Life Cycle Assessment of Biofertilizer Production and Use Compared with Conventional Liquid Digestate Management

Handling of digestate produced by anaerobic digestion impacts the environment through emission of greenhouse gases, reactive nitrogen, and phosphorus. Previous life cycle assessments (LCA) evaluating the extraction of nutrients from digestate using struvite precipitation and ammonia stripping did not relate synthetic fertilizer substitution (SFS) to nutrient use efficiency consequences. We applied an expanded LCA to compare the conventional management of 1 m³ of liquid digestate (LD) from food waste against the production and use of digestate biofertilizer (DBF) extracted from LD, accounting for SFS efficacy. Avoidance of CH₄, N₂O, and NH₃ emissions from LD handling and enhanced SFS via more targeted use of nutrients in the versatile DBF product could generate environmental savings of up to 0.129 kg Sb eq, 4.16 kg SO₂ eq, 1.22 kg PO₄ eq, 33 kg CO₂ eq, and 20.6 MJ eq per m³ LD, for abiotic resource depletion, acidification, eutrophication, global warming, and cumulative energy demand burdens, respectively. However, under worst-case assumptions, DBF extraction could increase global warming and cumulative energy demand by 7.5 kg CO₂e and 251 MJ eq per m³ LD owing to processing inputs. Normalizing these results against per capita environmental loadings, we conclude that DBF extraction is environmentally beneficial

Aortic rupture after spinal correction for scoliosis in the presence of a thoracic stent graft

Corrective surgery for scoliosis often results in a lengthening of the spinal column and relative change of the position of the adjacent anatomical structures such as the aorta. The extent of these anatomical changes could be affected by the presence of a rigid aortic stent graft in the descending thoracic aorta. We present a case of aortic rupture after spinal correction for scoliosis in a 56-year-old female with a thoracic aortic stent graft. Extensive elongation of the aorta with concentration of the stress forces at the lower margin of the stent graft resulted in a weakening of the aortic wall and subsequent rupture

Closing nutrient loops through decentralized anaerobic digestion of organic residues in agricultural regions: A multi-dimensional sustainability assessment

Decentralized anaerobic digestion (AD) of manure and organic residues is a possible strategy to improve carbon and nutrient cycling within agricultural regions, meanwhile generating renewable energy. To date, there has been limited adoption of decentralized AD technology in industrialized countries owing to low profitability for plant operators. There remains a need to demonstrate the wider sustainability of small-scale, decentralized AD in order to justify policy support for such a strategy. This study applies a multi-dimensional assessment of the environmental, economic and social sustainability of two scenarios of decentralized, farm-scale AD of pig slurry and organic residues in Southern Sweden. The environmental dimension was assessed by means of an expanded boundary life cycle assessment, in which trade-offs between fertilizer replacement, soil organic carbon accumulation, digestate/manure storage and application, transport and soil emissions were evaluated. The economic dimension was assessed through modelling of the net present value and internal rate of return. Finally, the social dimension was assessed by means of a stakeholder perception inquiry among key stakeholders in the field. It was concluded that the overall environmental balance of decentralized AD was favorable, while also the net present value could be positive. Fertilizer replacement, soil organic carbon and digestate storage effects were identified as important factors that should be accounted for in future life cycle assessments. A key issue for interviewed stakeholders was product quality assurance. Wider application of multi-dimensional sustainability assessment, capturing important nutrient cycling effects, could provide an evidence base for policy to support sustainable deployment of decentralized AD

Nutrient imbalance in Norway spruce

The studies presented in my thesis indicate that growing Norway spruce in monoculture does not constitute sustainable forest management in a high N and S deposition environment, such as in southern Sweden. The combination of N-induced high growth rates and leaching due to soil acidification causes soil reserves of nutrients to decrease. This will increase the risk of nutrient imbalance within the trees when nutrient demands are not met. The development of nutrient imbalance in Scania, southern Sweden, was shown as negative trends in needle and soil nutrient status from the mid-80s to the present in Norway spruce and Scots pine stands. This imbalance appears to be connected to high levels of N and S deposition. Clear negative effects on tree vitality were found when using a new branch development method. Today, growth and vitality seems to be limited by K, rather than N, in spruce stands older than 40 years. However, younger stands appear to be able to absorb the deposited N without negative effects on growth and vitality. When investigating effects of nutrient stress on tree vitality, indicators such as branch length and shoot multiplication rate, which include effects accumulated over several years, are suitable. Countermeasures are needed in order maintain the forest production at a high level. Positive effects on tree nutrient status after vitality fertilization (N-free fertilization) was shown in two micronutrient deficient stands in south-central Sweden. In addition, tree vitality was positively affected after the application of a site-adapted fertilizer to the canopy. Site-adaption of fertilizers will most likely improve the possibilities of a positive response on tree growth and vitality in declining stands. In a survey of Norway spruce in mixtures with beech, birch, or oak compared to monocultures it was shown that spruce nutrient status was higher in mixtures with deciduous species than in monocultures. By using mixed-species stands the needs for nutrient additions are most likely decreased. Nutrient imbalance may be counteracted by changed forest management and nutrient compensation. However, in the long term N deposition to the forest ecosystems must be decreased in order to maintain the productivity of the forest soils in southern Sweden

