Flocculation Capability Research Articles

Synthesis, characterization and performance of quaternized cellulose based flocculant derived from office paper waste for dye removal

Abstract The quaternized cellulose derivatives (QCs) were synthesized by reacting extracted cellulose from office paper waste with 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) in an aqueous solution of sodium hydroxide (NaOH) – urea. The characterization results by using Fourier-Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicate that the office paper waste properties changed after chemical treatment and the extract product was confirmed cellulose. In addition, the FT-IR and SEM results confirmed the successful introduction of cationic quaternary ammonium groups into the main chain of cellulose. Meanwhile, the XRD results revealed that the crystalline structure was destroyed during etherification reaction. By using synthetic Congo red dye, the flocculation performance of the QCs was evaluated via standard jar test method at different QC dosages, initial Congo red dye concentration and pH values. It was found that the QC10 exhibited a more effective flocculation capability as compared to other synthesized QCs for over a wide pH value. The QC10 performed the best at pH 7, 100 mg/L of Congo red dye concentration and 50 mg/L of QC dosage, with percentage removal of 89.09 %. These findings demonstrated the potential application of QC in dye removal.

Selective aggregation of fine copper minerals using charged polyacrylamides

Selective aggregation can be used to improve the collection of fine valuable mineral particles often lost in industrial separation processes. This approach might be applicable to flocculate fine copper mineral particles such as chalcopyrite. It is hypothesised that the polymeric flocculant charge type will influence selectivity between chalcopyrite and waste minerals. This work investigates the use of charged anionic (APAM) and cationic (CPAM) polyacrylamides to selectively aggregate negatively charged chalcopyrite from its common waste (quartz). The interaction of the polymers with the mineral's surfaces as well as its flocculation capability were investigated through adsorption isotherms, turbidity tests, and in-situ aggregate size measurement. Furthermore, the ability to selectively aggregate and recover the valuable chalcopyrite from a quartz mixture by sedimentation was assessed. The results indicated that both charged polymers can be used to aggregate fine chalcopyrite particles, however, CPAM is non-selective towards the valuable mineral, as it also aggregates quartz. CPAM has a stronger affinity for both minerals, probably due to charge-charge interaction adsorption mechanisms, whereas APAM adsorption was lower, and more likely to be driven by hydrogen bonding. The interaction of APAM with quartz was limited probably because its highly negatively charged surface tends to repel the anionic polymer. Finally, the recovery of the chalcopyrite by sedimentation separation improved when using both polymers, but higher recoveries were obtained when using APAM.

Magnetic polymeric composites: potential for separating and degrading micro/nano plastics

The pervasive presence of microplastics (MPs) and nanoplastics (NPs) across various ecological settings, organisms, and products has underscored the urgent need to collect data on their abundance and identify the polymer types in diverse substrates. NPs distinguish themselves from MPs by their smaller size. The application of magnetic composites in wastewater treatment has grown in popularity due to their remarkable flocculation capabilities and ferromagnetic properties. This comprehensive review centers on the synthesis methods, preparation technologies, and practical applications of magnetic polymeric composites for separating and degrading MPs/NPs. It offers an extensive overview of recent advancements in the separation and degradation of MPs/NPs within various wastewater sources. The review begins by consolidating efficient methods for the separation of MPs/NPs. This includes techniques such as adsorption, coagulation/flocculation, flotation, filtration, and magnetic separation. The subsequent section explores diverse approaches for the degradation of MPs/NPs, encompassing advanced oxidation processes (AOPs), electrochemical degradation, photocatalysis, and biological degradation. Additionally, the review offers in-depth insights into the synthesis and characterization of magnetic polymeric composites. Lastly, it discusses the current challenges and prospects associated with the separation and degradation of MPs/NPs in wastewater treatment.

