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1
Ma, Jun, e Guibai Li. "Laboratory and Full-Scale Plant Studies of Permanganate Oxidation as an Aid in Coagulation". Water Science and Technology 27, n. 11 (1 giugno 1993): 47–54. http://dx.doi.org/10.2166/wst.1993.0263.
Testo completoAbstract (sommario):
Standard jar tests and full-scale plant studies were conducted to evaluate the effectiveness of permanganate preoxidation as an aid to coagulation-flocculation of surface waters. The results of the Jar tests demonstrated that permanganate preoxidation obviously enhanced the coagulation-flocculation of the studied surface waters. Through full-scale plant studies, the positive effects of permanganate assistance in coagulation-flocculation of surface raters were confirmed by the turbidity reduction of about 4~11 FTU at permanganate dosages of 1~2 mg/L. It was observed that the size of flocs in the reaction tank became bigger if the water was preoxidized with permanganate, lowering the polyaluminium chloride (PAC) consumption by about 36%. In addition. the effectiveness of prechlorination and permanganate preoxidation on assisting in coagulation-flocculation were compared through full-scale studies at a water treatment plant using a shallow lake as its water source. showing that permanganate preoxidation was a more effective means to aid coagulation-flocculatlon.
2
Luna, Christine Lamenha, Carlos Edison Lopes e Giulio Massarani. "Recovery of Bacillus sphaericus spores by flocculation/sedimentation and flotation". Brazilian Archives of Biology and Technology 48, spe (giugno 2005): 61–70. http://dx.doi.org/10.1590/s1516-89132005000400008.
Testo completoAbstract (sommario):
The aim of this work was use flocculation/sedimentation and flotation for recovery of spores of the Bacillus sphaericus. Microorganism was produced batchwise using culture medium based skimmed milk, corn steep liquor and mineral salts. The best results of flocculation were obtained using CaCl2.2H2O, FeCl3.6H2O, Al2(SO4)3 and tannin as flocculating agents, with optimal flocculation concentrations of 1,500, 3,000, 2,000 and 1,700ppm, respectively. Flocculent suspensions were characterized based on floc diameter and density. Settling tests were performed in batch at different concentrations of the cellular suspensions and revealed high recovery of the solids in suspension in all cases. Flotation tests were accomplished using a mechanical agitated flotation cell and the process was favoured by the increase of the system agitation and for the presence of a cationic collector.
3
Ying Teh, Huey, Uganeeswary Suparmaniam, Man Kee Lam, Yoshimitsu Uemura, Jun Wei Lim, Inn Shi Tan, Jibrail Kansedo e Steven Lim. "Harvesting of Chlorella Vulgaris Biomass by Using Different Bio-Flocculants: A Comparison Study". International Journal of Biomass and Renewables 8, n. 2 (18 dicembre 2019): 17. http://dx.doi.org/10.61762/ijbrvol8iss2art5734.
Testo completoAbstract (sommario):
In the present study, several natural flocculants were extracted from natural resources to harvest Chlorella vulgaris. Jar tests were carried out to evaluate the flocculation efficiencies of the extracted flocculants in harvesting C. vulgaris cells. Chitosan and maize seeds were proven to be effective flocculants as they achieved more than 80 % efficiency after one(1) hour and four (4) hours of sedimentation time, respectively. Under the optimum flocculation conditions of pH 7, 2 mg/L dosage, 120 rpm of stirring speed for chitosan; and pH 3, 450 mg/L of dosage, 15 rpm of stirring speed for maize seeds flocculant; the flocculation efficiencies up to 97.9 % and 84.7 % are able to achieved, respectively. A scale-up study was done to test the flocculation ability of chitosan and maize seeds extracts to harvest 1 L of C. vulgaris. Approximately 97 % and 82 % of flocculation efficiencies were achieved by chitosan and maize seeds flocculants, respectively, under their optimum flocculation conditions. Comparatively, chitosan offer superiority in flocculating C. vulgaris than maize seeds extract in terms of floc size, dosage and sedimentation time.
Keywords: natural flocculant, chitosan, maize seed, microalgae, harvest
4
Xu, Yan, Kemin Gan, Siyi Liang, Haitao Liu e Qunhui Wang. "Investigation and Optimization of Chitosan Performance in Flocculating Kaolin Suspensions Using a Real-Time Suspending Solid Concentration Measuring Method". Water 13, n. 4 (16 febbraio 2021): 513. http://dx.doi.org/10.3390/w13040513.
Testo completoAbstract (sommario):
The performance of chitosan in flocculating kaolin suspensions was investigated. A real-time suspended solid (SS) concentration measuring method was applied. The influence of pH was examined from 2.0 to 13.0. The optimal pH value for low-grade (100 mg/L), middle-grade (500 mg/L), and high-grade (1000 mg/L) kaolin suspension samples was 8.0. The optimal dosage of chitosan for the three grades of kaolin suspensions was 5.0 mg/L, regardless of the initial SS concentration. An orthogonal array test was performed to determine the optimal hydraulic conditions. Range analysis and variance analysis showed that all four considered factors significantly influenced the flocculation performance of chitosan in the following order: paddle rotation speed in the mixing period > paddle rotation speed in the flocculating period > mixing period time > flocculating period time. Intermittent agitation tests were also performed, showing that alternating agitation and settling enhanced the flocculation performance of chitosan.
5
Monette, Frédéric, François G. Brière, Michel Létourneau, Marc Duchesne e Robert Hausler. "Traitement des eaux usées par coagulation-floculation avec recirculation des boues chimiques : Évaluation et validation à grande échelle". Canadian Journal of Civil Engineering 27, n. 4 (1 agosto 2000): 735–53. http://dx.doi.org/10.1139/l00-045.
Testo completoAbstract (sommario):
Two sequences of tests were carried out at the Centre d'épuration Rive-Sud wastewater treatment plant (Longueuil, Que.) to evaluate the performances of a coagulation-flocculation process with chemical sludge recycling. The tests consisted in following the evolution of the quality of the treated water when two flowsheets are supplied simultaneously in parallel with the same wastewater, one flowsheet incorporating the sludge recycling process. Results showed that the recycled sludge contributes significantly to water degradation compared with a classical coagulation-flocculation system. These results do not corroborate the previous work done by Monette et al. (F. Monette et al. Canadian Journal of Civil Engineering, 27: 702-718, 719-734, 2000). The problems observed are explained by inadequate plant installations for sludge recycling. High coagulant concentrations also limit the gains in efficiency associated with recyling. The process reacts rapidly to wastewater loading and reagent modifications. The recycled sludge conditioning is slightly more difficult because of the small particles created by recycling pump turbulence. Finally, turbidity measurements in the flocculator water tank could be used as an excellent indicator for sludge recycling load estimation.Key words: recycling, sludge, coagulation-flocculation, treatment, wastewater, full scale.
6
Fu, Chaochen, Zhengan Zhang, Yuying Li, Lin Li, Hongtian Wang, Shaobo Liu, Xia Hua e Bailian Li. "Optimizing the Flocculation Effect of Cationic Polyacrylamide Prepared with UV-Initiated Polymerization by Response Surface Methodology". Water 15, n. 6 (20 marzo 2023): 1200. http://dx.doi.org/10.3390/w15061200.
Testo completoAbstract (sommario):
Cationic polyacrylamide (CPAM) is a commonly used flocculant for water treatment. Factors that affect the flocculation effect and can be controlled manually include the type and dosage of CPAM, wastewater pH, stirring time and settling time, and their reasonable setting is critical to the flocculation effect of CPAM. In this paper, the optimal flocculation conditions of a novel CPAM were studied. First, single-factor tests were conducted to preliminarily explore the optimal range of factors that influence CPAM flocculation, and then response surface methodology (RSM) tests were performed to accurately determine the optimums of the influencing factors. The results showed that the flocculation effect was better when the intrinsic viscosity was larger or the cationic degree of CPAM was higher. The CPAM dosage, wastewater pH and stirring time significantly impacted the flocculation effect, and inflection points were observed. A model that could guide CPAM-8.14-40.2 flocculation was obtained by RSM tests. The model optimization showed that the optimal flocculation conditions of CPAM-8.14-40.2 for treating wastewater prepared with kaolin were as follows: the CPAM dosage, wastewater pH and stirring time were 5.83 mg·L−1, 7.28, and 5.95 min, respectively, and the turbidity of the treated wastewater was reduced to 6.24 NTU.
7
Monette, Frédéric, François G. Brière, Michel Létourneau, Marc Duchesne e Robert Hausler. "Traitement des eaux usées par coagulation-floculation avec recirculation des boues chimiques : Performance générale et stabilité du procédé". Canadian Journal of Civil Engineering 27, n. 4 (1 agosto 2000): 702–18. http://dx.doi.org/10.1139/l00-047.
