Structural changes and alkaline solubility of wood cellulose fibers after enzymatic peeling treatment

The authors are grateful to the publisher, Elsevier, for letting the manuscript being archived in this Open Access repository. The final publication is available at http://www.sciencedirect.com/International audienceTwo dissolving sulphite wood pulps were treated by an enzymatic peeling protocol and the changes in terms of structure and alkaline solubility were analyzed. The enzymatic treatment leads to a fast and large decrease of degree of polymerization and of crystallinity, showing that the enzymes do not simply act on the fiber surface. The swelling and dissolution behaviour of the treated samples showed that the enzyme mixture used has two effects at short peeling times (i) a digestion of the primary wall which is seen by the near absence of ballooning and (ii) a destructive action on the inside of the fiber which is seen by the large decrease in the degree of polymerization. At long peeling times, the external walls are totally digested and the fiber structure is totally destroyed, as seen by the absence of birefringence. The alkaline solubility of the different treated samples was investigated in a NaOH 8%-water solution. As expected from thermodynamic considerations, there is a direct correlation between the solubility and the degree of polymerization. However, aside thermodynamics, the removal of the external walls and the macrostructural destructuration of the fibers are key factors in the improvement of the dissolution of wood cellulose fibers. At constant intrinsic viscosities of the cellulose materials, the alkaline solubility is almost two times higher when the external walls are removed. The macrostructural destructuration of fibers by enzymes allows a high degree of polymerization to be preserved while keeping a good alkaline solubility

Ekostäders roll i hållbar stadsutveckling

Hur städer planeras och byggs har stor påverkan på miljön och klimatet. Stadsutveckling är därmed ett bidragande verktyg till att uppnå de globala målen och Parisavtalet. Ekostäder har förespråkats vara ett mer hållbart alternativ till traditionell stadsplanering. Målet i ekostäder är att skapa kretslopp av material och energi samt ha en genomtänkt markanvändning där ekologi och tillgänglighet prioriteras. I studien undersöks infrastrukturlösningar i Masdar City och Sino-Singapore Tianjin Eco-City. Fokus låg på infrastrukturlösningar inom energi, vatten och avlopp, mobilitet och avfall. För att få ett svenskt perspektiv och kunna genomföra en jämförelse med en svensk motsvarighet granskades Hammarby Sjöstad. Därefter undersöktes möjlig tekniköverföring till svenska städer. Jämförelsen baserades på framtagna nyckelindikatorer som togs fram genom att granska och sammanställa fyra ramverk för hållbar stadsutveckling. Detta gjordes eftersom det finns ett gap mellan globalt och lokalt utformade mål och indikatorer i ramverken. Utvärderingen av städerna baserades på resultat från litteratur. Det framtagna ramverket användes för analys av berörda ekoområden. Syftet var att undersöka om ett sammanställt ramverk kunde användas för att fylla de luckor som finns i de etablerade ramverken. Från analysen av ekostäderna framkom att Masdar City hade flest positiva trender utifrån de framtagna indikatorerna, därefter Hammarby Sjöstad och sist Sino-Singapore Tianjin Eco-City. För att bredda perspektivet intervjuades insatta informanter. Deras kompetens inom stadsutveckling, infrastrukturlösningar och kännedom om ekoområden var till stor hjälp och gav värdefulla insikter för det fortsatta arbetet. Dessutom diskuterades hur styrning och beslutsfattande påverkar hållbarhetsarbetet i en stad. Slutsatser som drogs efter studien var att Hammarby Sjöstad överlag var mer ekologiskt hållbar än Sino-Singapore Tianjin Eco-City. Masdar City hade flest positiva trender enligt hållbarhetsutvärderingen men Hammarby Sjöstad använder mer naturliga element i sin stadsutveckling. Dessutom är demokrati och deltagarbaserat beslutsfattande avgörande för långsiktigt hållbara städer. Holism är av högsta prioritet och fokus bör inte enbart riktas mot teknik

Influence of Pulp and Wood Properties on the Unreacted Residuals in Carboxymethyl Cellulose

In this work, the influence of pulp and wood properties on the amount and properties of unreacted residuals in carboxymethyl cellulose was evaluated. The results show that the presence of undissolved residuals in the CMC was not due to any chemical difference between these residuals and the reacted fibres. The undissolved residuals were also shown to consist mainly of swollen cell wall parts and some whole fibres, mainly thick-walled compression wood and latewood fibres.Pulp with a viscosity of about 1500 dm3/kg produced undissolved residuals with a higher degree of substitution (DS) in their hemicelluloses than pulps with a viscosity of about 1350 dm3/kg. The undissolved residuals from the pulp with a higher viscosity also contained more swollen particles. It was therefore believed that a higher DS of the hemicelluloses in the CMC increased the potential for the fibre structure to swell. It was also shown that the total DS of the CMC, the DS of the hemicelluloses in the CMC and also the DS of the residuals were related to the cellulose and galactoglucomannan contents of the original pulp. The amount of residuals seemed to be influenced mainly by the characteristics of the cellulose in the pulp</p

