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Megasatellites are large tandem repeats found in all fungal genomes but especially abundant in the opportunistic pathogen Candida glabrata. They are encoded in genes involved in cell-cell interactions, either between yeasts or between yeast and human cells. In the present work, we have been using an iterative genetic system to delete several Candida glabrata megasatellite-containing genes and found that 2 of them were positively involved in adhesion to epithelial cells, whereas 3 genes negatively controlled adhesion. Two of the latter, CAGL0B05061g or CAGL0A04851g, were also negative regulators of yeast-to-yeast adhesion, making them central players in controlling Candida glabrata adherence properties. Using a series of synthetic Saccharomyces cerevisiae strains in which the FLO1 megasatellite was replaced by other tandem repeats of similar length but different sequences, we showed that the capacity of a strain to flocculate in liquid culture was unrelated to its capacity to adhere to epithelial cells or to invade agar. Finally, to understand how megasatellites were initially created and subsequently expanded, an experimental evolution system was set up, in which modified yeast strains containing different megasatellite seeds were grown in bioreactors for more than 200 generations and selected for their ability to sediment at the bottom of the culture tube. Several flocculation-positive mutants were isolated. Functionally relevant mutations included general transcription factors as well as a 230-kbp segmental duplication. [ABSTRACT FROM AUTHOR]

Abstract High-rate activated sludge (HRAS) is an essential cornerstone of the pursuit towards energy positive sewage treatment through maximizing capture of organics. The capture efficiency heavily relies on the degree of solid separation achieved in the clarifiers. Limitations in the floc formation process commonly emerge in HRAS systems, with detrimental consequences for the capture of organics. This study pinpointed and overcame floc formation limitations present in full-scale HRAS reactors. Orthokinetic flocculation tests were performed with varying shear, sludge concentration, and coagulant or flocculant addition. These were analyzed with traditional and novel settling parameters and extracellular polymeric substances (EPS) measurements. HRAS was limited by insufficient collision efficiency and occurred because the solids retention time (SRT) was short and colloid loading was high. The limitation was predominantly caused by impaired flocculation rather than coagulation. In addition, the collision efficiency limitation was driven by EPS composition (low protein over polysaccharide ratio) instead of total EPS amount. Collision efficiency limitation was successfully overcome by bio-augmenting sludge from a biological nutrient removal reactor operating at long SRT which did not show any floc formation limitations. However, this action brought up a floc strength limitation. The latter was not correlated with EPS composition, but rather EPS amount and hindered settling parameters, which determined floc morphology. With this, an analysis toolkit was proposed that will enable design engineers and operators to tackle activated solid separation challenges found in HRAS systems and maximize the recovery potential of the process. Graphical abstract Image 1 Highlights • Collision efficiency and floc strength were main limitations in floc formation. • Protein (PN) to polysaccharide (PS) ratio as differentiating feature. • Low PN/PS ratio with low EPS amount led to collision efficiency limitation. • Improved PN/PS ratio with low EPS amount led to floc strength limitation. • Bioaugmentation of BNR sludge to high-rate systems improves collision efficiency. [ABSTRACT FROM AUTHOR]

This article aims to advance the understanding of particle interactions in low retention time flocculators and proposes a new flocculation model that appropriately considers the influence of retention time in flocculation processes. This consideration is important for units with flocculation time lower than 1 min, as seen in helically coiled tube flocculators (HCTFs), whose retention time is significantly lower than conventional flocculation units (about 30 min). With this, it was possible to obtain a more adherent model, reducing deviations between results obtained by physical modelling (using HCTFs, 48 tests) and those obtained with the proposed model, when compared with results obtained using the flocculation models commonly used for this purpose. The decreasing-rising behaviour presented by experimental data for process efficiency versus retention time, not verified in the benchmark models, was satisfactorily addressed by the proposed model. Furthermore, maximum and average absolute percentage deviations obtained using the model proposed in this study were less than or equal to the results obtained with the benchmark models and less for experimental uncertainty (10%). The results obtained indicate that this model can be a useful tool to support the rational design of low retention time units, including applications for the water industry and water recycling systems. [ABSTRACT FROM AUTHOR]

