This paper focuses on the characterization of highly variable biofuel properties such as moisture content, ash content and higher heating value by near-infrared (NIR) spectroscopy. Experiments were performed on different biofuel sample mixtures consisting of stem wood chips, forest residue chips, bark, sawdust, and peat. NIR scans were performed using a Fourier transform NIR instrument, and reference values were obtained according to standardized laboratory methods. Spectral data were pre-processed by Multiplicative scatter correction correcting light scattering and change in a path length for each sample. Multivariate calibration was carried out employing Partial least squares regression while absorbance values from full NIR spectral range (12,000–4000 cm^-1), and reference values were used as inputs. It was demonstrated that different solid biofuel properties can be measured by means of NIR spectroscopy. The accuracy of the models is satisfactory for industrial implementation towards improved process control. 

The development of smart grids is expected to shift the role of buildings in power networks from passive consumers to active players that trade on power markets in real-time and participate in the operation of networks. Although there are several studies that report on consumer views on buildings with smart grid features, there is a gap in the literature about the views of the energy and buildings sectors, two important sectors for the development. This study fills this gap by presenting the views of key stakeholders from the Swedish energy and buildings sectors on the active building concept with the help of interviews and a web survey. The findings indicate that the active building concept is associated more with energy use flexibility than self-generation of electricity. The barriers to development were identified to be primarily financial due to the combination of the current low electricity prices and the high costs of technologies. Business models that reduce the financial burdens and risks related to investments can contribute to the development of smart grid technologies in buildings, which, according to the majority of respondents from the energy and buildings sectors, are to be financed by housing companies and building owners. 

The effect of inhibiting nitrification on algal growth and nutrient uptake was studied in photobioreactors treating municipal wastewater. As previous studies have indicated that algae prefer certain nitrogen species to others, and because nitrifying bacteria are inhibited by microalgae, it is important to shed more light on these interactions. In this study allylthiourea (ATU) was used to inhibit nitrification in wastewater-treating photobioreactors. The nitrification-inhibited reactors were compared to control reactors with no ATU added.

Microalgae had higher growth in the inhibited reactors, resulting in a higher chlorophyll a concentration. The species mix also differed, with Chlorella and Scenedesmus being the dominant genera in the control reactors and Cryptomonas and Chlorella dominating in the inhibited reactors. The nitrogen speciation in the reactors after 8 days incubation was also different in the two setups, with N existing mostly as NH4-N in the inhibited reactors and as NO3-N in the control reactors.

Because microalgae are known for quick biomass growth and nutrient uptake, there has been much interest in their use in research on wastewater treatment methods. While many studies have concentrated on the algal treatment of wastewaters with low to medium ammonium concentrations, there are several liquid waste streams with high ammonium concentrations that microalgae could potentially treat. The aim of this paper was to test ammonium tolerance of the indigenous algae community of Lake Malaren and to use this mixed consortia of algae to remove nutrients from biogas digestate. Algae from Lake Malaren were cultivated in Jaworski's Medium containing a range of ammonium concentrations and the resulting algal growth was determined. The algae were able to grow at NH4-N concentrations of up to 200 mg L(-1) after which there was significant inhibition. To test the effectiveness of the lake water algae on the treatment of biogas digestate, different pre-cultivation set-ups and biogas digestate concentrations were tested. It was determined that mixing pre-cultivated suspension algae with 25% of biogas digestate by volume, resulting in an ammonium concentration of around 300 mg L(-1), produced the highest algal growth. The algae were effective in removing 72.8 ± 2.2% of NH4-N and 41.4 ± 41.4% of PO4-P.

This study demonstrates the application of FT-IR spectroscopy for investigating the remediation of pink water with the low cost adsorbent pine bark. The removal of 2,4,6-trinitrotoluene (TNT) from pink water by adsorption to pine bark was accompanied by a reduction in intensities of peaks at 1544 and 1347 cm-1 in the spectra of acetonitrile extracts of the pine bark. Hierarchial cluster analysis differentiated samples with high (30-180 mg/L) and low (0-4 mg/L) TNT concentrations, demonstrating the potential of this approach as a quick screening method for the control of the removal of TNT from pink water. The amount of lignin in pine bark was inversely proportional to the size of the pine bark particles, while the concentration of phenolic hydroxyl groups increases with increasing size of pine bark particles. FT-IR spectra showed that as well as TNT, pine bark can also adsorb nitramine explosives such as RDX and HMX.

