Possibilities for the use of membrane processes for the pre-treatment of wastewater from the production of dried potato purée

Our research focused on the membrane separation of wastewater resulting from the production of dried potato purée. Our aim was to investigate possibilities for recycling obtained retentate back to the actual production process, and, consequently, for reducing wastewater pollution. This paper describes trials of MF and RO membrane filtration of starch wastewater. The treated water contained starch, in either granulated or gelatinized form, and solids (fine pieces of potato skins). The trials were conducted in either one or two stages. We used a pilot plant equipped with a ceramic membrane with a filtration area of 0.35 m² and pore sizes of 500 and 100 nm. We also tested an organic RO membrane (7410) in the laboratory.High permeate flux above 100 l/(m² h) was measured for the 100 nm membrane, but with considerable fouling. Filtration through this membrane resulted in high COD and BOD₅ rejection (approximately 60%), an effect which was increased by the subsequent RO filtration. The content of soluble carbohydrate, 0.011% in permeate (with 0.44% dry substance), was analyzed using high-performance anion-exchange chromatography coupled with pulsed amperometric detection.     

Proposed EU legislation to force changes in sewage sludge disposal: A case study

The consequences of changes planned in the European Union legislation relevant to the disposal of sewage sludges are discussed. A specific municipal waste water treatment plant is analyzed in terms of drying and subsequent combustion or pyrolysis of the produced stabilized sludge, and the respective net energy balances are carried out. A simplified economic analysis of the two disposal options is presented, which suggest that combustion of the sludge would be economically infeasible while pyrolysis of the sludge in a modular, self-sufficient container unit can bring a small financial benefit due to the selling of the produced phosphorus-rich biochar.

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Lasioglossins: Three Novel Antimicrobial Peptides from the Venom of the Eusocial Bee Lasioglossum laticeps (Hymenoptera: Halictidae)

Three novel structurally related pentadecapeptides, named lasioglossins, were isolated from the venom of the eusocial bee Lasioglossum laticeps. Their primary sequences were established as H‐Val‐Asn‐Trp‐Lys‐Lys‐Val‐Leu‐Gly‐Lys‐Ile‐Ile‐Lys‐Val‐Ala‐Lys‐NH₂ (LL‐I), H‐Val‐Asn‐Trp‐Lys‐Lys‐Ile‐Leu‐Gly‐Lys‐Ile‐Ile‐Lys‐Val‐Ala‐Lys‐NH₂ (LL‐II) and H‐Val‐Asn‐Trp‐Lys‐Lys‐Ile‐Leu‐Gly‐Lys‐Ile‐Ile‐Lys‐Val‐Val‐Lys‐NH₂ (LL‐III). These lasioglossins exhibited potent antimicrobial activity against both Gram‐positive and Gram‐negative bacteria, low haemolytic and mast cell degranulation activity, and a potency to kill various cancer cells in vitro. The lasioglossin CD spectra were measured in the presence of trifluoroethanol and sodium dodecyl sulfate solution and indicated a high degree of α‐helical conformation. NMR spectroscopy, which was carried out in trifluoroethanol/water confirmed a curved α‐helical conformation with a concave hydrophobic and convex hydrophilic side. To understand the role of this bend on biological activity, we studied lasioglossin analogues in which the Gly in the centre of the molecule was replaced by other amino acid residues (Ala, Lys, Pro). The importance of the N‐terminal part of the molecule to the antimicrobial activity was revealed through truncation of five residues from both the N and C termini of the LL‐III peptide. C‐terminal deamidation of LL‐III resulted in a drop in antimicrobial activity, but esterification of the C terminus had no effect. Molecular modelling of LL‐III and the observed NOE contacts indicated the possible formation of a bifurcated H‐bond between hydrogen from the Lys15 CONH peptide bond and one H of the C‐terminal CONH₂ to the Ile11 oxygen atom. Such interactions cannot form with C‐terminal esterification.     

Multi-scale simulation of needle-shaped particle breakage under uniaxial compaction

The breakage of needle-shaped particles within a random packed bed subjected to uni-directional compaction has been simulated using the discrete element method (DEM). Elongated particles with a chosen aspect ratio have been created by linking individual spherical discrete elements by rigid bonds, characterized by a given ultimate bending strength. A randomly packed bed of these elongated particles has been formed and gradually compressed between two infinite parallel solid planes. The particle size distribution as function of the compaction ratio has been studied in dependence on the individual particle strength, the initial particle length, and their distribution. The simulations have shown that the fragmentation generally follows the sequential halving kinetics and that the formation of fines is most profound in systems with a distribution of particle strengths, both within and between individual particles.     

