PST varieties led to the important conclusion, against the current trend, that differences among them were found to be so significant that declaring a number of PSTs within the same EPD is not directly possible, and it needs preliminary verification to ensure compliance with the product category rule.

     

LCA applied to nano scale zero valent iron synthesis

Purpose

Application of zero valent iron nanoparticles is an innovative technology for ground water treatment and soil remediation. There are several methods to synthesise nano scale zero valent iron (nZVI), namely through bottom-up methods which consists on chemical reactions using strong reducing agents. In this work, the environmental impacts and costs were determined for two methods, namely the traditional one that uses sodium borohydride and the green method that uses extracts obtained from natural products.

Methods

The consideration of environment and economic aspects in the earlier stages of the synthesis processes and in the development of new materials is of great importance since it can help to decide if alternative methods are promising and should be further developed aiming more sustainable processes. In this work, life cycle assessment (LCA) was used as an ecodesign strategy evaluating environmental performance of the two synthesis methods, identifying critical stages of the synthesis processes of nZVI. An economic evaluation and a sensitivity analysis considering a different scenario for electricity production were also performed.

Results and discussion

The results obtained in this study showed that the green synthesis method presents lower environmental impacts than the traditional one, roughly 50% lower in the first scenario. In the second scenario, environmental impact of green synthesis corresponds to 38% of the environmental impact of traditional synthesis. In the green method, the critical stage is the extraction process which is closely related to the electricity production. In the traditional method, the reactant use is the critical stage that is related to the production of sodium borohydride. The economic evaluation indicated that the traditional synthesis method is much more expensive than the green synthesis (roughly eight times higher).

Conclusions

From the results obtained, it is possible to conclude that the green synthesis method presents lower environmental impacts in both scenarios and lower costs than the traditional synthesis.

     

RiboTagger: fast and unbiased 16S/18S profiling using whole community shotgun metagenomic or metatranscriptome surveys

Background

Taxonomic profiling of microbial communities is often performed using small subunit ribosomal RNA (SSU) amplicon sequencing (16S or 18S), while environmental shotgun sequencing is often focused on functional analysis. Large shotgun datasets contain a significant number of SSU sequences and these can be exploited to perform an unbiased SSU--based taxonomic analysis.

Results

Here we present a new program called RiboTagger that identifies and extracts taxonomically informative ribotags located in a specified variable region of the SSU gene in a high-throughput fashion.

Conclusions

RiboTagger permits fast recovery of SSU-RNA sequences from shotgun nucleic acid surveys of complex microbial communities. The program targets all three domains of life, exhibits high sensitivity and specificity and is substantially faster than comparable programs.

     

Life cycle assessment of the environmental performance of conventional and organic methods of open field pepper cultivation system

Purpose

As the scale of the organic cultivation sector keeps increasing, there is growing demand for reliable data on organic agriculture and its effect on the environment. Conventional agriculture uses chemical fertilizers and pesticides, whilst organic cultivation mainly relies on crop rotation and organic fertilizers. The aim of this work is to quantify and compare the environmental sustainability of typical conventional and organic pepper cultivation systems.

Methods

Two open field pepper cultivations, both located in the Anthemountas basin, Northern Greece, are selected as case studies. Life cycle assessment (LCA) is used to quantify the overall environmental footprint and identify particular environmental weaknesses (i.e. unsustainable practices) of each cultivation system. Results are analysed at both midpoint and endpoint levels in order to obtain a comprehensive overview of the environmental sustainability of each system. Attributional LCA (ALCA) is employed to identify emissions associated with the life cycles of the two systems. Results are presented for problem-oriented (midpoint) and damage-oriented (endpoint) approaches, using ReCiPe impact assessment.

Results and discussion

At midpoint level, conventional cultivation exhibits about threefold higher environmental impact on freshwater eutrophication, than organic cultivation. This arises from the extensive use of nitrogen and phosphorus-based fertilizers, with consequent direct emissions to the environment. The remaining impact categories are mainly affected by irrigation, with associated indirect emissions linked to electricity production. At endpoint level, the main hotspots identified for conventional cultivation are irrigation and fertilizing, due to intensive use of chemical fertilizers and (to a lesser degree) pesticides. For organic pepper cultivation, the main environmental hotspots are irrigation, machinery use, and manure loading and spreading processes. Of these, the highest score for irrigation derives from the heavy electricity consumption required for groundwater pumping associated with the fossil-fuel-dependent Greek electricity mix.