Testo completoAbstract (sommario):
Six series of tests were carried out to have a better understanding of the stability and efficiency of a coagulation-flocculation process with chemical sludge recycling. The tests consisted in sequential sludge recycling in 100-L pilot reactors. Other tests were performed to examine the stability following wastewater loading variations. Results showed that stability was reached immediately during the first recycling sequences. Furthermore, to obtain improved results compared with those of a classical coagulation-flocculation process, the flocculant concentration must be increased according to the sludge recycling load. Results also revealed that recycling sludge does not absorb wastewater load variations. Consequently, the implementation of sludge recycling in a wastewater treatment plant would not cause effluent degradation or entail major changes in a normal plant operation routine. The predominant coagulation-flocculation mechanisms that explained the increase in efficiency, in comparison with the classical process, were identified as enmeshment and sweep flocculation. Finally, the recycled sludge produced were conditioned and dewatered in a fashion similar to that of a classical process.Key words: recycling, sludge, preformed flocs, coagulation-flocculation, treatment, wastewater, stability.
8
Maćczak, Piotr, Halina Kaczmarek, Marta Ziegler-Borowska, Katarzyna Węgrzynowska-Drzymalska e Aleksandra Burkowska-But. "The Use of Chitosan and Starch-Based Flocculants for Filter Backwash Water Treatment". Materials 15, n. 3 (29 gennaio 2022): 1056. http://dx.doi.org/10.3390/ma15031056.
Testo completoAbstract (sommario):
Inorganic aluminum or iron salts supported with synthetic polymers are commonly used to eradicate colloidal particles from water in coagulation and flocculation processes. Nevertheless, these agents have several disadvantages, such as large volumes of sludge produced or environmental toxicity. Recently biodegradable polymers have been suggested as eco-friendly flocculants for water treatment. This study aimed to investigate the possibilities of using starch and chitosan and their oxidized derivatives as flocculants for filter backwash water treatment. Dialdehyde starch (DST) and dialdehyde chitosan (DCT) were synthesized by periodate oxidization of natural starch from corn and low molecular weight chitosan. The obtained materials have been characterized with scanning electron microscopy (SEM), ATR-FTIR spectroscopy, and thermogravimetric analysis (TGA). Furthermore, we studied the flocculation properties of polysaccharide flocculants in a series of jar tests. The effectiveness of chitosan and starched-based flocculants was compared to synthetic polymers commonly used to treat iron ions-rich filter backwash water. The environmental aspects of these chemicals, particularly the biodegradability of post-flocculation residues, were also addressed. It was found that oxidized starch and chitosan derivatives can be used as ecological flocculating materials to treat potable water or sludge.
9
Kaiser, M. "Operational tests on combined flocculation in coal processing". Fuel and Energy Abstracts 37, n. 3 (maggio 1996): 173. http://dx.doi.org/10.1016/0140-6701(96)88377-9.
Testo completo
10
Vanderborght, J. P., e R. Wollast. "Elimination of Micropollutants by NaAlo2 Flocculation During Primary Treatment of Mixed Wastewater". Water Science and Technology 18, n. 1 (1 gennaio 1986): 67–74. http://dx.doi.org/10.2166/wst.1986.0007.
Testo completoAbstract (sommario):
The influence of NaAlO2 -flocculation of mixed wastewater was investigated by conducting laboratory tests and using a pilot-scale flocculation reactor. In comparison with the primary sedimentation, aluminate addition results in a lower residual concentration for Zn and Cd. For all metals under investigation (Cu, Cr, Zn, Cd, and Ni), the removal was found to be irreversible. Biological treatment was uninhibited by an addition of these metals when NaAlO2 -flocculation was provided.
11
Xu, Ying, Yuebin Wu, Huan Liang e Qiang Sun. "Flow Field Research of the Reciprocating Baffled Flocculation Tank". Environmental Sciences Proceedings 2, n. 1 (18 agosto 2020): 29. http://dx.doi.org/10.3390/environsciproc2020002029.
Testo completoAbstract (sommario):
To research the reasons for the unsatisfactory hydraulic conditions of the reciprocating baffled flocculation tank, this paper investigates its flow field through PIV (Particle Image Velocimetry) laboratory experiment tests and numerical simulation. Three numerical schemes, the standard model, RNG model and realizable model, are calibrated and validated with the experimental data gained in this study. They are adopted for comparative study of their validity and accuracy for modeling the effect of the hydraulic characteristics of the flow field on flocculation. The best validated model is then applied to explain the reasons for the low flocculation efficiency and is applied to improve the structure of the reciprocating baffled flocculation tank.
12
Haarhoff, Johannes, e Hannes Joubert. "Determination of aggregation and breakup constants during flocculation". Water Science and Technology 36, n. 4 (1 agosto 1997): 33–40. http://dx.doi.org/10.2166/wst.1997.0080.
Testo completoAbstract (sommario):
The Argaman-Kaufman flocculation model holds great promise as a practical tool for the generalization of flocculation behaviour from relatively few, simple batch tests in the laboratory. There are, however, valid reasons that have prevented it from being widely accepted in design practice. This paper deals with a number of these obstacles: • There is the need of a standardized test method in terms of equipment, procedures and data analysis. The effects of settling time and the choice of the flocculation performance parameter are demonstrated. • The flocculation constants are critically dependent on the level of coagulant dosage. In the sweep flocculation regime, the optimum coagulant dosage cannot be precisely pinpointed with jar testing, which presents a formidable problem for routine application. • The flocculation constants are, contrary to the model, dependent on the initial particle concentration. This currently precludes the extrapolation of test results to raw water turbidities different from the turbidity at which the test was conducted. • The flocculation performance parameter is not an intuitive parameter in design practice, and the design procedure for flocculation systems will have to be adapted to reach a specific design objective.
13
Peng, Yunyan, e Dong Jin. "Screening Tests of Copper Mine Tailings Flocculation with Polyacrylamide". IOP Conference Series: Earth and Environmental Science 371 (13 dicembre 2019): 042004. http://dx.doi.org/10.1088/1755-1315/371/4/042004.
Testo completo
14
Haas, Sandra R., Fábio R. Nascimento, Ivo André H. Schneider e Christine Gaylarde. "Flocculation of fine fluorite particles with Corynebacterium xerosis". Revista de Microbiologia 30, n. 3 (luglio 1999): 225–30. http://dx.doi.org/10.1590/s0001-37141999000300007.
Testo completoAbstract (sommario):
The treatment of fine particles dispersed in liquids is common in several industries and especially important in mineral processing. The efficiency of settling operations can be substantially increased by flocculation. The aim of this work was to study the flocculation of fine fluorite particles by the bacterium Corynebacterium xerosis. Flocculation tests, microelectrophoresis measurements and optical microscopy were used to evaluate flocculation. The results showed that C. xerosis cells adhere to the fluorite surfaces promoting the aggregation of the particles. High quality flocs can be obtained rapidly at pH 7.0 using a cell concentration of 40 mg/l, considerably lower than previously reported in the literature. The results are discussed with reference to the surface characteristics of the mineral and of the microorganism.
15
Balemans, Sophie, Siegfried E. Vlaeminck, Elena Torfs, Leonie Hartog, Laura Zaharova, Usman Rehman e Ingmar Nopens. "The Impact of Local Hydrodynamics on High-Rate Activated Sludge Flocculation in Laboratory and Full-Scale Reactors". Processes 8, n. 2 (21 gennaio 2020): 131. http://dx.doi.org/10.3390/pr8020131.
Testo completoAbstract (sommario):
High rate activated sludge (HRAS) processes have a high potential for carbon and energy recovery from sewage, yet they suffer frequently from poor settleability due to flocculation issues. The process of flocculation is generally optimized using jar tests. However, detailed jar hydrodynamics are often unknown, and average quantities are used, which can significantly differ from the local conditions. The presented work combined experimental and numerical data to investigate the impact of local hydrodynamics on HRAS flocculation for two different jar test configurations (i.e., radial vs. axial impellers at different impeller velocities) and compared the hydrodynamics in these jar tests to those in a representative section of a full scale reactor using computational fluid dynamics (CFD). The analysis showed that the flocculation performance was highly influenced by the impeller type and its speed. The axial impeller appeared to be more appropriate for floc formation over a range of impeller speeds as it produced a more homogeneous distribution of local velocity gradients compared to the radial impeller. In contrast, the radial impeller generated larger volumes (%) of high velocity gradients in which floc breakage may occur. Comparison to local velocity gradients in a full scale system showed that also here, high velocity gradients occurred in the region around the impeller, which might significantly hamper the HRAS flocculation process. As such, this study showed that a model based approach was necessary to translate lab scale results to full scale. These new insights can help improve future experimental setups and reactor design for improved HRAS flocculation.
