A Systematic Analysis of Foam Drainage and Stability: Measurements, Mechanisms, and Implications for Anaerobic Digester Foaming

The formation of a substantial foam layer has severe impacts on the overall digestion process that is responsible for the major portion of waste stabilization. An understanding of dynamics of foam produced by three primary causes - dispersed gas bubbles, surface-active materials, and hydrophobic compounds - provides insight into the prevention of the foam layer and into the control of the foam stability. To better understand the mechanisms in three-phase foam dynamics, we developed a systematic methodology to characterize foam drainage behavior using electrical conductance measurements.With no sludge conditions, all tested sodium dodecyl sulfate (SDS) foams exhibit a node-dominated drainage regime with high mobility at bubble surfaces. Drainage regime under similar foaming conditions was consistent with existing drainage studies using other measurement techniques in the literature. The drainage of sodium dodecylbenzenesulfonate (SDBS) surfactant solution, a commercial form of linear alkylbenzene sulfonate (LAS) that is most frequently found in anaerobic sludge, was studied in detail by several approaches. Two complementary methods of macroscopic drainage investigations (forced and free drainage) were conducted to gain confidence in its validity. The experimental data can be fitted using a power law with an exponent of 1/3 for forced drainage and of 1.0 for free drainage. These data indicate the following drainage behavior: mobile bubble surfaces, causing plug-like flow within Plateau borders, thus dissipation mainly occurs inside the nodes.With the drainage studies for a variety of aqueous surfactant solutions, experimental and theoretical studies to include wastewater sludge are important for understanding the stability of three-phase foams, and therefore foaming in anaerobic digesters. The drainage behavior of sludge-containing foams was characterized by our developed method. The presence of anaerobic sludge at total solid (TS) concentrations of approximately 2.5-2.8% induced a transition from the node-dominated regime to a Plateau-border (PB)-dominated regime. This apparent transition was verified in both forced and free drainage experiments. These drainage studies supported a more detailed estimation of foam stability in relation to its structure. In summary, our developed method using the electrical conductance measurements was applied to understand the key aspects of foam stability required for prediction and control of foaming in anaerobic digesters. A systematic methodology for assessing foam dynamics was proposed and discussed in two- and three-phase foams

Engineered Approaches to Facile Identification of Tiny Microplastics in Polymeric and Ceramic Membrane Filtrations for Wastewater Treatment

Wastewater treatment plants (WWTPs) contribute to the release of significant quantities of microplastics into the aquatic environment. The facile identification of microplastics and an understanding of their occurrence and transport through WWTPs are essential for improving microplastic retention. Potential microplastic treatment technologies for both polymeric and ceramic membrane filtrations were systematically investigated to inform decisions on the optimal choice of membrane for effective microplastic retention. A blocking filtration model, based on a simple linear regression fitting, was used in experiments on the filtration of microplastic suspensions to determine the relative importance of individual fouling mechanisms. Unlike the commonly applied spectroscopic techniques, the facile identification approaches, that are closely related to the amounts of particles within wastewater samples, attempted to identify tiny microplastics (<1.0 μm) by comparing them against silica particles for reference. A larger decline in the normalized permeate flux was observed for 0.1 μm polystyrene microplastics, while standard pore blocking appeared to be the dominant fouling mechanism for all membranes. More microplastics based on turbidity and total solids were removed using the ceramic membrane than the other polymeric membranes. However, fewer microplastics, based on the particle size distribution analysis, were removed using the ceramic membrane as the pore size measurements gave a relatively large pore size for the ceramic membrane, compared with other polymeric membranes; even though a nominal pore size of 0.1 μm for all membranes were provided by the suppliers. The contribution of microplastic-containing synthetic wastewaters to overall flux decline was significantly greater than those of identical microplastic suspensions because of the aggregation of larger microplastics with dissolved organic matter in synthetic wastewater, leading to the formation of a cake layer on the membrane surface. Despite the challenges associated with the facile identification approaches, our findings provided deeper insights and understanding of how microplastics behave in membrane filtration, which could enable the application of potential microplastic treatment technologies

Polymer Having Dicationic Structure in Dumbbell Shape for Forward Osmosis Process

