Landfill gas is formed under anaerobic conditions in landfills by microbial degradation of organic material. The gas composition can vary, but at Swedish landfills the gas generally consists of 40-60% methane, 30-40% carbon dioxide and 5-20% nitrogen. Hydrogen sulphide (H₂S) is a highly toxic and corrosive gas, which occur in landfill gas in varying concentrations, from 10 to 30,000 ppm (equivalent to 0.001 to 3.0%). It is desirable that the landfill gas is used for electricity and/or heat production, but to do that there is a need to clean the gas to reach <200 ppm H₂S. High levels of H₂S increases wear on the engine/boiler and thus the frequency of servicing. This leads to expensive maintenance costs, and ultimately shortens the economic life of the plant. To reduce corrosion, it is common to adjust the flue gas temperature, but this also leads to a lower efficiency and thus reduces the energy utilization of the gas. In some cases the gas concentration of H₂S is judged to be too high to be used for energy production at all. In 2015, approximately 53 GWh of landfill gas was flared in Sweden, which in many cases is due to problems with high levels of H₂S.

Cleaning of landfill gas from H₂S leads to several values; the gas energy is used efficiently, maintenance and service costs of the engines/boiler are reduced, and emissions of acidifying sulphur dioxide from combustion of landfill gas decreases. There are commercial cleaning technologies for H₂S but they are expensive, both in terms of capital cost and operating cost. Thus, there is a need to develop new cost efficient cleaning technologies that improve the economic outcome at landfills and that enables landfill gas with high H₂S concentrations to be utilized for valuable energy transformation.

RISE (formerly JTI – Swedish Institute of Agricultural and Environmental Engineering) together with SLU develops new, potentially cost-efficient methods for upgrading biogas to fuel quality. One of the methods is based on the gas passing through a bed of moist ash (a so-called ash filter), where carbon dioxide and H₂S are fixed. The hypothesis of this project was that ashes originating from the incineration of waste, recycled waste wood etc., can be used to clean the high levels of H₂S in landfill gas. This type of ashes will usually be disposed of in landfills anyway and if the treatment effect is good, it would generate synergy effects in the form of the ash first being used to clean landfill gas from sulphur before it is used as a construction material at landfills.

This project performed two trials in pilot scale at a Swedish landfill with very high concentration of H₂S, approximately 15,000 ppm. Different gas flow rates were studied (0.7 to 7.6 m³ / h), while the volume of ash used were similar in the two trials, 0,37 m³. The concentration of H₂S in the cleaned gas was consistently very low during treatment, < 10 ppm at low gas flow rates and < 200 ppm at high gas flow rates. Two types of ash were investigated and both proved to have very good capacity to fix H₂S, 44-61 g H₂S/kg dry ash. In comparison with literature values, there is only one study showing an uptake capacity in the same order. Other studies report an order of magnitude lower uptake capacity.

Based on the experimental results, the technical and economic potential for an ash filter as the cleaning method was assessed. The calculations were made for various typical landfills to cover the different range of landfills. For normal sized landfills with gas flow rates of 100-1 000 m³/h and H₂S concentrations between 100 and 1 000 ppm, the amount of ash needed is 10-130 tons of dry ash per year. For the special case where the H₂S concentration is extremely high, the amount of ash increases and a plant with 15 000 ppm H₂S and a gas flow rate of 200 m³/h requires approximately 800 tons of dry ash per year. However, overall modest amounts of ash is required and considering all Swedish landfills the requirement of ash would be only 0.2-0.3% of the annual production of ash in Sweden.

The economic calculations show that the ash filter is a competitive method for removal of H₂S. For the special case of extremely high levels of H₂S, it turned out that the cost of the ash filter is approximately 20% lower in comparison with the cheapest feasible conventional cleaning technology on the market. Also for the cleaning of landfill gas at more normal levels of H₂S, the ash filter is competitive. At low gas flow rates (100 m³/h), the ash filter is clearly competitive compared to literature values for conventional cleaning technologies. The economy of scale seems to be higher for the conventional cleaning technologies, and consequently the difference between the cost of ash filter cleaning and other technologies is less at higher gas flow rates.