Enhanced Adsorption Of Humic Acid On Amino-Modified Bentonite

AbstractHumic acid (HA) can cause environmental pollution, due to which, its removal from aqueous solutions has become an increasingly important issue. Although bentonite has an affinity for HA, the adsorption capacity of raw bentonite is still poor. As a commonly used organic modifier, 3-aminopropyltriethoxyorganosilane (APTES) exhibits excellent flocculation capability for HA. Therefore, the objective of the present study was to investigate the effectiveness of the addition of 3-aminopropyltriethoxyorganosilane (APTES) to raw bentonite to increase the adsorption of HA from aqueous solution. The experimental results showed that, when the solid-to-liquid ratio was 1:1, the amino-modified bentonite exhibited the highest adsorption capacity (qmax = 272.23 mg g-1). The adsorption affinity of amino-modified bentonite was mainly determined by the number of amino groups loaded onto its surface. The adsorption of HA on amino-modified bentonite occurred through electrostatic interactions and hydrogen bonding. These findings demonstrate the excellent potential of amino-modified bentonite in effectively remediating HA pollution.

Effects of hydrodynamic conditions on the composition, spatiotemporal distribution of different extracellular polymeric substances and the architecture of biofilms

Microbial biofilms are common on abiotic and biotic surfaces, especially in rivers, which drive crucial ecosystem processes. The microorganisms of biofilms are surrounded by a self-produced extracellular polymeric substance (EPS). In this study, we investigated the effects of different hydrodynamic conditions on the composition, spatiotemporal distribution of different extracellular polymeric substances, and the architecture of biofilms. Multidisciplinary methods offer complementary insights into complex architecture correlations in biofilms. The biofilms formed in turbulent flow with high shear force were thin but dense. However, the biofilms formed under laminar flow conditions were thick but relatively loose. The thickness and compactness of the biofilms formed in the transitional flow were different from those of the other biofilms. The compact structure of the biofilm helped to resist shear forces to minimize detachment. Under the turbulent flow condition, bacteria, exopolysaccharides, and extracellular proteins permeated through the biofilm, and more extracellular polysaccharides enveloped bacteria and extracellular proteins. However, under the transitional flow condition, the extracellular polysaccharides and proteins were fewer than those under the turbulent flow condition; bacteria and algae were seen more prominently in the upper layer of the biofilm. Under the laminar flow condition, the distribution of extracellular polysaccharides, extracellular proteins, and bacteria was relatively uniform throughout the biofilm. The number of extracellular polysaccharides was greater than that of extracellular proteins. The total number of EPS in the biofilm was the largest under turbulent flow condition, followed by that under transitional flow condition and then under laminar flow condition. This study also observed that soluble EPS (S-EPS) were secreted first, followed by loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS). In particular, the adhesion of LB-EPS and flocculation capability of TB-EPS play some role in regulating biofilm formation. This study would help to perfect the five-stages theory of biofilm formation.

Amine-Modified Chitosan Flocculant Synthesized via Single-Mode Microwave Method for Laundry Wastewater Treatment.

In this study, an effective and environmentally friendly polyaminated cross-linked chitosan (M-PACTS) flocculant was successfully synthesized via circular focus single-mode microwave synthesizer irradiation. Epichlorohydrin and tetraethylenepentamine were used as the cross-linking agent and active cationic reagent, respectively. The same formation was used to prepare cationic lightly cross-linked chitosan (C-PACTS) via the conventional heating method. The flocculant was characterized using Fourier transform infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy. The flocculation capability of C-PACTS and M-PACTS was compared using laundry wastewater as a model pollutant. The pH, PACTS dosage, temperature, stirring rate, stirring time, and setting time were systematically investigated. The experimental results showed that circular focus single-mode microwave synthesizer irradiation was a more efficient method to modify chitosan. M-PACTS exhibited a higher capacity for turbidity and chemical oxygen demand (CODCr) removal. Under optimal conditions, the removal rate values of M-PACTS were up to 96% (turbidity) and 78% (CODCr). The proposed PACTS is suitable for treatment of polluted wastewater in an eco-friendly manner without causing secondary pollution.

