The effect of contact time between CPAM and colloidal silica on the flocculation behavior in the approach flow

TAPPI Journal ◽  
2021 ◽  
Vol 20 (1) ◽  
pp. 39-47
Author(s):  
PAUL KROCHAK ◽  
KLAS JOHANSSON ◽  
IGNACIO DE SAN PIO
Keyword(s):  
Contact Time ◽  
High Speed ◽  
Colloidal Silica ◽  
Pilot Scale ◽  
Cationic Polymer ◽  
Fiber Suspension ◽  
Flow Loop ◽  
Hydrodynamic Shear ◽  
Focused Beam ◽  
Optimal Implementation

Multicomponent wet-end systems have become increasingly common in papermaking, with the objective of improving the retention-formation-dewatering relationship. It is quite common to use at least a cationic polymer, often in combination with an anionic microparticle. In some cases, a fixative is also used. However, there is still debate on the optimal implementation of these systems. In particular, optimizing the contact time of the cationic polymer prior to addition of the anionic microparticle is still poorly understood. In this work, we investigate the effect of the contact time of a cationic polyacrylamide (CPAM) prior to addition of colloidal silica on the flocculation response in a flowing fiber suspension. The effect of using a fixative is also investigated. Focused beam reflectance measurements (FBRM) are combined with zeta-potential measurements for optimizing the addition levels of a two- and three-component system, as well as for elucidating the effect of contact time on CPAM performance. Trials are then performed on a pilot scale flow loop, where the time between addition of these two components is varied and the resulting flocculation response is characterized using high-speed filming and image analysis techniques. It is shown that the efficacy of CPAM can be improved through use of a fixative and that a longer CPAM contact time may be beneficial in terms of immediate flocculation; however, hydrodynamic shear tends to dominate the flocculation response regardless of contact time due to floc rupture.

Effect of Physicochemical Variables on Algal Autoflotation

1992 ◽  
Vol 26 (7-8) ◽  
pp. 1769-1778 ◽  
Author(s):  
S.-I. Lee ◽  
B. Koopman ◽  
E. P. Lincoln
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Retention Time ◽  
Contact Time ◽  
Pilot Scale ◽  
Dissolved Oxygen Concentration ◽  
Physicochemical Variables ◽  
Rise Rate ◽  
Mixing Intensity ◽  
Maximum Rise

Combined chemical flocculation and autoflotation were examined using pilot scale process with chitosan and alum as flocculants. Positive correlation was observed between dissolved oxygen concentration and rise rate. Rise rate depended entirely on the autoflotation parameters: mixing intensity, retention time, and flocculant contact time. Also, rise rate was influenced by the type of flocculant used. The maximum rise rate with alum was observed to be 70 m/h, whereas that with chitosan was approximately 420 m/h. The efficiency of the flocculation-autoflotation process was superior to that of the flocculation-sedimentation process.

Pilot-scale neutralisation of underground mine water

1996 ◽  
Vol 34 (10) ◽  
pp. 141-149 ◽  
Author(s):  
J. P. Maree ◽  
G. J. van Tonder ◽  
P. Millard ◽  
T. C. Erasmus
Keyword(s):  
Mine Water ◽  
Contact Time ◽  
Pilot Scale ◽  
Underground Water ◽  
Underground Mine ◽  
Economic Feasibility ◽  
Fluidised Bed ◽  
Chemical Composition Of Water ◽  
Before And After ◽  
Time Required

Traditionally acid mine water is neutralised with lime (Ca(OH)2). Limestone (CaCO3) is a cheaper alternative for such applications. This paper describes an investigation aimed at demonstrating that underground mine water can be neutralised with limestone in a fluidised-bed. The contact time required between the limestone and the acid water, chemical composition of water before and after treatment, and economic feasibility of the fluidised bed neutralisation process are determined. A pilot plant with a capacity of 10k1/h was operated continuously underground in a gold mine. The underground water could be neutralised effectively using the limestone process. The pH of the water was increased from less than 3 to more than 7, the alkalinity of the treated water was greater than 120 mg/l (as CaCO3) and the contact time required between mine water and limestone was less than 10 min (the exact contact time depends on the limestone surface area). Chemical savings of 56.4% can be achieved compared to neutralisation with lime.