Here we report the results of a study to establish a replacement WHO International Standard (IS) for tetanus toxoid for use in flocculation test. The standard was calibrated in flocculation units (Lf) against the 2nd IS using the Ramon flocculation method. At its 70th meeting in October 2019, WHO ECBS established the material (coded 16/302) as the 3rd WHO IS, with an assigned value of 970 Lf/ampoule from the results of seventeen laboratories across ten different countries. The study also provided an opportunity to assess the use of alternative methods for measuring Lf. Participants were asked to use an in-house Enzyme Linked Immunosorbent Assay (ELISA) developed at NIBSC, or other suitable in-house methods, to determine ELISA-specific Lf values (Lf-eq units are specific only for pre-calibration of antitoxin in the flocculation test) of 16/302 to compare to those of the flocculation test. Nine laboratories participated by performing the NIBSC ELISA, one laboratory performed flocculation by laser light-scattering following an in-house protocol, and three laboratories performed ELISA following in-house protocols. The results intimate that these alternative methods could be useful for monitoring consistency of production at different stages of vaccine manufacturing., (Copyright © 2023. Published by Elsevier Ltd.)

At the moment, it is vital for mineral industries to abide environmental regulation to dispose of the wastes generated in the beneficiation process. The redesign of dewatering process is required to meet the present demand. This paper reports the results of systematic investigations on the flocculation, sedimentation and consolidation characteristics of the chromite ore process tailings using different polyacrylamide flocculants. Laboratory batch sedimentation tests were performed to assess the performance of flocculants. Different categories of flocculants such as anionic, cationic, non-ionic with varying ionicity and molecular mass were used to improve the settling rate. The influence of flocculants on the settling rate, solid consolidation, and supernatant liquid clarity was recorded. Ionicity and molecular weight of the flocculants have a significant effect on the tailings settling properties. Anionic flocculants with low ionic strength and molecular weight show higher settling efficiency, whereas, cationic flocculants bearing high ionic strength and molecular weight also display the similar settling behaviour. The opaqueness of consolidated solids is greater with cationic than the anionic polyacrylamide. The anionic Alstafloc 40, 60 and cationic Alstafloc 155XX have exhibited excellent turbidity removal efficiency with 19.5 cm/min settling rate at 15 g polymer/tonne solid dosage. The non-ionic polyacrylamide was not found efficient for the tailings flocculation. [ABSTRACT FROM AUTHOR]

The size and settling velocity of oil-mineral aggregates (OMAs) derived from diluted bitumen are primary constituents in predictive models for evaluating the potential fate of oil spilled in the aquatic environment. A series of low sediment concentration (15 mg·L − 1 ), colder water (< 10 °C) wave tank experiments designed to measure variability in these parameters in naturally-formed OMAs in response the presence or absence of chemical dispersant are discussed. Corresponding lab experiments revealed settling velocities of artificially formed OMAs on the order of 0.1–0.4 mm·s − 1 . High-resolution imagery of settling particles were analyzed for particle size, density and settling velocity. In situ formation of OMAs in the wave tank was unsuccessful. Possible effects of chemical dispersant on natural sediment flocculation, the size of suspended oil droplets and clearance rates of suspended particles are discussed. [ABSTRACT FROM AUTHOR]

