Contamination issues in a continuous ethanol production corn wet milling facility

Low ethanol yields and poor yeast viability were investigated at a continuous ethanol production corn wet milling facility. Using starch slurries and recycle streams from a commercial ethanol facility, laboratory hydrolysates were prepared by reproducing starch liquefaction and saccharification steps in the laboratory. Fermentations with hydrolysates prepared in the laboratory were compared with plant hydrolysates for final ethanol concentrations and total yeast counts. Fermentation controls were prepared using hydrolysates (plant and laboratory) that were not inoculated with yeast. Hydrolysates prepared in the laboratory resulted in higher final ethanol concentrations (15.8 % v/v) than plant hydrolysate (13.4 % v/v). Uninoculated controls resulted in ethanol production from both laboratory (12.2 % v/v) and plant hydrolysates (13.7 % v/v), indicating the presence of a contaminating microorganism. Yeast colony counts on cycloheximide and virginiamycin plates confirmed the presence of a contaminant. DNA sequencing and fingerprinting studies also indicated a number of dissimilar communities in samples obtained from fermentors, coolers, saccharification tanks, and thin stillage.     

Noise assessment in LCA - a methodology attempt: A case study with various means of transportation on a set trip

The present work focuses on impact assessment of noise disturbance in the framework of LCA studies. A number of difficulties arose in the course of the study, namely expressing noise measurements in an easy-to-handle unit, imputing disturbance engendered by several simultaneous sources to every single source, handling additive quantities non-linearly, taking into account the space and time dependence of potential impacts associated with noise, It is shown how all these issues were tackled in a I.CA study that assessed different modes of transportation. The methodology developed takes into account the disturbance to noise level exceeding a set threshold and no other kinds of noise effects. It is obvious that disturbance due to noise emissions depends on people density in the neighborhood of the emission source. In this context, a “site-dependent approach” was taken, meaning that we did include local factors into the valuation. The methodology developed in this article may be extended to other types of emissions when it is necessary to integrate local factors in the assessment phase of LCA. This document is the property of Ecobilan and can not be reproduced without its prior authorization     

Farm-scale production of fuel ethanol and wet grain from corn in a batch process

The batch production of fuel grade ethanol and distillers' wet grain (wet solids) in a farm-scale process (1240-15,580 L/batch) is described. The employs yeast fermentation of amylase-treated corn mash and a two-stage distillation. Primary emphasis in this study was on the cooking, fermentation, and centrifugation steps. Without recycling, fermentation of the mash yield beers with 10.0-10.5% ethanol. Recycling of stillage supernatant at full, 75, or 50% strengths produced enriched mashes that after 48-h fermentation yielded beers with 5-;14% more ethanol. Recycling twice with full-strength supernatant at pH 7.0 increased the ethanol yield in the final beer 16.5%; however, the time to complete the final fermentation was extended form 48 to 72 h and salt buildup occurred. By recycling at pH 5.4, it was possible to avoid rapids salt buildup and obtain beers with 10.3-10.5% ethanol. Recycling resulted in increased levels of glucose, starch, crude protein, and fat in the beer and a reduced moisture content while the wet solids showed an increased starch content. Centrifugation after cooking or fermentation yield in the subsequently produced beer. Fermentation of a volume-resorted mash supernatant gave a beer with only 9.25% ethanol. Mash wet solids varied somewhat chemically from beer and stillage solids. An economic and energy balance analysis of various modes of plant operation are provided and plant considerations are suggested.     

LCA of a newsprint paper machine: a case study of capital equipment

Purpose

The environmental aspects of paper as a consumer good have been extensively studied. However, the paper machine has been mostly neglected in the literature. The purpose of this article is to present a LCA case study that explicitly focuses on the system of a newsprint paper machine and its environmental impacts and not on the system of the consumer good paper. The relevance of the paper machine as capital equipment is analyzed, and conclusions for the environmental improvement of paper machines are drawn based on identified hotspots. The article hereby answers the more general research questions of whether capital equipment has rightly been neglected in other studies regarding pulp and paper and which impact categories are important for analyzing the environmental burdens of a paper machine.

Methods

The study has been executed in collaboration with Voith Paper, an original equipment manufacturer. Hence, in distinction to literature-based studies, primary data on the paper machine was available resulting in a high overall data quality. Based on the ISO 14040 (2006) and 14044 (2006) standards, this article pursues a cradle-to-grave approach for the paper machine. It assesses the environmental impacts in the impact categories defined by the ReCiPe impact assessment methodology. Different types of energy generation are examined in a scenario analysis with combined heat and power generation (CHP) as the baseline case. For interpretation, a normalization and a sectoral analysis are performed.