The low treatment cost of the ash filter reveals opportunities for landfills that currently do not clean the gas from H₂S. During the project 15 Swedish landfills was contacted and none of these reported any form of H₂S cleaning. When using cleaning, the landfill gas can be used effectively, i.e. reduced flaring, increased efficiency of electricity and heat production with reduced wear on boilers and combustion equipment as well as reduced emissions of sulphur into the atmosphere, which also reduces the potential odour problems around the landfill.

For further development, the design of an ash filter module prototype at full-scale is important. Furthermore, the treated ashes should be analysed for leaching characteristics, storability and usability as construction materials or as cover landfills along with an assessment of the overall environmental impact. Further tests at full scale should be made at other landfills with various gas flow rates and H₂S concentrations to verify the performance of the conducted pilot tests.

BACKGROUND: More extensive utilization of bacterial nanocellulose (BNC) is severely restricted by the low efficiency and small scale of the traditional static cultivation. Submerged fermentation in stirred-tank reactors (STRs) is potentially favourable for large-scale production of BNC, but scale-up of cultivation remains challenging. Even though the STR is most commonly used for submerged cultivation in the fermentation industry, there are few previous attempts to scale-up production of BNC to pilot scale using an STR. Furthermore, the question of how scale-up of submerged cultivation affects the properties of the BNC has received very little attention. RESULTS: Four strains were compared in 250-mL shake flasks. Strain DHU-ATCC-1 displayed the highest volumetric productivity, 0.56 g L−1 d−1, and was then cultivated in a 400-mL STR, showing a similar productivity of 0.55 g L−1 d−1. Scale-up using a 75-L STR pilot bioreactor resulted in enhancement of the BNC production rate from 0.056 g d−1 in the shake flasks to 17.3 g d−1 in the 75-L STR, although the productivity decreased to 0.43 g L−1 d−1. During scale-up from shake flasks to 400-mL STR and further on to 75-L STR, the BNC fibers formed more bundles, whereas the fiber diameter decreased from 25.6 to 21.7 nm. The BNC from the 75-L STR exhibited a higher degree of polymerization, specifically 3230, higher degree of crystallinity, specifically 83%, larger crystallites, and improved strength including higher tensile energy absorption index and superior stretch at break. CONCLUSION: It is possible to enhance BNC production, and maintain or improve its properties when scaling up submerged cultivation in STRs. © 2018 Society of Chemical Industry.

Utilization of bacterial nanocellulose (BNC) for large-scale applications is restricted by low productivity in static cultures and by the high cost of the medium. Fiber sludge, a waste stream from pulp and paper mills, was enzymatically hydrolyzed to sugar, which was used for the production of BNC by the submerged cultivation of Komagataeibacter xylinus. Compared with a synthetic glucose-based medium, the productivity of purified BNC from the fiber sludge hydrolysate using shake-flasks was enhanced from 0.11 to 0.17 g/(L × d), although the average viscometric degree of polymerization (DPv) decreased from 6760 to 6050. The cultivation conditions used in stirred-tank reactors (STRs), including the stirring speed, the airflow, and the pH, were also investigated. Using STRs, the BNC productivity in fiber-sludge medium was increased to 0.32 g/(L × d) and the DPv was increased to 6650. BNC produced from the fiber sludge hydrolysate was used as an additive in papermaking based on the chemithermomechanical pulp (CTMP) of birch. The introduction of BNC resulted in a significant enhancement of the mechanical strength of the paper sheets. With 10% (w/w) BNC in the CTMP/BNC mixture, the tear resistance was enhanced by 140%. SEM images showed that the BNC cross-linked and covered the surface of the CTMP fibers, resulting in enhanced mechanical strength.

The purpose of this paper is to increase the understanding for the challenges and opportunities inherent to the cross-sectoral development of the bioeconomy. It takes the project “Forest Chemistry” as a case study, which was a collaboration project between Swedish forest industry and petrochemical industry clusters with the goal to develop forest based value chains for production of commodity chemicals. The project considered forest-based production of methanol, ethylene, propylene and butanol. We discuss the project and its outcomes from an innovation systems perspective applying a framework for technological innovation systems analysis. The original Forest Chemistry project also led to a number of spin-off projects, some of which are covered by this paper.