16
García-Ávila, Fernando, Angel Méndez-Heredia, Alex Trelles-Agurto, Esteban Sánchez-Cordero, Emigdio Antonio Alfaro-Paredes, Freddy Criollo-Illescas, María D. Tonon-Ordoñez e Gina Heredia-Cabrera. "Experimental Evaluation of Tubular Flocculator Implemented in the Field for Drinking Water Supply: Application in the Developing World". Water 15, n. 5 (21 febbraio 2023): 833. http://dx.doi.org/10.3390/w15050833.
Testo completoAbstract (sommario):
The purpose of this study was to evaluate the efficiency of a large-scale Horizontal Tubular Flocculator (HTF) as an easy-to-implement technology for potable water provision compared to the efficiency of a traditional baffle flocculator. The HTF was built with a 4-inch diameter PVC pipe and coupled to a sedimentation and filtration process. Experimental tests were performed using lengths of 68.4 m and 97.6 m for the HTF. These lengths were combined with raw water flow rates of 0.25, 0.5, 0.75, 1, and 2 L/s and five turbidity ranges <10 NTU, 10–20 NTU, 21–50 NTU, 51–100 NTU, >100 NTU, giving a total of 100 tests for one year. Jar tests were performed to determine the optimal dose of aluminum sulfate used as a coagulant. Hydraulic characteristics such as time of retention (TR) and velocity gradient (G) were evaluated; likewise, plug flow, dead volume, and short-circuit ratios were determined by tracer tests using the Wolf–Resnick model. The average results determined a removal of 98.8% of turbidity and 99.93% of color. The TR varied between 4.62 and 36.97 min and G varied between 6.15 and 109.62 s−1. The results showed that HTF can be useful as a flocculation unit in a purification system.
17
Schmidt, Beata, Krzysztof Kowalczyk e Beata Zielinska. "Synthesis and Characterization of Novel Hybrid Flocculants Based on Potato Starch Copolymers with Hollow Carbon Spheres". Materials 14, n. 6 (18 marzo 2021): 1498. http://dx.doi.org/10.3390/ma14061498.
Testo completoAbstract (sommario):
Novel carbon nanofiller-based starch-g-polyacrylamide hybrid flocculation materials (St-PAM-CS) were in situ prepared using potato starch (St), acrylamide (AM), and hollow mesoporous carbon spheres (CSs; diameters of 300–400 nm). Structures of different St-PAM-CS systems were characterized by Fourier transform infrared (FTIR) spectroscopy, X-Ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), laser scanning microscopy (LSM), and particle size analysis. The flocculation tests were evaluated by removing high turbidity kaolin suspension—initial absorbance 1.84. The effect of the St to AM molar ratio, doses, and content of CSs in hybrids on flocculation efficiency were examined. Satisfactory flocculation efficiency was obtained for all hybrids with 1 wt.% of the CS component. The highest reduction of the kaolin suspension absorbance (to 0.06) was observed for a 3 mL dose of the starch hybrid with the highest AM content. Additionally, St-PAM-CS showed a reduction in the sludge volume in time. The hybrids reached better flocculation efficiency in relation to the reference systems without CSs. The proposed flocculation mechanism (considering bridging, patching, and formation of hydrogen bonds) has been confirmed by the recorded results.
18
Wu, Silin, Yuyang Zhu, Wei Zhu, Shi Shu e Yan Cui. "A study on the differences in the flocculation of dredged slurries and the influencing mechanisms". Water Science and Technology 80, n. 9 (1 novembre 2019): 1751–62. http://dx.doi.org/10.2166/wst.2019.428.
Testo completoAbstract (sommario):
Abstract In the water treatment process of natural water bodies, a large amount of dredged slurry with high water content is generated and required for treatment. The coagulation–flocculation method can improve the efficiency of separation, and a suitable scheme is of great significance. It is unclear whether there is a significant difference in flocculation and separation of dredged slurries from different sources and which constituents dominate this process. Facing these problems, the tests were conducted for dredged sediments from 10 different sources, including rivers, lake, and ocean. Under the same flocculation conditions, the difference in the increment of particle size d10, the specific resistance of filtration, and the suspended solids (SS) of the supernatant after sedimentation are 0–4.6 times, 0–2.4 orders of magnitude, and 0–4 orders of magnitude, respectively. It was found that the main constituents in the dredged slurries, such as clay minerals, fulvic acid and humic acid, impact on flocculation and separation effects by affecting the zeta potential of the particles. However, there is no single constituent in the dredged slurry which dominates the flocculation and separation effect. When these constituents are incorporated, the zeta potential exhibited in the slurry determines the difference in flocculation and separation effects.
19
Calderón, Roberto Robles, Hugo David Chirinos Collantes, Laida Vilca Calderón e Jaqueline Heidy Chirre Flores. "EVALUATION OF THE COAGULANT EFFICIENCY OF MORINGA SEED (MORINGA OLEÍFERA) FOR THE WATER TREATMENT OF THE CHURÍN RIVER, PACHANGARA DISTRICT, LIMA, PERU". PERIÓDICO TCHÊ QUÍMICA 21, n. 46 (30 marzo 2024): 19–25. http://dx.doi.org/10.52571/ptq.v21.n46.2024_04_chirinos_pgs_19_25.pdf.
Testo completoAbstract (sommario):
Background: In the research, Moringa Oleifera - MO seeds were used in coagulation-flocculation processes, identifying the main properties it presents such as coagulant activity. Aims: The purpose of the research was to evaluate the coagulant and flocculating effect of moringa seed flour in the treatment of turbid water (with turbidity between 700 NTU and 800 NTU). Methods: The experimental tests were carried out under the following conditions: shelled moringa seed flour in NaCl solution, 1 M, it was observed that it has no effect on the clarification of turbid water and modifies the pH to 4.47; The mixture of moringa seed flour with aluminum sulfate (Aquapol brand) was investigated in jar tests with 300 mL of turbid water at conditions of: shelled moringa seed flour 1.02 g, 5.01 g and 10, 02 grams; with aluminum sulfate 0.1 mL, 0.5 mL, and 0.7 mL, respectively; at 200 rpm for 2 minutes, Results: Evaluating water quality after 1.5 h and 12 h of sedimentation; It was determined that the best performance was the mixture of: 1.02 g of moringa seed flour with 0.1 mL of aluminum sulfate, 200 rpm for 2 minutes, then at 70 rpm for 15 minutes and 12 h of sedimentation. Discussion: Experimental tests have been carried out using Moringa Oleifera (MO) for raw river water treatment processes in places of low economic availability and due to its abundant availability, low cost, and non-toxic. Conclusions: It was concluded that its most viable application would be as a flocculation adjuvant, since, when used with a Chemical coagulant, it reduces the concentration of the chemical coagulant with good removal results.
20
Matsui, Yoshihiko, Norihito Tambo, Tokio Ohto e Yasushi Zaitsu. "Dual Wavelength Photometric Dispersion Analysis of Coagulation and Flocculation". Water Science and Technology 27, n. 11 (1 giugno 1993): 153–65. http://dx.doi.org/10.2166/wst.1993.0274.
Testo completoAbstract (sommario):
A technique to evaluate the coagulat ion/flocculation process on fluctuating light intensity transmitted through a flowing suspension has been developed recently for online monitoring in a flocculation system. In this paper, the authors tried to expand this technique to perform direct evaluation of floc size, settling velocity, and residual color after aluminum coagulation from the fluctuating light absorption using dual wavelengths. A theoretical study was carried out to establish the data handling algorithms for the evaluation of the above mentioned values from the fluctuating light absorbance. Two specific wavelengths were selected at near infrared and ultraviolet regions in order to characterize suspended matters and soluble colored organics. The usefulness of the proposed theory was verified in a series of batch coagulation tests with a newly developed dual wavelength photometric dispersion analyzer (DPDA). With an improved high precision photometer and data processing ci rcuits, the extent of color colloid removal can be estimated at the beginning stage of coagulation/flocculation. The algorithms for the evaluation of floc size were calibrated and verified in flocculation experiments with micro photography. Flocculation and sedimentation experiments showed that settling velocity was successfully estimated by the proposed algorithms.
21
Bretas, Pedro Lopes, Otávia Martins Silva Rodrigues e José Aurélio Medeiros da Luz. "Selective flocculation and floc-flotation of iron bearing mineral slimes". Research, Society and Development 11, n. 5 (12 aprile 2022): e45011528289. http://dx.doi.org/10.33448/rsd-v11i5.28289.