You like it,you learn it: affectivity and learning in competitive social role play gaming

Despite the alleged ability of digital game-based learning (DGBL) to foster positive affect and in turn improve learning, the link between affectivity and learning has not been sufficiently investigated in this field. Regarding learning from team-based games with competitive elements, even less is known about the relationship between competitiveness (as a dispositional trait) and induced positive affect. In this media comparison study with between-subject design, participants (N?=?325; high school and college students) learned about the EU’s policy agenda by means of a debate-based method delivered through one of three educational media: a) through a social role-playing game with competitive elements played on computers, b) through a very similar game played without computers and c) through a non-game workshop. Unlike many previous DGBL studies, this study used participant randomization and strived to address the teacher effect and the length of exposure effect, while also using the same learning materials and a very similar educational method for all three treatments. Both games induced comparatively higher generalized positive affect and flow. Participants also learned more with the games. Positive affect, but not flow, mediated the influence of educational media on learning gains. Participants’ competitiveness was partly related to positive affect and experiencing flow but unrelated to learning gains. These outcomes held both when the game was played using computers, as well as without them. The study indicates that the ability of an educational intervention to instigate positive affect is an important feature that should be considered by educational designers.     

Electric field driven addressing of ATPS droplets in microfluidic chips

The possibility of controlled droplet motion (droplet addressing) mediated by DC electric field in aqueous two-phase systems (ATPS) is here reported for the first time. Three ATPS of polyethylene glycol (PEG)/salt type, namely PEG/phosphate, PEG/sulphate, and PEG/carbonate, were selected for this study. We observed fast motion of salty droplets dispersed in PEG continuous phase induced by electric field of relative low strength. Hence, three fluidic systems with separated electrode chambers for the evaluation of electrophoretic mobilities and for addressing experiments were fabricated. Electrophoretic mobilities of salty droplets always exceeded the value of \(1\times 10^{-7}\, \hbox {m}^2\hbox {V}^{-1}\hbox {s}^{-1}\), which is about by one magnitude higher value than those typically measured in water–oil droplet systems. The electrophoretic mobilities in systems with free surface are the same or even smaller than in closed microfluidic structures, which is accounted mainly to the fact that a significant part of salty droplets is exposed to air and does not contribute to droplet forcing. Series of addressing and merging experiments in a microfluidic chip shows that DC electric field can be used as a powerful tool for smart manipulation of droplets in microfluidic systems with PEG/salt ATPS.     

Decontamination of Radionuclides from Concrete by Microwave Heating. I: Theory

The paper analyzes a proposed scheme of decontamination of radionuclides from concrete structures, in which rapid microwave heating is used to spall off a thin contaminated surface layer. The analysis is split in two parts: (1) the hygrothermal part of the problem, which consists in calculating the evolution of the temperature and pore pressure fields, and (2) the fracturing part, which consists in predicting the stresses, deformations and fracturing. The former is assumed to be independent of the latter, but the latter is coupled to the former. The heat and moisture transfer governing the temperature and pore pressure fields induced by the decontamination process is analyzed using an improved form of Ba?ant and Thonguthai’s model for heat and moisture transfer in concrete at high temperatures. The rate of the distributed source of heat due to the interaction of microwaves with the water contained in concrete is calculated on the basis of the standing wave normally incident to the concrete wall. Since the microwave time period is much shorter than the time a heating front takes to propagate over the length of microwave, and since concrete is heterogeneous, the ohmic power dissipation rate is averaged over both the time period and the wavelength. The reinforcing bars parallel to the surface are treated as a smeared steel layer. The recently developed microplane model M4 serves as the constitutive model for nonlinear deformation and distributed fracturing of concrete. Application of the present model in numerical computations is relegated to a companion paper which follows.     

Random growth of crack with R-curve: Markov process model

A probabilistic model for the randomness of the progressive crack growth in a quasi-brittle material such as concrete is presented. The model consists of a Markov chain adapted to R-curve behavior. It yields the crack propagation probability in any loading step as well as the probability of failure at any stage of the fracture process. The R-curve is obtained from the given test data on the effect of structure size on the maximum loads. The standard deviation of the peak load is the minimum statistical information required. According to the available test results, this standard deviation is approximately a linear function of the crack propagation distance. The parameter estimation method is formulated and some applications are illustrated.