Comparison of a sMBR and a CASP system for wastewater reclamation and re-use

The performance of a submerged membrane bioreactor (sMBR) for municipal wastewater reclamation and re-use was compared with that of a current classic activated sludge process (CASP). The average chemical oxygen demand (COD) of CASP effluent was 75 mg/l, while the average COD of sMBR filtrate was 15 mg/l. In general, COD removal was above 98%. However, the best results were obtained at a sludge rentention time (SRT) of 50 days. The total phosphorus (TP) content of the filtrate decreased to a level <1 mg/l under aerobic conditions in which aeration occurred continuously. It was shown that the filtrate TP and orthoposphate (Orto-P) concentrations increased dramatically during the periods of intermittent aeration because phosphorus is released under anoxic conditions. In the CASP effluent, the average TP and Orto-P were 7.9 mg/l and 7.1 mg/l, respectively. The filtrate was free of suspended solids (SS) and total coliform bacteria. The effluent SS in the CASP was 40 mg/l. The turbidity removal in the sMBR reached almost 99%, i.e. generally less than 1 NTU, while the average turbidity of the CASP effluent was almost 15 NTU. The removal of ammonium nitrogen (NH₄⁺-N) in the sMBR was almost 99.8%. In addition, the nitrate concentration in the filtrate decreased to 2.4 mg/l under both aerobic & anoxic conditions. It was shown that both nitrification and denitrification could be successfully reduced through intermittent aeration. Average total Kjeldehl nitrogen (TKN) and NH₄⁺-N in the CASP effluent were 30.2 mg/l and 20 mg/l, respectively, i.e. the nitrification efficiency was 42.9%, and the denitrification value was not available. When these results are compared with those in the CASP, it indicated that the sMBR could be successfully used for reclamation and re-use of municipal wastewater.     

Electrorheological properties of kaolinite,polyindole, and polyindole/kaolinite composite suspensions

In this study, polyindole (PIN) and polyindole/kaolinite (PIN/KAO) composite were synthesized by free radical polymerization using FeCl₃ as an initiator. Average particle sizes (d₅₀) of PIN and PIN/KAO composite were determined by dynamic light scattering (DLS) as 7.2 and 6.2 μm, respectively. The samples were characterized by FTIR, elemental analysis, DSC/TGA and SEM measurements. Suspensions of KAO, PIN, and PIN/KAO composite were prepared in silicone oil (SO) and the sedimentation stabilities were determined. Electrorheological (ER) properties of these suspensions were studied as a function of dispersed phase concentration, shear rate, shear stress, and temperature; and yield stresses and excess shear stresses determined. Further, dielectric properties of KAO, PIN, and PIN/KAO composite were investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Estimation of thermal and flow fields due to natural convection using support vector machines (SVM) in a porous cavity with discrete heat sources

Support vector machines (SVM), a soft programming technique, has been used to estimate the temperature distribution and flow fields in a square porous enclosure heated discretely by three isothermal heaters from the left vertical wall. Right vertical wall of the cavity was isothermal but it has colder temperature than the heaters while remaining walls were adiabatic. A database was prepared by solving the governing equations which were written using Darcy flow model. Using finite difference method to discretize the equation, a computational fluid dynamics (CFD) code was written. A correlation was developed between Nusselt and Rayleigh numbers. Using obtained database, further values of temperature and velocities were estimated by SVM technique at different Rayleigh numbers and locations of heater. It was observed that SVM was a useful technique on estimation of streamlines and isotherms. Thus, SVM reduces the computational time and helps to solve some cases when CFD fails to solve due to numerical instability.     

