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The main goal of this study was to develop a cost-efficient biological method for the removal of sulfate from mining effluents in cold conditions. A consortium of cold-tolerant sulfate-reducing bacteria (SRB) was tested at 6 °C regarding the utilization of economically viable, low-cost carbon sources, i.e., whey, conditioned sewage sludge, and peat, in the removal of sulfate from synthetic mining water. Succinate was used as a reference carbon source. Of all the studied low-cost carbon sources, conditioned sewage sludge proved to be the most efficient. Nuclear magnetic resonance (NMR) spectroscopy revealed that sewage sludge contained propionic acid, which proved to be utilizable by SRB under cold conditions. Peat both adsorbed the sulfate and acted as a nutrient source in the sulfate reduction process. When whey was used as a carbon source, only a slight decrease in sulfate concentration was detected. Succinate was found to work in a truly predictable and efficient way as a carbon source in biological sulfate reduction, even at the lowest concentration tested. The use of conditioned sewage sludge increased the bacterial diversity in liquid cultivations significantly. However, the number of SRB was highest in the succinate cultivations. HIGHLIGHTS Cold-tolerant sulfate-reducing bacteria (SRB) were successfully cultivated using low-cost carbon sources.; Kemicond-treated sewage sludge was the most efficient low-cost carbon source.; Simultaneous sulfate adsorption and reduction were observed with natural peat.; Organic compounds utilized and produced by the bacteria were characterized by nuclear magnetic resonance (NMR).; Synthetic mining water was treated to model real water pollution control.

In this study, four ternary liquid–liquid equilibrium systems containing a solvent, furfural, and water were investigated by performing liquid–liquid equilibrium measurements at two different tempe...

Ion exchange technology removes ionic compounds from waters effectively but treatment of the spent regenerant is expensive. The bioregeneration of sulfate-laden strong base anion exchange resin was successfully tested using both pure and mixed sulfate-reducing bacterial cultures. The resin was first used for removal of sulfate from neutral (pH 6.7 ± 0.5) synthetic sodium sulfate solutions, after which the spent resin was regenerated by incubating with a viable sulfate-reducing bacterial culture in batch and column modes. In the batch bioregeneration tests, the achieved bioregeneration was 36–95% of the original capacity of the fresh resin (112 mg SO₄ 2−/g) and it increased with regeneration time (1–14 days). The capacity achieved in the column tests during 24 hours of bioregeneration was 107 mg SO₄ 2−/g after the first regeneration cycle. During the bioregeneration, sulfate was mainly reduced by the sulfate-reducing bacteria (approx. 60%), but part of it was only detached from the resins (approx. 30%). The resin-attached sulfate was most likely replaced with ions present in the liquid sulfate-reducing bacterial culture (e.g., HCO₃−, HS−, and Cl−). During the subsequent exhaustion cycles with the bioregenerated resin, the pH of the treated sodium sulfate solution increased from the original 6.7 ± 0.5 to around 9. The study showed that biological sulfate reduction could be used for sulfate removal in combination with ion exchange, and that the exhausted ion exchange resins could be regenerated using a liquid sulfate-reducing bacterial culture without producing any brine.

The current work focuses on studying the aqueous phase reforming (APR) of pine and birch hydrolysate obtained from waste wood by using organic acids available from biorefineries. Processing of representative synthetic mixtures was utilized in the work in order to support data interpretation related to the influence of different chemical compound and processing parameters on the APR of the actual hydrolysates. It was shown, that hydrogenation of the hydrolysates prior to APR was not feasible in the presence of formic acid, which ruled out one potential processing route. However, it was successfully demonstrated that birch and pine hydrolysates could be directly processed obtaining close to full conversion. The best results were obtained with tailored bimetallic Pd-Pt/sibunit catalyst in a trickle bed reactor system in the temperature range 175 °C–225 °C.

The aim of this study was to develop a biological method for the simultaneous removal of sulfate and metals from acidic low-temperature mining effluents. A mixed consortium of cold-tolerant sulfate-reducing bacteria (SRB) and other microorganisms was immobilized on glass beads and exploited in an up-flow biofilm reactor for the continuous treatment of actual and synthetic mining-impacted waters (MIWs) with initial sulfate concentrations between 1580 and 5350 mg L-1. The proton acidity of the mine waters was neutralized by microbial sulfidogenesis. Metals present in the MIWs were precipitated either off-line or in-line, inside the reactor vessel. High sulfate reduction rates (SRRs), from 1000 to 4500 mg L-1 d-1 at a temperature of 11.7 ± 0.2 °C, were achieved (sulfate removal 43–87%). The bacterial consortium was found to be robust and resistant to changes in growth conditions during the bioreactor experiment. The relative abundance of SRB and the SRR increased at higher sulfate concentrations. Sulfidogenic bioreactors have the potential for treatment of acid mine drainage even at low temperature. It was demonstrated that neutral reactor conditions and high SRRs were maintained when acidic influent was fed into the reactor.

European Union bioeconomy policy emphasizes that the production of renewable transportation fuels should replace fossil fuels as much as possible. In particular, the utilization of waste or side-stream lignocellulosic materials for fuel production is highly recommended. Moreover, future crises forcing a reliance on locally available sources for fuels and energy may become increasingly common. Barley straw, a common agricultural residue in northern Europe, is a potential raw material for bioalcohol production via fermentation. In this study, the technoeconomic and environmental sustainability of bioethanol and biobutanol production from barley straw were evaluated. When compared with fossil gasoline production and use, the greenhouse gas emissions reduction 77.6% and 72.1% were achieved for ethanol and butanol production, respectively. Thus, the emission reduction of 65% for biofuels demanded by the European Union renewable energy directive was achieved in both biofuel production processes evaluated. However, our results indicated that ethanol production from barley straw, a well-known and mature technology, was an economically feasible process (NPV positive, IRR 20%) but that butanol production with Clostridium species through acetone-butanol-ethanol fermentation has still technoeconomic challenges to overcome (NPV negative, IRR below 10%). This was mainly due to the low yield and high recovery costs of butanol.

