Polymeric Substances Research Articles

Perbedaan metode pembuatan VCO antibakteria terhadap sifat Fisikokimia, dan uji organoleptik, Antibakteri VCO terhadap Bakteri Staphylococcus Aureus

Wounds have slowed healing due to the formation of biofilms, which are the surface formation of bacterial cells that are covered by the polymeric substance. Staphylococcus aureus is a gram-positive bacteria that play a role in producingmultilayer in biofilms and is very easy to resistant to antibiotics. VCO has the ability as ana anti-bacterial content based on lauric acid and kaprat acid. This study used experimental Quasy with a mixed Methode method. VCO is made with 3 methods, fishing, heating and mixing on physicochemical test. Physicochemical test results show, the highest water content is found in the VCO heating, the same three-type weight, the highest peroxide number is in the VCO mixing and the highest free fatty acids on the VCO fishing. The results of antibacterial test with Kirby-Baur method There is no barrier zone from the 3 types of VCO. VCO used as a topical is VCO fishing.The results of a test analysis of the results of observations in patients as much as 15 people for 9 days in 3 treatments with chronic wounds obtained p < 0.05 (0.000) which means during the treatment that the wound condition is better. Keyword : Organoleptic, Staphylococcus aureus, Physicochemical, VCO

Assessment of cassava peels as renewable substrate for production of poly-γ-glutamic acid by Bacillus subtilis

Poly-γ-glutamic acid (γ-PGA) is a polymeric substance with diverse applications as thickening, anti-freezing, sticking and bitterness relieving agent. This study was aimed at utilizing cassava peels as the major substrate for production of γ-PGA by Bacillus subtilis. Pretreatment of the cassava peels was carried out using alkali, acid and organosolv methods. Effects of different carbon, nitrogen and process parameters were subjected to one-factor-at-a-time method. The raw cassava peel gave significantly (p < 0.05) higher yield of γ-PGA of 3.20 ± 0.08 mg/g when compared with all the other pretreated samples. The highest yield of γ-PGA (6.23 ± 0.13 mg/g) was obtained in a medium containing 1% (w/w) citric acid and 0.5% (w/w) (NH4)2SO4, initial moisture content 65%, inoculum concentration at 2% and incubation time of 4 days at 35 °C. Following the FTIR analysis, γ-PGA samples showed characteristic amide absorption at ~ 3753.4 cm−1, carbonyl absorption at 1600–1636.4 cm−1, and hydroxyl absorption at 3200–3276.3 cm−1. The relative viscosity (9.92 ± 0.06 mPas), and melting point (193 ± 0.04 °C) were found to be comparable with the values obtained for commercially available γ-PGA. This study demonstrates that cassava peels can be utilized as renewable raw material for production of γ-PGA by B. subtilis.

Zwitter‐wettable acrylic polymeric coating on glasses for anti‐fog applications

AbstractAnti‐fog coatings have received significant attention because of their versatile applications to reduce light scattering during high humid conditions. Primarily, hydrophilic/superhydrophilic coatings are applied upon the transparent substrate to improve visibility at high humidity. The high solubility of the hydrophilic/superhydrophilic coatings in water is the main drawback for their long‐term operational durability. We will report for the first time the development of functional copolymers which produces water insoluble hydrophilic coating upon application on glass surfaces. Such surfaces are commonly known as “Zwitter‐Wettable” surfaces that have been developed from entirely polymeric substances using methacrylic and acrylic monomers. A series of random copolymers were synthesized using free radical polymerization of the common and commercially available monomers which were subsequently characterized using various analytical techniques, such as, GPC, 1H‐NMR, and FTIR. These newly designed copolymers contained both the hydrophobic parts made up of methyl and 2‐ethylhexyl groups, which provide good stability under high humid conditions and hydroxyl and carboxylic acid groups which will provide the required hydrophilicity or water absorption capacity. These polymeric coatings on the glass surfaces exhibit water advancing contact angles in the range of 57 ± 3° to 78 ± 3° with excellent anti‐fog property. The anti‐fog property of the polymeric films could be tuned easily by changing the ratio of hydrophobic and hydrophilic monomers.