Removal of Metals from Stormwater in Rain Gardens with Different Sorption Materials

Polluted stormwater is a common problem in urban environments. With large parts of cities made up of impermeable areas and an expected increase of heavy rain, this is an issue that likely will get more attention in the coming years. In order to relieve pollution effects on the aquatic ecosystems’ stormwater treatment alternatives must be developed. One possible treatment system is rain gardens, where polluted stormwater can be treated by both infiltration and retention techniques. This project was carried through at a pilot rain garden located in Gårda where stormwater from the catchment is treated in bioretention filters with different sorption materials such as ash, biochar, peat, and a control filter with compost. Three types of sampling were done, one after that different amounts of water volumes were added and then the effluents were sampled, the second at different depths in the filter beds through soil-water samplers under vacuum, and the third through passive sampling from a pipe inserted in the filter bed at the corresponding depths as the soil-water samplers. Sampling was carried out during winter conditions when the plants in filter beds were believed to be inactive. Three sampling occasions were done of treated stormwater per sampling method and the untreated stormwater, i.e., the influent The concentrations of eight metals, As, Pb, Cd, Co, Cu, Cr, Ni, and Zn, both dissolved and total metal concentrations, were analysed in all samples and additional analysis of TSS, VSS, IC, TOC, and TN were conducted in the laboratory. The results showed high removal capacities of the metals mostly occurring in high concentrations in urban stormwater such as Co, Cu, Ni, and total Pb and Cu. Arsenic in general and dissolved Pb, Cd, and Cr were not effectively removed, instead, these metals leached from all filters. Three metals, Cu, Cr, and Zn had concentrations exceeding the guideline values of the Gothenburg municipality for discharge of polluted water to recipients from all filters. The removal efficiency of total suspended solids (TSS) and volatile suspended solids (VSS) was high in all filters whereas the removal efficiency of cations, anions, dissolved organic carbon (DOC), and dissolved total nitrogen (TN) varied among the different filters. Of the four filters studied, biochar was the most efficient for the removal of metals and organic matter, and the remaining three filters performed quite similarly. The conclusion of this thesis work is that biochar filters are recommended for the removal of TSS, VSS, and metals emitted in urban environments. Further research is recommended to clarify why some metals,such as Asleach from the soil and sorption materials. The results for the removal efficiency of anions, cations DOC, and TN were inconclusive and further studies are recommended

Operational experience from, and arguments for investment in, absorption heat pumps for district cooling production in Sweden

Absorption heat pumps can generate cooling water from heat and are therefore an interesting alternative for district heating companies who have access to waste heat, especially during the summer. However, the technology has not had any major breakthrough on the Swedish market yet despite the possible potentials. This article summarises some of the findings from a study made by SP Technical Research Institute of Sweden, which investigated experience from operation and important investment factors among district heating companies in Sweden. The study included companies both with and without absorption heat pumps.</p

Developing Geothermal Heat Pumps in Smart Cities and Communities

Författare: European Geothermal Energy Council (EGEC), Belgium; Universidad Politécnica de Valencia (UPVLC), Spain; Romanian Geoexchange Society (RGS), Romania; Bureau Recherches Géologiques Miniéres (BRGM), France; UBeG GbR of Wetzlar (UBEG), Germany; Center for Renewable Energy Sources and Saving (CRES), Greece; SP Technical Research Institute (SP), Sweden; Nationale Geologiske Undersogelser for Denmark og Gronland (GEUS), Denmark; SLR Consulting (SLR), Ireland; IF Technology (IF), The Netherlands; Scuola Superiore di Studi Universitari e di Perfezionamento Sant'Anna (SSSA), Italy; Service Public de Wallonie (SPW), Belgium</p

Förstudie till energioptimering av tankdrift i uppvärmda oljetankar genom CFD-modellering

Proposals to energy saving measures during oil storage and handling are presented in this report. The proposals are based on measurements and evaluations of operating and storage conditions in non-stirred oil storage tank equipped with hot water coils. Detailed knowledge about flow and temperature fields in both tank and heating coils has rendered possible by modelling the system in CFD. A model has been created by gradually simplifications in the geometry of the tank. The model has been able to render a solution despite limited computer capacity, a solution which correlated with measurement data. The investigated tank has proved to have large energy losses, about 65 % of the supplied heat, which arises from the inferior insulation. Theoretical calculations have been carried out at different insulation thicknesses and a moderately improved insulation can reduce the energy losses to about 10 %. The results from the simulations have shown that the hot water coils are poorly dimensioned in order to enable a quick heating of the oil. A large part of the heat transfer area of the coils is not utilized due to a quick temperature drop of the hot water which is caused by a low flow rate inside the coils. The investigated tank is shown to provide satisfactory spontaneous mixing, which leads to the conclusion that no mixing equipment is necessary. The measurements have indicated that the regulation of the hot water flow is insufficient. There are several problems that should be further investigated and attended to. Examples of these are the response time of the system, unstable hot water flow and high energy consumption in an empty tank. This report is the basis for future decisions about measures that could be taken in order to reduce the energy consumption during oil storage and handling