Prospective life cycle assessment of adipic acid production from forest residue

Moving from a fossil-based to a bio-based economy requires the development of novel technologies for the production of bio-based chemicals and materials, and the Swedish forestry sector may play a major role in this. These technologies may become part of novel biorefinery concepts that combine the production of bulk and fine chemicals. This paper presents the life cycle assessment (LCA) of such a technology, in its early stages of development, which targets the biochemical production of adipic acid from Swedish forest residue. Adipic acid is a bulk chemical and its yearly production is approximately 2.3 million tonnes. It is mainly used as a precursor in the production of nylon, and its current fossil-based production process emits significant quantities of nitrous oxide (N2O), a strong greenhouse gas. Preliminary calculations showed that, compared to conventional adipic acid production, eliminating the emission of N2O would lead to a reduction of GWP by 75%, and that switching from a fossil-based to a biomass-based feedstock would reduce GWP by an additional 10%. This LCA focused on the technology for producing adipic acid, but also considered its connection with other technologies in the biorefinery concept. An anaerobic digestion process is used to produce biogas from the waste water. As well, lignin is produced as a by-product. The heat from biogas and lignin incineration can be used to meet the energy demands of the adipic acid production. Lab-scale experimental results were used in the assessment, and scaling up these results to an industrially relevant process capacity was done by using process modelling and simulation. Furthermore, an assessment was done of the impact of extracting forest residue from the Swedish forest. The results of this LCA show that the environmental impacts of producing adipic acid from forest residues, except for acidification potential, are significantly lower than those of its conventional production. The environmental hotspot of the technology is the downstream processing stage due to its need of additional energy which was assumed to be fossil. This additional energy is needed because of the low concentration of adipic acid in the fermentation broth. Further improvements can thus be made by minimizing fossil energy use in this stage, or by aiming for a higher end concentration of adipic acid in the fermentation broth. Lastly, the extraction of forest residue was found to only marginally contribute to global warming

Prospective life cycle sssessment of bio-adipic acid production from forest residues