Effect of extracellular polymer substances on the tetracycline removal during coagulation process

In this study, the effect of extracellular polymer substances on the tetracycline removal under hydroxyl aluminium treatment was investigated, and the molecular mechanisms of extracellular polymeric substances mediated coagulation of tetracycline were also explored. The results show that the presence of extracellular polymeric substances could significantly enhance the removal efficiency of tetracycline in hydroxyl aluminium coagulation. Findings suggest that tyrosine and tryptophan in extracellular proteins acted as binding sites to capture tetracycline. Evidences provided by the density functional theory calculations in combination with spectroscopy analysis indicated that two main mechanisms accounted for tetracycline removal in the presence of extracellular polymeric substances and polyaluminum chloride: (1) amino group in proteins and carbonyl in tetracycline were bridged by Al3+; (2) benzene rings in tryptophan and tyrosine were π–π stacked with tetracycline, and the amino group in complexes were further coordinated with Al3+.

Removal of heavy metal ions by ultrafiltration with recovery of extracellular polymer substances from excess sludge

To solve the difficult problem of separating extracellular polymeric substances (EPSs) with adsorbed heavy metal ions (HMIs) from aqueous solutions, EPS recovery and HMI adsorption were combined into dead-end ultrafiltration (EPS-enhanced ultrafiltration, EPS-UF). First, an EPS solution was concentrated via UF into a cake on the membrane, which was then used to filter heavy-metal-containing wastewater. EPS-UF could effectively remove HMIs in wastewater, with a 94.8% Pb2+ removal efficiency and 85.5% EPS recovery efficiency with concentrations of 0.1 g/L EPS and 10 μM Pb2+. During concentration, the filtration resistance increased with increasing filtration pressure because of the high compressibility of the EPS cake and as filtration proceeded. During removal, a high filtration pressure (200 kPa) could not increase the filtration rate, and the removal efficiency of Pb2+ decreased markedly (78.9%). Ca2+ was proposed as a strategy for controlling membrane fouling because it was completely released from the cake after adsorbing Pb2+ and barely affected the characteristic groups in EPS. Fourier transform infrared and X-ray photoelectron spectroscopy revealed that carboxyls or esters from carboxylate and uronic acids in EPS bonded with HMIs via ion exchange or complexation, and the main characteristic groups in EPS remained unchanged, while more complex proteins formed.

Exploration of potential jarosite biomineralization mechanism based on extracellular polymer substances of Purpureocillium lilacinum Y3

In the present study, the mechanism of jarosite biosynthesis mediated by extracellular polymer substances (EPSs) of Purpureocillium lilacinum strain Y3 at gene level was investigated. Yellow-ocher jarosite minerals covered mycelia pellets entirely within 72h, corresponding to a reduction of Fe3+ of 70.9% in the biomineralization process induced by P. lilacinum Y3. The maximum biomass accumulation reached to 12.9 g/L in pure culture, 2.8 g/L with only 0.02M Fe3+ addition, and 6.4 g/L with both 0.02M Fe3+ and 0.1M K+ addition, respectively, indicating that jarosite biosynthesis largely alleviated the inhibition of Fe3+ to the fungal strain. Thereafter, the analysis of EPSs compositions suggested that protein content was affected more evidently than polysaccharides in the biomineralization system. Furthermore, real time quantitative PCR assays revealed that signal transduction genes and abundance of membrane transporters were activated quickly in responding to the stimulation of Fe3+ and fungus-mineral interactions. Then, the expression of adhesive proteins and extracellular proteins was highly up-regulated to facilitate the formation of jarosite minerals on the cell surface. Finally, X-ray photoelectron spectroscopy analysis supported that amine, carboxyl, phosphate groups present on the mycelia provided Fe3+ and K+ binding sites for biosynthesis of jarosite.

Tuning the Wettability and Surface Free Energy of Poly(vinylphenol)Thin Films by Modulating Hydrogen-Bonding Interactions.