Cryptosporidiosis and cyclosporiasis are caused by waterborne coccidian protozoan parasites of the genera Cryptosporidium and Cyclospora, respectively. This study was conducted to detect Cryptosporidium and Cyclospora oocysts from environmental water abstracted by drinking water treatment plants and recreational activities in Sarawak, Malaysia. Water samples (12 each) were collected from Sungai Sarawak Kanan in Bau and Sungai Sarawak Kiri in Batu Kitang, respectively. In addition, 6 water samples each were collected from Ranchan Recreational Park and UNIMAS Lake at Universiti Malaysia Sarawak, Kota Samarahan, respectively. Water physicochemical parameters were also recorded. All samples were concentrated by the iron sulfate flocculation method followed by the sucrose floatation technique. Cryptosporidium and Cyclospora were detected by modified Ziehl-Neelsen technique. Correlation of the parasites distribution with water physicochemical parameters was analysed using bivariate Pearson correlation. Based on the 24 total samples of environmental water abstracted by drinking water treatment plants, all the samples (24/24; 100%) were positive with Cryptosporidium, and only 2 samples (2/24; 8.33%) were positive with Cyclospora. Based on the 12 total samples of water for recreational activities, 4 samples (4/12; 33%) were positive with Cryptosporidium, while 2 samples (2/12; 17%) were positive with Cyclospora. Cryptosporidium oocysts were negatively correlated with dissolved oxygen (DO). [ABSTRACT FROM AUTHOR]

The aim of this study was to compare two rearing systems for freshwater prawn Macrobrachium rosenbergii: one with use of a recirculating aquaculture system with biofilters ( RAS) and another with use of microbial flocs (F). Thirty postlarvae of freshwater prawn with an initial average weight of 0.13 ± 0.05 g were randomly stocked in six experimental units with 0.20 m² and volume of 50 L. The experiment lasted thirty days. Dissolved oxygen, temperature and pH were monitored daily; ammonia concentration was determined three times per week; nitrite concentration, alkalinity and hardness were measured weekly. For the formation of microbial floc, molasses was used to keep the ammonia concentrations within safe levels for prawn farming. The variables of water quality remained within the suitable range for the production of the species, except for ammonia concentrations at the F treatment, which exceeded the safe levels. At the end of the experiment, the following parameters were evaluated: survival, specific growth rate, weight gain and feed conversion rate. Differences were found only in feed conversion rate with better values on RAS treatment. The microorganisms present in the RAS and F treatment were also evaluated. The densities of rotifers, amoebas and total bacteria were higher at the F treatment although the same organisms were found at the RAS treatment. The results of this study showed the possibility of rearing M. rosenbergii in biofloc system technology. [ABSTRACT FROM AUTHOR]

We have previously reported that flocculation of a yeast co-transformed with the human DNA methyltransferase 1 (DNMT1) and DNMT3B genes was inhibited by DNMT inhibitors. It is well known that epigenetic mutagens can disturb nucleosome positioning via DNA methylation and/ or histone modification. In this study we first examined the effects of trichostatin A (TSA), a histone deacetylase inhibitor, on the flocculation level of yeast. TSA dose-dependently promoted the flocculation exhibited by the yeast transformed with the DNMT genes or empty vectors. Furthermore, TSA induced the expression of the flocculin-encoding gene FLO1. The anthracenederived alizarin, a natural madder root dye, has a potential for carcinogenesis promotion; however, the mode of action has not been elucidated. It is considered that epigenetic changes can promote cancer. Alizarin but not anthracene enhanced the flocculation level of the yeast. Similar to TSA, alizarin also upregulated FLO1 mRNA. Surprisingly, western blotting indicated that alizarin, but not anthracene, reduced the level of histone H3 in yeast, and alizarin-treated cells frequently displayed abnormally shaped nuclei. These findings suggest that alizarin uniquely influences nucleosome structure. Taken together with our previous findings, this study suggests that the DNMT genetransformed yeast strains are a useful tool for screening various classes of epigenetic mutagens. [ABSTRACT FROM AUTHOR]

We present the results of a collaborative study for the establishment of a replacement International Standard (IS) for diphtheria toxoid for use in flocculation test and its calibration in Lf units. Calibration was performed using Ramon flocculation method, standardized using the 2nd IS. The candidate standard was assigned a unitage of 1870 Lf/ampoule based on results from 25 laboratories in 15 different countries and was established as the 3rd IS for diphtheria toxoid for use in flocculation test by the WHO Expert Committee on Biological Standardization (ECBS) in October 2015. The study also assessed the use of alternative methods for measuring Lf. Participants were asked to determine the Lf value of the candidate standard using an Enzyme Linked Immunosorbent Assay (ELISA) established at NIBSC, or other suitable in-house method. 10 laboratories performed ELISA according to the NIBSC protocol, 1 laboratory performed flocculation using laser-light scattering according to an in-house protocol, and 1 laboratory performed another in-house ELISA. Results suggest these methods may provide suitable alternatives to the Ramon flocculation test, subject to validation, and that the new standard could act as a suitable reference preparation in these methods. [ABSTRACT FROM AUTHOR]