Levulinic acid derived from biomass is a versatile platform molecule, which can be used in manufacturing different compounds to replace fossil-based chemicals. In this study, the effect of sulfolane as solvent in sulphuric acid catalysed levulinic acid production from glucose was investigated. The broad sulfolane concentration range was systematically studied and a kinetic model was developed to describe the levulinic acid production. A significant increase in glucose conversion rate was observed when the proportion of sulfolane in the solvent mixture was increased. The maximum selectivity of the levulinic acid production was found to be slightly over 50% and independent of the solvent composition. Thus, with sulfolane solvent, the same yields can be obtained in a significantly shorter time or at a lower temperature as when water is used as solvent. Sulfolane was also found to keep the generated by-products in soluble form. This will decrease fouling of the process equipment, which has been a major issue in designing of levulinic acid production processes.

This study was aimed at examining the possible utilization of iron-rich groundwater treatment sludge in the synthesis of zerovalent iron (ZVI) as a conjugate with kaolin clay (Slu-KZVI), and its application for vanadium adsorption from aqueous solutions. Iron was extracted from the sludge using 1 M HCl and was used in ZVI synthesis by the sodium borohydride reduction method. The characteristics and performance of Slu-KZVI were compared to a kaolin modified with synthetic iron (FeCl3·6H2O) (Syn-KZVI). Adsorption results showed a competitive performance by both classes of KZVI, with Syn-KZVI slightly outperforming Slu-KZVI. X-ray photoelectron spectroscopy, X-ray diffraction and transmission electron microscopy confirmed the formation of Fe0 on the core-shell structure of both modified adsorbents. In addition, the surface analysis of Slu-KZVI indicated the presence of P and Ca to a small extent, originating from the sludge. Both classes of sorbents performed better in solutions with acidic and neutral pH values (3–7). Surface complexation was thought to be the primary mechanism whereas simultaneous V(V) reduction and Fe oxidation (redox) reactions may also have taken place to some extent. A sorption test with groundwater confirmed that adsorbents were able to reduce vanadium to a very low concentration.

Ferric groundwater treatment residual (Fe-GWTR) collected from a Finnish groundwater treatment plant were recovered for use after acid dissolution as an iron source for an inorganic-organic hybrid material. Acid dissolution, performed with 1 mol/L hydrochloric acid and mixing for one hour at room temperature, was determined as the optimal condition based on a high Fe concentration and low concentration of interfering elements. Peat modification was conducted at pH values of 3, 5 and 7 with both a commercial iron reagent (FeCl3·6H2O) and Fe-GWTR solution for comparison. A modification pH of 3 resulted in the highest vanadium removal efficiency for both iron sources. The isoelectric point (pHIEP) of Fe-GWTR-modified peat at pH 3 (Fe-GWTR-P3) was found to be 5.0. After modification, it was confirmed that BET surface area and pore volume of the peat were enlarged. Maximum capacity was found to be around 16 mg/g with a 24-hour contact time at pH 4 and a good fit was achieved with the Redlich-Peterson isotherm model. The kinetic data followed the Elovich equation, which refers to the chemisorption mechanism. According to intra-particle diffusion and Boyd models, the adsorption was a two-step diffusion process, with intra-particle diffusion being the slowest step. This study demonstrates that Fe-GWTR could safely be used as an iron source for biomass modification, and Fe-GWTR-P3 could be used as a low-cost and effective sorbent for vanadium-containing wastewater treatment.

In this study, two-step surface modification of sawdust using triethanolamine (at 180 °C) and iodomethane (at 42 °C) was performed to produce a novel quaternized biosorbent, TEA-I-SD. The characterization studies revealed significant morphological changes in the sawdust and successful quaternization with a nitrogen content of 5.75%. The highest vanadium removal (96.2%) was achieved at pH 4 (dosage 1 g/L, initial vanadium concentration 19.1 mg/L). Equilibrium was achieved within 8 h of contact time and the adsorption kinetics were well fitted with the pseudo-second-order model. Both film diffusion and intra-particle diffusion contributed to the adsorption process, while the latter was the rate-limiting step. The maximum vanadium adsorption capacity of TEA-I-SD (35.0 mg/g, pH 4) was close to the theoretical value obtained from the Langmuir model. The best fit was achieved with the Redlich-Peterson model, exhibiting a monolayer adsorption phenomenon. Tests with real mine water containing 11 mg/L of vanadium also confirmed its high removal (91.3%, dosage 1 g/L) using TEA-I-SD at pH 4. The TEA-I-SD could be reused three times without significant capacity loss after regeneration, although the desorption efficiency was rather low (synthetic solution: 38.5–40.5% and mine water: 26.2–43.1%).

Aminated peat (termed PG-Peat) produced using polyethylenimine and glycidyltrimethylammonium chloride was used for the removal of sulphate from real acid mine drainage (AMD) in batch and column mode sorption studies. In the batch tests, the highest sulphate removal capacity achieved was 125.7 mg/g. PG-Peat was efficient and rapid in sulphate removal from AMD even at low temperatures (2–5 °C), achieving equilibrium within a contact time of 30 min. The PG-Peat column treating real AMD showed even higher sulphate uptake capacity (154.2 mg SO42−/g) than the batch sorption studies. The regenerative and practical applicability of PG-Peat was also tested in column set-ups using synthetic sulphate solutions (at pH 5.8 and pH 2.0). The sulphate uptake capacity obtained was higher in column mode when the solutions were treated at acidic pH (2.0) compared to pH 5.8. This could be attributed to the presence of cationized amine groups on PG-Peat under acidic pH conditions. Almost complete sulphate desorption was achieved with NaCl in the column that treated synthetic sulphate solution at pH 5.8, while the lowest desorption rates were observed in the column that treated acidic synthetic sulphate solution (pH 2).