The ability to tune the surface properties of a polymer film in a simple and effective manner is important for diverse biological, industrial, and environmental applications. In this work, we investigated whether or not the surface free energy of poly(vinyl phenol; PVPh) can be tuned by adjusting the casting solvent and the thermal treatment time, which alters the proportions of intra-and intermolecular hydrogen bonding interactions. Compared to the untreated sample, in tetrahydrofuran (THF) system, the thermal treatment resulted in a lower proportion of intermolecular hydrogen bonds and a concomitant decrease in the surface free energy (from 39.3 to 18.8 mJ/m2). In contrast, the thermal treatment in propylene glycol methyl ether acetate (PGMEA) and ethyl-3-ethoxypropionate (EEP) systems increased the proportion of intermolecular hydrogen bonds and the surface free energy of the polymer thin films, from 45.0 to 54.3 mJ/m2 for PGMEA and from 45.5 to 52.9 mJ/m2 for EEP. Controlling intermolecular hydrogen-bonding interactions is a unique and easy method for tuning the surface free energies of polymer substances.

Role of Biofilms in Microbiologically Influenced Corrosion of Metals

Data obtained in the recent years on the effect of bio-films in the development of metal microbiologically influenced corrosion (MIC) are summarized. The main way of sessile cells adaptation and survival on metal surfaces lies in formation of biofilms consisting of living cells surrounded by a multicomponent extracellular polymer substance (EPS). Biosystem created possesses new properties that are different from the properties of individual components. Biofilm ways of formation, growth and survival, functions of the extracellular matrix in regard to the microbial consortium and to the metal surface are presented. Mechanisms of biocorrosion involving the electron transmembrane transition from a metal to the living cell cytoplasm, as well as the extracellular pathways of metal oxidation under aerobic and anaerobic conditions, are considered.

Design 30 GT Catamaran Fishing Boat with Variations of Hull Type and Inter-Demihull Length for Minimum Resistance

Fuel savings are closely related to ship resistance. Research on reducing resistance continues to be done in various ways, ranging from hull modification, optimization of the propulsion system and the addition of polymer substances. Resistance are also influenced by ship’s velocity and variations of inter-demihulls length. This challenge has been widely discussed by experts, especially the variety of inter-demihull length. This research aims to analyze the 30 GT catamaran fishing boat resistance with variations in hull type and inter-demihull length. The main aim is to get the obstacle characteristics of these variations. The advantage of this research lies in the more varied shapes and inter-demihull lengths of each model where the characteristics of the obstacles will also vary, so that this research can later be an alternative for the community in the use of catamarans to increase fishing productivity. The study was conducted using CFD (Computational Fluid Dynamics). From the results, one of the most optimal form of the model is the type of hull Symmetrical Hard Chine with a variation of S / L 0.5 at maximum speed.Tthis model has a wave resistance value of 9.87 kN, a viscous resistance of 5.04 kN, and a total resistance value of 14.92 kN. Where there is a reduction of the wave resistance of 12.1%, viscous resistance of 1.5%, and a total resistance of 8.779% from the original model. Another advantage of this type for the Purseseine Boat is the use of a fairly wide deck for the laying of fishing gear.

Design of pH-Responsive Dissociable Nanosystem Based on Carbon Dots with Enhanced Anti-biofilm Property and Excellent Biocompatibility.