A bioflocculant-producing bacterium, Bacillus megaterium SP1, was isolated from biofloc in pond water and identified by using both 16S rDNA sequencing analysis and a Biolog GEN III MicroStation System. The optimal carbon and nitrogen sources for Bacillus megaterium SP1 were 20 g L−1 of glucose and 0.5 g L−1 of beef extract at 30°C and pH 7. The bioflocculant produced by strain SP1 under optimal culture conditions was applied into aquaculture wastewater treatment. The removal rates of chemical oxygen demand (COD), total ammonia nitrogen (TAN), and suspended solids (SS) in aquaculture wastewater reached 64, 63.61, and 83.8%, respectively. The volume of biofloc (FV) increased from 4.93 to 25.97 mL L−1. The addition of Bacillus megaterium SP1 in aquaculture wastewater could effectively improve aquaculture water quality, promote the formation of biofloc, and then form an efficient and healthy aquaculture model based on biofloc technology. [ABSTRACT FROM AUTHOR]

The interactions between precipitated calcium carbonate (PCC) and sterically stabilized nanocrystalline cellulose (SNCC) have been studied. SNCC is produced by periodate oxidation of cellulose fibres and consists of a crystalline cellulose region from which dialdehyde modified cellulose chains are protruding from both ends. The morphology of SNCC can be controlled by the degree of oxidation, which depends on the amount of periodate and the reaction time. In this study, three SNCCs with different reaction times were prepared and their interactions with PCC particles were examined. These SNCC particles have similar diameters (5–10 nm) and their length is reduced with increasing reaction time, whereas the length of the protruding chains is increased. Adsorption isotherms of three SNCCs and dialdehyde modified cellulose (DAMC) on PCC particles were determined. It was found that DAMC had a higher affinity than SNCCs, and the affinity of SNCC increased with reaction time. This indicates that DAMC chains adsorb stronger than the crystalline region of SNCC on PCC. The PCC flocculation induced by three SNCCs was monitored by photometric dispersion analysis, which showed that SNCC particles could bridge PCC to induce flocculation at low dosages (above 1 mg/g). SNCC induced the maximum flocculation when its fractional coverage is above 50%, implying that PCC particles coated by SNCC continue to flocculate, as observed experimentally. Further addition of SNCC to PCC suspensions results in slower flocculation rates and smaller floc sizes. [ABSTRACT FROM AUTHOR]

The sedimentation behavior of semi-dilute suspensions of sodium montmorillonite in the flocculation regime was studied as a function of ionic strength at pH 4.0 and 9.5 to elucidate the response of variation of macroscopic sedimentation behavior with microscopic particle association. The maximum velocity of the boundary between the supernatant and sediment and ultimate sediment height were chosen as indexes to evaluate the sedimentation behavior. Increment ratio of effective volume fraction of the particles (α) caused by the formation of flocs and hydrodynamic floc diameter were evaluated by Michaels and Bolger method on the basis of the Richardson–Zaki formula. The results clearly demonstrate that the maximum velocity of the boundary is strongly affected by both pH and salt concentration. The two observed patterns of variation of maximum sedimentation rate and ultimate sediment height can be clearly defined using 0.25–0.5 M NaCl as an inflection range. This range is consistent with the transition point at 0.3 M NaCl for the swelling behavior of sodium montmorillonite reported by Norrish. Below 0.25 M NaCl, the effect of pH on the sedimentation rate is remarkably enhanced compared with that at higher salt concentration. This effect is ascribed to the dominant appearance of edge–face (EF) particle interactions, which can be regarded as negligible at higher salt concentration. The reason for this is that the breakage of weak EF bonds is induced by the dominant appearance of face–face particle interactions at higher salt concentrations. That is, the decrease of repulsion strengthening the attraction between neighboring particles is responsible for EF bond breakage. The small influence of pH on ultimate sediment height at high salt concentration can be ascribed to the residual strong EF bonds. The Michaels and Bolger method can be used qualitatively at range of NaCl greater than 0.5 M. [ABSTRACT FROM AUTHOR]