Testo completoAbstract (sommario):
The mineral processing of friable iron ores usually generates ultrafine (smaller than 15 µm) particles, normally called slimes, which usually have a high iron grade and are usually disposed into tailings dam. The traditional mineral process techniques for iron ore do not work efficiently with ultrafines; however, selective flocculation is an alternative to concentrate that fraction. The physical-chemical treatment of iron ore slime was studied here, on a bench scale, based on the scientific foundations of selective flocculation and flotation. Samples of slimes from two Brazilian iron ore processing plants (CEII and VGII) and industrial process waters were used in the tests. Complexometric titration of calcium and magnesium indicated that the process waters were adequate for selective flocculation. Only selective flocculation, even under optimum conditions, did not achieve good results. However, its use prior to flotation led to promising results. The VGII sample has stood out, for which the final concentrate achieved 60.1 % of Fe, the mass recovery was 64.5 % and 13.5 % of Fe in the tailing, resulting selectivity index of 6.58, only with one stage of selective flocculation and one stage of flotation.
22
Baumer, Patrik, Peter Volkart e Peter Krebs. "Dynamic loading tests for final settling tanks". Water Science and Technology 34, n. 3-4 (1 agosto 1996): 267–74. http://dx.doi.org/10.2166/wst.1996.0440.
Testo completoAbstract (sommario):
Dynamic experiments conducted in a pilot scale settling tank at Zurich's wastewater treatment plant (WWTP) are presented. The experiments were carried out with real activated sludge. They showed that vertical perforated walls transverse to the main flow direction are very beneficial particularly for wet-weather flow. The increase of the effluent suspended solids concentration is significantly dampened with dynamic hydraulic loading. Installing several perforated walls enables uniform velocity profiles to be attained, enhancing flocculation. The total sludge mass stored in the final settling tank may be increased by this system and requires special attention when the removal system is designed.
23
Pivokonska, L., e M. Pivokonsky. "The influence of agitation on aggregates formed during treatment of water with a content of humic substances". Water Supply 6, n. 1 (1 gennaio 2006): 211–18. http://dx.doi.org/10.2166/ws.2006.026.
Testo completoAbstract (sommario):
This study aims to evaluate the influence of agitation conditions on the efficiency of the aggregation process when treating surface water containing humic substances. Laboratory tests were conducted by the jar tests using a variable speed paddle gang stirrer. Optimization of agitation intensity was determined by a Couette flocculator. Suspension was prepared using aluminium chloride as a destabilising reagent. Aggregation efficiency was evaluated by the determination of the degree of aggregation and by the test of aggregation. For all surface waters treated, the optimum treatability was demonstrated by applying higher velocity gradients (G=200–250 s−1). In addition to the laboratory tests, the plant measurements with water containing increased amounts of humic substances were taken to evaluate the aggregation efficiency. The results obtained by the aggregation efficiency measurements show that the intensity of agitation, with the assistance of perforated baffle-type flocculation chamber, attains a low level of velocity gradient (G=22–113 s−1), in contrast to the optimized velocity gradient level (G=200–250 s−1). The aggregates formed in the water treatment plant have an unsuitably wide size-distribution.
24
Xu, Kun, Yao Liu, Yang Wang, Ying Tan, Xuecheng Liang, Cuige Lu, Haiwei Wang, Xiusheng Liu e Pixin Wang. "A novel poly(acrylic acid-co-acrylamide)/diatomite composite flocculant with outstanding flocculation performance". Water Science and Technology 72, n. 6 (9 giugno 2015): 889–95. http://dx.doi.org/10.2166/wst.2015.290.
Testo completoAbstract (sommario):
Series of anionic flocculants with outstanding flocculation performance, poly(acrylic acid-co-acrylamide)/diatomite composite flocculants (PAAD) were successfully prepared through aqueous solution copolymerization and applied to flocculate from oil-field fracturing waste-water. The structure of PAAD was characterized by Fourier transform infra-red spectroscopy , 13C nuclear magnetic resonance and X-ray diffraction tests, and its properties were systematically evaluated by viscometer, thermogravimetry analysis and flocculation measurements. Furthermore, the influences of various reaction parameters on the apparent viscosity of flocculant solution were studied, and the optimum synthesis condition was determined. The novel composite flocculants exhibited outstanding flocculation properties. Specifically, the dosage of composite flocculants that could make the transmittance of treated wastewater exceed 90% was only approximately 12–35 ppm, which was far lower than that of conventional flocculants. Meanwhile, the settling time was lower than 5 s, which was similar to that of conventional flocculants. This was because PAAD flocculants had a higher absorption capacity, and larger chain extending space than conventional linear flocculants, which could refrain from the entanglement of linear polymer chains and significantly improve flocculation capacity.
25
Liu, Zhisheng, Jianhui Wang, Guang Li, Shaodong Yang, Haipeng Yang, Jinlong Zuo e Yuyang Wang. "Study on Flocculation Characteristics of Potato Starch Wastewater". Coatings 13, n. 10 (12 ottobre 2023): 1762. http://dx.doi.org/10.3390/coatings13101762.
Testo completoAbstract (sommario):
Herein, a chitosan film (CS) was modified using 2,3-epoxy-propyl trimethyl ammonium chloride (GTA) to flocculate granular pollutants in potato starch wastewater, aiming at the deficiencies of poor water solubility and weak electropositivity of the chitosan film. By examining the degree of substitution of chitosan film amino under different factors and different levels and response surface optimization tests, the optimum preparation conditions of chitosan film quaternary ammonium salt (HTCC) were obtained. Using scanning electron microscopy (SEM), Fourier infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and 1H-nuclear magnetic spectroscopy, the nucleophilic substitution reaction of the GTA molecule with the hydrogen atoms in the chitosan film amino group successfully improved the water solubility and electropositivity of the chitosan film. HTCC was used to treat potato starch wastewater, and the optimal flocculation conditions were obtained. The flocculation product was recovered, and the composition analysis of the flocculation product demonstrated that HTCC-potato protein flocculation precipitate was rich in high protein, which is a good choice of feed and can realize sustainable utilization of resources.
26
Li, Yu, Leigang Li, Reham Yasser Farouk e Yuanyuan Wang. "Optimization of Polyaluminum Chloride-Chitosan Flocculant for Treating Pig Biogas Slurry Using the Box–Behnken Response Surface Method". International Journal of Environmental Research and Public Health 16, n. 6 (19 marzo 2019): 996. http://dx.doi.org/10.3390/ijerph16060996.
Testo completoAbstract (sommario):
Flocculation can remove large amounts of nitrogen and phosphorus from wastewater, and the resulting nitrogen- and phosphorus-rich floc can be used to produce organic fertilizer. For biogas slurries containing high levels of nitrogen and phosphorus, ordinary flocculants can no longer meet the flocculation requirements. In this study, to fully utilize the advantages of the two flocculants and achieve efficient removal rates of nitrogen and phosphorus from a biogas slurry, chitosan (CTS) and polyaluminum chloride (PAC) were used as a composite flocculation agent to flocculate pig biogas slurries. The response surface method was used to study the effect of PAC added (PACadded) to the composite flocculant (CF), composite flocculant added (CFadded) to the biogas slurry and the pH on flocculation performance, and optimize these three parameters. In the tests, when the PACadded was 6.79 g·100 mL−1CF, the CFadded was 20.05 mL·L−1 biogas slurry and the pH was 7.50, the flocculation performance was the best, with an absorbance of 0.132 at a wavelength of 420 nm. The total phosphorus (TP) concentration was reduced from 214.10 mg·L−1 to 1.38 mg·L−1 for a removal rate of 99.4%. The total ammonia nitrogen (TAN) concentration was reduced from 1568.25 mg·L−1 to 150.27 mg·L−1 for a removal rate of 90.4%. The results showed that the CF could form larger flocs, and had greater adsorption capacity and more stable flocculation performance than ordinary flocculants. Furthermore, the CF could exhibit better chelation, electrical neutralization and bridge adsorption.
27
Shestopalov, Oleksii, Oleksandr Briankin, Nadegda Rykusova, Oksana Hetta, Valentina Raiko e Musii Tseitlin. "OPTIMIZATION OF FLOCCULAR CLEANING AND DRAINAGE OF THIN DISPERSED SLUDGES". EUREKA: Physics and Engineering 3 (11 maggio 2020): 75–86. http://dx.doi.org/10.21303/2461-4262.2020.001239.