Bacterial biofilm poses a serious threat to human health, leading to increased and prolonged bacterial infections. How to solve the problem of eliminating biofilms effectively and rapidly while being nontoxic to normal cells is still a challenge. Here, we design a pH-sensitive anti-biofilm nanosystem formed by self-assembly between negatively charged carboxyl groups of poly(ethylene glycol_-COOH-polyethylenimine-2,3-dimethylmaleic anhydride (PPD) and positively charged amines on the surface of carbon dots derived from the ashes of calcined l-lysine powder (CDLys) (PPD@CDLys for short). The outmost copolymer could make PPD@CDLys facilely diffuse into the dense biofilm and reverse to be positively charged via hydrolysis, which lead to the acid-triggered disassembly of the nanosystem. After hydrolyzation, PPD would turn into a biocidal cationic polymer, which is prone to attaching on bacteria inside the biofilm and efficiently killing them. In addition, the released CDLys could induce intracellular reactive oxygen species (ROS) across the whole biofilm to degrade the matrix of extracellular polymer substances and kill resident bacteria deep into the biofilm. Finally, the prepared nanosystem effectively inhibits the formation of Staphylococcus aureus biofilm and rapidly destroys the mature biofilm by the synergy antibacterial effects of the cation and ROS. We also evaluate the biocompatibility of the nanocomposites. The results show that PPD@CQDLys has no toxicity to L929 and 3T3 cells and exhibits a zero hemolytic rate even when the concentration is up to 2000 μg/mL. The outstanding biocompatibility coupled with rapid anti-biofilm ability of the nanosystem presents an opportunity for it to be utilized as an effective pH-responsive and targetable anti-biofilm agent for controlling bacterial infections.

Unignorable toxicity of formaldehyde on electroactive bacteria in bioelectrochemical systems

Formaldehyde poses significant threats to the ecosystem and is widely used as a toxicity indicator to obtain electrical signal feedback in electroactive biofilm (EAB)-based sensors. Although many optimizations have been adopted to improve the performance of EAB to formaldehyde, nearly no studies have discussed the toxicity of formaldehyde to EAB. Here, EABs were acclimated with a stable current density (8.9 ± 0.2 A/m2) and then injected with formaldehyde. The current density decreased by 27% and 98% after the injection of 1 and 10 ppm formaldehyde, respectively, compared with that in the control. The ecotoxicity of formaldehyde caused the irreversible loss of current with 3% (1 ppm) and 81% (10 ppm). Confocal laser scanning microscopy and scanning electron microscopy results showed that the redox activity was inhibited by formaldehyde, and the number of dead/broken cells increased from 2% to 40% (1 ppm) and 91% (10 ppm). The contents of the total protein and extracellular polymer substances decreased by more than 28% (1 ppm) and 75% (10 ppm) because of the cleavage reaction caused by formaldehyde. Bacterial community analysis showed that the proportion of Geobacter decreased from 81% to 53% (1 ppm) and 24% (10 ppm). As a result, the current production was significantly impaired, and the irreversible loss increased. Toxicological analysis demonstrated that formaldehyde disturbed the physiological indices of cells, thereby inducing apoptosis. These findings fill the gap of ecotoxicology of toxicants to EAB in a bioelectrochemical system.

STRUCTURAL REORGANIZATION OF THE RATS’ SUBMANDIBULAR GLANDS ACINI AFTER THE INFLUENCE OF 1% METHACRYLATE

Introduction: Polymeric substances, which are used in medicine, can lead to the development of pathological conditions. Therefore, in toxicological evaluation of polymeric materials for medical purposes the primary task is the creation of the appropriate adequate methods of study. The aim: To studytheacinioftherats'submandibularsalivaryglandsin normalcondition andafter exposureof 1% methacrylate. Material andmethods:Were studied 50 white rats during the influence of 1% methacrylate on the mucosa of the oral cavity. Histological sections of the rats'submandibularsalivary glands in normalcondition, on day 14 and 30 of experiment were studied using the UMPT - 7 ultramicrotome of Sumy PA "Selmi". Results and conclusions:Themorphometric study hasestablishedthat in control group thevaluesof theouterdiameterof thesubmandibularglands' acini, the diameter of the lumen and the height of the acini epithelial cells was 36,27±2,17 µm,9,47±0,63 µm and 14,18±1,05 µm, respectively. Histological specimens showed that the acini cells had a prominent basophilia of the cytoplasm and the basally located nucleus. Numerous large homogeneous granules were located in the apical pole of the cells. After influence of the 1% methacrylat there is an increase in the activity of secretory cells, which is confirmed by an increase in the height of epitheliocytes by 25.04% and is a compensatory metacrylate reaction. The increase in salivation further leads to complete depletion of the secretory apparatus of the seromucosal cells, which is confirmed by a decrease in the outer and inner diameters with a decrease in the height of the mandibular salivary glands acini cells by 24.40%.