Colloidal aqueous suspensions of vanadium pentoxide ( V 2 O 5 ) ribbons and iron oxide ( F e 3 O 4 ) nanoparticles display extreme sensitivity to magnetic fields, which promises their use in novel magneto-optic devices. However, application of these systems requires that stable colloidal suspensions can actually be achieved in a given range of concentration of each component. We explored the ( V 2 O 5 , F e 3 O 4 ) stability diagram of this complex colloidal system by preparing samples of selected compositions and by studying them by visual inspection, optical microscopy, DLS, electrokinetic potential, and TEM. We found that, on the time scale of several weeks, the colloidal system is stable up to C F e 3 O 4 ≈ 0.025 v o l . % and C V 2 O 5 ≈ 0.1 − 1.1 v o l . % . Such concentrations are indeed suitable for applications and the high sensitivity to the magnetic field of the suspension in a stable concentration region is demonstrated. However, the system lacks chemical stability at long-term (several months) as V V eventually oxidizes F e I I , resulting in flocculation of the dispersion. [ABSTRACT FROM AUTHOR]

A mechanistic isopercentile flocculent sedimentation model was derived from basic fractal behavior of colloidal particles in turbid water. The model showed the fractal nature of growing particles, which was in opposition to the most commonly used semiempirical models that assume growth of particles as compact spheres. The model development was based on particle size distribution (PSD) analysis results from settling batch column experiments. The experimental batches were conducted at initial concentrations ranging from 150 to 350 mg=L and coagulant doses in the range of 10-70 mg=L. From the collected PSD data, a fractal dimension D (L), fractal settling velocity av (LT-1), and model-fit parameters affecting the shape of isopercentile removal trajectories were obtained. The resulting calibrated model performed better than previously proposed semiempirical models. Lower degrees of fitting error, represented by sum of squares error (SSE) = 0.44-0.90, were achieved using the new model, which was much lower than the SSE range of 3.10-9.44 from previous models fitted to the same data set. The improved fitness of the new model was attributed to its ability to capture the fractal growth property of settling particles, which resulted in incipient buoyancy and settling deceleration of the formed flocs-properties that were not represented in previous models. [ABSTRACT FROM AUTHOR]

Samples of a culture of S cenedesmus sp. grown in a pilot raceway photo bioreactor were processed in the laboratory by flocculation and centrifugation, to assess the efficiency of solid concentration of both methods. Three flocculation agents were tested, ferrous sulfate (FeSO 4 ), ferric chloride (FeCl 3 ) and aluminum sulfate Al 2 (SO4) 3 using concentrations of 0.05, 0.2, 0.8, 1.5, 3.0 y 7.0 g L −1 and pH range between 4.0 and 11.0 for the better concentration response of each flocculant. Additional flocculation tests were carried out to measure the sedimentation kinetics of the concentrated biomass. All these tests were performed with culture samples of 800 cm 3 for 12 min of stirring and 10 min of sedimentation with three repetitions. In the case of centrifugation the testing was carried out using a laboratory centrifuge run at speeds of 1500, 1800 and 2200 rpm with culture samples of 300 cm 3 for 15 min and three repetitions. In order to quantify the efficiency of the concentration, initial and final turbidity of the cleared water and concentrated portion were measured. The flocculation experiments showed that a limit of maximum concentration efficiency of 97.9% that was reached with 1.5 g L −1 of Al 2 (SO 4 ) 3 at pH of 8.5 and an average sedimentation velocity of about 2.7 cm min −1 . Testing also showed that FeSO 4 was the worst flocculant agent in the range tested. With respect to the centrifugation test, the solid concentration efficiency varied from 95.2% at speed of 1500 rpm up to 96.0% at speed of 2200 rpm. [ABSTRACT FROM AUTHOR]