Effect of osmotic pretreatment and microwave frying on acrylamide formation in potato strips

BACKGROUND: The presence of acrylamide, a probable carcinogen, is currently a major concern relating to the consumption of fried products. Therefore, recent frying studies have focused on ways of reducing the acrylamide content. The main objective of the present study was to determine the effects of microwave frying and osmotic treatment prior to frying on acrylamide formation in potato strips. RESULTS: Potatoes fried using 400 W microwave power for 1.0 min had an 87.85% lower acrylamide content than potatoes fried conventionally for 4.5 min (i.e. an 81.82% reduction in frying time) but a comparable moisture content. The acrylamide content of fried potatoes treated osmotically prior to both microwave and conventional frying was found to be lower than that of fried potatoes not pretreated osmotically. However, the reduction in acrylamide content was lower when osmotic treatment was applied before microwave frying. CONCLUSION: As a result of this study, it was concluded that microwave frying can be an alternative to conventional frying. Copyright © 2007 Society of Chemical Industry     

Characterization of water distribution in xanthan-curdlan hydrogel complex using magnetic resonance imaging, nuclear magnetic resonance relaxometry, rheology, and scanning electron microscopy

Abstract: Xanthan‐curdlan hydrogel complex (XCHC) has been shown capable of retaining moisture up to 5 freeze‐thaw cycles (FTCs); however, moisture distribution in the complex in relation to the hydrogel composition and structure remains uncharacterized. In the present study, magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR) relaxometry, rheology, and scanning electron microscopy (SEM) were used to examine the effect of water distribution and interaction with 2.0% aqueous solutions of xanthan, curdlan, and XCHC consisting of equal amounts of both polysaccharides. A gel structure with an indication of syneresis was clearly seen in the MR image of curdlan alone, whereas the distribution of protons throughout xanthan and XCHC samples remained homogeneous and showed no detectable syneresis. The three‐dimensional network, indicated by frequency sweeps, of curdlan was responsible for curdlan's gel structure. The frequency sweep and slope of the storage modulus (G′) of XCHC was significantly closer to curdlan with higher elasticity and less dependency upon angular frequency than xanthan alone. The reduction in XCHC dynamic moduli (G′ and G″) compared to curdlan could be attributed to the formation of wavy layers instead of a fully cured three‐dimensional structure. Addition of xanthan to curdlan restricted XCHC spin–spin relaxation time (T₂) to intermediate and slower exchange regimes, namely approximately 110 and 342 ms, respectively, promoting the polymer's interaction with water while inhibiting interpolymer interactions found in curdlan. A 3rd proton pool with the slowest T₂ seen in curdlan was not found in XCHC, correlating to the absence of syneresis. Practical Application: The combination of texture measurements and discrete noninvasive techniques was found capable of providing insightful understanding of water distribution in a gel system. These techniques may be applied to other hydrogel complexes. The XCHC system investigated has the potential to enhance freeze‐thaw stability in frozen food products by minimizing syneresis due to undesirable temperature fluctuations during distribution and consumer application.     

The Synthesis and Characterization of s-Triazine-Cored and [Fe(III)Salen]-Capped Polymer Complexes

2,4,6-Trichloro-1,3,5-triazine (cyanuric chloride, C₃N₃Cl₃, 1) was used as the starting material. 2-(4-Carboxyphenylamino)-4,6-dichloro-1,3,5-triazine (2) was obtained from the reaction of cyanuric chloride with 4-aminobenzoic acid in the presence of sodium bicarbonate in acetone. A mononuclear complex (4) was obtained by reacting 2 and [FeSalen]₂O (3). A series of polymeric compounds was obtained by reacting 4 with a series of diamines. The polymeric complexes were characterized by elemental analysis, AAS, FT-IR, ¹H NMR, TGA and magnetic susceptibility measurements. The complexes are low-spin, distorted octahedral Fe(III) species that are bridged by carboxylic acids. The [FeSalen]-containing compounds may have the electronic structure t_2g⁵e_g⁰. All the complexes have six coordination and are polymeric.     

Entropy production due to free convection in partially heated isosceles triangular enclosures

A numerical analysis of the entropy production has been performed due to natural convection heat transfer and fluid flow in isosceles triangular enclosures with partially heated from below and symmetrically cooled from sloping walls. Governing equations are solved by finite difference method. Governing parameters on flow and temperature fields are Rayleigh number (10³  Ra  8.8 × 10⁵), dimensionless length of heater (0.25  (ℓ′ = ℓ/L)  1.0), dimensionless location of heater (0.25  (c′ = c/L)  0.75) and inclination angle of slopping walls (30°  β  60°). Heat transfer results are presented in terms of local and mean Nusselt numbers (Nu) while entropy production results are shown with entropy production number (N_s) and Bejan number (Be). Isotherms, streamlines, contours of entropy production due to heat transfer and fluid friction irreversibility are plotted. It is observed that entropy production number increases but Bejan number decreases with increasing of Rayleigh number. However, both entropy production due to heat transfer and fluid friction irreversibility are affected by higher inclination angle of triangle and length of heater.     