Performance and microbial community of the CANON process in a sequencing batch membrane bioreactor with elevated COD/N ratios.

In this study, the effects of elevated chemical oxygen demand/nitrogen (COD/N) ratios on nitrogen removal, production and composition of the extracellular polymer substances (EPS) and microbial community of a completely autotrophic nitrogen removal via nitrite (CANON) process were studied in a sequencing batch membrane bioreactor (SBMBR). The whole experiment was divided into two stages: the CANON stage (without organic matter in influent) and the simultaneous partial nitrification, anaerobic ammonia oxidation and denitrification (SNAD) stage (with organic matter in influent). When the inflow ammonia nitrogen was 420 mg/L and the COD/N ratio was no higher than 0.8, the addition of COD was helpful to the CANON process; the total nitrogen removal efficiency (TNE) was improved from approximately 65% to more than 75%, and the nitrogen removal rate (NRR) was improved from approximately 0.255 kgN/(m3·d) to approximately 0.278 kgN/(m3•d), while the TNE decreased to 60%, and the NRR decreased to 0.236 kgN/(m3•d) when the COD/N ratio was elevated to 1.0. For the EPS, the amounts of soluble EPS (SEPS) and loosely bound EPS (LB-EPS) were both higher in the CANON stage than in the SNAD stage, while the amount of tightly bound EPS (TB-EPS) in the SNAD stage was significantly higher due to the proliferation of heterotrophic bacteria. The metagenome sequencing technique was used to analyse the microbial community in the SBMBR. The results showed that the addition of COD altered the structure of the bacterial community in the SBMBR. The amounts of Candidatus 'Anammoxoglobus' of anaerobic ammonia oxidation bacteria (AAOB) and Nitrosomonas of ammonia oxidizing bacteria (AOB) both decreased significantly, and Nitrospira of nitrite oxidizing bacteria (NOB) was always in the reactor, although the amount changed slightly. A proliferation of denitrifiers related to the genera of Thauera, Dokdonella and Azospira was found in the SBMBR.

ИССЛЕДОВАНИЕ СОСТАВОВ ТЯЖЕЛЫХ МЕТАЛЛОВ И ФОСФАТОВ В ПОЛИМЕРНЫХ ВЕЩЕСТВАХ БИОМАССЫ АКТИВНЫХ ИЛОВ

Introduction. Heavy metals discharged with wastewater can lead to a toxic effect on the microbiocenosis of activated sludge and significantly decrease the degree of wastewater treatment, which dictates the need for a more detailed study and search for ways to detoxify activated sludge at the recycling stage and, at the same time, solve the problems of the neutralization of sewage sludge for safe soil disposal. To ensure the adequacy of the approach to the choice of the methodology for the neutralization of sludge, including sewage sludge, it is necessary to perform compositional analysis of their organic fractions and heavy metal compositions. Methods. To determine the quantitative content of organic components in activated sludge, a sample of sludge was dried to an air-dry state and then subjected to separation into fractions using a method based on the different solubility of compounds with the use of different solvents. Then, extractants were added step by step to the weighted samples of sewage sludge weighing about 2 g each (in a volume 20 times greater than the weight of the weighted sample (40 ml)). Results. The results of the study show that polysaccharides are the dominant form of the organic fraction (polymers) in sewage sludge. Most heavy metals were identified in acidic polysaccharides, humic-like acids and lipids. Significant concentrations of phosphates were observed for the same components of polymer substances in the biomass of activated sludges. Conclusion. The products of extraction of polymer substances of the activated sludge biomass and the content of heavy metals in them may indicate the biosorption of heavy metals by zoogleal accumulations (having a polysaccharide structure) of activated sludges in aeration tanks during biological treatment. Therefore, extracellular biopolymers can be a “target” in the development of targeted technologies for the neutralization of activated sludges.