Testo completoAbstract (sommario):
The efficiency of solid phase retention and dehydration of finely dispersed products of a coal processing plant and a metallurgical enterprise on the module for cleaning and dewatering sludge is investigated. A technique for selecting the operating parameters of equipment based on the determination of the strength criterion of flocs is proposed. A methodology for technological tests has been developed to control the flocculation process and optimize the flow of flocculant depending on the concentration of the solid phase. Industrial tests on the module for wastewater treatment and sludge dewatering using flocculants proved the effectiveness of the developed methodology. It is shown that the conditions for conducting tests on flocculation should correspond to the operating conditions of the circuit apparatus for cleaning and dewatering sludge. These conditions include sludge performance, sludge flow rate in the cross section of pipes and apparatuses, and the flow time from the flocculator to the centrifuge. During the testing of the Module, the solids retention efficiency of 97–99 % was achieved with the strength criteria of flocs in front of a centrifuge of 2–2.5 mm/s. The conditions for the high efficiency of the apparatus chain are the optimization of the aggregation process itself. It is revealed that for the formation of strong flocs it is necessary to regulate the concentration of the solid phase. For coal sludge, the concentration of the solid phase before the flocculant is fed must be maintained no higher than 50–60 g/l, and for gas treatment sludge – no higher than 20–25 g/l. Correction of the concentration of sludge before the flocculator is possible by diluting it with clarified water to the optimum concentration for aggregation. It is found that the moisture content of the sediment and the efficiency of the retention of the solid phase depend on the strength criterion of the flocs. Therefore, the optimization of the flocculant flow rate is possible by controlling and the residual floccule deposition rate after mechanical action in front of the dewatering equipment. The flocculant flow rate must be adjusted depending on the concentration of the solid phase in the sludge to achieve the desired criterion for the strength of the flocs
28
Liu, J. C., e C. S. Lien. "Pretreatment of bakery wastewater by coagulation-flocculation and dissolved air flotation". Water Science and Technology 43, n. 8 (1 aprile 2001): 131–37. http://dx.doi.org/10.2166/wst.2001.0482.
Testo completoAbstract (sommario):
The pretreatment of wastewater from a large-scale bakery was studied. In the coagulation-flocculation reaction, it was found that both alum and FeCl3 were effective in the jar tests. When at coagulant dosage of 90 to 100 mg/l, 55 % of COD and 95 to 100% of SS could be removed. The optimum pH was at 6.0. In addition, the removal of SS was affected by pH more significantly, while the removal of COD was not affected in the pH range of 6.0 to 8.0. In the DAF experiments, 48.6% of COD and 69.8% of SS were removed in 10 min at a pressure of 4 kg/cm2, recycle ratio of 0.3 l/min, and pH of 6.0. Upon the addition of 100 mg/l of alum, the removal efficiency of COD did not increase while SS removal increased to 82.1%. It was found that 5-min flocculation time did improve the COD removal while it had little effect on SS removal. Flocculation for longer than 5 min did not enhance the flotation performance. Similar phenomena were observed when FeCl3 was used as the coagulant, except that flocculation had an insignificant effect on COD and SS removal. It was also found that FeCl3 was relatively more effective than alum. In summary, both coagulation-flocculation and DAF were efficient for the pretreatment. The advantages and disadvantages were discussed.
29
Cruz, Dafne, Marcio Pimentel, Ana Russo e Wilson Cabral. "Charge Neutralization Mechanism Efficiency in Water with High Color Turbidity Ratio Using Aluminium Sulfate and Flocculation Index". Water 12, n. 2 (19 febbraio 2020): 572. http://dx.doi.org/10.3390/w12020572.
Testo completoAbstract (sommario):
Most of the water supplied in Brazil comes from water streams that may have higher values for apparent color than turbidity. Treatability trials were performed for color and turbidity removal to evaluate the advantages of coagulation during the charge neutralization mechanism when compared to sweep flocculation for water with those characteristics. There were three types of trials: conventional Jar Test with raw water, with and without filtration, and in a pilot Water Treatment Plant, direct downward filtration, with synthetic water. Auxiliary equipment such as Continuous Flocculation Monitoring Equipment (CFME) and image analysis were used to evaluate the growth of flocs. In the Jar Tests experiments, similar levels of color (61.49%) and turbidity (61.30%) removal were observed, with a lower dosage of coagulant (46 mg/L) in the charge neutralization mechanism compared to the ones with sweep flocculation (58.22% for color and 54.73% for turbidity removal with 52 mg/L of aluminium sulfate). Similar results were found on pilot plant. At filtration rates of 180 and 300 m3 m−2 day−1, sweep flocculation mechanism had shorter filtration cycle (<5 m3) compared to other mechanisms. Therefore, a change in the operation of Water Treatment plants that use a coagulant dosage associated with sweep flocculation can bring advantages such as the reduction of coagulant consumption and sludge productions, as well as the increase of chlorine disinfection and filtration cycles.
30
Sun, Weimin, Guangcheng Zhang, Ling Pan, Helin Li e Aihua Shi. "Synthesis, Characterization, and Flocculation Properties of Branched Cationic Polyacrylamide". International Journal of Polymer Science 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/397027.
Testo completoAbstract (sommario):
A water soluble branched cationic polyacrylamide (BCPAM) was synthesized using solution polymerization. The polymerization was initiated using potassium diperiodatocuprate, K5[Cu(HIO6)2](Cu(III)), initiating the self-condensing vinyl copolymerization of acrylamide and acryloxyethyltrimethyl ammonium chloride (DAC) monomer. The resulting copolymer was characterized by the use of Fourier-transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Its flocculation properties were evaluated with standard jar tests of sewage. The effects of initiator concentration, monomer concentration, reaction temperature, and the mass ratio of monomers on intrinsic viscosity and flocculation properties of the product were determined using single-factor experiments and orthogonal experiment.
31
Leiva, Williams H., Norman Toro, Pedro Robles, Gonzalo R. Quezada, Iván Salazar e Ricardo Jeldres. "Clay Tailings Flocculated in Seawater and Industrial Water: Analysis of Aggregates, Sedimentation, and Supernatant Quality". Polymers 16, n. 10 (20 maggio 2024): 1441. http://dx.doi.org/10.3390/polym16101441.
Testo completoAbstract (sommario):
High-molecular-weight anionic polyacrylamide was used to analyze the effect of kaolin on the structure of particle aggregates formed in freshwater and seawater. Batch flocculation experiments were performed to determine the size of the flocculated aggregates over time by using focused beam reflectance measurements. Sedimentation tests were performed to analyze the settling rate of the solid–liquid interface and the turbidity of the supernatant. Subsequently, a model that relates the hindered settling rate to the aggregate size was used to determine the mass fractal dimension (Df). Flocculation kinetics revealed that greater amounts of kaolin generated larger aggregates because of its lamellar morphology. The maximum size was between 10 and 20 s of flocculation under all conditions. However, the presence of kaolin reduced the settling rate. The fractal dimension decreased with the increase in the kaolin content, resulting in the formation of irregular and porous aggregates. By contrast, factors such as the flocculation time, water quality, and quartz size had limited influences on the fractal dimension. Seawater produced a clearer supernatant because of its higher ionic strength and precoagulation of particles. Notably, the harmful effect of clays in seawater was reduced.
32
Zangooei, Hossein, Mohammad Delnavaz e Gholamreza Asadollahfardi. "Prediction of coagulation and flocculation processes using ANN models and fuzzy regression". Water Science and Technology 74, n. 6 (24 giugno 2016): 1296–311. http://dx.doi.org/10.2166/wst.2016.315.
Testo completoAbstract (sommario):
Coagulation and flocculation are two main processes used to integrate colloidal particles into larger particles and are two main stages of primary water treatment. Coagulation and flocculation processes are only needed when colloidal particles are a significant part of the total suspended solid fraction. Our objective was to predict turbidity of water after the coagulation and flocculation process while other parameters such as types and concentrations of coagulants, pH, and influent turbidity of raw water were known. We used a multilayer perceptron (MLP), a radial basis function (RBF) of artificial neural networks (ANNs) and various kinds of fuzzy regression analysis to predict turbidity after the coagulation and flocculation processes. The coagulant used in the pilot plant, which was located in water treatment plant, was poly aluminum chloride. We used existing data, including the type and concentrations of coagulant, pH and influent turbidity, of the raw water because these types of data were available from the pilot plant for simulation and data was collected by the Tehran water authority. The results indicated that ANNs had more ability in simulating the coagulation and flocculation process and predicting turbidity removal with different experimental data than did the fuzzy regression analysis, and may have the ability to reduce the number of jar tests, which are time-consuming and expensive. The MLP neural network proved to be the best network compared to the RBF neural network and fuzzy regression analysis in this study. The MLP neural network can predict the effluent turbidity of the coagulation and the flocculation process with a coefficient of determination (R2) of 0.96 and root mean square error of 0.0106.
33
Yue, Tao, Xiqing Wu, Xiao Chen e Tianyu Liu. "A Study on the Flocculation and Sedimentation of Iron Tailings Slurry Based on the Regulating Behavior of Fe3+". Minerals 8, n. 10 (21 settembre 2018): 421. http://dx.doi.org/10.3390/min8100421.