Isolating and modifying cellulose from waste papers as flocculant for treating drinking water

In this study, cellulose was extracted from waste paper using alkaline and bleaching treatments. The flocculation performance of six quaternized cellulose (QC) samples (QC-1, QC-5, QC-10, QC-15, QC-20, and QC-30) was evaluated through kaolin suspension using the standard jar test method at varying flocculant dosages, kaolin concentrations, pH values, and settling times. The cellulose content of the waste paper and extracted celluloses were 68.6% and 78.1%, respectively. Fourier-transform infrared spectroscopy, x-ray diffraction, thermogravimetric analysis, and scanning electron microscopy showed that the waste paper properties changed after chemical treatment, confirming that the extracted product was cellulose. The QC derivatives were homogeneously synthesized by reacting the extracted cellulose with 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHPTAC) in the aqueous medium of sodium hydroxide/urea. QC-15 exhibited a highly effective flocculation capability (99.67%) compared to alum (83.91%), with good performance in a wide pH range. The flocculation kinetics (kNo: 5.9 × 10−1 s-1) supported this finding. QC-15 removed 99.67% of turbidity compared to alum (83.9%). Besides, filtration of the conditioned sludge with QC-15 was relatively easy, with low specific resistance compared to the commercial alum. Overall, Q-15 was an effective and environmentally friendly flocculant with potential application for treating drinking water.

Effect of RIM21 gene disruption on flocculation of lager yeast

Lager yeast is the most popular yeast strain used for beer production in China. The flocculation of yeast plays an important role in cell separation at the end of fermentation. Therefore, appropriately enhancing the flocculation capability of the lager yeast without affecting its fermentation performance would be desirable for beer industry. Our previous study showed that the defect of gene RIM21 might contribute to the enhanced flocculation capability of a lager yeast G03. To further investigate the role of the RIM21 gene in flocculation of strain G03, this study constructed a RIM21-deleted mutant strain G03-RIM21Δ through homologous recombination. Deletion of RIM21 improved the flocculation capability of strain G03 during wort fermentation at 11 °C without changing its fermentation performance significantly. The expression of FLO5, Lg-FLO1 and some other genes involved in cell wall integrity pathway were up-regulated in strain G03-RIM21Δ. In addition, the disruption of RIM21 enhanced resistance of yeast cells to cell wall inhibitors. These results provide a basis for elucidating the flocculation mechanism of lager yeast under low-temperature fermentation conditions.

Contribution of bacterial extracellular polymeric substances (EPS) in surface water purification.

Naturally present aquatic microorganisms play an important role in water purification systems, such as the self-purification of surface waters. In this study, two water sources representing polluted surface water (Olympic Green; OG) and unpolluted surface water (Jingmi river; JM), were used to explore the self-purification of surface water by bacteria under different environmental conditions. The dominant bacterial community of OG and JM waters (both are Firmicutes and Proteobacteria) were isolated, cultured, and then used to carry out flocculation tests. Results showed that the flocculation ability of the dominant bacteria and extracellular polymeric substances (EPS) obtained from OG isolation was significantly greater than that from JM. Further examination illustrated that the main components of EPS were polysaccharides, which played an important role in improving the flocculation ability of bacteria. EPS from dominant cultural bacteria strains (OG1 and JM3) isolated from the two different sources lacked hydrophilic groups (e.g. COOH) and had a networked structure which are the main reasons to enhance the flocculation ability. The bacterial diversity and redundancy analysis (RDA) results also showed that microbial community composition is determined by water quality (SS, TOC, and NH4+), and different Bacteroidetes, Actinobacteria and Proteobacteria community structures can improve the water body's ability to remove environmental pollutants (such as SS, humic acid and fulvic acid). These findings provide new information showing how bacterial communities change with environmental factors while maintaining the purity of surface water.

Determination of mechanical and hydraulic properties of polyacrylamide-added bentonite-sand mixtures

Bentonite-sand mixtures are typically used in engineering applications such as cutoff walls for waste containment facilities or barriers in landfills and freshwater reservoirs. However, low or reduced mechanical and hydraulic performance of a bentonite-sand mixture might result in the failure of the engineering structure. In order to enhance the mechanical and hydraulic properties of a bentonite-sand mixture, an anionic and a cationic polyacrylamides with a content of 1, 2, 5, 10, and 15% respectively were added to the bentonite-sand mixtures. The polyacrylamides used in this study were water-soluble synthetic polymers with high molecular weights. They had enhanced flocculation capability when coming into contact with soil and water. Standard Proctor compaction, consolidated-drained direct shear, unconfined compression, falling-head permeability, and free swell tests were performed on the bentonite-sand mixtures that had different bentonite contents. Test results indicated that cohesion, unconfined compressive strength, maximum dry unit weight, and swell index increased while internal frictional angle, permeability, and optimum water content decreased as a result of the polyacrylamide addition. The rate of change was much higher when the polyacrylamide content was increased up to 2%. The performance of the anionic polyacrylamide was found to be slightly better than that of the cationic polyacrylamide in terms of both strength and permeability. In conclusion, 2% anionic polyacrylamide addition resulted in a sufficient increase in the shear and compressive strength, a slight increase in the swell index, and a sufficient decrease in the permeability of the bentonite-sand mixtures.