Umweltbelange im Zusammenhang mit der Produktion von Massenchemikalien nehmen zu. Adipinsäure als wichtige Massenchemikalie in der Herstellung von Nylon 6,6 emittiert erhebliche Menge an N2O, einem bedeutenden Treibhausgas, während seiner Herstellung aus fossilen Brennstoffen. Forscher sind derzeit bestrebt effiziente Wege der Nutzung erneuerbarer Ressourcen, wie etwa Lignozellulose, als Alternative zur fossil-basierten Produktion zu finden.Restholz als Nebenprodukt der Forstwirtschaft, ist eine Quelle für Lignozellulose. Schweden als eines der waldreichen Länder Europas, hat dabei ein großes Potential zur Bereitstellung solcher Forstabfälle. In dieser Studie wurde eine prospektive Ökobilanz (LCA) der Adipinsäure Produktion aus Holzabfällen in einem frühen Entwicklungsstadium durchgeführt. Darüber hinaus wurde der ökologische Fußabdruck des Prozesses mittels des Sustainable Process Index (SPI) bewertet. ^Zwei verschiedene Vorbehandlungsmethoden, saure und alkalische, wurden angewandt sowie Szenarien und Sensitivitätsanalysen durchgeführt. Die möglichen Auswirkungen auf die Umwelt und den ökologischen Fußabdruck dieser alternativen Prozesse wurden mit jenenen auf fossiler Basis verglichen.Die Ergebnisse der Ökobilanz zeigen, dass die biogene Adipinsäure-Produktion aus Forstabfällen erhebliche Vorteile für die Umwelt gegenüber fossilen Methoden im Hinblick auf das Treibhauspotenzial (GWP), Eutrophierungspotenzial (EP) und das photochemische Ozonbildungspotenzial (POCP) bringt. Allerdings kann eine Verschiebung der Umweltbelastung hin zu erhöhtem Versauerungspotenzial (AP) beobachtet werden, wie es für die meisten Szenarien der biogenen Adipinsäure-Produktion zutrifft. SPI-Analysen welche die Standard Daten anwenden, zeigen einen geringeren ökologischen Fußabdruck wenn Säurevorbehandlungsverfahren eingesetzt werden. ^Darüber hinaus deuten die Ergebnisse der Sensitivitätsanalysen darauf hin, dass ein größerer Nutzen für die Umwelt erzielt werden kann, wenn Biomasse anstelle von fossilen Brennstoffen zur Bereitstellung von Prozessenergie verwendet wird.Environmental concerns related to the production of bulk chemicals are growing. Adipic acid as an important bulk chemical for Nylon 6,6 production emits significant amount of N2O, a major greenhouse gas, during its production via fossil fuel pathway. Researchers are currently finding alternative pathways to divest from fossil-based economy by exploring the efficient ways of utilizing renewable resources, such as lignocellulosic feedstocks.Forest residues are the byproduct of forestry harvesting that contains lignocellulosic materials. Sweden as one of forest-rich countries in Europe is known to have a lot of potential of forest residues. In this study, a prospective life cycle assessment (LCA) of adipic acid production from forest residues at early development stage was conducted. In addition, ecological footprints of the processes were also assessed by using Sustainable Process Index (SPI). Two different pretreatment methods, acid and alkaline, were employed and scenarios and sensitivity analyses were also conducted. The potential environmental impacts and ecological footprints of this alternative pathway were compared to those of fossil-based adipic acid production.The LCA results show that the bio-based adipic acid production from forest residues has significant environmental benefits compared to the fossil-based pathway, in terms of global warming potential (GWP), eutrophication potential (EP), and photochemical ozone creation potential (POCP). However, environmental burden shifting can be observed for acidification potential (AP), as in most of the scenarios the bio-adipic acid production displays higher AP than that of fossil-based pathway. The SPI analyses that utilize the default database show that lower ecological footprint can be obtained if acid pretreatment method is employed. Furthermore, sensitivity analyses suggest that more environmental benefits can be achieved if biomass, instead of fossil fuel, is used to fulfil process energy demands.Rio AryapratamaZusammenfassungen in Deutsch und EnglischKarl-Franzens-Universität Graz, Masterarbeit, 2016(VLID)145517

Prospective life cycle assessment of bio-based adipic acid production from forest residues

Abstract Environmental concerns related to the production of bulk chemicals are growing. Researchers and technology developers are currently looking into alternative production pathways for such chemicals by utilizing renewable resources, such as lignocellulosic feedstocks. Adipic acid is an example of such a bulk chemical, and its conventional fossil-based production emits significant amounts of N2O, a major greenhouse gas. In this study, a prospective life cycle assessment (LCA) of bio-based adipic acid production from forest residues at an early development stage, situated in Sweden, was conducted. Acid-catalyzed (using SO2) and alkaline (using NaBH4) pretreatment were employed and scenarios and sensitivity analyses were conducted. The potential environmental impacts of this technology under development were compared to those of conventional adipic acid production. The results show that bio-based adipic acid production has a lower impact on global warming, eutrophication and photochemical ozone creation compared to fossil-based production. In contrast, it has a higher impact on acidification. An increased efficiency of mitigating \{N2O\} emissions from the fossil-based production may alter this comparison. Producing bio-based adipic acid using the alkaline pretreatment has a higher environmental impact than producing it using acid-catalyzed pretreatment. Furthermore, if biomass is used to fulfil process energy demands, instead of fossil fuel, the environmental impact of the bio-based production decreases. It is therefore important to reduce the amount of NaBH4 used in the alkaline pretreatment or to lower the environmental impact of its production

