Simulation and Empirical Studies of Solvent Evaporation Rates in Vacuum Evaporation Crystallization

Simulation results for continuous vacuum evaporation crystallization obtained by Aspen Plus and experimental results for semi‐batch vacuum evaporation crystallization are presented. In the crystallization experiments, the fixed heat duty was used to compare the water evaporation rates and crystal properties obtained at different pressures. The solution selected was aqueous glycine. It has the ability to form a number of different crystalline polymorphs, which allows it to exhibit a variety of different physical properties while maintaining its chemical properties. X‐ray diffraction results demonstrated that mainly the γ‐crystal form is produced under the conditions applied in vacuum evaporation crystallization.     

Dynamic population balance and flow models for granular solids in a linear vibrating screen

Vibrating screens are a widely applied form of particle separations. In spite of this significance, their understanding is still an obstacle. Three approaches were used to characterize the flow of granular material in a linear vibrating screen. The statistical model, mass action, and kinetic model based on conservation of momentum were derived. Experiments were then conducted on a multi‐sized prototype screen and glass beads of sizes 0.75, 1, 2, 3 mm. Deck inclinations were varied over 7.5,12.5, and 17.5°, and frequencies over 7, 15, and 20 Hz. A total of 72 feed batches and a constant power of 50 W was used. The experimental data was then used to validate the models. The three models provided accurate flow prediction over the screens. Additionally, the kinetic model also provided a basis for optimal design of the screening unit operation, by allowing manipulation of seven design variables to obtain a 95–100% efficient vibrating screen. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3889–3898, 2016     

Purification of Nickel Sulfate by Batch Cooling Crystallization

Cooling crystallization was successfully carried out in a batch cooling crystallizer from impure acidic solutions to recover nickel as nickel sulfate salt with three different cooling rates. The compositions of the solutions included impurities of sodium, magnesium, chloride, and sulfuric acid to mimic industrial nickel electrowinning process solutions. The results show that NiSO₄·6H₂O mainly crystallized, and its solubility and purity decreased with the increase in the mass ratio of chloride to sulfate. Cooling rates did not have a significant influence on crystal purity; however, it did affect the filter cake moisture; lower moisture can be obtained with a lower cooling rate. The sequence of impurity removal efficiency from high to low was Cl > Na > Mg.     

Assessment of water quality in the vicinity of peat extraction sites: The case of Pien‐Saimaa,Finland

Peatlands have an important global role as carbon sinks. Locally, however, peat bog extraction can cause pollution in nearby watercourses. The aim of this study is to investigate the application of multivariate methods in the renovation and protection of eutrophic lakes surrounded by agricultural and peat extraction areas. The analytical data used in the study originated from a national water quality database and the period studied was 2000–2013. Multivariate methods: Principal Component Analysis (PCA) and Parallel Factor Analysis (PARAFAC) were applied to solve interactions of variables and pollution sources in a complex water ecosystem. Leaching from the peat bog area was found to be the main source of iron, which has an important role as a precipitator of phosphorus in loose sediment and in water. Nutrient ratios had no direct correlation to algae blooms, but high ratios indicated an increased likelihood of an upcoming bloom.     

Artificial reconstruction of two cryptic angucycline antibiotic biosynthetic pathways

Genome-sequencing projects have revealed that Streptomyces bacteria have the genetic potential to produce considerably larger numbers of natural products than can be observed under standard laboratory conditions. Cryptic angucycline-type aromatic polyketide gene clusters are particularly abundant. Sequencing of two such clusters from Streptomyces sp. PGA64 and H021 revealed the presence of several open reading frames that could be involved in processing the basic angucyclic carbon skeleton. The pga gene cluster contains one putative FAD-dependant monooxygenase (pgaE) and a putatively bifunctional monooxygenase/short chain alcohol reductase (pgaM), whereas the cab cluster contains two similar monooxygenases (cabE and cabM) and an independent reductase (cabV). In this study we have reconstructed the biosynthetic pathways for aglycone synthesis by cloning and sequentially expressing the angucycline tailoring genes with genes required for the synthesis of the unmodified angucycline metabolite-UWM6-in Streptomyces lividans TK24. The expression studies unequivocally showed that, after the production of UWM6, the pathways proceed through the action of the similar monooxygenases PgaE and CabE, followed by reactions catalysed by PgaM and CabMV. Analysis of the metabolites produced revealed that addition of pgaE and cabE genes directs both pathways to a known shunt product, rabelomycin, whereas expression of all genes from a given pathway results in the production of the novel angucycline metabolites gaudimycin A and B. However, one of the end products is most probably further modified by endogenous S. lividans TK24 enzymes. These experiments demonstrate that genes that are either inactive or cryptic in their native host can be used as biosynthetic tools to generate new compounds.     