Metagenomic Insights into the Effects of Seasonal Temperature Variation on the Activities of Activated Sludge.

It is well acknowledged that the activities of activated sludge (AS) are influenced by seasonal temperature variation. However, the underlying mechanisms remain largely unknown. Here, the activities of activated sludge under three simulated temperature variation trends were compared in lab-scale. The TN, HN3-H, and COD removal activities of activated sludge were improved as temperature elevated from 20 °C to 35 °C. While, the TN, HN3-H, COD and total phosphorus removal activities of activated sludge were inhibited as temperature declined from 20 °C to 5 °C. Both the extracellular polymer substances (EPS) composition (e.g., total amount, PS, PN and DNA) and sludge index of activated sludge were altered by simulated seasonal temperature variation. The variation of microbial community structures and the functional potentials of activated sludge were further explored by metagenomics. Proteobacteria, Actinobacteria, Acidobacteria and Bacteroidetes were the dominant phyla for each activated sludge sample under different temperatures. However, the predominant genera of activated sludge were significantly modulated by simulated temperature variation. The functional genes encoding enzymes for nitrogen metabolism in microorganisms were analyzed. The enzyme genes related to ammonification had the highest abundance despite the changing temperature, especially for gene encoding glutamine synthetase. With the temperature raising from 20 °C to 35 °C. The abundance of amoCAB genes encoding ammonia monooxygenase (EC:1.14.99.39) increased by 305.8%. Meanwhile, all the enzyme genes associate with denitrification were reduced. As the temperature declined from 20 °C to 5 °C, the abundance of enzyme genes related to nitrogen metabolism were raised except for carbamate kinase (EC:2.7.2.2), glutamate dehydrogenase (EC:1.4.1.3), glutamine synthetase (EC:6.3.1.2). Metagenomic data indicate that succession of the dominant genera in microbial community structure is, to some extent, beneficial to maintain the functional stability of activated sludge under the temperature variation within a certain temperature range. This study provides novel insights into the effects of seasonal temperature variation on the activities of activated sludge.

Sequential vertical flow trickling filter and horizontal flow multi-soil-layering reactor for treatment of decentralized domestic wastewater with sodium dodecyl benzene sulfonate

Sequential vertical flow trickling filter and horizontal flow multi-soil-layering bioreactor were investigated for the treatment of decentralized domestic wastewater at various concentrations of sodium dodecyl benzene sulfonate (SDBS). Results have shown that the removal rate of COD could reach 92.1% at initial COD concentration of 960 mg/L (800 mg/L was provided by SDBS). NH4+-N concentration could be reduced from 52.4 to 9.71 mg/L without aeration. Besides, a quadratic function model was fit to describe the relationship between the relative activity of amylase and the protein content in extracellular polymer substance. SDBS could inhibit the transport and metabolisms of amino acids, lipids and carbohydrates in biofilms. The analysis of three-dimensional fluorescence diagram indicated that the peak in excitation/emission wavelengths = 310–340/370–430 nm was the characteristic peaks of some active substances such as some enzymes in EPS. Only Microbacterium could totally offset the toxicity of SDBS degradation products.