The thermal-responsive polymers, poly(alkane-1,#-diylbis(tri-n-butylphosphonium) 4-vinylbenzenesulfonate) (PSSBP#, # = 8, 6, and 4), where # is the number of carbon atoms in the central bridge structure of the dicationic phosphonium moiety, were synthesized to examine their potential application as draw solutes in forward osmosis (FO). The polymers exhibited low critical solution temperature (LCST) characteristics in aqueous solutions, which is essential for recovering a draw solute from pure water. The LCSTs of the 20 wt% aqueous solutions of PSSBP8, PSSBP6, and PSSBP4 were confirmed to be approximately 30, 38, and 26 °C, respectively, which is advantageous in terms of energy requirements for the recovering draw solute. When the concentration of the PSSBP4 draw solution was 20 wt%, water flux and reverse solute flux were approximately 1.61 LMH and 0.91 gMH, respectively, in the active layer facing the draw solution (AL-DS) system when the feed solution was distilled water. The PSSBP# thermal-responsive draw solute has considerable potential for use as a next-generation draw solute because of its excellent osmotic performance and efficient recovery. Therefore, this study provides inspiration for novel ideas regarding structural transformations of polymers and their applicability as draw solutes

Vertical Liquid Crystal Alignment of Comb-Like Alkyl Hydroxybenzoate-Substituted Polystyrene

We investigated the liquid crystal (LC) alignment behaviors of butyl hydroxybenzoate-substituted polystyrene (PBHB#; # = 20, 40, 60, 80, and 100, where # indicates the molar fraction of butyl hydroxybenzoate in the side chain), methyl hydroxybenzoate-substituted polystyrene (PMHB100), and ethyl hydroxybenzoate-substituted polystyrene (PEHB100). Generally, LC cells made employing polymer films having longer alkyl groups in the side chain show vertical LC alignment. For instance, a LC cell fabricated with the PMHB100 film showed random planar LC alignment, while the LC cells made from the PEHB100 and PBHB100 films exhibited vertical LC alignment. Moreover, LC cells prepared from a polymer film having a higher molar content of butyl hydroxybenzoate in the side chain exhibited vertical LC alignment. The observed vertical LC alignment behaviors are closely related to the surface energy of these polymer films. For instance, vertical LC alignment was observed when the surface energy of the polymer film was less than ~43.86 mJ/m2, which could result from the nonpolar alkyl groups of the alkyl hydroxybenzoate moiety. The LC cell prepared from PBHB100 as the LC alignment layer showed good electro-optical characteristics such as voltage holding ratio, residual DC voltage, and alignment stability at 200 °C

Recent Advances in Structural Design of Efficient Near‐Infrared Light‐Emitting Organic Small Molecules

Organic light-emitting materials in the near-infrared (NIR) region are important to realize next-generation lightweight and wearable applications in bioimaging, photodynamic therapy, and telecommunications. Inorganic and organometallic light-emitting materials are expensive and toxic; thus, the development of purely organic light-emitting materials is essential. However, the development of highly efficient NIR light-emitting materials made of organic materials is still in its infancy. Therefore, this review outlines molecular design strategies for developing organic small-molecule NIR light-emitting materials with high emission efficiency that can overcome the energy-gap law to be applied to next-generation wearable devices. After briefly reviewing the basic knowledge required for the NIR emission of organic molecules, representative high-efficiency molecules reported over the past 5 years are classified according to their core moieties, and their molecular design, physical properties, and luminescence characteristics are analyzed. Further, the perspective and outlook regarding the development of next-generation high-efficiency NIR organic light-emitting materials are provided.11Nsciescopu

Genetic Relationship of Productive Life, Production and Type Traits of Korean Holsteins at Early Lactations

The present study was performed to study the genetic relationship of productive life with production and type traits of Korean Holsteins at first three lactations. The data for the analysis from 56,054, 28,997, and 11,816 animals of first, second and third parity cows which were born from 2006 to 2011 were collected by Dairy Cattle Improvement Center, National Agricultural Co-operative Federation. Milk, protein and fat yields adjusted for 305 days and average somatic cell score considered as production traits and analyzed type traits were stature, strength, body depth, dairy form, rump angle, rump width, rear leg side view, foot angle, front attachment placement, rear attachment height, rear attachment width, udder cleft, udder depth, front teat placement and front teat length. A multi trait genetic analysis was performed using Wombat program with restricted maximum likelihood animal model composed of fixed effect of birth year, farm and the random effect of animal and random residual effect according to the traits. Heritability estimates of productive life were between 0.06 and 0.13. Genetic and phenotypic correlations between production and productive life traits ranged from 0.35 to 0.04 for milk, 0.16 to 0.05 for protein and 0.18 to 0.02 f 15-0034 (2nd) 150520 or fat. Somatic cells score showed a negative genetic and phenotypic correlation with productive life and also udder type traits, indicating that the selection for higher udder traits will likely to improve resistance to mastitis and persistence in the herd. Among all dairy form type traits, udder characters such as udder cleft showed a significant relationship with productive life. However, a specific change of heritabilities or correlations were not observed with the change of parity. Moreover, further studies are needed to further confirm the significance of the above traits and the effect of parity on above relationships in order to minimize both voluntary and involuntary culling rates while improving herd health and maintaining high yielding dairy cows