In this work, a new microscale flocculation test (MFT) method was developed that is ideally-suited for optimizing separation performance. A critical and complicated task in wastewater treatment is to identify the flocculation conditions that yield the optimal separation of water from suspended solid materials. The standard ‘jar test’ method is inadequate for conducting a full process optimization because a typical set-up only allows for a maximum of 6 tests to be conducted at once and fairly large volumes of materials (approximately 1 to 2 L) are needed for each individual test. The microplate-based, parallel processing format of the MFT method allows for dozens of flocculation tests to be conducted simultaneously, with each test requiring only a few millilitres of material. As a demonstration of the MFT method, ten cationic polymer flocculants were evaluated with various digestate types. The optimal separation performance, as determined by the lowest capillary suction time (CST), was found by rigorously evaluating the effect of flocculant type (including molecular weight and charge density) and dosage conditions (including total amount added and single versus staged addition). For example, the dose-dependent profiles for certain flocculants exhibited a nearly 10-fold greater decrease in CST compared to other flocculants. Process optimization in environmental separations is not trivial, but rather, is a complicated task that requires an extensive amount of experimental work for which the MFT method is ideally suited. [ABSTRACT FROM AUTHOR]

Poly-γ-glutamic acid (γ-PGA) broth was found to be a good bioflocculant of microalgae. However, the mechanism governing this bioflocculation process is not fully understood. In this study, Zeta potential measurement, microscopy examination and classical DLVO theory (named after Derjaguin, Landau, Verwey and Overbeek) analysis were used to explore the flocculability of microalgae induced by bacterial γ-PGA broth bioflocculant. Microalgae flocculation could be significantly improved by modifying ionic strength of the microalgae suspension, lowering pH value and bioflocculant addition due to the stronger attraction interactions between microalgal cells. In the present study, both the pH reduction with the bioflocculant induced better the flocculation process compared to the modification of ionic strength of the microalgae suspension in the presence of the bioflocculant. The DLVO theory indicated that when the bioflocculant was introduced, the total interaction energy decreased sharply, resulting in higher flocculation efficiency (>96 %) at a separation distance of 5 nm and shorter settling time (from 2 h to 10 min) compared with that obtained only by reducing the initial pH. The microalgae interaction energy was found to be dependent on the Zeta potential. This study provided a detailed interpretation of conceivable mechanism of microalgae bioflocculation by γ-PGA broth. [ABSTRACT FROM AUTHOR]

The consumption of water that has a high level of fluoride can result in dental or skeletal fluorosis, which causes changes in the teeth and bones. Thus, this study aimed to verify the efficiency of the reduction of fluoride in groundwater using coagulation with extracts of Moringa oleifera Lam seeds (MO) combined with microfiltration. Coagulation/flocculation tests were carried out in Jar test with different concentrations of the coagulant and subsequent treatment of water by microfiltration membranes. The concentration of fluoride in water was adjusted to 5 mgF-/L and pH set to 7.0. The test used 1.5 g/L of the coagulant MO, for a 3 mgF-/L initial concentration of fluoride and pH 3.0 proved effective for the removal of fluoride, colour, and turbidity of water with residual amounts of 1.07 mgF-/L, 19 mgPt-Co/L, and 3 NTU, respectively. The best results were obtained using 5 g/L of the coagulant MO and 2 bar pressure in the microfiltration step. Under these conditions, the final water quality complies with the recommendations of the Brazilian legislation, with residual fluoride at 1.2 mgF-/L, 1.56 NTU turbidity and 8.56 mgPt-Co/L colour. These results indicate the potential of the proposed treatment and that this represents an alternative for reducing excessive fluoride from water by combining the use of a natural and biodegradable coagulant with microfiltration processes, which contributes to the final quality of water. [ABSTRACT FROM AUTHOR]