Operational and structural A-stage improvements for high-rate carbon removal.

Biosorption of organics is investigated at two sites in order to optimize operation and infrastructure for carbon removal and redirection in upstream, high-rate processes. Sufficient process temperature and stable mixed liquor solids concentration were established as the key impact parameters for the process performance. Improved COD removal was achieved by either substantially enhanced aeration (elevated metabolic state) or by enhanced flocculation capability (dosed chemicals). Separation and thickening of organics are typically operated as continuous-flow processes. The optimization of performance parameters led to a new A-stage process named alternating activated adsorption. The AAA process is presented as a novel configuration linking biosorption and thickening capabilities in an alternating scheme without mechanical equipment. The performance data from its first trial indicate benefits from process dynamics including high organics capture rates and thickening capabilities reaching solid concentrations higher than 40g(TSS)/L. COD removal could be increased further by adding biologically generated polymer, that is waste sludge from B-stage. © 2020 Water Environment Federation PRACTITIONERS POINTS: Enhanced preliminary treatment helps to increase capacity and energy efficiency. Low RAS rates, SRT control, aeration, high temperatures, and metal dosing are key performance parameters for removal rates and energy efficiency. The Triple-A process offers new possibilities for A-stage in terms of performance increase and flexibility showing similar or better results compared with conventional A-stage. Adding B-sludge improved COD and nutrient removal rates. High preliminary removal rates of COD and N foster sidestream processes.

Microbial origin of bioflocculation components within a promising natural bioflocculant resource of Ruditapes philippinarum conglutination mud from an aquaculture farm in Zhoushan, China.

Ruditapes philippinarum conglutination mud (RPM) is a byproduct from the aquiculture of an important commercially bivalve mollusk R. philippinarum and has been recently reported as a promising natural bioflocculant resource. However the origin of bioflocculation components within RPM is still a pending doubt and impedes its effective exploitation. This study investigated the probability that RPM bioflocculation components originate from its associated microbes. RPM samples from an aquaculture farm in Zhoushan of China were applied to characterize its microbial community structure, screen associated bioflocculant-producing strains, and explore the homology between extracellular polysaccharides (EPS) from bioflocculant-producing isolates and RPM flocculation components. Results showed that RPM exhibited high bacterial biodiversity, with Proteobacteria, Bacteroidetes and Actinobacteria as the most abundant phyla; hgcI_clade, CL500_29_marine_group, Fusibacter, MWH_UniP1_aquatic_group and Arcobacter as the dominant genera. Fourteen highly efficient bioflocculant-producing strains were screened and phylogenetically identified as Pseudoalteromonas sp. (5), Psychrobacter sp. (3), Halomonas sp. (2), Albirhodobacter sp. (1), Celeribacter sp. (1), Kocuria sp. (1) and Bacillus sp. (1), all of which except Bacillus sp. were reported for the first time for their excellent flocculation capability. Furthermore, EPS from the bioflocculant-producing strains exhibited highly similar monosaccharide composition to the reported flocculation-effective RPM polysaccharides. On the other hand, the existence of fungi in RPM was rare and showed no flocculation functionality. Findings from Zhoushan RPM strongly supported that RPM flocculation components were of bacterial origin and make RPM reproduction possible by fermentation approach.