The forest industry is one of Sweden’s most important business sectors. Thanks to its biobased rawmaterials and products, the forest industry plays a key role in the development towards asustainable, circular economy. To meet market needs, and to drive the growth of the circulareconomy, the forest industry is continually developing its processes and products. It is seeking to useits raw material, the forest, as efficiently as possible and is constantly seeking to improve quality andincorporate new functions into materials and products.Pulp and paper makes up the largest part of the forest industry, followed by sawn wood productsand products made from paper and paperboard. 3.9 million tons of pulp and 10.1 million tons ofpaper were produced in Sweden in 2016.The pulp and paper industry uses stem wood as its raw material. Stem wood consists of cellulose,hemicellulose, lignin, and extractives. Cellulose and hemicellulose are separated in the pulpingprocess and the economically most important components in wood. Lignin and extractives areusually burned to provide the mill with heat and power, but the use/needs has changed over timedue to development of more energy efficient mills. Today lignin is extracted from the black liquor forexternal use, while extractives are fractionated and used for production of a wide range of productssuch as, biodiesel, adhesives, and chemical intermediates.The extractives make up between 3 and 5 weight-% of the wood and consists of a wide range ofcompounds. The majority of those compounds are fatty acids such as oleic- and linoleic acid androsin acids, such as abietic- and pimaric acid. The remaining compounds are commonly referred to as“neutrals” and are dominated by β-sitosterol. The extractives in Scots pine for example, consist of 70% fatty acids, 20 % rosin acids and 5 % neutrals.Today, the extractives are separated at the pulp and paper mills during the regeneration of cookingchemicals into a product called crude tall oil (CTO). 2.5 million metric tons of CTO is producedglobally with 80% of the production situated in North America and Scandinavia. 1.3 million tons isproduced in North America and 600 000 tons is produced in Scandinavia. 2.0 million metric tons iscurrently refined globally, while the rest is used internally by the mills for the production of heat andpower.CTO is currently refined into a range of products which can be divided up into (i) chemicalintermediates, (ii) biodiesel, and (iii) tall oil pitch. The chemical intermediates are mostly used for theproduction of adhesives, while the biodiesel is used as a transport fuel, and the tall oil pitch is usedfor production of heat and power.To meet market needs, and to drive the growth of the circular economy, extractives could potentiallybe used for the production of other products, either through new refinement routes of CTO or novelextraction and separation methods from the raw material. In order to identify opportunities for theproduction of other extractives based products, the extractives value chain must first be mapped.Second, refinement routes as well as extraction and separation methods suitable for isolation andprocessing of valuable compounds must be identified.

Hydrothermal carbonization (HTC) can be used to break down sludge structure and generate carbonaceous hydrochar suitable for solid fuel or value-added material applications. The separation of char and the reaction medium however generates a filtrate, which needs to treated before potential discharge. Thus, this work determined filtrate properties based on HTC temperature and sludge moisture content and estimated the discharge emissions and the potential increase in analyte loads to an industrial wastewater treatment plant based on derived regression models. Direct discharge of HTC filtrate would significantly increase effluent emissions at the mill, indicating the filtrate treatment is crucial for the future implementation of HTC at pulp and paper mills. Recycling the HTC filtrate to the wastewater plant would lead to only a nominal increase in effluent flow, but would increase the suspended solids, BOD, COD and total nitrogen loads by 0.1-0.8%, 3.8-5.3%, 2.7-3.1% and 42-67%, respectively, depending on HTC temperature.