The stimulating effect of apatite on ectomycorrhizal growth diminishes after PK fertilization

The objective of this study was to test if apatite amendment stimulates growth of ectomycorrhizal (EM) fungi and if this is influenced by the phosphorus status of the forest. The production of EM mycelia was estimated in four Norway spruce forests in south-western Sweden by incubating sand-filled mesh bags (with or without apatite amendment) in the soil for 8 or 20 months. Fungal biomass in the mesh bags was estimated by phospholipid fatty acid (PLFA) analysis. Subplots of the forests were fertilized with phosphorus and potassium to alleviate possible deficiencies of these elements. The addition of apatite had a positive influence on the growth of EM mycelia but this effect diminished when the forests were fertilized with PK. The extent of the EM growth response to apatite was strongly correlated to the needle P status which supports the view that the forest trees regulate growth of EM fungi in response to P source in the soil. Rare earth elements originating from the apatite accumulated in ectomycorrhizal root tips surrounding the mesh bags but no differences in concentration were found between root tips from control and PK fertilized plots. The potential of EM fungi to reduce phosphorus deficiency in phosphorus poor forests by increasing weathering rates is discussed. (C) 2008 Elsevier Ltd. All rights reserved

Investigating causes of damages to historical timber structures by use of FEM

Historical timber structures are often complex, their static behaviour being difficult to grasp. Such structures are usually statically indeterminate. To determine how a statically indeterminate structure carries the load it supports, the stiffness of its separate parts needs to be taken into account. Knowledge of the static behaviour and of the factors that influence it is important when investigating the causes of damages. The damage analyses suggested involve several steps. First, a thorough investigation of the structure is needed, aimed at collecting the basic facts required for obtaining sufficient background information for creating the computational model. The next step is to create a computational model based on the Finite Elements Method. Having access to an appropriate computational model allows possible causes of damages to readily be simu-lated. The roof structure of the medieval Swedish castle of Glimmingehus was selected as an example of how such an analysis can be performed

Static Behaviour of a Historic Roof Structure

Historic roof structures of large monumental buildings are often complex with static behavior that is difficult to grasp. Yet, understanding their static behavior is necessary to adequately preserve and maintain them. The aim of this paper is twofold. The more general aim is to develop use of the finite element method in combination with visualization and to demonstrate its potential both for providing an understanding of historic structures and their static behavior and for supporting a dialogue regarding these matters. The more specific aim is to examine the static behavior of one particular roof structure and the damages to it that occurred. The roof structure selected was that of the medieval Swedish castle of Glimmingehus. A detailed computational model of the roof truss was developed, in terms of which a set of possible causes of the damages observed was simulated. Reliable causes were found and three-dimensional visualizations were carried out to demonstrate their respective influence on the overall structural behavior. As expected, use of visualization in the analysis was found to be very helpful for interpreting the relationship between the computational model and the computed results

Horizontal support of historic roof structures: Design and structural efficiency

In historic buildings, a variety of different types of timber roof structures reflecting different building traditions and different ideals for the inner space are found. In Sweden, damage to historic roof structures due to a lack of support for horizontal thrust is common. Knowledge of the relation between structurally efficient horizontal support and the extension of a structure in space is essential for obtaining an adequate understanding of the development of building techniques and for making sound decisions concerning restoration. An approach that involves a classification of horizontal supporting structures, together with a mechanical model that defines and distinguishes between inner and outer support, is introduced, with the aim of offering a tool for comparison of different roof-truss designs with focus on the occupation in space. Comparison of the efficiency of different designs is carried out by comparing horizontal stiffness. Eleven different designs divided into four spatial groups have been analyzed. © 2008 ASCE