Testo completoAbstract (sommario):
Based on the regulating behavior of Fe3+, flocculation and sedimentation tests of iron tailings slurry flocculated using 2 mg/L anionic polyacrylamide (APAM) were studied, including the tests of Fe3+ dosage, regulating time, and pH. Flocculation–sedimentation tests showed that: a recommended addition of 56 mg/L Fe3+ produced a surprisingly bad flocculation effect; sedimentation ability decreased with the increase of regulating time, however, the regulating ability during the first 1 min was low; Fe3+ displayed a high regulating effect at pH 6–7, and then decreased with the increase of slurry pH. Size analysis demonstrated that the regulating ability of Fe3+ was related to the change of floc size, which increased with the decrease of size. Zeta potential analysis and calculation showed that small concentrations of Fe3+ and certain hydroxyl complex ions (such as Fe(OH)2+ and Fe(OH)2+) adsorbed onto the APAM molecular chains, resulting in a decreased charge density of the APAM molecules, and this electrostatic adsorption was able to make the polymer curl more easily. Fourier Transform Infrared Spectroscopic (FTIR) indicated the APAM on the hematite was slightly degraded into a monomer-like short-chain polymer while adding certain concentration of Fe3+. Scanning Electron Microscope (SEM) imaging showed that the network structure of APAM molecules treated by Fe3+ collapsed, and the APAM adsorption amount on hematite was significantly reduced. Therefore, the effect of Fe3+ on the APAM could be recommended as a new method for desorption and degradation of the APAM contained in the tailings slurry or flocs.
34
Kfir, R., B. W. Bateman, B. A. Pitout e P. Coubrough. "Disinfection of Polluted Water by Chlorine-Flocculant Tablet". Water Science and Technology 21, n. 3 (1 marzo 1989): 207–13. http://dx.doi.org/10.2166/wst.1989.0101.
Testo completoAbstract (sommario):
Two water treatment tablets were evaluated for their efficacy of removal of E. coli bacteria, coliphage V1 and polio 1 from water. The activity of both tablets is based on flocculation as well as disinfection with additional straining. The tablets differ from each other only in their disinfectant source, i.e. Chlor-floc A contains Halazone and Chlorfloc B contains dichloro-S-triazine-trione. Tests were carried out using simulated hard and coloured water at room temperature. Results indicated both tablets to be efficient but showed tablet B to be of superior quality. Tablet B was shown to eliminate all bacteria and viruses from the test water after 4 minutes at room temperature (22 °C). Studies on partial removal of the test organisms by filtration or flocculation without chlorination showed that both steps partially removed the organisms, but the combined process of flocculation chlorination followed by filtration proved to be the most effective treatment.
35
Szpak, Joseph P., Donald R. Woods e Kyle Bouchard. "Critique of Jar Testing for the Design of Coagulation-Flocculation Systems". Water Quality Research Journal 31, n. 1 (1 febbraio 1996): 51–64. http://dx.doi.org/10.2166/wqrj.1996.004.
Testo completoAbstract (sommario):
Abstract The effects of clay type and concentration, jar shape, paddle shape, rapid mix time and flocculation velocity gradient on batch, bench-scale jar tests of turbidity were studied using a fractional factorial design. The two-parameter kinetic model for flocculation of Agraman, Kaufman and Bratby was used. This model provided a good fit of the data when they were log-transformed. The variables that had a statistically significant effect on the kinetics constants for floc agglomeration and breakup were the interaction of clay concentration and flocculation velocity gradient, plus clay type combined with rapid-mix time. The jar shape and the paddle shapes did not have significant effects. The kinetic constants measured in this analysis agreed with those reported previously by Agraman and Kaufman. The work assumes that turbidity is an acceptable measure of the number concentration. The results confirm the usefulness of the kinetic model and emphasize the importance of testing the goodness-of-fit of the model before analyzing the data.
36
Choumane, Fatima Zohra, Fatiha Zaoui, Fatma Kandouci, Bouhana Maachou e Belkacem Benguella. "Valorization of potato peel residues to produce a bioflocculant to be used in the treatment of liquid effluents". IOP Conference Series: Materials Science and Engineering 1204, n. 1 (1 novembre 2021): 012002. http://dx.doi.org/10.1088/1757-899x/1204/1/012002.
Testo completoAbstract (sommario):
Abstract The present study aims primarily to investigate the flocculation capacity of a novel potato peel-based bioflocculant in wastewater treatment. The analysis of wastewater revealed high COD and BOD5 contents that could respectively reach the values 529.08 mg O2/l and 317.03 mg O2/l. In addition, the effect of experimental parameters such as the pH, coagulant/flocculant dosage, and contact time, was studied using the coagulation-flocculation treatment technique. The experiments were carried out with a lab-scale jar-test apparatus where aluminum chloride (AlCl3) was used as a coagulant agent. It should be noted that the optimal dose of AlCl3 was equal to 0.6 g at 10 mn, with turbidity reduction of 99.01%. Moreover, the flocculation tests showed higher turbidity removal (98%), for a flocculant dosage of 0.2g. The results obtained in this study indicated that using the natural potato peel-based flocculant, in the presence of a coagulant, provides an effective and environmentally friendly coagulation option for wastewater treatment.
37
Matovelle, Carlos, María Quinteros e Diego Heras. "Machine Learning Techniques in Dosing Coagulants and Biopolymers for Treating Leachate Generated in Landfills". Water 15, n. 24 (5 dicembre 2023): 4200. http://dx.doi.org/10.3390/w15244200.
Testo completoAbstract (sommario):
The leachate discharges generated in sanitary landfills contain many pollutants that are harmful to the environment; treatments are scarce and should be carried out better. The use of coagulation–flocculation processes has been one of the most widely used, but due to the complexity of the characterization of the leachate, the dosing strategy of coagulants and biopolymers needs to be clarified. Therefore, the present study was carried out to determine the doses of coagulants and biopolymers suitable for coagulation–flocculation processes in the treatment of leachates using computational models of machine learning techniques such as artificial neural networks (ANNs); these allow for decreasing the operations of the tests of jars in the laboratory, optimizing resources. Through laboratory experimentation, there are real results of the effectiveness of applying biopolymers in leachate treatments at different concentration levels. The laboratory results were taken as input variables for the algorithms used; after the validation and calibration process, we proceeded to estimate predicted data with the computational model, obtaining predictions of optimal doses for treatment with high statistical adjustment indicators. It is verified that the applied coagulation–flocculation treatments reduce the turbidity values in the leachate and contaminants associated with suspended solids. In this way, the jar tests are optimized so that the operational costs decrease without affecting the results of adequate dosing.
38
Ai, Heng Yu, Ming Ming Wang, Lu Han, Burigude, Bo Wei e Yan Qiu Jia. "Features on Head Loss of Flocculation Tank Installed with Small Mesh Grid". Advanced Materials Research 777 (settembre 2013): 424–29. http://dx.doi.org/10.4028/www.scientific.net/amr.777.424.
Testo completoAbstract (sommario):
Small mesh grid is mostly used as flocculation equipment in present water plant, and its head loss is closely related to flocculation effect. Flocculation tank installed with several grid groups in different mesh sizes were tested with a view to evaluating its head loss characteristics, including the frictional and local head losses. The tests were carried out at pilot scale, using a steel tank as flocculation basin. The grids are made of plastic material and the cross section size of the grid trips is 7 mm in width and 2 mm in height. The results indicate that relative roughness is most associated with frictional resistance coefficient (FRC), whereas Reynolds number was unrelated to that. The ratio of frictional head loss to total head loss of the basin does not vary with the variation of channel velocity, and the ratio is always less than 6% in this case. Local resistance coefficient (LRC) decreases with the increase of mesh size. In order to improve the utilization rate of head loss, the preferred mesh size of the grid should be 30-40 mm. The optimal space between the neighboring grid layers can maximize the utilization of turbulent kinetic energy loss generated by grids.
39
Shin, Gwy-Am, e Mark D. Sobsey. "Removal of norovirus from water by coagulation, flocculation and sedimentation processes". Water Supply 15, n. 1 (30 settembre 2014): 158–63. http://dx.doi.org/10.2166/ws.2014.100.