Pulp digesters can be continuous or batch reactors with significant residence time which are fed with woodchips and cooking chemicals. They deliver the pulp-fibers that are used in the production of paper, as well as black liquor that is combusted in the chemical recovery boiler. The possibility to measure what is happening inside the digester is limited. The most important quality properties of the feedstock material is content of lignin, which is being dissolved during the process, and related material reactivity. Pulp quality after the process is measured by Kappa number which is a measure of residual lignin in the pulp. One of the biggest challenges in pulp production process is the great variability in feedstock material properties. If the process is not adjusted by well-timed and appropriate operational control measures i.e. control of inlet and outlet flows and setting of the cooking recipe, it will result in the large variations in Kappa number, lower fiber quality or excess use of environmentally harmful cooking chemicals. This becomes particularly important during the swing between softwood and hardwood as part of meeting the final paper product quality requirements. Therefore, a rapid method that is capable of continuous feedstock material characterization is required.Near infrared (NIR) spectroscopy can be used for non-destructive characterization of the feedstock material. In this study, both Fourier transform and grating NIR spectrophotometers were used for NIR absorbance spectra acquisition. Each spectrum was recorded in the range between 700 and 2500 nm. During the calibration of spectra of various wood species with known lignin content, wood samples were placed on a tray so that the tray may move horizontally in a reciprocating manner underneath the sensor while maintaining the constant distance between the sensor and sample. This was done in order to simulate the movement of a real conveyor belt as used for transporting feedstock to the digester. In the on-line application the NIR meter is situated above the conveyor belt that wood up to the digester.Spectral data were pretreated with different methods such as normalization, scatter correction, smoothing, first and second derivative (Savitzky-Golay algorithm), selection of different spectral ranges and its combinations. Mathematical models to estimate lignin content were constructed using Partial Least Square Regression (PLS-R) and Principle component regression (PCR) statistical methods. Response data for model build-up were determined in the chemical laboratory according to standardized procedures including test repetitions. Different combinations of NIR instrument used, pre-treatment methods and statistical methods were evaluated in order to find the model with the best prediction performance.Results are promising and demonstrate that it is possible to characterize the lignin content and reactivity of the feedstock material by NIR spectrophotometers with reasonable prediction model performance. Improved prediction can be obtained if only selected spectral ranges are included as an input for statistical modelling; similarly using derivatives is better than using the raw spectrum. In the next step, developed statistical models for rapid lignin content prediction will be used as a feed-forward input for dynamic process control.

This two-week anaerobic batch study evaluated 2,4,6-trinitrotoluene (TNT) removal efficiency from industrial pink water by (1) adsorption on low-cost adsorbent pine bark, and (2) adsorption coupled with TNT biotransformation by specialised microbial communities. Samples of the supernatant and acetonitrile extracts of pine bark were analysed by HPLC, while the composition of the bacterial community of the experimental batches, inocula and pine bark were profiled by high-throughput sequencing the V6 region of the bacterial 16S rRNA gene. Integrated adsorption and biotransformation proved to be the most efficient method for TNT removal from pink water. The type of applied inoculum had a profound effect on TNT removal efficiencies and microbial community structures, which were dominated by phylotypes belonging to the Enterobacteriaceae family. The analysis of acetonitrile extracts of pine bark supported the hypothesis that the microbial community indigenous to pine bark has the ability to degrade TNT.

Buildings are expected to play a key role in the development and operation of future smart energy systems through real-time energy trade, energy demand flexibility, self-generation of electricity, and energy storage capabilities. Shifting the role of buildings from passive consumers to active players in the energy networks, however, may require closer cooperation between the energy and buildings sectors than there is today. Based on 23 semi-structured interviews and a web survey answered by key stakeholders, this study presents the views of the energy and buildings sectors on the current energy challenges in a comparative approach. Despite conflicting viewpoints on some of the issues, the energy and buildings sectors have similar perspectives on many of the current energy challenges. Reducing CO₂ emissions is a shared concern between the energy and buildings sectors that can serve as a departure point for inter-sectoral cooperation for carbon-reducing developments, including the deployment of smart energy systems. The prominent energy challenges were identified to be related to low flexibilities in energy supply and use, which limit mutually beneficial cases, and hence cooperation, between the energy and buildings sectors today.

Microalgae grown in photo-bioreactors can be a valuable source of biomass, especially when combined with wastewater treatment. While most published research has studied pure cultures, the consortia of algae and bacteria from wastewater have more complex community dynamics which affect both the biomass production and pollutant removal. In this paper we investigate the dynamics of algal and bacterial growth in wastewater treating batch photo-bioreactors. The photo-bioreactors were inoculated with water from a nearby lake. Lake water was obtained in August, November and December in order to add native algal species and study the effects of the season. The photo-bioreactors inoculated with lake water obtained in August and November produced more biomass and grew faster than those that only contained the algae from wastewater. The results indicated a rapid decline in bacterial abundance before algae began to multiply in reactors supplemented with lake water in November and December. The reactors were also successful in removing nitrogen and phosphorous from wastewater.