Multibranch Strategy To Decorate Carboxyl Groups on Cellulose Nanocrystals To Prepare Adsorbent/Flocculants and Pickering Emulsions

A simple multibranch strategy was employed to increase the carboxyl contents on the cellulose nanocrystal (CNC) surface. The effects of various sequential grafting of ascorbic acid or citric acid on the morphology, microstructure, thermal stability, dye adsorption capability (methylene blue), and coagulation–flocculation capacity (model kaolin suspension) of the functionalized CNCs were investigated. Cellulose nanocrystals with multicarboxyl groups (CNC-g-AA-g-CA) showed better thermal stability (Tmax = 359.3 °C), and possessed the highest carboxylic groups of 4.073 mmol/g, which led to a high absolute ζ potential value up to 47.7 mV. Furthermore, the CNC-g-AA-g-CA exhibited excellent coagulation–flocculation capability to kaolin suspension with a turbidity removal rate of 91.07% and good cationic dye (methylene blue) removal rate of 87.8%, indicating that the CNC-g-AA-g-CA can be used as excellent adsorbent and efficient flocculants. In addition, CNC-g-AA-g-CA have good stabilizing effects on soybean oil...

Comparisons of Functional Properties of Polysaccharides from Nostoc flagelliforme under Three Culture Conditions.

Nostoc flagelliforme is an edible cyanobacterium with excellent food and herbal values. It has been used as food in China for more than 2000 years. Many studies have been focused on improving the yield and bioactivity of Nostoc flagelliforme polysaccharides although these have ignored the functional properties. In this study, we extracted and purified three polysaccharides (WL-CPS, NaCl-CPS and Glu-CPS) from Nostoc flagelliforme under normal, salt stress and mixotrophic culture conditions, respectively, in order to change the physicochemical properties of polysaccharides with the aim of obtaining better functional properties. Both salt stress and mixotrophic culture conditions increased the specific yield of polysaccharides. Their functional properties were comparatively investigated and the results showed that NaCl-CPS exhibited the highest emulsification activity and flocculation capability, which was also higher than that of some commercial products. In contrast, Glu-CPS exhibited the highest water and oil holding capacities, foaming property, intrinsic viscosity and bile acids binding capacity. Our results indicated that both NaCl-CPS and Glu-CPS could be considered to be functional polysaccharides according to their respective characteristics, which have great potential in numerous applications, such as food, pharmaceutical, cosmetic, chemical and mineral industries. These findings also demonstrated the potential application of the proper regulation of culture conditions in the development of polysaccharides with desired functional properties.

Synthesis of a starch–acrylic acid–chitosan copolymer as flocculant for dye removal

ABSTRACTFlocculants prepared with modified natural polymers have recently attracted extensive attention in the field of water treatment. In this work, acrylic acid was successfully grafted onto the backbones of starch and chitosan by free radical polymerization. The synthesis parameters of initiator concentration, reaction temperature, and neutralization degree of acrylic acid were optimized as 0.4 wt %, 50 °C, and 70%, respectively, according to the flocculation performance. The ternary copolymer starch–acrylic acid–chitosan (SAAC) could completely remove Acid Blue 113 from 100 mg/L of simulated wastewater (color removal efficiency 99.7%) at the flocculant dosage of 100 mg/L. The SAAC also had effective flocculation capability in a wide range of flocculant dosages and pH values of wastewater. The ternary copolymer based on two natural polymers has enormous potential as flocculant with its advantages of low price, ecofriendliness, and high performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47437.

Preparation and Dewatering Property of Two Sludge Conditioners Chitosan/AM/AA and Chitosan/AM/AA/DMDAAC

Two new chitosan-grafting copolymers (chitosan-g-PAM-AA and C-chitosan-g-PAM-AA) as sludge conditioners (flocculation and aggregation) have been prepared by employing ceric sulfate as a free radical initiator under nitrogen atmosphere in aqueous solution. The optimum condition for synthesizing chitosan-grafting copolymer was determined by orthogonal experiments. The structure, morphology and property of the obtained graft polymers were characterized by FT-IR, XRD, SEM, TGA and contact angle. Further, the municipal activated sludge dewatering performance of the synthesized copolymers was evaluated by the filter cake moisture content. Herein, the effects of pH value and dewatering temperatures of activated sludge, loading dosage or cationic degree of C-chitosan-g-PAM-AA on the filter cake moisture content were investigated. The synthesized amphoteric flocculant C-chitosan-g-PAM-AA showed a highly effective flocculation capability for activated sludge compared with chitosan-g-PAM-AA, chitosan, polyacrylamide (PAM). Also, the lowest filter cake moisture content was up to 61.41%.