Natural seed gum derived from Cassia obtusifolia was experimentally evaluated for its efficiency compared to aluminum sulfate (alum) to treat high-strength wastewater in this study. Agro-industrial wastewater is commonly defined by high total suspended solids (TSS) and chemical oxygen demand (COD); one example of this is palm oil mill effluent (POME). In this study, the removal of TSS and COD from POME was studied in relation to wastewater strength, coagulant dosage, initial pH of wastewater, settling time, slow stirring speed and temperature. Earlier investigation showed that generally, C. obtusifolia seed gum performed better than alum in removing TSS and COD from the POME. Additionally, this study found that wastewater temperature had a negligible effect on the treatment efficiency when C. obtusifolia seed gum was used compared to alum, which was more sensitive to temperature change. Optimized treatment conditions when using C. obtusifolia seed gum for the treatment of POME (7500 mg/L) were determined to include a natural coagulant dosage of 1.0 g/L, initial pH of 3 and a settling time of 45 min. Various coagulation mechanisms (i.e., charge neutralization, sweep and bridging) were identified through Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses. Although thermal gravimetric analysis (TGA) indicated that alum has higher thermal stability, C. obtusifolia seed gum showed better stability in terms of treatment efficiency at high temperatures. [ABSTRACT FROM AUTHOR]

Flocculation properties of amphiphilic starch derivatives of varying degrees of substitution (DS) of benzyl- and 2-hydroxypropyl-trimethylammonium moieties have been investigated in dispersions of kaolin, calcium carbonate, and silica. Moderate hydrophobic substitution leads to a decrease of efficient flocculant dose and increase of flocculation window width. Samples with high DS of hydrophobic moieties are effective only at significantly higher doses but in a broader concentration range compared to solely cationic ones of the same DS. Joint analysis of adsorption isotherms and flocculation test data has revealed that the surface coverage required to induce phase separation ranges between 10-25% and is minimal for amphiphiles, whose floc sizes are moreover less dependent on the flocculant dose. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel sulfonated polytriazine (SP) is synthesized by the condensation polymerization reaction of 2-(4,6-dichloro-1,3,5-triazin-2-ylamino)benzene-1,4-disulfonic acid (Compound I) and 1,4-diaminobenzene. The structure of SP is characterized by FTIR spectroscopy, 1H-NMR, and gel permeation chromatography (GPC). The flocculation performances for the cationic dyes are evaluated. The experimental results show that SP can efficiently remove the color of wastewater containing cationic dyes. The rates of color removal from C.I. Basic red 18 and C.I. Basic blue 9 reach as high as 99.6% and 98.5%, respectively. The synthesized SP shows high adsorption capacities of 1719 and 1988 mg/g for C.I. Basic blue 9 and C.I. Basic red 18, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39669. [ABSTRACT FROM AUTHOR]

The application of coagulation-flocculation (CF) process for treating the paper-recycling wastewater in jar-test experiment was employed. The purpose of the study was aimed to examine the efficiency of alum and poly aluminum chloride (PACl) in combination with a cationic polyacrylamide (C-PAM) in removal of chemical oxygen demand (COD) and turbidity from paper-recycling wastewater. Optimization of CF process were performed by varying independent parameters (coagulants dosage, flocculants dosage, initial COD and pH) using a central composite design (CCD) under response surface methodology (RSM). Maximum set required 4.5 as pH, 40 mg/L coagulants dosage and 4.5 mg/L flocculants dosage at which gave 92% reduction of turbidity, 97% of COD removal and SVI 80 mL/g. The best coagulant and flocculants were alum and chemfloc 3876 at dose of 41 and 7.52 mg/L, respectively, correspondingly at pH of 6.85. These conditions gave 91.30% COD and 95.82% turbidity removals and 12 mL/g SVI. [ABSTRACT FROM PUBLISHER]