Experimental Characterization of Two-Phase Swirl Flow Interacting With a Circular Bluff Body

2021 ◽  
Author(s):  
Rafael Gonzalez Hernandez ◽  
Afshin Goharzadeh ◽  
Mahmoud Meribout ◽  
Lyes Khezzar
Keyword(s):  
High Speed ◽  
Bluff Body ◽  
Transition Period ◽  
Swirl Flow ◽  
Critical Distance ◽  
High Speed Photography ◽  
Flow Loop ◽  
Two Phase ◽  
Air Pocket ◽  
Air Core

Abstract This study presents an experimental investigation of two-phase swirl flow interacting with a circular bluff body. A horizontal and transparent multiphase flow loop is employed to investigate the dynamic of swirl flow close to the circular bluff body. Using high-speed photography, air-core development during the transition period is characterized. Analysis of both instantaneous and averaged images provides key information on air-core length and diameter for steady state conditions. The distance from air-core tip to the disk depends on a critical gas-liquid ratio (GLRc). The presence of air pocket behind the circular bluff body depends on a critical distance to the disk.

Advanced wastewater disinfection technologies: short and long term efficiency

1998 ◽  
Vol 38 (12) ◽  
pp. 109-117 ◽  
Author(s):  
V. Lazarova ◽  
M. L. Janex ◽  
L. Fiksdal ◽  
C. Oberg ◽  
I. Barcina ◽  
...  
Keyword(s):  
Peracetic Acid ◽  
Contact Time ◽  
Pilot Scale ◽  
Coli Strain ◽  
Plate Count ◽  
Galactosidase Activity ◽  
Virus Removal ◽  
E Coli ◽  
Bacteriophage Ms2 ◽  
Short And Long Term

Advanced disinfection processes (peracetic acid, UV irradiation and ozonation) have been tested and evaluated through bench and pilot scale studies. 3 log removals of total coliforms, faecal coliforms and faecal streptococci were achieved by 10mg/L peracetic acid at a 10min contact time, by UV radiation at 35mW.s/cm2 and by ozone at 5mg/L for 10min contact time. Higher doses are required for virus removal by UV and PAA and especially for highly resistant viruses such as F-specific bacteriophage MS2. Ozonation has the advantage of having a strong effect on all types of bacteriophages and protozoa cysts even when low treatment doses and short contact times are applied. The results of this study demonstrated that evaluation of disinfection efficiency of ozone, UV and PAA depends on the criteria and methods employed. Standard method (plate count) results showed an important disinfection effect on culturability, while results from non-standard methods (respiratory activity and β-galactosidase activity assay) indicated less reduction of viable cells. Moreover, the results confirm that disinfectants act on bacteria in different ways. It has been clearly demonstrated that b-galactosidase activity is affected by PAA while UV treatment has no or very limited effect on the enzyme activity. Even without sunlight reactivation, bacterial regrowth in seawater was observed after disinfection of sewage effluents. This study also shows that the biodegradability of sewage effluent for an E coli strain was affected differently by the oxidative disinfectants ozone and PAA. Biodegradability should therefore be considered when evaluating the total disinfection efficiency.

Control of 2-Methylisoborneol and Geosmin by Ozone and Peroxone: A Pilot Study

1992 ◽  
Vol 25 (2) ◽  
pp. 291-298 ◽  
Author(s):  
B. Koch ◽  
J. T. Gramith ◽  
M. S. Dale ◽  
D. W. Ferguson
Keyword(s):  
Hydrogen Peroxide ◽  
Ferrous Sulfate ◽  
Contact Time ◽  
Pilot Scale ◽  
Ozone Dose ◽  
Ammonia Addition ◽  
Removal Efficiencies ◽  
Odorous Compounds ◽  
Water District ◽  
Percent Removal