Testo completoAbstract (sommario):
In this study, we determined the removal of a prototype human norovirus (Norwalk virus, NV) by bench-scale alum coagulation, flocculation and sedimentation processes using reverse transcriptase polymerase chain reaction (RT-PCR) for norovirus assays. After determining optimum conditions for the coagulation, flocculation and sedimentation processes in terms of turbidity reduction, jar tests were performed using the same waters seeded with test viruses. For comparison, two other important health-related viruses, poliovirus 1 (PV1) and coliphage MS2, were included in this study. The removal of NV by coagulation, flocculation and sedimentation processes based on RT-PCR assay in this study was 1.5 log10, which was similar to that of PV1 and a little lower than that of coliphage MS2 (2 log10) based on the same RT-PCR assay. The removal of NV in this study (1.5 log10) is considerably higher than the one in a recent study using recombinant norovirus virus-like particles (∼0.7 log10). Overall, the results of this study suggest that human noroviruses can be appreciably reduced by a properly-operated coagulation, flocculation and sedimentation processes and the contamination of drinking water by noroviruses should be controlled by conventional water treatment processes with conventional physico-chemical processes and disinfection.
40
Faez Abdulmohsin Al-Kathili e Doaa hameed khalaf. "Spiral tube flocculation for drinking water treatment plants". GSC Advanced Engineering and Technology 4, n. 1 (30 settembre 2022): 059–71. http://dx.doi.org/10.30574/gscaet.2022.4.1.0052.
Testo completoAbstract (sommario):
Almost all water treatment plants for either surface raw water or water from reservoirs needs to have some kind of a system to eliminate time required for particles to settle down in the settling tanks (This occurs by increase turbidity particle size). A coagulant to be added and a flocculation’s system to inshore a good and homogenous distribution of chemicals to form up the correct size of particles to settled within the settling tanks. In water treatment plants many types of clary- flocculates are used either the mechanicals paddle or hydraulic jumps of steam water or using the spiral tubes (As on this study). In addition, a Jar Test should be used to assess the suitability of flocculation treatment for a given raw water. Unfortunately, even Jar Test suffers from a number of disadvantages. a number of study for Spiral Flocculate, has been shown I claimed to be a better method for continuous assessment of flocculation. Within multimedia sands and a spiral flocculate’s. Constant flow (generated from a tank with spill way to ensure a constant head all through the test cycles, results are recorded, and a number of remarks and suggestions are produced. This study will make use of a number of laboratory tests on a small model of treatment plants made for this purpose consist mainly of a gravity filter compares the performance of Spiral Flocculate The experiments conducted reveal that the Spiral Flocculate has a better effective energy. Even that this method need more future study and theoretical equations for the developing of chain flocs are needed. However, the size of flocs in Spiral Flocculate seems to be overestimated relative to the real flocculate and coagulations. Purpose: A continuous need for improving water treatment techniques allows for new technologies for obtaining adequate water, both in terms of quality and quantity. In order to obtain an efficient, rapid and low-cost clarification system, this study proposes the use of spired coiled tubes as a coagulation-flocculation reactor to evaluate the proposed clarification system, a number of experimental test where generated and a pumped kaolin with controlled quantities are pumped to city water and used in this study. Water with controlled head is used all the time and records are generated for the evaluation.
41
Sun, Wei Min, Guang Cheng Zhang, He Lin Li, Dong Dong Li, Pei Pei Li, Bai Chen Liu, Die Zhang, Xia Lei e Qing Ren Zhao. "Synthesis, Characterization, and Flocculation Properties of Branched Polyacrylamide". Advanced Materials Research 476-478 (febbraio 2012): 2311–16. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.2311.
Testo completoAbstract (sommario):
A water soluble branched polyacrylamide has been synthesized through solution polymerization. The polymerization was initiated by potassium diperiodatocuprate, K5[Cu(HIO6)2](Cu(III)), in alkaline medium and capable of initiating the self condensation vinyl polymerization of acrylamide monomer. The polymer obtained was characterized using Fourier-transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Its flocculation properties were evaluated with clay suspensions using standard jar tests. The concentration of monomers, concentration of initiators, reaction temperature and solution pH on the influence of intrinsic viscosity and flocculation properties of production were studied. The results demonstrate that the branched polymer can be used as a kind of novel flocculant in water and wastewater treatment.
42
Chen, Yanfei, Yuanlin Chen e Lei Zhang. "Effect of the Molecular Weight of Carboxymethyl Cellulose on the Flotation of Chlorite". Materials 16, n. 9 (25 aprile 2023): 3356. http://dx.doi.org/10.3390/ma16093356.
Testo completoAbstract (sommario):
The present study aimed to investigate the influence mechanism of carboxymethyl cellulose (CMC) on the flotation of fine chlorite. To this end, a series of flotation tests, sedimentation tests, and microscope analyses were conducted. Flotation tests revealed an inverse relationship between particle size and the recovery of chlorite, indicating that finer particles exhibited higher recovery rates. Moreover, it was observed that the recovery of fine chlorite was significantly associated with the water recovery (proportion of water entering the floated product to the weight of water in the initial flotation suspension) and a variety of frother types. Based on these findings, it can be inferred that froth entrainment may constitute a crucial component of the recovery mechanism underlying fine chlorite. Thus, reducing froth entrainment (the phenomenon of hydrophilic minerals entering floated products through foam water) is the key to depress chlorite flotation. Flotation tests indicate that fine chlorite recovered into froth products can be depressed effectively by CMC with a high molecular weight. The results of sedimentation tests and microscope analyses in the presence of CMC prove that CMC with a high molecular weight generates flocculation on fine chlorite particles while that with a low molecular weight does not. It is suggested that the depression of chlorite flotation may be attributed to the reduction in the entrainment resulting from the flocculation induced by CMC.
43
Rusten, B., B. Eikebrokk e G. Thorvaldsen. "Coagulation as Pretreatment of Food Industry Wastewater". Water Science and Technology 22, n. 9 (1 settembre 1990): 1–8. http://dx.doi.org/10.2166/wst.1990.0060.
Testo completoAbstract (sommario):
Jar-tests, pilot-plant and full-scale experiments on chemical pretreatment of food industry wastewater have been performed. The objectives were to find maximum removal efficiencies, suitable coagulation and flocculation agents, and the optimum process design. The results showed that the wastewater composition greatly influences the maximum removal efficiencies and also the conditions for optimum coagulation and flocculation. Optimum pH depends on the chemical agent and the actual dosage used. With proper pH-adjustment, addition of either 0.10-0.15 mg FeCl3-6H2O/mg COD, or about 0.20 mg Al2(SO4)3.18H2O/mg COD, was sufficient to obtain good removal of organic matter. Maximum removal efficiencies of 67-90 % total COD were achieved, depending on wastewater composition.
44
Li, Gang, Dengpan Qiao e Jincheng Xie. "Optimization of Flocculation and Sedimentation Parameters of Total Tailing Filling Material Based on Response Surface Method". Journal of Nanomaterials 2022 (28 marzo 2022): 1–8. http://dx.doi.org/10.1155/2022/4804721.
Testo completoAbstract (sommario):
Using sulfide ore and oxide ore tailings of a tin mine in Yunnan as raw materials, 17 groups of flocculation settling tests were designed by Box-Behnken in Design-Expert software, and the settling velocity and underflow concentration of mixed tailings with sulfur/oxygen ratio of 5 : 5 were studied. The effects of volume concentration, flocculant unit consumption, and flocculant concentration on settling velocity and underflow concentration were explored, and the optimal parameters of settling velocity and underflow concentration were obtained. Results. The best mixing parameters of mixed tailings are volume concentration of 17.66%, flocculant unit consumption of 39.589 g/t, and flocculant concentration of 0.195%. At this time, the settling speed is 2.231 mm/s and the underflow concentration is 65.289%. The flocculation settling velocity under this parameter condition was tested, and the experimental results were consistent with the predicted results of the model. This surface method can be used to design the flocculation and settlement test of mine tailings, which has certain guiding significance for the selection of parameters in actual production of mines.
45
Etiégni, L., M. Wakoli e K. Ofosu-Asiedu. "Design of an efficient tannin extract effluent treatment system". Water Science and Technology 39, n. 10-11 (1 maggio 1999): 321–24. http://dx.doi.org/10.2166/wst.1999.0674.
Testo completoAbstract (sommario):
A study was undertaken on the combined wastewater effluent from a Tannin extract plant (90%) and a Mushroom Production Unit (10%). The effluent had BOD5 of 2350 mg/l, COD of 4600 mg/l, and high levels of total suspended solid (0.43-4.20 mg/l), phosphorus (2078 mg/l), free ammonia (2982 mg/l) and colour index of 50 to 150°H. These values are effluent Standards of Eldoret Town in Kenya. To address these problems, three potential treatment processes were considered: VITOX system using pure oxygen, lagoon evaporation system, and Step-alum coagulation/flocculation process using wood ash leachate for pH adjustment. The latter was chosen because of its efficiency for not only BOD5, COD, phosphorus and free ammonia reduction but also for the complete colour removal when alum was added in two stages as laboratory Jar-tests indicated. A plant was subsequently designed that incorporated a two-step alum coagulation/flocculation process in two upflow tanks with wood-ash leachate for pH adjustment during and after flocculation.