Investigation of the effect of water chemistry on biologically mediated flocculation in the aquatic environment

Extracellular Polymeric Substances (EPS) in the water environment assemble fine, colloidal particles, such as clays, microorganisms and biomass, in large flocs, which are eventually subject to sedimentation and deposition and determine water/sediment quality and quantity. This study hence aimed to investigate the way that water and colloidal chemistry affects EPS-mediated flocculation of colloidal particles, using a jar-test experiment. Especially, ionic strength, divalent cation and humic substances concentrations were selected as experimental variables in the jar-test experiments, to elucidate their effects on EPS-mediated flocculation. A higher ionic strength increased flocculation capability, reducing electrostatic repulsion between EPS-attached colloidal particles and enhancing particle aggregation. 0.1 M NaCl ionic strength had higher flocculation capability, with 3 times larger floc size and 2.5 times lower suspended solid concentration, than 0.001 M NaCl. Divalent cations, such as Ca2+, built divalent cationic bridges between colloidal particles and EPS (i.e., colloid-Ca2+-EPS or EPS-Ca2+-EPS) and hence made colloidal particles to build into large, settelable flocs. A small Ca2+ concentration enhanced flocculation capability, reducing suspended solid concentration 20 times lower than the initial dosed concentration. However, humic substances, adsorbed on colloidal particles, reduced flocculation, because they blocked EPS adsorption on colloidal particles and increased negative charges and electrostatic repulsion of colloidal particles. Suspended solid concentration in the tests with humic substances remained as high as the initial dosed concentration, indicating stabilization rather than flocculation. Findings about EPS-mediated flocculation in this research will be used for better understanding the fate and transport of colloidal particles in the water environment and for developing the best management practices for water/sediment quality.

Poly-γ-glutamic acid coupled Pseudomonas putida cells surface-displaying metallothioneins: composited copper(ii) biosorption and inducible flocculation in aqueous solution

Schematic illustration of the preparation, biosorption, and induced flocculation of the biocomposite MB546-PGA.

Collagen Hydrolysates of Skin Shavings Prepared by Enzymatic Hydrolysis as a Natural Flocculant and Their Flocculating Property.

A series of collagen hydrolysates (CHs) were prepared from pigskin shavings by using pepsin (PCH), trypsin (TCH), Alcalase (ACH), HCl (HCH), and NaOH (NCH). Their physicochemical properties, including degree of collagen hydrolysis, molecular weight distribution, electric charge, and microstructure, were investigated, and their flocculation performance was evaluated in a kaolin suspension, at varied pHs and concentrations. PCH exhibited high flocculation capability under acidic and neutral conditions, and its efficiency for removing suspended particles was approximately 80% at a concentration of 0.05g/L. TCH, ACH, HCH, and NCH showed almost no flocculation capability. The flocculation capability of PCH could be mainly due to a combination of optimal molecular weight distribution and electric charge. This study could provide an environment-friendly natural flocculant and also proposes a promising approach for the reuse of collagen wastes. Graphical Abstract ᅟ.

Synthesis, characterization and evaluation of dewatering properties of chitosan-grafting DMDAAC flocculants

Flocculation is one of the most widely applied techniques for water treatment and sludge dewatering. A fresh environmentally friendly and powerful flocculant is highly eager in the sludge dewatering area. In this work, a highly efficient cationic flocculant, chitosan-g-PDMDAAC was synthesized through grafting a monomer, dimethy ldiallyl ammonium chloride(DMDAAC), onto chitosan initiated by ceric sulfate under ultrasonic-assisted and conventional heating condition. The graft copolymer was characterized using FT-IR, XRD and SEM. Further, the dewatering performance of municipal activated sludge was evaluated by the filter cake moisture content and specific resistance in filtration. Its application as a flocculant for wastewater treatment was investigated. The prepared chitosan-g-PDMDAAC showed a highly effective flocculation capability for activated sludge compared with chitosan, polyacrylamide(PAM), cationic polyacrylamide(CPAM).