Background: Aquaculture represents a solution to the future world demand for healthy protein while challenges that require urgent solutions are emerging in feed production, such as the rising costs of feed protein and massive imports. From a European perspective, a large proportion of the protein demand is met with imported protein. This article will focus on the development of protein-rich microorganisms (i.e. Single cell protein) as a novel raw material in fish feed which can be produced as an important co-product in wood-based biorefineries, increasing sustainability and the utilization of organic waste material. Scope and Approach: Developing a safe and sustainable protein resource from local organic waste-material represents an opportunity for Europe to decrease its reliance on nutritional imports, and address mounting food sector sustainability concerns and a growing protein deficit. At the same time, the nutrient recycling industry represents a growing industry, addressing waste valorization and protein feed production concerns at once. Key Findings and Conclusion: An industry and research collaboration has focused on selecting which microorganisms and residual streams from a wood-biorefinery site that would be best suited for production of SCP. The study showed that 38-68% of the fishmeal in a Nile tilapia (Oreochromis niloticus) feed could be replaced with SCP while maintaining a similar or slightly improved fish growth. As reported by FAO, aquaculture production of Nile tilapia in 2014 was 3.7 million tonnes, making it one of the most produced fish species in the world.

For an integrated steel plant, the blast furnace (BF) is the most energy intensive process unit in which coke and pulverized coal (PC) are used as reducing agents and energy carriers, leading to huge amount of fossil CO2 emission. Recent years, the steel industry has been putting much effort to reduce CO2 emissions especially for BFs. Biofuel is considered as one shortterm solution for CO2 emission reduction especially via the tuyere injection into BFs to replace PC. Much work has been carried out to inject wood charcoal in BFs due to the fact that the wood charcoal has the similar properties as PC [1]. However, the availability of forestry wood and high price of wood charcoal limit the charcoal’s utilization in BFs. So far, the charcoal injection is only realized in small scale BFs in Brazil.

The realization of process solutions for a sustainable bioeconomy depends on the efficient processing of biomass. High-gravity technology is one important alternative to realizing such solutions. The aims of this work were to expand the knowledge-base on lignocellulosic bioconversion processes at high solids content, to advance the current technologies for production of second-generation liquid biofuels, to evaluate the environmental impact of the proposed process by using life cycle assessment (LCA), and to develop and present a technically, economically, and environmentally sound process at high gravity, i.e., a process operating at the highest possible concentrations of raw material. The results and opinions presented here are the result of a Nordic collaborative study within the framework of the HG Biofuels project. Processes with bioethanol or biobutanol as target products were studied using wheat straw and spruce as interesting Nordic raw materials. During the project, the main scientific, economic, and technical challenges of such a process were identified. Integrated solutions to these challenges were proposed and tested experimentally, using wheat straw and spruce wood at a dry matter content of 30% (w/w) as model substrates. The LCA performed revealed the environmental impact of each of the process steps, highlighting the importance of the enzyme dose used for the hydrolysis of the plant biomass, as well as the importance of the fermentation yield.

The ability of the multispecies biofilm membrane reactors (MBM reactors) to provide distinguished niches for aerobic and anaerobic microbes at the same time was used for the investigation of the consolidated bioprocessing of cellulose to short chain fatty acids (SCFAs). A consortium based consolidated bioprocess (CBP) was designed. The rumen microbiome was used as the converting microbial consortium, co-cultivated with selected individual aerobic fungi which formed a biofilm on the tubular membrane flushed with oxygen. The beneficial effect of the fungal biofilm on the process yields and productivities was attributed to the enhanced cellulolytic activities compared with those achieved by the rumen microbiome alone. At 30 °C, the MBM system with Trichoderma reesei biofilm reached a concentration 39% higher (7.3 g/L SCFAs), than the rumen microbiome alone (5.1 g/L) using 15 g/L crystalline cellulose as the substrate. Fermentation temperature was crucial especially for the composition of the short chain fatty acids produced. The temperature increase resulted in shorter fatty acids produced. While a mixture of acetic, propionic, butyric, and caproic acids was produced at 30 °C with Trichoderma reesei biofilm, butyric and caproic acids were not detected during the fermentations at 37.5 °C carried out with Coprinopsis cinerea as the biofilm forming fungus. Apart from the presence of the fungal biofilm, no parameter studied had a significant impact on the total yield of organic acids produced, which reached 0.47 g of total SCFAs per g of cellulose (at 30 °C and at pH 6, with rumen inoculum to total volume ratio equal to 0.372).