Boreal peatlands with low iron availability are a potential, but rarely studied, source for the isolation of bacteria for applications in metal sorption. The present research focused on the isolation and identification of Actinobacteria from northern Finland, which can produce siderophores for metal capture. The 16S rDNA analysis showed that isolated strains belonged to Firmicutes (Bacillus sp.) and Actinobacteria (Microbacterium sp.). The culture most efficiently producing siderophores in the widest array of the media was identified as Microbacterium sp. The most appropriate media for siderophore production by the Microbacterium strain were those prepared with glucose supplemented with asparagine or glutamic acid, and those prepared with glycerol or fructose supplemented with glutamic acid. The microorganism obtained and its siderophores were used to develop Sphagnum moss-based hybrid biosorbents. It was showed that the hybrid sorbent could bind nickel ions and that the nickel removal was enhanced by the presence of siderophores. Bacterial cells did not have a significant effect on sorption efficiency compared to the use of siderophores alone. The microbial biosorbent could be applied in the final effluent treatment stage for wastewater with low metal concentrations.

A novel bio-based hydrogen production process concept is simulated using Aspen Plus software. In the concept, hemicellulose is first extracted from birch wood using aqueous formic acid (FA). The dilute FA is then decomposed and used synergistically as a source of H2. The hemicellulose monosaccharides in the dilute aqueous hydrolysate are hydrogenated to their corresponding sugar alcohols, which are further processed to H2, various alkanes and carbon dioxide using aqueous phase reforming (APR). In addition to H2 and electricity, cellulose and lignin rich solid wood fraction is produced. However, the case study revealed high heating requirements of dilute aqueous hydrolysate stream to APR reaction temperatures. High degree of APR effluent recycling to the extraction stage is considered, resulting in a relatively high concentration of the required fresh FA stream in the process concept.

Lignin modification opens the possibility of using it in polyol bio-based polymers, such as phenol–formaldehyde resins, polyurethanes, composites, and binders. Pine kraft lignin Indulin AT was partially depolymerized and the resulting products analyzed to determine their degree of valorization. Depolymerized lignin products were analyzed by GPC-SEC (molar mass), ∆ε-IDUS (phenolic hydroxyls), HACL (formaldehyde uptake), 13C-NMR (hydroxyl and methoxyl groups), and 1H-DOSY (molar mass distribution). The dominant parameter in lignin depolymerization by solvolysis was reaction temperature. According to the results, a higher reaction temperature decreases the average molar masses and PDI of lignin as well as the primary and secondary aliphatic hydroxyls, while simultaneously increasing the phenolic hydroxyls and formaldehyde uptake of lignin. Other variables (time, formic acid wt %, ethanol wt %, lignin load) had lesser effects. Partial depolymerization by solvolysis in mild conditions without catalyst is a viable valorization route for lignin, by which lignin properties can be significantly improved.

Large scale fermentations face challenges in mixing and mass transfer as well as in the design and construction of the equipment. Scale-up from laboratory and pilot scale experiments is difficult because different phenomena – such as mixing times and mass transfer conditions – scale in a different way. We study the effect of mass transfer, reactor type and scale on the growth of Pichia pastoris yeast. Batch cultivation experiments monitoring the cell growth and ethanol formation are conducted in laboratory scale in two reactor types — stirred tank and an Outotec OKTOP®9000 draft tube reactor. Model for the yeast growth – including respirative and fermentative metabolism and the effect of dissolved oxygen – is formed based on literature. For scale-up studies, the growth model is used along with one dimensional reactor model that accounts for liquid mixing, gas phase dynamics and local gas hold-up and mass transfer coefficient. By using a realistic growth model along with the reactor model, the simulated effects of scale-up are presented in terms of cell yield. A decrease in yield is noticed due to oxygen depletion in gas and insufficient liquid mixing. Potential improvements are related to the gas handling capacity and liquid mixing of the reactor.

This study investigated the sorption behaviour of natural (N peat) and HCl-acid-modified peat (HCl peat) for contaminants in water collected at a mine site in northern Finland. Batch sorption experiments were conducted at room temperature and at 5 °C. Characterization of the sorbents by FTIR and XPS revealed no substantial change in the peat’s functional groups due to the acid treatment. Generally, the N peat was a more efficient sorbent for the mine water, although the HCl peat exhibited better nickel uptake capacity (21 mg Ni/g) than the N peat (16 mg Ni/g) from synthetic water. This is attributed to the lower equilibrium pH in samples treated with the HCl peat as well as the water’s different chemical composition. At room temperature, the N peat removed As(V) (80%) and Ni (85%) at low dosage (1–2 g/L), whereas the HCl peat presented good removal of As(V) (80%) at low dosage (1 g/L) but did not achieve satisfactory removal of Ni, even at a higher dosage (4 g/L). The performance of both sorbents was significantly affected by contact time. Ni removal by N peat increased substantially with contact time whereas removals achieved by HCl peat increased slightly up to 60 min, but decreased significantly at 24 h. Unlike with HCl peat, the N peat was less efficient in the experiments conducted at 5 °C. Overall, for both sorbents, As(V) and Ni were the most efficiently removed contaminants from the mine water. HCl peat had slightly better settling properties, however, both products settled poorly, thus rendering the studied mixing and settling system unsuitable for the proposed application. Nevertheless, both peat products, and especially the N peat, exhibited high contaminant removal potential and could represent a cost-effective and sustainable option for mine water treatment.