A pilot-scale study of ozone and PEROXONE (ozone in combination with hydrogen peroxide) for the removal of the odorous compounds 2-methylisoborneol (MIB) and geosmin in drinking water has been conducted at the Metropolitan Water District of Southern California. The study investigated the effects of ozone dosage, ratio of hydrogen peroxide to ozone (H202/03), and contact time. It was found that MIB and geosmin removal increased with higher applied ozone doses, but longer contact times over the range of 6-12 min were not significant. It was determined that 80-90 percent removal could be achieved with an ozone dose of approximately 4.0 mg/l, as compared to an ozone dose of approximately 2.0 mg/l at a H202/03 ratio of 0.2. Also investigated were the effects of alternative contactor configurations, ferrous sulfate as an alternative coagulant, bromide and ammonia addition, and simulated turbidity on the removal efficiencies of the two odorous compounds.

Measurements of Gas Bubble Size Distributions in Flowing Liquid Mercury

2012 ◽  
Author(s):  
Mark Wendel ◽  
Bernard Riemer ◽  
Ashraf Abdou
Keyword(s):  
Bubble Size ◽  
High Speed ◽  
National Laboratory ◽  
Size Distributions ◽  
Flow Loop ◽  
Proton Beam Irradiation ◽  
Flowing Liquid ◽  
Cavitation Damage ◽  
Oak Ridge ◽  
Liquid Mercury

Pressure waves created in liquid mercury pulsed spallation targets have been shown to induce cavitation damage on the target container. One way to mitigate such damage would be to absorb the pressure pulse energy into a dispersed population of small bubbles, however, measuring such a population in mercury is difficult since it is opaque and the mercury is involved in a turbulent flow. Ultrasonic measurements have been attempted on these types of flows, but the flow noise can interfere with the measurement, and the results are unverifiable and often unrealistic. Recently, a flow loop was built and operated at Oak Ridge National Labarotory to assess the capability of various bubbler designs to deliver an adequate population of bubbles to mitigate cavitation damage. The invented diagnostic technique involves flowing the mercury with entrained gas bubbles in a steady state through a horizontal piping section with a glass-window observation port located on the top. The mercury flow is then suddenly stopped and the bubbles are allowed to settle on the glass due to buoyancy. Using a bright-field illumination and a high-speed camera, the arriving bubbles are detected and counted, and then the images can be processed to determine the bubble populations. After using this technique to collect data on each bubbler, bubble size distributions were built for the purpose of quantifying bubbler performance, allowing the selection of the best bubbler options. This paper presents the novel procedure, photographic technique, sample visual results and some example bubble size distributions. The best bubbler options were subsequently used in proton beam irradiation tests performed at the Los Alamos National Laboratory. The cavitation damage results from the irradiated test plates in contact with the mercury are available for correlation with the bubble populations. The most effective mitigating population can now be designed into prototypical geometries for implementation into an actual SNS target.

Pilot Scale Studies of Geosmin and 2-Methylisoborneol Removal

1988 ◽  
Vol 20 (8-9) ◽  
pp. 229-236 ◽  
Author(s):  
E. A. Vik ◽  
R. Storhaug ◽  
H. Naes ◽  
H. C. Utkilen
Keyword(s):  
Activated Carbon ◽  
Water Treatment ◽  
Contact Time ◽  
Pilot Scale ◽  
Oxidation Products ◽  
Adsorption Sites ◽  
One Year ◽  
Ozonation Process ◽  
Organic Oxidation ◽  
Water Blooms

Water blooms of O.bornettii, a producer of off-flavour compounds, occasionally occur in Lake Mjoesa. Accordingly a new water works is planned to alleviate the associated taste and odour problems. A pilot plant was constructed in 1985 and a continuous water treatment study was performed over a one year period. Granular activated carbon (GAC) was compared with ozonation-GAC. Filtrasorb-400 was used and the empty-bed contact-time of the GAC-filters was 21 min. The ozone dosage varied from 2 to 5 mg O3/l. To simulate water blooms, commercially produced geosmin and 2-methyliso-borneol (MIB) were added to the water in concentrations from 10 to 190 ng/l. A slightly higher TOC-uptake was seen in the ozonation-GAC combination. This may indicate that the ozonation process is forming organic oxidation products that are competing with the geosmin and MIB for adsorption sites in the GAC-filter.

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