Prospective life cycle assessment of adipic acid production from forest residue

Moving from a fossil-based to a bio-based economy requires the development of novel technologies for the production of bio-based chemicals and materials, and the Swedish forestry sector may play a major role in this. These technologies may become part of novel biorefinery concepts that combine the production of bulk and fine chemicals. This paper presents the life cycle assessment (LCA) of such a technology, in its early stages of development, which targets the biochemical production of adipic acid from Swedish forest residue. Adipic acid is a bulk chemical and its yearly production is approximately 2.3 million tonnes. It is mainly used as a precursor in the production of nylon, and its current fossil-based production process emits significant quantities of nitrous oxide (N2O), a strong greenhouse gas. Preliminary calculations showed that, compared to conventional adipic acid production, eliminating the emission of N2O would lead to a reduction of GWP by 75%, and that switching from a fossil-based to a biomass-based feedstock would reduce GWP by an additional 10%.This LCA focused on the technology for producing adipic acid, but also considered its connection with other technologies in the biorefinery concept. An anaerobic digestion process is used to produce biogas from the waste water. As well, lignin is produced as a by-product. The heat from biogas and lignin incineration can be used to meet the energy demands of the adipic acid production. Lab-scale experimental results were used in the assessment, and scaling up these results to an industrially relevant process capacity was done by using process modelling and simulation. Furthermore, an assessment was done of the impact of extracting forest residue from the Swedish forest.The results of this LCA show that the environmental impacts of producing adipic acid from forest residues, except for acidification potential, are significantly lower than those of its conventional production. The environmental hotspot of the technology is the downstream processing stage due to its need of additional energy which was assumed to be fossil. This additional energy is needed because of the low concentration of adipic acid in the fermentation broth. Further improvements can thus be made by minimizing fossil energy use in this stage, or by aiming for a higher end concentration of adipic acid in the fermentation broth. Lastly, the extraction of forest residue was found to only marginally contribute to global warming

Performance evaluation of hollow fiber air gap membrane distillation module with multiple cooling channels

The hollow fiber air gap membrane distillation (AGMD) module equipped with the multiple cooling channels network made of stainless steel was developed. The performance of the developed AGMD module was evaluated by conducting several experiments, including the effect of feed temperature and flow rate, ratio of membrane surface area to condensation surface area, membrane packing position, comparison with hollow fiber DCMD, and the effect of inner and outer module channels to process performance. Moreover, theoretical model was suggested for the multiple cooling channels module. This study reveals that the produced flux and thermal efficiency of this module were up to 12.5 kg/m2 h and 81.7%, respectively, which is higher than most of previous studies that used polymeric fibers as coolant channels. Furthermore, the optimum ratio of membrane area to condensation surface area to produce optimum flux and thermal efficiency is known to be around 0.55. Further experimental results show that the outer channel has significant contribution in reducing the amount of heat loss. This is also could be the reason why the average flux of hollow fiber AGMD module was only 22% lower, while the average thermal efficiency is 58% higher than that of hollow fiber DCMD module

Assessment of bacterial community structure in nitrifying biofilm under inorganic carbon-sufficient and -limited conditions

In this work, nitrification and changes in the composition of the total bacterial community under inorganic carbon (IC)-limited conditions, in a nitrifying moving bed biofilm reactor, was investigated. A culture-independent analysis of cloning and sequencing based on the 16S rRNA gene was applied to quantify the bacterial diversity and to determine bacterial taxonomic assignment. IC concentrations had significant effects on the stability of ammonia-oxidation as indicated by the reduction of the nitrogen conversion rate with high NH4+-N loadings. The predominance of Nitrosomonas europaea was maintained in spite of changes in the IC concentration. In contrast, heterotrophic bacterial species contributed to a high bacterial diversity, and to a dynamic shift in the bacterial community structure, under IC-limited conditions. In this study, individual functions of heterotrophic bacteria were estimated based on taxonomic information. Possible key roles of coexisting heterotrophic bacteria are the assimilation of organic compounds of extracellular polymeric substances produced by nitrifiers, and biofilm formation by providing a filamentous structure and aggregation properties.close0