FORMULATION DEVELOPMENT AND EVALUATION OF GASTRORETENTIVE FLOATING TABLETS OF TRAZODONE HYDROCHLORIDE

FORMULATION DEVELOPMENT AND EVALUATION OF GASTRORETENTIVE FLOATING TABLETS OF TRAZODONE HYDROCHLORIDE Vivek Jain1, Halki Kushwah*1, Anwar Iqbal Khan1, Geeta Parkhe2 NRI Institute of Pharmacy, Bhopal, Madhya Pradesh, India. ABSTRACT Formulation development is an important part of drug design and development. Bioavailability and bioequivalence are totally dependent on formulation development. Now-a-days formulation development is done by following QbD (Quality by Design).Floating drug delivery systems are the gastro retentive forms that precisely control the release rate of target drug to a specific site which facilitate an enormous impact on health care. This can be achieved by use of various polymeric substances. Trazodone Hydrochloride (TRZ), is a well-known chemical compound that is used as an antidepressant that belongs to a selective serotonin reuptake inhibitors (SARI). TRZ is used as anti-anxiety and sleep-inducing agent. The tablets of TRZ were prepared by direct compression method using gas generating agent and different polymer combinations. The prepared tablets of TRZ were evaluated for hardness, thickness, friability, weight variation, drug content uniformity, buoyancy lag time, total floating time, swelling index, in-vitro dissolution study, etc. All the compositions were resulted in adequate Pharmacopoeial limits. The varying concentration of gas generating agent and polymers was found to effect on in-vitro drug release and floating lag time. In vitro drug release of floating gastro retentive tablet of TRZ shown that the formulation F9 was found to be the best formulation as it releases 97.98% TRZ in a controlled manner for an extended period of time (up to 12 hours). The release data was fitted to various mathematical models such as higuchi, Korsmeyer-Peppas, first order and zero order to evaluate the kinetics and mechanism of the drug release. Prepared floating tablets of TRZ may prove to be a potential candidate for safe and effective controlled drug delivery over an extended period of time for gastro retentive drug delivery system. Keywords: Trazodone Hydrochloride, Gastro retentive, floating tablet, Total floating time. Full Text Article

Conditioning of resuspension excess sludge with chemical oxidation technology: The respective performance of filtration and expression stage in compression dewatering

Excess sludge has a high yield, rich in organic matter and high water content. The combinational method from chemical oxidation treatment and secondary mechanical dehydration is a powerful approach to further reduce the moisture content of the sludge. This work mainly studies the physicochemical properties of resuspension excess sludge (RES) with the treatment of chemical oxidation, the samples are processed by the compression filter device in a laboratory scale, and the three-stage Terzaghi-Voigt model was used to characterize the expression stage dewatering of samples. The experimental results indicate that: i) The improvement of the dewaterability of resuspension excess sludge is due to moderate chemical oxidation, which is related to the mode of migration and mineralization of organic substances in the stratified structure of the extracellular polymer substance (EPS). ii) When the protein in supernatant + slime is more mineralized than moved in, the dewaterability of the sample is improved. iii) The change of moisture removal for ternary consolidation was very consistent with the change of SRF in the filtration stage (ρ = 0.95, p < 0.01). Based on the results, we discuss how chemical oxidation affects the dewatering performance of filtration and expression stages in the solid-liquid separation. This means that the surface characteristics of the sludge particle and the liquid properties play critical roles in solid-liquid separation mechanism.

Use of Extracellular Polymer Substance as an Additive to Improve Biogas Yield and Digestion Performance

To understand how extracellular polymer substance (EPS) used as an additive promotes methanogenesis, batch tests of methane production potential in anaerobic reactors with the addition of EPS and w...

From lignin-derived bio-oil to lignin-g-polyacrylonitrile nanofiber: High lignin substitution ratio and maintaining good nanofiber morphology

In this work, lignin-based nanofibers were produced from corn stalk lignin (CSL)/lignin-derived bio-oil (LBO) and polyacrylonitrile (PAN) co-polymers via electrospinning. During depolymerization, the addition of phosphotungstic acid (PTA) promoted the CSL catalytic conversion to some extent, the decrease of β-O-4 aryl ether bond, molecular weight (Mw) and polydispersity (PDI) was obvious. Compared with CSL, LBO can promotes the formation of uniform and smooth lignin-based nanofibers under high replacement rates condition and maintaining good morphology. Subsequent reactions between LBO and PAN fragments formed a better-integrated co-polymers structure containing linear PAN backbone. The Td of LBO-g-PAN was improved to 153 °C and the Tg was decreased to 96.5 °C. Rheological conclusions displayed that the viscosity of PAN/LBO/DMF was 0.082 Pa s, illustrating the polymer substance could be continuously spun into filament without causing degradation of the polymer substance. LBO-g-PAN also had high thermal stability, yielding of residual mass was 56.32 wt% at 700 °C.