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Sorlini, Sabrina, Michela Biasibetti, Francesca Gialdini e Maria Cristina Collivignarelli. "How can drinking water treatments influence chlorine dioxide consumption and by-product formation in final disinfection?" Water Supply 16, n. 2 (21 settembre 2015): 333–46. http://dx.doi.org/10.2166/ws.2015.142.
Testo completoAbstract (sommario):
In this study water samples of different origins (subalpine lake, artificial lake and river) were treated by pre-oxidation, coagulation/flocculation, adsorption on granular activated carbon and disinfection. Different laboratory-scale tests were carried out to evaluate the treatment impact on ClO2 consumption in disinfection and on the formation of disinfection by-products (trihalomethanes, adsorbable organic halogen, chlorite and chlorate). The results showed that coagulation/flocculation and activated carbon adsorption have the most significant impact on reducing disinfectant consumption. Pre-oxidation of artificial lake water with KMnO4 and NaClO determines the highest ClO2 consumption. Regardless of the water source, the amount of chlorite produced after disinfection with ClO2 is 40–60% lower using NaClO as the pre-oxidant rather than KMnO4 or ClO2. Otherwise, NaClO leads to a high formation of adsorbable organic halogens and trihalomethanes in artificial lake water (up to 60 μg/L and 20 μg/L respectively), while in the case of ClO2 oxidation, trihalomethane formation is 98% less compared to NaClO. Further, adding ferrous ion in coagulation/flocculation improves the removal of chlorite produced during pre-oxidation, with a 90% removal, mainly due to the reduction of chlorite to chloride. Finally, activated carbon adsorption after pre-oxidation and coagulation/flocculation removes adsorbable organic halogens and trihalomethanes respectively by 50–60% and 30–98%, and completes the chlorite and chlorate removal.
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Eichhorn, Christian, Sina Weckmüller e Wilhelm Urban. "Natural Flocculant from a Combination of Moringa oleifera Seeds and Cactus Cladodes (Opuntia ficus-indica) to Optimize Flocculation Properties". Water 14, n. 21 (6 novembre 2022): 3570. http://dx.doi.org/10.3390/w14213570.
Testo completoAbstract (sommario):
The lack of access to clean water worldwide and organic, inorganic as well as biological contamination of existing freshwater sources are a major problem for around 2 billion people, especially in the countries of the global south. One sign of polluted water is turbidity. It is generally caused by colloidal and particulate suspended solids. Chemical flocculants are often used to reduce turbidity and thus eliminate the mostly harmful substances that cause it. However, these have some disadvantages, such as cost and availability, so increasingly natural plant-based flocculants are coming into focus and are considered as an alternative option. In this study, Moringa seeds (Moringa oleifera) and cactus cladodes (Opuntia ficus-indica) were investigated as innovative and environmentally friendly flocculants for water treatment. The parameters investigated included absolute turbidity reduction and flocculation activity, as well as shear strength of the resulting flocs. The flocculation experiments were conducted as simultaneous tests in beakers. Experiments were conducted using both a laboratory-prepared model suspension with an initial turbidity of approximately 139 NTU and natural surface water with an initial turbidity of approximately 136 NTU. The flocculant dosages used ranged from 100 to 300 mg/L. The results show that although Moringa seeds had the highest flocculation activity (up to 93%), the flocs were very fragile and were destroyed again even at low induced shear forces. Flocculants from cactus yielded stable flocs, but the flocculation activity (maximum at 54%) was not as high as that of Moringa. The combination of the two materials resulted in a flocculant with sufficiently high flocculation activity (76%) and stable flocs, which could withstand higher shear forces potentially induced in further treatment steps.
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SEIDEL, IAN J., MICHAEL S. LITAVECZ, SARAH PUTNEY, MORGAN E. DAVIS e MARTIN A. HUBBE. "Effects of carboxymethyl starch as a papermaking additive". February 2024 23, n. 2 (27 febbraio 2024): 78–87. http://dx.doi.org/10.32964/tj23.2.78.
Testo completoAbstract (sommario):
Carboxymethyl starch (CMS) is a bio-based, anionic polymer that has potential as part of a dry-strength additive program for papermaking. Due to its negative charge, its effects can be expected to depend on its interactions with various cationic agents. In this work, the effects of CMS were observed following its sequential addition after one of three selected cationic strength agents at different dosage levels. In selected tests, the furnish was pretreated at the 1% level by a dispersant, sodium polyacrylate, which might represent a high level of anionic contaminants in a paper mill system. Laboratory tests were conducted to show the effects on dewatering, fine-particle retention, and flocculation. These tests were supplemented with measurements of charge demand, zeta potential, and handsheet properties. Sequential addition of cationic glyoxylated acrylamide copolymers (gPAM) and CMS were found to strongly promote dewatering. Two gPAM products and a poly(vinylamine) product in sequential addition with CMS were very effective for promoting fine-particle retention. These same sequential treatments of the stock contributed to moderate fiber flocculation, though severe flocculation was caused by further treatment of the furnish with colloidal silica. Handsheet strength results were mixed. In the default recycled copy paper furnish, the average breaking length for the sheets made with cationic additives followed by CMS was not greatly different from the blank condition. Superior strength resulted when the default furnish was treated with a dispersant alone. When the dispersant-contaminated furnish was treated with the same combinations of cationic additives and CMS, the strength returned to the baseline achieved in the absence of the dispersant. The results were discussed in terms of the charged character of the different additives and their interactions not only with the fiber surfaces but also with each other.
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Fitzpatrick, C. S. B., E. Fradin e J. Gregory. "Temperature effects on flocculation, using different coagulants". Water Science and Technology 50, n. 12 (1 dicembre 2004): 171–75. http://dx.doi.org/10.2166/wst.2004.0710.
Testo completoAbstract (sommario):
Temperature is known to affect flocculation and filter performance. Jar tests have been conducted in the laboratory, using a photometric dispersion analyser (PDA) to assess the effects of temperature on floc formation, breakage and reformation. Alum, ferric sulphate and three polyaluminium chloride (PACl) coagulants have been investigated for temperatures ranging between 6 and 29°C for a suspension of kaolin clay in London tap water. Results confirm that floc formation is slower at lower temperatures for all coagulants. A commercial PACl product, PAX XL 19, produces the largest flocs for all temperatures; and alum the smallest. Increasing the shear rate results in floc breakage in all cases and the flocs never reform to their original size. This effect is most notable for temperatures around 15°C. Breakage, in terms of floc size reduction, is greater for higher temperatures, suggesting a weaker floc. Recovery after increased shear is greater at lower temperatures implying that floc break-up is more reversible for lower temperatures.
50
Anjos, Bruna Ferreira dos, Tatiane Kelly Barbosa de Azevêdo, Bruna Rafaella Ferreira da Silva, Renata Martins Braga, Alexandre Santos Pimenta e Francisca Adriana Ferreira De Andrade. "Tannins from cashew tree (Anacardium occidentale) bark as a flocculant for water clarification". Ambiente e Agua - An Interdisciplinary Journal of Applied Science 17, n. 3 (25 maggio 2022): 1–12. http://dx.doi.org/10.4136/ambi-agua.2815.
Testo completoAbstract (sommario):
Concern about the overexploitation of natural resources has increased in recent decades, especially involving water and its treatment. Paradoxically, one of the sources of water pollution is the treatment itself, due to the use of chemical flocculants, which end up generating sludge that may be highly aggressive to the environment. One of the ways to solve this problem is to use natural flocculants for this purpose, since they are biodegradable and do not harm nature. This study evaluated the efficiency of a natural flocculant produced from tannins extracted from the bark of the cashew tree (Anacardium occidentale) and compared it with two commercial coagulants, Tanfloc® and iron chloride. The water for treatment was collected from a weir. The cashew trees’ bark was collected, ground, and submitted to hot-water extraction to yield the tannins, and the extraction product was cationized. The flocculation tests were carried out using the jar test with solutions having concentrations of 33.3, 66.7, and 100 mg L-1. Turbidity and pH were analyzed before and after flocculation. Among the assessed flocculants, the cationized tannins produced the best responses both for removal of turbidity and final pH of the treated water. Tanfloc® also produced satisfactory results regarding turbidity removal. The iron chloride, besides not properly clarifying the water, left it very acidic. Since the cationized tannins practically did not change the pH and were effective in the removal of turbidity, they represent an interesting, sustainable alternative product to treat the water.
Keywords: cationized tannins, natural flocculating agente, removal of turbidity, water treatment.