Conclusions

Organic and conventional cultivation systems have similar total environmental impacts per unit of product, with organic cultivation achieving lower environmental impacts in ‘freshwater eutrophication’, ‘climate change’, ‘terrestrial acidification’ and ‘marine eutrophication’ categories. Conventional cultivation has a significantly greater effect on the freshwater eutrophication impact category, due to phosphate emissions arising from application of chemical fertilizers.

     

Identifying metabolic elements that contribute to productivity of 1-propanol bioproduction using metabolomic analysis

Introduction

Previously constructed Escherichia coli strains that produce 1-propanol use the native threonine pathway, or a heterologous citramalate pathway. However, based on the energy and cofactor requirements of each pathway, a combination of the two pathways produces synergistic effects that increase the theoretical maximum yield with a simultaneous unexplained increase in productivity.

Objective

Identification of key factors that contribute to synergistic effect leading to 1-propanol yield and productivity improvement in E. coli with native threonine pathway and heterologous citramalate pathway.

Method

A combination of snapshot metabolomic profiling and dynamic metabolic turnover analysis were used to identify system-wide perturbations that contribute to the productivity improvement.

Result and Conclusion

In the presence of both pathways, increased glucose consumption and elevated levels of glycolytic intermediates are attributed to an elevated phosphoenolpyruvate (PEP)/pyruvate ratio that is known to increase the function of the native phosphotransferase. Turnover analysis of nitrogen containing byproducts reveals that ammonia assimilation, required for the threonine pathway, is streamlined when provided with an NAD(P)H surplus in the presence of the citramalate pathway. Our study illustrates the application of metabolomics in identification of factors that alter cellular physiology for improvement of 1-propanol bioproduction.

     

Analysis of influencing factor of coexisting prediabetes and prehypertension in adult residents of Jilin Province

Background

To explore the risk factors of coexisting prediabetes and prehypertension, to provide theoretical basis for early intervention.

Methods

A multi-stage stratified random cluster sampling method was used to randomly select adult residents from Jilin Province in 2013 for questionnaire surveys, physical examinations, and laboratory tests.

Results

The prevalence of coexisting prediabetes and prehypertension in Jilin Province was 11.3%. The binary Logistic regression results showed that age, sex, education, triglyceride (TG), BMI, waist circumference and alcohol consumption were the effects of factor coexisting prediabetes and prehypertension.

Conclusion

It is important to pay attention to the early stage of hypertension and diabetes, control the transition from prehypertension and prediabetes to hypertension and diabetes, and improve the health of residents.

     

Emission payback periods for increased residential insulation using marginal electricity modeling: a life cycle approach

Purpose

Increases in residential insulation can reduce energy consumption and corresponding life cycle emissions, but with increased manufacturing and transportation of insulation and the associated impacts. In this study, we conducted life cycle analyses of residential insulation and estimated payback periods for carbon dioxide (CO₂), nitrogen oxides (NOx), and sulfur dioxide (SO₂) emissions, using modeling techniques that account for regional variability in climate, fuel utilization, and marginal power plant emissions.

Methods

We simulated the increased production of insulation and energy savings if all single-family homes in the USA increased insulation levels to the 2012 International Energy Conservation Code, using an energy simulation model (EnergyPlus) applied to a representative set of home templates. We estimated hourly marginal changes in electricity production and emissions using the Avoided Emissions and Generation Tool (AVERT), and we estimated emissions related to direct residential combustion. We determined changes in upstream emissions for both insulation and energy using openLCA and ecoinvent. Payback periods were estimated by pollutant and region. In sensitivity analyses, we considered the importance of marginal versus average power plant emissions, transportation emissions, emission factors for fiberglass insulation, and sensitivity of emission factors to the magnitude of electricity reduction.

Results and discussion

Combining the life cycle emissions associated with both increased insulation manufacturing and decreased energy consumption, the payback period for increased residential insulation is 1.9 years for CO₂ (regional range 1.4–2.9), 2.5 years for NOx (regional range 1.8–3.9), and 2.7 years for SO₂ (regional range 1.9–4.8). For insulation, transportation emissions are limited in comparison with manufacturing emissions. Emission benefits displayed strong regional patterns consistent with relative demands for heating versus cooling and the dominant fuels used. Payback periods were generally longer using average instead of marginal emissions and were insensitive to the magnitude of electricity savings, which reflects the structure of the intermediate complexity electricity dispatch model.