Results and discussion

The normalized results indicate fossil resource depletion and global warming as the most important impact categories. Global warming impacts are highly dependent on the energy processes and result to 432.7 kg CO2e per production of 1 t of paper for CHP and to 701.7 kg CO2e for EU25 grid mix. The sectoral analysis shows that the machinery's operations/use phase is clearly dominating most impact categories due to its long lifetime. An exception is the metal depletion, for which the materials and manufacturing processes are most important.

Conclusions

These findings prove that for most categories, the operations/use phase of the paper machine is the most important life cycle stage. In systems focusing on the consumer good paper, it is therefore sufficient to model the operation of the paper machine, whereas the manufacturing, transport, and end-of-life processes regarding the paper machine equipment can be neglected, unless metal depletion is important to the study.     

Allocation procedure in ethanol production system from corn grain i. system expansion

We investigated the system expansion approach to net energy analysis for ethanol production from domestic corn grain. Production systems included in this study are ethanol production from corn dry milling and corn wet milling, corn grain production (the agricultural system), soybean products from soybean milling (i.e. soybean oil and soybean meal) and urea production to determine the net energy associated with ethanol derived from corn grain. These five product systems are mutually interdependent. That is, all these systems generate products which compete with or displace all other comparable products in the market place. The displacement ratios between products compare the equivalence of their marketplace functions. The net energy, including transportation to consumers, is 0.56 MJ_net/MJ of ethanol from corn grain regardless of the ethanol production technology employed. Using ethanol as a liquid transportation fuel could reduce domestic use of fossil fuels, particularly petroleum. Sensitivity analyses show that the choice of allocation procedures has the greatest impact on fuel ethanol net energy. Process energy associated with wet milling, dry milling and the corn agricultural process also significantly influences the net energy due to the wide ranges of available process energy values. The system expansion approach can completely eliminate allocation procedures in the foreground system of ethanol production from corn grain.     

Assessing resource depletion in LCA: a review of methods and methodological issues

Purpose

Political interest in the future availability of natural resources has spiked recently, with new documents from the European Union, United Nations Environment Programme and the US National Research Council assessing the supply situation of key raw materials. As resource efficiency is considered a key element for sustainable development, suitable methods to address sustainability of resource use are increasingly needed. Life cycle thinking and assessment may play a principal role here. Nonetheless, the extent to which current life cycle impact assessment methods are capable to answer to resource sustainability challenges is widely debated. The aim of this paper is to present key elements of the ongoing discussion, contributing to the future development of more robust and comprehensive methods for evaluating resources in the life cycle assessment (LCA) context.

Methods

We systematically review current impact assessment methods dealing with resources, identifying areas of improvement. Three key issues for sustainability assessment of resources are examined: renewability, recyclability and criticality; this is complemented by a cross-comparison of methodological features and completeness of resource coverage.

Results and discussion

The approach of LCA to resource depletion is characterised by a lack of consensus on methodology and on the relative ranking of resource depletion impacts as can be seen from a comparison of characterisation factors. The examined models yield vastly different characterisations of the impacts from resource depletion and show gaps in the number and types of resources covered.

Conclusions

Key areas of improvement are identified and discussed. Firstly, biotic resources and their renewal rates have so far received relatively little regard within LCA; secondly, the debate on critical raw materials and the opportunity of introducing criticality within LCA is controversial and requires further effort for a conciliating vision and indicators. We identify points where current methods can be expanded to accommodate these issues and cover a wider range of natural resources.     