Natural water with a high specific ultraviolet absorbance (SUVA) value (4.3) and high vanadium concentration (1.2–1.9 mg/l) was investigated for vanadium(V) removal through sorption using solid sorbents and co-precipitation with a ferric sulphate coagulant. Although there are studies on vanadium removal by sorption and co-precipitation, the removal of vanadium in the presence of natural organic matter has not been adequately addressed. In the sorption method, hexadecyltrimethylammonium bromide (HDTMA) modified clinoptilolite (Cp) and synthetic zeolite (Na-P1), and ferric oxyhydroxide (CFH-12) were tested as sorbents. In the co-precipitation method, vanadium removal may occur simultaneously with the coagulation process of humic substances. Co-precipitation with iron was proven to be more efficient than sorbent-based processes. A ferric sulphate coagulant dosage (as product) of 75 mg/l resulted in a residual vanadium concentration of 70–80 μg/l and vanadium removal closely followed the removal of humic substances. This might be related to the binding of vanadium by the humic substances. Regarding sorbents, 1–2 g/l dosages of Na-P1 (at pH ∼6) and CFH-12 (pH 3.7–4.7) were required to reach a low vanadium concentration. A much higher dosage was required for Cp, which can be explained by the lower loading of HDTMA on the zeolite surface. Na-P1 increased the pH of the treated water whereas CFH-12 decreased the pH. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the pH change was due to the leaching of hydroxides and calcite from the Na-P1 and jarosite from the CFH-12. The organo-zeolites exhibited fast kinetics. The surface binding of vanadium and vanadium-humic substances can be regarded as the main mechanism. For CFH-12, the diffusion of vanadium into pores was a significant, albeit slow mechanism, in addition to the sorption on the external surface. The humic substances present in natural water significantly affected the mechanism of vanadium uptake. The XPS data confirmed the strong binding of organic matter on CFH-12 whereas organic matter was only weakly bound to the organo-zeolites.

The aim of this research was to investigate the regeneration and reuse of a commercial granular iron sorbent (mainly goethite) when used in vanadium removal. A regeneration rate of 3 M NaOH was the highest (85%) achieved, followed by 2 M NaOH (79%) and 1 M NaOH (68%). The breakthrough curves show that the regenerated material can be reused. The BET (Brunauer–Emmett–Teller) surface area increased by 35–38% and the total pore volume increased by 123–130% as a consequence of NaOH treatment. The results indicated that sodium hydroxide could be used for the regeneration of iron sorbent although the regeneration was incomplete. This may be explained by the fact that vanadium diffusion into pores is a significant sorption mechanism in addition to complex formation with surface functional groups. As a consequence, vanadium desorbability from pores is not as effective as the regeneration of surface sites. X-ray photoelectron spectroscopy analyses confirmed a very low vanadium content on the surface of the NaOH-treated iron sorbent.

The coagulation efficiency of novel coagulant aluminium formate was studied in the treatment of highly contaminated effluent from a styrene butadiene latex manufacturing plant. The coagulation behaviour of the aluminium formate was compared to the behaviour of the commonly used polyaluminium chloride and aluminium sulphate. The effects of the coagulant type and dose and coagulation pH on the treatment efficiency were studied as well as the role of polyacrylamide coagulant aid. Floc separation was done using three different methods sedimentation, filtration and centrifugation. Their functionality was evaluated as part of the coagulation performance studies. Good purification results were obtained with all of the tested coagulants, the lowest residual turbidities achieved being 0.7 NTU with aluminium formate, 1.4 NTU with polyaluminium chloride and 0.7 NTU with aluminium sulphate. It was also observed that aluminium formate is as effective as commercial coagulants and is thus a potential novel coagulant chemical due to its less harmful and biodegradable counter anion. When using only aluminium coagulants, flocs were found to be too fine to be removed by sedimentation but they could be effectively removed by filtration or centrifugation. The use of polyacrylamide was found to be useful in the sense that it enables the separation of flocs by simple sedimentation because the floc size is significantly increased. In this study new knowledge about the coagulation behaviour of highly contaminated effluent from latex manufacturing was gained and aluminium formate was proved to be promising coagulant also in industrial effluent treatment.

In the enzymatic hydrolysis of cellulose, several phenomena have been proposed to cause a decrease in the reaction rate with increasing conversion. The importance of each phenomenon is difficult to distinguish from batch hydrolysis data. Thus, kinetic models for the enzymatic hydrolysis of cellulose often suffer from poor parameter identifiability. This work presents a model that is applicable to fed-batch hydrolysis by discretizing the substrate based on the feeding time. Different scenarios are tested to explain the observed decrease in reaction rate with increasing conversion, and comprehensive assessment of the parameter sensitivities is carried out. The proposed model performed well in the broad range of experimental conditions used in this study and when compared to literature data. Furthermore, the use of data from fed-batch experiments and discretization of the model substrate to populations was found to be very informative when assessing the importance of the rate-decreasing phenomena in the model.

Purpose. Potato fruit juice, a residue of starch industry, contains up to 2.5% [w/w] of proteins that are potentially valuable raw-materials of food, cosmetic, and pharma industries. The recovery of protein from the potato fruit juice is limited by the lack of industrially feasible concentration and separation technologies. The present research thus aimed at development of such process for the separation of active protease inhibitors from potato fruit juice.Methods. Low temperature mechanical vapor recompression evaporation was applied for concentration of potato fruit juice followed by ethanol precipitation for recovery of active proteins. The effects of precipitation temperature and precipitative agents were investigated employing response surface modeling methodology.Results. Concentration of potato fruit juice by evaporation was successful without loss of trypsin inhibition activity. Precipitation using 6.5 M ethanol at low temperature (0–+4°C) was found suitable for the recovery of active protease inhibitors from the concentrate. Piloting at starch industry yielded 50% of total proteins, with a high quantity of active protease inhibitors and a minor inclusion of other proteins.Conclusion. Concentration by low-temperature evaporation, followed by ethanol precipitation of protease inhibitors at optimized temperature, is an attractive option for valorization of potato fruit juice.