Glycation of soy protein isolate with two ketoses: d-Allulose and fructose

Modification of food proteins to have improved functional properties is of great importance. In this study, modification of soy protein isolate (SPI) was achieved through glycation. SPI was glycated in a spray dryer (SD) and an incubator followed by freeze drying (FD). d -Allulose, an important rare sugar, was used in SPI glycation as the carbohydrate source, and results were compared with fructose. In addition to the sugar type, two different SPI powder: sugar ratios (1:1 and 5:1) were investigated. For the glycated samples, emulsification activity, free amino groups, protein solubility, Fourier-transform infrared spectroscopy analysis, antioxidant activity experiments and time-domain NMR relaxometry measurements for hydration were conducted. According to the results, the solubility of SPI that is limited in native form has shown a significant improvement after glycation through both FD and SD methods. Besides, glycation through the FD method was found to be more favourable due to its milder conditions than the SD method. Considering the physicochemical properties, the best combination for the highest glycation degree was found to be the samples prepared at the 1:1 ratio with d -Allulose in the FD method. Overall, it was concluded that glycation of SPI enhanced its functional properties such as antioxidant and emulsification activities.     

Determination of the quality and purity characteristics of olive oils obtained from different regions of Turkey,depending on climatic changes

Virgin olive oils (VOOs) obtained from olives grown in different regions of Turkey under changing climatic conditions sometimes show different sensory and chemical properties. This study was planned to determine whether these deviations are due to climatic changes or not. For this purpose, five different olive varieties (Ayvalık, Memecik, Gemlik, Nizip Yağlık, Kilis Yağlık) of commercial importance were harvested from the provinces/districts (four different region) where cultivation is intense during the 2017/2018–2020/2021 harvest years. Every year, olive samples were collected from 3 orchards from 13 provinces/districts. One hundred and fifty-six samples were subjected to the purity, quality and sensory analysis. Basic climatic values (average, minimum and maximum temperature, humidity and precipitation) were examined for four consecutive years. All of the examined olive oil samples were determined within the legal limits in terms of fatty acid composition and fatty acid ethyl ester values. However, delta-7-stigmastenol value from the sterol composition was found to be above 0.5% in some samples in all the years studied (total 21 samples). Delta-7-stigmastenol values of olive oil samples varied between 0.16% and 1.14%. Multiple linear regression analysis was applied using a genetic algorithm-based inverse least squares method to determine whether there is a relationship between climate data and delta-7-stigmastenol values. According to this result, it has been determined that the delta-7-stigmastenol value is high when the annual average relative humidity is low and the annual average temperature is high. There is an urgent need to make forward-looking plans due to climate change.     

Investigation of the performance of carbide cutting tools with hard coatings in hard milling based on the response surface methodology

Machining of hard materials has become a great challenge for several decades. One of the problems in this machining process is early tool wear, and this affects the machinability of hard materials. In order to increase machinability, cutting tools are widely coated with nanostructured physical vapor deposition hard coatings. The main characteristics of such advanced hard coatings are high microhardness and toughness as well as good adhesion to the substrate. In this paper, the influence of hard coatings (nanolayer AlTiN/TiN, multilayer nanocomposite TiAlSiN/TiSiN/TiAlN, and commercially available TiN/TiAlN) and cutting parameters (cutting speed, feed rate, and depth of cut) on cutting forces and surface roughness were investigated during face milling of AISI O2 cold work tool steel (～61 HRC). The experiments were conducted based on 3¹³ factorial design by response surface methodology, and response surface equations of cutting forces and surface roughness were obtained. In addition, the cutting forces obtained with the coated and uncoated tools were compared. The results showed that the interaction of coating type and depth of cut affects surface roughness. The hard coating type has no significant effect on cutting forces, while the cutting force F _z is approximately two times higher in the case of uncoated tool.