Life cycle assessment of fuel ethanol derived from corn grain via dry milling

Life cycle analysis enables to investigate environmental performance of fuel ethanol used in an E10 fueled compact passenger vehicle. Ethanol is derived from corn grain via dry milling. This type of analysis is an important component for identifying practices that will help to ensure that a renewable fuel, such as ethanol, may be produced in a sustainable manner. Based on data from eight counties in seven Corn Belt states as corn farming sites, we show ethanol derived from corn grain as E10 fuel would reduce nonrenewable energy and greenhouse gas emissions, but would increase acidification, eutrophication and photochemical smog, compared to using gasoline as liquid fuel. The ethanol fuel systems considered in this study offer economic benefits, namely more money returned to society than the investment for producing ethanol. The environmental performance of ethanol fuel system varies significantly with corn farming sites because of different crop management practices, soil properties, and climatic conditions. The dominant factor determining most environmental impacts considered here (i.e., greenhouse gas emissions, acidification, eutrophication, and photochemical smog formation) is soil related nitrogen losses (e.g., N2O, NOx, and NO3-). The sources of soil nitrogen include nitrogen fertilizer, crop residues, and air deposition. Nitrogen fertilizer is probably the primary source. Simulations using an agro-ecosystem model predict that planting winter cover crops would reduce soil nitrogen losses and increase soil organic carbon levels, thereby greatly improving the environmental performance of the ethanol fuel system.     

LCA of aquaculture systems: methodological issues and potential improvements

The International Journal of Life Cycle Assessment - The aquaculture sector is the fastest growing food production industry. Life-cycle assessment (LCA) can be a useful tool to assess its...     

Towards a methodology for taking physical degradation of ecosystems into account in LCA

An analytic procedure has been followed to select adequate methods to express ecosystem degradation in LCA. This procedure consisted of problem definition, identification of relevant issues, of a quantitative expression for ecosystem degradation and of possible nature value indicators and building a framework of criteria for selecting adequate methods. With the selection framework a first screening of methods was performed. For full quantification the following formula is proposed: ED = L (N_r- N_a), with land use I. = A t and nature value change (N_r- N_a) Degradation due to an activity appears difficult to operationalise, but ecosystem suppression by activities can well be assessed. N_r is then the natural background or would-be natural situation. N_a can best be described by the actual state during the activity, unless hard data on restoration is available. N_a and N_r can be expressed in the biomass production indicator NPP - NCR Biodiversity and/or erosion may be added to include irreversible effects.     

Data strategy for environmental assessment of agricultural regions via LCA: case study of a French catchment

Purpose

Various approaches have been carried out to extrapolate environmental assessments of farms to the regional level, some of them oversimplified and thus leading to high uncertainty. Key challenges include selection of a representative sample, construction of a farm/land use typology, the extrapolation strategy and dealing with data limitations. This work proposes a method for addressing these issues by means of statistically supported approaches.

Methods

We applied a novel approach combining a sampling strategy, estimation of farm-level environmental impacts via life cycle assessment (LCA), a farm typology based on principal component analysis, a statistical method for extending the farm sample given data constraints and finally linear extrapolation based on regional production and land use, taking into account the regional import–export balance. The approach was applied to a French case study, the Lieue de Grève catchment in the dairy-intensive Brittany region. A decision flowchart was developed to generalise the approach for similar applications dealing with farm and LCA data constraints. Additionally, innovative farm practices were modelled and their impacts propagated to the regional level.

Results and discussion

The typology developed identified “dairy”, “beef”, “dairy + beef” and “swine” farms as the dominant farm types in the region. While swine farms had the highest mean impacts per hectare, dairy and dairy + beef farms had impacts two to five times as high as those of beef and swine farms, when extrapolated to the entire catchment. Multiple linear regressions based on an extended farm and LCA dataset were used to predict environmental impacts of dairy farms lacking LCA results, thus increasing their sample size before extrapolation. The inclusion of farm and LCA data from a neighbouring region did not contribute to the accuracy of predicted impacts, as determined by comparing them to those of the farm closest to the dairy cluster’s centre, but rather produced significantly larger coefficients of variation. Results of tests of including two extra-regional farm and LCA datasets helped determine decision rules for the decision flowchart. Modelling of innovative agricultural practices yielded regional impacts consistent with previous estimates.

Conclusions

This approach provides a generalisable approach for farm typologies, data handling and regional extrapolation of farm-level LCAs, applicable to estimate environmental impacts of any agricultural area if requirements of a representative farm sample are met. We demonstrate the utility of the method for estimating effects of innovative agricultural practices on a region’s impacts by modelling practices on virtual farms and extrapolating their results.