Biological sulfate removal is challenging in cold climates due to the slower metabolism of mesophilic bacteria; however, cold conditions also offer the possibility to isolate bacteria that have adapted to low temperatures. The present research focused on the cold acclimation and characterization of sulfate-reducing bacterial (SRB) consortia enriched from an Arctic sediment sample from northern Finland. Based on 16S rDNA analysis, the most common sulfate-reducing bacterium in all enriched consortia was Desulfobulbus, which belongs to the δ-Proteobacteria. The majority of the cultivated consortia were able to reduce sulfate at temperatures as low as 6 °C with succinic acid as a carbon source. The sulfate reduction rates at 6 °C varied from 13 to 42 mg/L/d. The cultivation medium used in this research was a Postgate medium supplemented with lactate, ethanol or succinic acid. The obtained consortia were able to grow with lactate and succinic acid but surprisingly not with ethanol. Enriched SRB consortia are useful for the biological treatment of sulfate-containing industrial wastewaters in cold conditions.

Lignin solubility is a varying property, as depending on the type of lignin and its origin, its solubility in different solvents will differ. This is due to the highly heterogeneous nature of lignin. Solubilizing lignin could improve its potential valorization by making it more conducive to chemical reactions. Solvent fractionation could be utilized as the first step in lignin refining to adjust some of its properties before further processing. It is known that kraft lignin is completely soluble in alkaline solvents such as aqueous NaOH. The purpose of this study was to assess the solubility of Indulin AT lignin in aqueous ethanol solvents and to determine the useful properties of the resulting fractions: namely, molar mass distribution and phenolic hydroxyl groups. The highest concentration of lignin was achieved in 60 wt% ethanol solution with 235.89 g/L at a solid-to-liquid ratio of 300 gLignin/LSolvent. The original lignin had a mass average molar mass of 4.7 kDa. When only water was utilized, the average molar mass of the dissolved fraction was between 1 and 2 kDa and the molecular size distribution was mostly between 0.1 and 1 kDa. When using pure ethanol, the molecular size distribution ranged from 0.1 kDa to 10 kDa, with a mass average molar mass between 1 and 1.3 kDa. With an ethanol content in the solvent higher than 90 wt%, the bigger molar mass molecules (>10 kDa) could be separated as the insoluble fraction. Additionally, the polydispersity of both fractions decreased with an ethanol concentration above 80 wt%. The hydroxyl group content of the insoluble fraction was higher when fractionating with less than 20 wt% ethanol, whereas with 20 wt% ethanol and higher, the soluble fraction retained most of the phenolic hydroxyls. Fractionating lignin prior to use or further processing may be potentially beneficial if the lower molar mass molecules can be used as they are, leaving only the higher molar mass molecules to be further processed or burned for energy.

A novel bio-based anion exchanger was developed to remove sulphate from synthetic solutions and mine water. Different modification parameters such as chemical dosage and reaction time were tested when using a unique combination of branched polyethylenimine (PEI) and glycidyltrimethylammonium chloride (GTMAC) to produce an aminated biosorbent (termed PG-Peat). The novel and environment-friendly modification method was shown by FTIR and XPS analyses to be able to introduce quaternary ammonium and N-H groups into PG-Peat. The optimal modification conditions (PEI: 0.26 mmol/g, GTMAC: 0.0447 mol/g, reaction time: 18 h) resulted in the maximum sulphate uptake capacity (189.5 ± 2.7 mg/g) with a partition coefficient value of 0.02 mg/g/μM under acidic conditions. At low pH, amine groups on the peat surface became cationized, thereby resulting in a higher sulphate removal capacity. Batch sorption tests using PG-Peat exhibited rapid sulphate sorption after only five minutes of contact. The sulphate uptake by PG-Peat was unaffected by the presence of varying chloride concentrations, while slightly lower uptake capacity was observed when different concentrations of nitrate were present. The biosorbent showed high recyclability, which was revealed in regeneration studies. Tests were performed involving real mine water, where PG-Peat showed its potential to be a highly efficient biosorbent for sulphate removal at low pH values, indicating its suitability for treating acidic mine waters.

High initial viscosity in the high-solids (>15% (w/v)) enzymatic hydrolysis of lignocellulose is problematic especially in stirred tank reactor concepts. One potential way to avoid the high viscosity is the fed-batch feeding of lignocellulosic material to the reactor. In the current study the hydrolysis of filter paper with final concentration of 19.1% (w/w) was evaluated with different fed-batch procedures. Feeding was based on visual observation, stepwise feeding and the power requirement of the stirrer motor. All the fed-batch procedures resulted in similar yields within 30 h (47–49%) which were higher than with the batch process in similar reactor (38%). However, the mixing behavior was superior in the power based feeding as the instantaneous power of the stirrer motor was kept lower ( 20 W). The power controlled procedure was further evaluated with different enzyme doses, tip speeds and the power levels of substrate feed. Further study showed that the power controlled feeding is applicable also to other hydrolysis and mixing conditions if power levels of substrate feed are set correctly. Higher (15 FPU/g) enzyme dose caused shorter feeding time (3.0 ± 0.5 h) and lower energy consumption during the feeding period (14 ± 3 Wh) compared with lower (5 FPU/g) enzyme dose (7.0 ± 1.3 h and 33 ± 5 Wh, respectively). The tip speed and the power level of substrate feed had fewer effect on these factors. The performance of the hydrolysis process can thus be enhanced by the substrate feed controlled by the power of the stirrer motor.

A new homotopy-based strategy is presented that can be used in the robust determination of multiple steady-state solutions for continuous stirred tank reactor (CSTR) systems. The strategy relies on the features of homotopy parameter and variables bounding, and requires only that one feasible solution of the system is either known beforehand or can be solved with an existing solving algorithm. The strategy systematically results in all the multiple solutions, or alternatively confirms that the problem does not have multiple solutions, within the predefined problem domain. The strategy was successfully demonstrated with CSTR cases gathered from the literature. Finding all the feasible solutions was verified in simple CSTR systems by applying tools available in the literature. Variables bounding constrained the homotopy path to travel only within the pre-defined variable domain. The strategy is applicable for determining multiple steady states for a variety of chemical engineering systems.