Malolactic fermentation in four varieties of sea buckthorn (Hippophaë rhamnoides L.)

Malolactic fermentation (MLF) used in winemaking was applied to four varieties of sea buckthorn (Hippophaë rhamnoides L.). Sensory properties and chemical components of fermented and unfermented juices were studied in order to see whether the MLF can have an effect on sensory quality of sea buckthorn and if there are differences between varieties. The juices were inoculated with unadapted Oenococcus oeni at a cell density of 10⁹ CFU/mL and the fermentation was performed over 18 h at 28 °C. The fermentation decreased sourness and astringency in the samples, and fruity flavor as well as fermented flavor were increased. However, the ML reaction was different between the varieties. The size of the reaction was not proportional to the initial pH or malic acid content of the juice. Larger the ML reaction, more changes were observed in the sensory properties.     

Neighbours or Enemies? Competing Variants Causing Differences in Transitional Dialects

The aim of this study is to show how clusteranalysis can shed light on very complexvariation in a transitional dialect zone ineastern Finland. In the course of history thisarea has been on the border between Sweden andRussia and the population has clearly been oftwo kinds: the Savo people and the Karelians.It is a well-known fact that there is variationamong these dialects, but the spread and extentof the variation has not been demonstrated previously.The idiolects of the area were studied in thelight of ten phonological and morphologicalfeatures. The material consisted of recordingsof 198 idiolects, totalling around 195 hoursand representing 19 parishes. The variation wasanalysed using hierarchical cluster analysis.While the analysis showed the extent of thevariation between idiolects and parishes, italso demonstrated how the effects of the oldparishes, borders and settlements are stillvisible in the dialects. On the parish level,the data formed clear clusters that correspondwith the main dialects in the area and itssurroundings. On the idiolect level, however,the speakers from the surrounding areas formedfairly homogenous clusters but the idiolectsfrom the Savonlinna area were spread acrossalmost all clusters.     

Influence and CFD analysis of cooling air velocity on the purification of aqueous nickel sulfate solutions by freezing

Finite energy resources and their rapidly waning imprint necessitate a sustainable wastewater treatment method. Nature could be exploited to freeze wastewater in locations which experience subzero temperatures during winter. The two most vital components that influence the efficiency of natural freezing are the ambient temperature and air velocity. The turbulent and unsteady air‐cooled natural freezing is simulated for ice crystallization from 0.1 wt % and 1 wt % NiSO₄ (aq) solutions. The efficiency of natural freezing is tested for different air velocities (2 ms^?1, 5 ms^?1) and levels of undercooling (ΔT = 0.5°C, 1°C) from the freezing temperature of the corresponding solution. The airflow in the winter simulator is modeled by computational fluid dynamics to investigate its behavior and to assess its effect on freezing. © 2017 American Institute of Chemical Engineers AIChE J, 63: 200–208, 2018     

Oxidation of Aqueous Paracetamol by Pulsed Corona Discharge

Oxidation of paracetamol in aqueous solution was studied by using pulsed corona discharge as a means for advanced oxidation. Pulse repetition frequency, the delivered energy dose, and oxidation media were the main parameters evaluated. The pulsed corona discharge treatment appeared to be effective in oxidation of paracetamol: complete degradation of target pollutant together with partial mineralization was achieved at moderate energy consumption; oxidation proceeds faster in alkaline media, the fastest oxidation rate was observed in oxygen-enriched air. Low-molecular carboxylic acids were identified as the products formed in the reaction.     

Dynamic and perturbative system analysis of granular material in a vibrating screen

In most particulate classification systems, feed rates in excess of 80% of the designed capacity leads to inefficiency and conversely feed rates below this value significantly diminishes the operational efficiencies. It therefore implies that maximum efficiency is only attainable at the expense of low capacity, and vice versa. This problem is caused by transience in granular flow due to start-ups and fluctuating feed-rates, in addition to fluctuations in feed material properties. If these variations are not checked, they cause instabilities, resulting in chaotic saddles responsible for in-process systemic error generation. These errors produce intermittent disruptions in production process and control. We have applied perturbation theory to study the effects of infinitesimal changes on the material balance analysis of the unit operation. The problem was identified as one of the highly multi-stable dynamic systems, characterized by ‘predator-prey’ phenomenon in dynamical systems theory. The study allowed formulation of optimal state equations, whose numerical solutions resulted in establishment of optimal operating conditions required to sustain stability, and consistently high tonnages and efficiency up to 99% simultaneously. The study also led to development of an optimization algorithm, which upon validation with experimental data showed a close relationship, with a minimal absolute error of 0.8 and a relative error of 6%. Finally, a representative case study was conducted on screen dimensioning, based on the determined parameters. Successful evolution of this methodology may be applied for up-scaling of real systems in future.