Oxidation of microcystin-LR by the Fenton process : Kinetics, degradation intermediates, water quality and toxicity assessment

The Fenton process was assessed as a cost-effective technology for the removal of Microcystin-LR (MC-LR) among UV, UV/H2O2, and Fenton process according to efficiency and electrical energy per order (EE/O). The determined practical concentrations of the Fenton reagents were 5 mg/L Fe(II) and 5 mg/L H2O2, respectively. The Fenton process is a fast reaction, completed within 5–30 min (Fe(II), H2O2 = 0.2–10 mg/L; MC-LR0 = 200 μg/L). The degradation intermediates of MC-LR by the Fenton process were firstly reported as m/z 1029.5, 1011.5, 835.5, 795.4, and 783.4, associated with the diene bond in the Adda chain, then alleviate their toxicity. The effects of organic matter were examined in the range of Nak-Dong River water, as a drinking water source, monitored for six months in 2015. Fulvic acid was affected more than humic acid and natural organic matter (NOM). The degradation efficiency in the raw water was lower than that of distilled water because of the competing effect of NOM, geosmin, and 2-methylisoborneol, and the higher pH (7.64), furthermore, dissolved organic matter, geosmin, and 2-methylisoborneol was removed 7.39%, 4.28% and 12.30% after the Fenton process in the river water. The final concentration of MC-LR after treatment was under the drinking water guideline level with initial MC-LR concentration of 2 μg/L. No acute toxicity was observed to Daphnia magna (TU = 0) after the Fenton process

Oxidation of microcystin-LR by the Fenton process : Kinetics, degradation intermediates, water quality and toxicity assessment

The Fenton process was assessed as a cost-effective technology for the removal of Microcystin-LR (MC-LR) among UV, UV/H2O2, and Fenton process according to efficiency and electrical energy per order (EE/O). The determined practical concentrations of the Fenton reagents were 5 mg/L Fe(II) and 5 mg/L H2O2, respectively. The Fenton process is a fast reaction, completed within 5–30 min (Fe(II), H2O2 = 0.2–10 mg/L; MC-LR0 = 200 μg/L). The degradation intermediates of MC-LR by the Fenton process were firstly reported as m/z 1029.5, 1011.5, 835.5, 795.4, and 783.4, associated with the diene bond in the Adda chain, then alleviate their toxicity. The effects of organic matter were examined in the range of Nak-Dong River water, as a drinking water source, monitored for six months in 2015. Fulvic acid was affected more than humic acid and natural organic matter (NOM). The degradation efficiency in the raw water was lower than that of distilled water because of the competing effect of NOM, geosmin, and 2-methylisoborneol, and the higher pH (7.64), furthermore, dissolved organic matter, geosmin, and 2-methylisoborneol was removed 7.39%, 4.28% and 12.30% after the Fenton process in the river water. The final concentration of MC-LR after treatment was under the drinking water guideline level with initial MC-LR concentration of 2 μg/L. No acute toxicity was observed to Daphnia magna (TU = 0) after the Fenton process

Evaluation of diffusion coefficients as surrogate indicators for electrostatic repulsion in ultrafiltration membrane fouling

Impacted by the electrostatic repulsion between ultrafiltration (UF) membranes and natural organic matter (NOM), organic fouling precipitates significant operational difficulties in water treatment facilities. This study investigated the applicability of diffusion coefficients as surrogate indicators to evaluate the electrostatic repulsive forces between NOMs and UF membrane surfaces. We utilized three distinct types of NOMs and three different UF membranes, each possessing different charge characteristics. Notably, we found that the reduction in diffusion coefficients was markedly pronounced when membranes rich in ionizable functional groups with strong negative charges were involved, indicating heightened electrostatic repulsion. To confirm the reliability of diffusion coefficient reduction as a surrogate indicator of the electrostatic repulsive force, a comprehensive membrane fouling test was conducted. The results revealed a strong correlation between the two parameters, enhancing our understanding of the intricate dynamics of membrane fouling (R2 = 0.9744-0.9907). Thus, this study proposes the concept of utilizing the reduction in the diffusion coefficient as a surrogate indicator to represent the electrostatic repulsive force between NOMs and the UF membrane surface. This innovative approach contributes to enables proactive and predictive assessments of membrane performance, fostering a shift toward proactive maintenance and enhances the operational efficiency of water treatment facilities