Mining wastewater was treated using quaternized pine sawdust (QPSD) anion exchanger. The wastewater contained heavy metals (e.g. Sb, As, Co, Cr, Ni, V, U), NO3(-), among others, and a high concentration of SO4(2-). A series of column cycles imitating a real treatment process was conducted (three sorption/desorption cycles, a maintenance cycle with HCl and two sorption/desorption cycles). The effects of contact time and temperature (5°C and 23°C) were studied to assess the applicability of QPSD in the treatment of cold mining effluents. At 5°C, 85% of nickel was removed but the sorption was slower than at 23°C (initial Ni concentration was about 39 µg/l). Nickel was also removed in column efficiently (85-100% reduction). Treatment with HCl during the maintenance cycles did not hinder nickel sorption. Nickel was desorbed with both NaCl and HCl. Contrary to expectations, nitrate was not sorbed. QPSD showed selectivity towards nickel. However, uptake of uranium and cobalt was detected in column. Neutron activation analysis was used to detect metals sorbed onto the QPSD, and uptake of several metals was confirmed.

In this study, the utilization of silicalite–1 membrane pervaporation for butanol recovery from an acetone-butanol-ethanol (ABE) fermentation broth solution was investigated. In particular, the negative effect of butyric acid on the pervaporation performance was tested. The presence of butyric acid was observed to decrease both the butanol flux and selectivity of the membrane. Clear relation between the severity of the decreased performance and the amount of butyric acid was observed. Increasing the pH of the feed solution was observed to improve butanol pervaporation in the presence of butyric acid. In pervaporation of ethanol, butanol and butyric acid, there are significant interactions in adsorption and diffusion between the components. The presence of butanol restricts the permeation of ethanol while the butanol permeation is restricted by the presence of butyric acid. The effects likely arise from adsorptive competition and are further amplified due to the rates of diffusion. In addition, butyric acid exposure may change the membrane properties over time, although they may be restored by heating. The results suggest that the selective recovery of butanol with a silicalite–1 membrane is not feasible if the concentration of butyric acid is significant and the pH value in the solution is low.

In this study the interactions between ethanol and water penetrating in a supported polydimethylsiloxane membrane were investigated both using experimental and mathematical modelling work. To reach comprehensive analysis of the membrane performance and the penetrant interactions, the experimental work included a wide range of pervaporation and vapor permeation experiments with pure and binary ethanol-water mixtures. A Maxwell-Stefan model was used to further analyze the membrane performance with a Flory-Huggins formulation to describe the sorption behavior. According to the formed model, both water and ethanol permeation are slowed down from the permeation rates observed with pure feeds and in binary permeation especially the experimental ethanol flux is lower than the flux expected by the model. This suggests that the interactions between the penetrants in PDMS are high resulting to decreased diffusion rate of both ethanol and water.

Sphagnum moss extract residue (SMER), obtained after pressurized hot water extraction, was modified with Fe(III) and investigated for phosphate sorption. Although moss extract contains value-added compounds, SMER is considered to be waste until suitable uses can be developed. The effect of modification conditions were investigated, i.e. different initial Fe(III) concentrations (0.024, 0.048 and 0.072 mol/L Fe 3+ ) and modification pH values (5, 7 and 9). A modification pH of 5 and the highest initial Fe(III) concentration (0.072 mol/L Fe 3+ ) resulted in the highest phosphate removal efficiency, and thus was selected for further study. The removal efficiency was found to decrease with increasing pH in the range of 3–9. Maximum removal efficiency (82%) for phosphate sorption was observed at pH 3 after 24 h contact time (dosage 2 g/L, initial concentration 15 mg P/L). With increased contact time, the phosphate removal efficiency improved and reached equilibrium within 48 h. The Elovich model was found to provide the best fit to the kinetic data. A capacity of 9–13 mg P/g was obtained with a 24-h contact time at pH 4. A good fit was achieved with the Redlich–Peterson equation. FTIR analysis confirmed that carboxylic acid groups were involved in the modification process. X-ray diffraction analyses showed that amorphous two-line ferrihydrite was precipitated onto SMER, which was supported by X-ray photoelectron spectroscopy analyses.

Extraction of starch from potato leads to formation of potato fruit juice (PFJ), which consists of proteins, fibers, starch and water. PFJ contains 1% – 3% [w/w] of proteins, including protease inhibitors that are potentially valuable for various applications, and could thus bring added value to the potato industry. The use of proteins of PFJ in bioactive form is limited by lack of benign and cost-efficient concentration technologies. The present approach combines a previously introduced low-temperature mechanical vapor compression evaporation technology with option to enzymatic viscosity management in case of high-viscosity fluids. In pilot-scale evaporation, an increase of solid content from 10% to 40% was achieved without major technical challenges. The proposed method offers a low-energy means for the concentration potato industry wastewater and reclamation of valuable proteins in active form.

The aim of this research was to convert potato peel waste (PPW) to single cell protein (SCP), and to extract valuable phenolic compounds from the spent medium. PPW is an abundant by-product of potato processing industry, consisting mostly of starch, fibre and protein in a form of watery sludge. The PPW from a chip manufacturing plant was pre-treated with sulphuric acid, and used as a substrate for an acidophilic Scytalidium acidophilum fungus under non-aseptic conditions. The produced SCP had a promising amino acid composition to be used in animal feed. Phenolic compounds were not recovered from the spent medium, most likely due to the low pH in the medium. The present findings suggest that PPW is a suitable raw material for acidophilic SCP production, whilst the extraction of phenolic acids would require milder cultivation conditions or separation before pre-treatments of SCP production. The BOD5 of the PPW was reduced by in 98% due to fungal cultivation. Thus the feed production also served as an efficient means for reduction of organic load in the PPW.