A universal environmental friendly method was developed to turn sand into effective flocculants for mitigating harmful algal blooms (HABs) in marine and freshwater systems. The isoelectric point of sand was largely increased from pH 4.5 to 10.5 after been modified by Moringa oleifera coagulant (MO) abstracted form MO seeds. However, when sand was modified by MO alone, maximum removal efficiencies of 80% and 20% for Amphidinium carterae (A.C.) and Chlorella sp. (C.S.) in seawater and 60% for Microcystis aeruginosa (M.A.) in fresh water were achieved in 30 min. The limited removal improvement was due to the form of only small floes (20-100 μm) by surface charge modification only. Large floes (270-800 μm) and high removal rate of 96% AC. and C.S. cells in seawater and 90% of MA cells in fresh water were achieved within 30 min when the small MO-algae-sand floes were linked and bridged by chitosan. High HAB removal rate is achievable when the sand is modified by the bicomponent mechanism of surface charge and netting-bridging modification using biodegradable modifiers such as MO and chitosan. The optimized dosage of modified sand depends on the property of algal cells and water conditions [ABSTRACT FROM AUTHOR]

During jar tests on alum-based drinking water treatment, dissolved Al determinations on solutions coagulated at pH ≥ 6.5 were not reproducible. These determinations were performed by inductively coupled plasma mass spectrometry after syringe filtration (0.45 μm polyethersulfone membrane). In order to better define these anomalies, the filtrates were collected in sequential fractions of 7.5 mL. At coagulation pHs of 6.5 and 7.0, retention changes were demonstrated by large filtrate concentration reductions at all temperatures tested (0.1, 5.0, and 17.0 °C). In all cases, the concentrations converged to levels <50 μg/L within the fourth sequential fraction. In comparison, no retention change was observed for jar tests conducted at the same temperatures but in the low range of the minimum solubility domain, at pHs 5.5 and 6.0. The retention changes were also eliminated by precentrifugation (7000g for 45 min; pH 6.5-7.2). At weaker precentrifugation conditions, as well as by varying membrane surface area or membrane fouling, the filtrate concentrations behaved according to a barrier buildup at the membrane-solution interface by unsettled flocculation residuals. The influence of flocculation time and temperature emphasized the importance of reaction rates, which could be enhanced at the interface by concentration polarization effects. These phenomena have implications on analytical protocols and on filtration in full-scale treatment. [ABSTRACT FROM AUTHOR]

The arctic form of Trichinella spiralis that infects terrestrial and marine mammals is of importance in public health because persons living in arctic regions still depend on wild animals for economic subsistence. In 1975, an extended common-source epidemic of trichinosis attributed to consumption of walrus meat involved 29 persons in Barrow, Alaska. Of those persons eating this meat, 64% became ill, and the rate of infection of persons eating meat prepared with little or no cooking was four times as great as that of persons eating cooked meat. One year later a second outbreak occurred when a family ate partially cooked meat from an infected walrus. Clinical illness differed little from the disease acquired in temperature climates; however, only 70% had a positive bentonite flocculation titer, whereas 96% had eosinophilia. These epidemics of trichinosis are the first reported in Alaska to be associated with the consumption of walrus meat. [ABSTRACT FROM AUTHOR]

Production of extracellular polysaccharides by halophilic Archaea and Bacteria has been widely reported and the members of the genus Halomonas have been identified as the most potential producers. In the present work, a novel exopolysaccharide (EPS-S6) produced by the extremely halotolerant newly isolated Halomonas elongata strain S6, was characterized. According to the HPAE-PAD results, EPS-S6 was mainly composed of glucosamine, mannose, rhamnose and glucose (1:0.9:0.7:0.3). EPS-S6 was highly negatively charged and its molecular weight was about 270 kDa. Studies on its functional properties showed that EPS-S6 had several potential features. It has noticeable antioxidant activities on 2,2-diphenyl-1-picrylhydrazyl (DPPH • ) inhibition and DNA protection, good ability to inhibit and to disrupt pathogenic biofilms, excellent flocculation of kaolin suspension and interesting emulsifying properties at acidic, neutral and basic pH. Therefore, EPS-S6 could have potential biotechnological concern in several fields such as in food, cosmetic and environmental industries., Competing Interests: Declaration of competing interest We declare that we have no conflict of interest., (Copyright © 2020. Published by Elsevier B.V.)