Conclusions

The life cycle benefits of increased residential insulation greatly exceed the adverse impacts related to increased production across all regions, given insulation lifetimes of multiple decades. The strong regionality in benefits and the influence of a marginal modeling approach reinforce the importance of site-specific attributes and time-dynamic modeling within LCA.

     

Resource depletion assessment of renewable electricity generation technologies—comparison of life cycle impact assessment methods with focus on mineral resources

Purpose

Renewable energies are promoted in order to reduce greenhouse gas emissions and the depletion of fossil fuels. However, plants for renewable electricity production incorporate specifically higher amounts of materials being rated as potentially scarce. Therefore, it is in question which (mineral) resources contribute to the overall resource consumption and which of the manifold impact assessment methods can be recommended to cover an accurate and complete investigation of resource use for renewable energy technologies.

Methods

Life cycle assessment is conducted for different renewable electricity production technologies (wind, photovoltaics, and biomass) under German conditions and compared to fossil electricity generation from a coal-fired power plant. Focus is given on mineral resource depletion for these technologies. As no consensus has been reached so far as to which impact assessment method is recommended, different established as well as recently developed impact assessment methods (CML, ReCiPe, Swiss Ecoscarcity, and economic scarcity potential (ESP)) are compared. The contribution of mineral resources to the overall resource depletion as well as potential scarcity are identified.

Results and discussion

Overall resource depletion of electricity generation technologies tends to be dominated by fossil fuel depletion; therefore, most renewable technologies reduce the overall resource depletion compared to a coal-fired power plant. But, in comparison to fossil electricity generation from coal, mineral resource depletion is increased by wind and solar power. The investigated methods rate different materials as major contributors to mineral resource depletion, such as gallium used in photovoltaic plants (Swiss Ecoscarcity), gold and copper incorporated in electrical circuits and in cables (CML and ReCiPe), and nickel (Swiss Ecoscarcity and ReCiPe) and chromium (ESP) for stainless steel production. However, some methods lack characterization factors for potentially important materials.

Conclusions

If mineral resource use is investigated for technologies using a wider spectrum of potentially scarce minerals, practitioners need to choose the impact assessment method carefully according to their scope and check if all important materials are covered. Further research is needed for an overall assessment of different resource compartments.

     

Life cycle environmental and economic assessment of lead refining in China

Purpose

Lead is one of the most commonly used metals in the past millennium because of its various properties. Moreover, lead is easy to extract and handle. However, the lead industry often encounters strong public opposition because of lead poisoning. This study analyzes the economic and environmental impacts of lead in China, which is the world’s largest producer and consumer of lead.

Methods

Life cycle assessment coupled with life cycle costing was conducted to estimate the environmental and economic impacts of primary and secondary lead refining in China. The internal cost (i.e., raw materials and energy consumption, labor, tax, interest, transport, infrastructure, depreciation, and maintenance) and external market price (i.e., carbon, ammonia, arsenic, COD, lead, mercury, nitrogen oxides, particulates, sulfur dioxide, and land eco-remediation) are considered.

Results and discussion

The overall environmental burden was mainly generated from the human toxicity and marine ecotoxicity categories for both primary and secondary lead refining scenarios because of the direct lead emission in the air and water. For the primary lead refining, the effect on metal depletion represented an additional dominant contribution to the overall environmental burden. The overall economic impact was mainly attributed to lead ore or waste lead, tax, labor fee, and emission cost of ammonia and chromium. In 2013, approximately 5.61 Mt CO₂ eq, 5.81 Mt 1,4-DB eq, 6.59 kt 1,4-DB eq, 7.86 kt 1,4-DB eq, 1.82 Mt·kg Fe eq, 2.37 Mt·kg oil eq, and $9.9 billion were recorded from the lead industry in China in the climate change, human toxicity, freshwater ecotoxicity, marine ecotoxicity, metal depletion, fossil depletion, and economic impact categories, respectively. Additionally, approximately 0.4 kt lead, 18.4 kt sulfur dioxide, 15.6 kt nitrogen oxide, and 6.4 kt particulate emissions in the same year were released from the lead industry in China.

Conclusions

Approximately 57 to 96 % environmental benefits through waste lead recycling in all key categories were observed, whereas its economic benefit was low. The key factors that contribute in reducing the overall environmental and economic impacts include reducing direct lead emissions in air and water, increasing the national recycling rate of lead, replacing coal with clean energy sources for electricity production, improving heavy metal-removing technologies from mining wastewater, and optimizing the efficiency of electricity, lead ore, coal, oxygen, natural gas, and sodium carbonate consumption.