Peat is commonly known as a biofuel but it also has other more or less traditional uses, for example in folk medicine, building materials, or preservation of foods. Several studies suggest that the main composers of peat lands, Sphagnum mosses, may also have potential for a variety of other value-added products. Typically, those are related to the antibacterial and other preservative properties of Sphagnum, or to their high water adsorption ability. Molecular level applications, however, are still rarely reported. This might owe to the complex chemistry of Sphagnum and lacking cost-efficient technologies for the isolation of components of interest. In this literature survey, the structural and chemical properties of Sphagnum are reviewed together with their suggested uses. This is expected to facilitate new efforts to find commercially feasible applications for these extraordinary plants.

The effect of temperature, sulphate and phosphate, and the initial nitrate concentration on nitrate removal was studied with synthetic solutions. Chemically modified pine sawdust (Pinus sylvestris) anion exchange resin (MPSD) was used in the sorption studies. The resin was synthesized by reacting pine sawdust with epichlorohydrin, ethylenediamine and triethylamine in the presence of N,N-dimethylformamide. Nitrate removal was successful at 5-70 °C. Higher temperatures caused nitrate removal to decrease moderately, but sorption capacities of 22.2-32.8 mg/g for NO3-N were achieved. The removal of nitrate in the presence of sulphate or phosphate was studied at concentrations of 30 mg N/l, 10-500 mg S/l and 1-50 mg P/l. A significant decrease in nitrate reduction was observed at sulphate and phosphate concentrations of 100 mg S/l and 50 mg P/l, respectively. The effect of initial nitrate concentration was studied in column. Nitrate sorption was clearly dependent on the initial concentration. Desorption of nitrate in column was completed using about 80 bed volumes of 0.1 M NaCl solution. The sorption data were fitted to the Langmuir, Freundlich and Redlich-Peterson adsorption models. The Redlich-Peterson and Langmuir models gave the best fit, which suggests monolayer sorption. Thermodynamic studies revealed that the sorption of nitrate was spontaneous and exothermic in nature. The results imply that modified pine sawdust could be a feasible alternative in the treatment of real industrial wastewaters.

Pervaporation of binary ethanol/water solutions of 5–10 wt.% ethanol was studied experimentally through a thin supported high-silica MFI zeolite membrane of hydrophobic character in the temperature range of 30–70 °C. The fluxes obtained were very high, 2–14 kg m -2 h -1 with ethanol/water separation factors of 4–7. The loss of effective driving force was significant in the supporting layers, which limited the membrane performance. The correlation between the experimental data and three different semi-empirical mass-transfer models was examined. The correlation was good especially when the driving force for mass-transfer was determined based solely on bulk feed, or the bulk feed and permeate conditions together. Somewhat lower correlation was observed when the driving force was corrected with the effect of support resistance. This was most likely due to the inaccuracies of the used mass transfer parameters in the support. The investigated semi-empirical models can be applied for initial stage process design purposes.

Peat is an excellent material for metal sorption since it naturally contains different kinds of functional groups that can sorb metal cations from water. The main objective of this work was to test low-cost treatment (acid and alkali) methods for natural peat, which would improve the settling properties of peat particles while maintaining its metal removal efficiency. Particularly, the poor settling properties of peat hinder its practical application. The study revealed that NaOH-treated peat (0.1 M) had excellent settling properties and could be applied in wastewater applications having mixing and settling systems without a settling aid. The superior leaching of humic and fulvic acids in alkaline treatment caused a change in morphology, making it a harder and sticky material. Moreover, the NaOH-treated (0.1 M) peat was proven to be the most efficient material for nickel removal followed by the HCl-treated (0.2 M) peat, citric acid-treated (0.16 M) peat and water-treated peat. A higher temperature and longer time slightly increased the Ni removal efficiency with NaOH-treated peat material. The settling of HCl-treated peat was studied further using polyacrylamide flocculants (cationic, neutral, anionic). Cationic flocculants performed best and the cationic charge density also had an effect on the flocculation performance of peat particles. This study provides further evidence that peat can be applied in the treatment of metal-containing wastewaters.

The study was performed to evaluate chemically modified biosorbents, hydrochloric acid treated peat (HCl-P) and citric acid treated sawdust (Citric acid-SD) for their metal removal capacity from dilute industrial wastewater and urban runoff and compare their efficiency with that of commercially available mineral sorbents (AQM PalPower M10 and AQM PalPower T5M5 magnetite). Batch and column experiments were conducted using real water samples to assess the sorbents' metal sorption capacity. AQM PalPower M10 (consisting mainly of magnesium, iron and silicon oxides) exhibited excellent Zn removal from both industrial wastewater and spiked runoff water samples even at low dosages (0.1 g/L and 0.05 g/L, respectively). The high degree of Zn removal was associated with the release of hydroxyl ions from the sorbent and subsequent precipitation of zinc hydroxide. The biosorbents removed Ni and Cr better than AQM PalPower M10 from industrial wastewater and performed well in removing Cr and Cu from spiked runoff water, although at higher dosages (0.3–0.75 g/L). The main mechanism of sorption by biosorbents was ion exchange. The sorbents required a short contact time to reach equilibrium (15–30 min) in both tested water samples. AQM PalPower T5M5 magnetite was the worst performing sorbent, leaching Zn into both industrial and runoff water and Ni into runoff water. Column tests revealed that both HCl-P and AQM PalPower M10 were able to remove metals, although some leaching was witnessed, especially As from AQM PalPower M10. The low hydraulic conductivity observed for HCl-P may restrict the possibilities of using such small particle size peat material in a filter-type passive system.

Hemicellulose has been extracted from birch (Betula pendula) sawdust by formic acid aided hot water extraction. The maximum amount of hemicellulose extracted was about 70 mol% of the total hemicellulose content at 170 °C, measured as the combined yield of xylose and furfural. Lower temperatures (130 and 140 °C) favored hemicellulose hydrolysis rather than cellulose hydrolysis, even though the total hemicellulose yield was less than at 170 °C. It was found that formic acid greatly increased the hydrolysis of hemicellulose to xylose and furfural at the experimental temperatures. The amount of lignin in the extract remained below the detection limit of the analysis (3 g/L) in all cases. Formic acid aided hot water extraction is a promising technique for extracting hemicellulose from woody biomass, while leaving a solid residue with low hemicellulose content, which can be delignified to culminate in the three main isolated lignocellulosic fractions: cellulose, hemicellulose, and lignin.