     

A methodology for projecting hospital bed need: a Michigan case study

Michigan's Department of Community Health (MDCH) is responsible for managing hospitals through the utilization of a Certificate of Need (CON) Commission. Regulation is achieved by limiting the number of beds a hospital can use for inpatient services. MDCH assigns hospitals to service areas and sub areas by use patterns. Hospital beds are then assigned within these Hospital Service Areas and Facility Sub Areas. The determination of the number of hospital beds a facility subarea is authorized to hold, called bed need, is defined in the Michigan Hospital Standards and published by the CON Commission and MDCH. These standards vaguely define a methodology for calculating hospital bed need for a projection year, five years ahead of the base year (defined as the most recent year for which patient data have been published by the Michigan Hospital Association). MDCH approached the authors and requested a reformulation of the process. Here we present a comprehensive guide and associated code as interpreted from the hospital standards with results from the 2011 projection year. Additionally, we discuss methodologies for other states and compare them to Michigan's Bed Need methodology.     

LCA study of a plasma television device

Purpose  

Nowadays, there is one television device for every four human beings, making television one of the most popular pieces of electrical and electronic equipment in our society, with the so-called flat-screen technologies gaining more and more market share. For one such technology, the plasma display panel (PDP), no complete life cycle assessment (LCA) studies have existed thus far, and therefore, the question as to their environmental performance, especially as compared with LCD technology, is still open. This paper describes a detailed LCA study of a PDP television, including a first comparison of it with the two competing technologies, the cathode ray tube and the liquid crystal display technologies.     

LCA and ecodesign in the toy industry: case study of a teddy bear incorporating electric and electronic components

Background, aim, and scope  A cradle-to-grave life cycle assessment (LCA) of a toy incorporating electric and electronic components is carried out following the ISO 14044 standard, with the purpose of identifying the environmental hotspots and suggesting ecodesign measures to the manufacturer. Materials and methods  The product under study is a teddy bear which sings songs and tells stories while moving its body, using conventional alkaline batteries as a source of energy. This toy is designed by a Spanish company, but manufactured entirely in China, from where it is exported to Europe, America, and Africa. The LCA study includes production of all components in China, maritime and road distribution, use phase, and end-of-life. Life cycle impact assessment is focused on five standard impact categories from the CML 2001 method. Results  The use phase is identified as potentially the most important life cycle stage, due to the impact of battery production. It is responsible for 50% to 64% of the overall life cycle impact, depending on the impact category. Toy production is also an important stage, with 28% to 34% of the total contribution. Maritime distribution also involves relevant contributions in some impact categories. Based on the results of the study, a set of ecodesign measures were suggested to the manufacturer, with most of them being judged as feasible, and applied in a new product. Discussion  Important data gaps were encountered during the study, especially concerning the use phase, due to lack of data on consumer behavior, and background inventory data on alkaline battery production. A sensitivity analysis applied to the use phase showed that the relative importance of this life cycle stage is strongly affected by the assumptions made in this work. Conclusions  The LCA study was found as a very helpful tool to define ecodesign measures for this product. Several measures suggested have been actually implemented by the manufacturer in a similar product. Recommendations and perspectives  This case study, together with others, will help in the long run to define general ecodesign measures for the toy sector in Catalonia.

Thermodynamic resource indicators in LCA: a case study on the titania produced in Panzhihua city, southwest China

Purpose

While life cycle assessment (LCA) has standardized methods for assessing emission impacts, some comparable methods for the accounting or impact assessment of resource use exist, but are not as mature or standardized. This study contributes to the existing research by offering a comprehensive comparison of the similarities and differences of different resource indicators, in particular those based on thermodynamics, and testing them in a case study on titania (titanium dioxide pigment) produced in Panzhihua city, southwest China.

Materials and methods

The system boundary for resource indicators is defined using a thermodynamic hierarchy at four levels, and the case data for titania also follow that hierarchy. Seven resource indicators are applied. Four are thermodynamics-based??cumulative energy demand (CED), solar energy demand (SED), cumulative exergy demand (CExD), and cumulative exergy extraction from the natural environment (CEENE)??and three have different backgrounds: abiotic resource depletion potential, environmental priority strategies, and eco-indicator 99. Inventory data for the foreground system has been collected through on-site interviews and visits. Background inventory data are from the database ecoinvent v2.2. Characterizations factors are based on the CML-IA database covering all major methods. Computations are with the CMLCA software.

Results and discussion

The scores of resource indicators of the chloride route for titania system are lower than that of the sulfate route by 10?C35?%, except in terms of SED. Within the four thermodynamic indicators for resources, CED, CExD, and CEENE have similar scores, while their scores are five orders of magnitude lower than the SED score. Atmospheric resources do not contribute to the SED or CEEND score. Land resources account for a negligible percentage to the SED score and a small percentage to the CEENE score. Non-renewable resources have a dominant contribution to all seven resource indicators. The global production of titania would account for 0.12 and 0.14?% of the total anthropogenic non-renewable resource demand in terms of energy and exergy, respectively.