Dissolved air flotation (DAF) was studied for treatment of 2 m-% oil-in-water emulsions (O/W emulsions) prepared from synthetic oils by adding chemicals such as the cationic surfactant CTAB (cetyltrimethylammonium bromide), the coagulant PolyDADMAC (polydiallyldimethylammonium chloride) (also studied for oily wastewaters) or Epi–DMA (epichlorohydrin–dimethylamine copolymer) directly into the saturator (PosiDAF) in two different concentrations, or by performing coagulation–flocculation followed by DAF. The efficiencies of various DAF treatments were evaluated by measuring the chemical oxygen demand (COD) and total surface charge (TSC). Flow cytometry (FCM) was used to measure the number of hydrophobic particles in the selected samples. According to the results, the performance of PosiDAF with CTAB was poor compared to that with PolyDADMAC and Epi–DMA. PosiDAF performed better with PolyDADMAC (with a dose of 334 ppm, the highest COD reduction was 100%) than with Epi–DMA (with a dose of 596 ppm, the highest COD reduction was 93%) for the treatment of O/W emulsions. The COD reduction was higher when the concentration of both the PolyDADMAC and Epi–DMA was higher in the saturator. The efficiency of PosiDAF with PolyDADMAC proved to be better than the efficiency of the conventional coagulation–flocculation followed by DAF for breaking up O/W emulsions. PosiDAF with PolyDADMAC also proved to perform very well for treatment of real oily wastewaters; the COD reduction was 70% with an optimal PolyDADMAC dosage of 200 ppm with the TSC value totally neutralized. FCM studies performed on O/W emulsions and oily wastewater samples were successful with repeatable results, thus proving to be a promising analysis method for waters containing oil emulsions.

Furfural is one of the key chemicals produced from hemicellulose pentosans in acidic conditions. In the same conditions, furfural also undergoes degradation reactions leading to yield loss. In this study, the kinetics of furfural degradation in a formic acid medium containing 2 to 30% (w/w) formic acid and 0.05 to 0.16 mol L−1 furfural was studied in small batch reactors. The reaction temperatures were 160, 180, and 200 °C. The results showed that the overall order of the reaction changes with the amount of formic acid catalyst: in high acid concentration (30%) the apparent order of reaction is over one and in low acid concentration (2%) the order of reaction is below one. The proposed kinetic model, which includes an uncatalysed and an acid-catalysed term, is capable of estimating this behaviour. The model and findings presented in this study can support the optimisation of furfural production conditions.

This study focused on the regeneration of iron sorbents and the investigation of sorbent properties after exposure to four sorption-desorption cycles. Batch regeneration tests with sodium hydroxide were conducted on two commercial sorbents (CFH-12 and GEH 101) saturated with vanadium. CFH-12 is ferric oxyhydroxide that also contains some gypsum and goethite (Kemira Oyj). GEH 101 is ferric hydroxide containing akaganeite (s-FeOOH) and ferrihydrite (GEH Wasserchemie). Both materials displayed similar performance in sorption and desorption studies despite their mineralogical difference. Both materials can be reused but the sorption efficiency decreased from 95–97% to about 53–55% after the first sorption (initial V 50 mg/L, dosage 10 g/L) and then remained at the same level. NaOH desorbed 84–86% of vanadium in the first cycle. X-ray photoelectron spectroscopy confirmed that the surface did not contain vanadium after regeneration. Thus the desorption-resistant fractions were located in the pores of the materials. Subsequent desorption stages provided the same or higher recovery of vanadium. Both materials showed some wider pore size distribution, whereas pore volume increased significantly only with CFH-12. This study confirmed that regeneration with alkali and reuse of iron sorbents is a viable option although the sorption and desorption efficiency are affected by the treatment.

The pervaporative mass transfer of pure ethanol and water through a thin (0.5 μm) supported high-silica MFI membrane was studied experimentally at 30–70 °C, and modeled on the basis of the Maxwell–Stefan formalism. The temperature dependency of adsorption was described with the temperature dependency of pure component saturated vapor pressure. Two scenarios of coverage dependency, i.e., coverage-dependent and coverage-independent Maxwell–Stefan diffusivity, were applied in the modeling of the mass transfer through the zeolite film. In addition, the mass-transfer resistance of the support layers was taken into account. The derived unary models provided good representations of ethanol and water pervaporation flux. The study illustrates that pure component steady-state pervaporation flux measurements at different conditions offer a feasible basis for determining diffusion coefficients. Basically, pure component adsorption isotherms and derived diffusivities can be used in the modeling of pervaporative mass t...

Nickel and vanadium were removed from real ammoniacal industrial wastewater (Ni 2–4, V 40–50 mg/L) obtained from a synthesis gas scrubber. The aim of the study was to develop an industrial application for simultaneous removal of nickel and vanadium. The studied methods were adsorption (activated carbon (AC), AquaSorb® 2000), anion exchange (Amberjet™ 4200 Cl) and cation exchange (Amberjet™ 1200 H). AC removed > 95% of nickel at pH 5.5–9 (dose > 2 g/L) but the vanadium uptake remained poor. In batch cation exchange, all nickel was removed (optimum pH 4–7) and 70–75% of vanadium was removed at pH 7 (5–10 g/L). All nickel was removed in batch anion exchange (optimum pH 5.5–9, 2–10 g/L). Over 89% of vanadium was removed in batch anion exchange at pH 7 (1–10 g/L). Adsorption capacities of 4.36 and 48.9 mg/g were obtained for nickel and vanadium in anion exchange at pH 7. In column anion exchange, all nickel and 92–98% of vanadium were removed in all three ion exchange cycles at pH 7–9. In regeneration,...