Conclusions

First, we demonstrate the feasibility of thermodynamic resource indicators. We recommend CEENE as the most appropriate one within the four thermodynamic resource indicators for accounting and characterizing resource use. Regarding the case study on the titania produced in China, all the resource indicators except SED show that the sulfate route demands more resource use than the chloride route.     

Microbial development in distillers wet grains produced during fuel ethanol production from corn (Zea mays)

Distillers grains are coproduced with ethanol and carbon dioxide during the production of fuel ethanol from the dry milling and fermentation of corn grain, yet there is little basic microbiological information on these materials. We undertook a replicated field study of the microbiology of distillers wet grains (DWG) over a 9 day period following their production at an industrial fuel ethanol plant. Freshly produced DWG had a pH of about 4.4, a moisture content of about 53.5% (wet mass basis), and 4 x 10(5) total yeast cells/g dry mass, of which about 0.1% were viable. Total bacterial cells were initially below detection limits (ca. 10(6) cells/g dry mass) and then were estimated to be approximately 5 x 10(7) cells/g dry mass during the first 4 days following production. Culturable aerobic heterotrophic organisms (fungi plus bacteria) ranged between 10(4) and 10(5) CFU/g dry mass during the initial 4 day period, and lactic acid bacteria increased from 36 to 10(3) CFU/g dry mass over this same period. At 9 days, total viable bacteria and yeasts and (or) molds topped 10(8) CFU/g dry mass and lactic acid bacteria approached 10(6) CFU/g dry mass. Community phospholipid fatty acid analysis indicated a stable microbial community over the first 4 days of storage. Thirteen morphologically distinct isolates were recovered, of which 10 were yeasts and molds from 6 different genera, 2 were strains of the lactic-acid-producing Pediococcus pentosaceus and only one was an aerobic heterotrophic bacteria, Micrococcus luteus. The microbiology of DWG is fundamental to the assessment of spoilage, deleterious effects (e.g., toxins), or beneficial effects (e.g., probiotics) in its use as feed or in alternative applications.     

Developing characterisation factors for land fragmentation impacts on biodiversity in LCA: key learnings from a sugarcane case study

Purpose

Habitat change was identified by the Millennium Ecosystem Assessment as the main direct driver of biodiversity loss. However, while habitat loss is already implemented in Life Cycle Impact Assessment (LCIA) methods, the additional impact on biodiversity due to habitat fragmentation is not assessed yet. Thus, the goal of this study was to include fragmentation effects from land occupation and transformation at both midpoint and endpoint levels in LCIA.

Methods

One promising metric, combining the landscape spatial configuration with species characteristics, is the metapopulation capacity λ, which can be used to rank landscapes in terms of their capacity to support viable populations spatially structured. A methodology to derive worldwide regionalised fragmentation indexes based on λ was used and combined with the Species Fragmented-Area Relationship (SFAR), which relies on λ to assess a species loss due to fragmentation. We adapted both developments to assess fragmentation impacts due to land occupation and transformation at both midpoint and endpoint levels in LCIA. An application to sugarcane production occurring in different geographical areas, more or less sensitive to land fragmentation, was performed.

Results and discussion

The comparison to other existing LCIA indicators highlighted its great potential for complementing current assessments through fragmentation effect inclusion. Last, both models were discussed through the evaluation grid used by the UNEP-SETAC land use LCIA working group for biodiversity impact assessment models.

Conclusions

Midpoint and endpoint characterisation factors were successfully developed to include the impacts of habitat fragmentation on species in LCIA. For now, they are provided for bird species in all forest ecoregions belonging to the biodiversity hotspots. Further work is required to develop characterisation factors for all taxa and all terrestrial ecoregions.

     

Taking into account water use impacts in the LCA of biofuels: an Argentinean case study

Purpose  

The assessment of biofuels has until now mainly focused on energy demand and greenhouse gas emissions. Only little attention has been given to other impacts, although the general importance of water use for the life cycle assessment (LCA) of agricultural products has been recognized in recent publications. The aim of this work is to assess in detail the water consumption along a biofuel production chain taking into account irrigation efficiencies, levels of water scarcity, and type of feedstock, and to integrate those results in a full LCA. Furthermore, we compare the results for biofuels from various feedstocks and regions with conventional petrol.