Flotation of algae for water reuse and biomass production: role of zeta potential and surfactant to separate algal particles

2015 ◽  
Vol 72 (5) ◽  
pp. 762-769 ◽  
Author(s):  
Dong-Heui Kwak ◽  
Mi-Sug Kim
Keyword(s):  
Zeta Potential ◽  
Anionic Surfactant ◽  
Water Reuse ◽  
Separation Efficiency ◽  
Microalgae Cultivation ◽  
Separation Processes ◽  
Dissolved Air Flotation ◽  
Chemical Coagulation ◽  
Dissolved Air

The effect of chemical coagulation and biological auto-flocculation relative to zeta potential was examined to compare flotation and sedimentation separation processes for algae harvesting. Experiments revealed that microalgae separation is related to auto-flocculation of Anabaena spp. and requires chemical coagulation for the whole period of microalgae cultivation. In addition, microalgae separation characteristics which are associated with surfactants demonstrated optimal microalgae cultivation time and separation efficiency of dissolved CO2 flotation (DCF) as an alternative to dissolved air flotation (DAF). Microalgae were significantly separated in response to anionic surfactant rather than cationic surfactant as a function of bubble size and zeta potential. DAF and DCF both showed slightly efficient flotation; however, application of anionic surfactant was required when using DCF.

scholarly journals Modeling the Separation of Microorganisms in Bioprocesses by Flotation

Processes ◽  
2018 ◽  
Vol 6 (10) ◽  
pp. 184 ◽  
Author(s):  
Stefan Schmideder ◽  
Christoph Kirse ◽  
Julia Hofinger ◽  
Sascha Rollié ◽  
Heiko Briesen
Keyword(s):  
Fluid Dynamics ◽  
Separation Efficiency ◽  
Algebraic Model ◽  
Balance Model ◽  
Separation Processes ◽  
Dissolved Air Flotation ◽  
Computational Fluid Dynamics Cfd ◽  
Air Flotation ◽  
Cell Size Distributions ◽  
Dissolved Air

Bioprocesses for the production of renewable energies and materials lack efficient separation processes for the utilized microorganisms such as algae and yeasts. Dissolved air flotation (DAF) and microflotation are promising approaches to overcome this problem. The efficiency of these processes depends on the ability of microorganisms to aggregate with microbubbles in the flotation tank. In this study, different new or adapted aggregation models for microbubbles and microorganisms are compared and investigated for their range of suitability to predict the separation efficiency of microorganisms from fermentation broths. The complexity of the heteroaggregation models range from an algebraic model to a 2D population balance model (PBM) including the formation of clusters containing several bubbles and microorganisms. The effect of bubble and cell size distributions on the flotation efficiency is considered by applying PBMs, as well. To determine the sensitivity of the results on the model assumptions, the modeling approaches are compared, and suggestions for their range of applicability are given. Evaluating the computational fluid dynamics (CFD) of a dissolved air flotation (DAF) system shows the heterogeneity of the fluid dynamics in the flotation tank. Since analysis of the streamlines of the tank show negligible back mixing, the proposed aggregation models are coupled to the CFD data by applying a Lagrangian approach.

scholarly journals Modeling the Separation of Microorganisms in Bioprocesses by Flotation

2018 ◽  
Author(s):  
Stefan Schmideder ◽  
Christoph Kirse ◽  
Julia Hofinger ◽  
Sascha Rollié ◽  
Heiko Briesen
Keyword(s):  
Fluid Dynamics ◽  
Separation Efficiency ◽  
Algebraic Model ◽  
Balance Model ◽  
Separation Processes ◽  
Dissolved Air Flotation ◽  
Computational Fluid Dynamics Cfd ◽  
Cell Size Distributions ◽  
Fermentation Broths ◽  
The Impact

Bioprocesses for the production of renewable energies and materials lack efficient separation processes for the utilized microorganisms such as algae and yeasts. Dissolved air flotation (DAF) and microflotation are promising approaches to overcome this problem. The efficiency of these processes depends on the ability of microorganisms to aggregate with microbubbles in the flotation tank. In this study, different new or adapted aggregation models for microbubbles and microorganisms are compared and investigated for their range of suitability to predict the separation efficiency of microorganisms from fermentation broths. The complexity of the heteroaggregation models range from an algebraic model to a 2D population balance model (PBM) including the formation of clusters containing several bubbles and microorganisms. The effect of bubble and cell size distributions on the flotation efficiency is considered by applying PBMs, as well. To determine the impact of the model assumptions, the modeling approaches are compared and classified for their range of applicability. Evaluating computational fluid dynamics (CFD) of a DAF system shows the heterogeneity of the fluid dynamics in the flotation tank. Since analysis of the streamlines of the tank show negligible backmixing, the proposed aggregation models are coupled to the CFD data by applying a Lagrangian approach.

Removal of clay and blue-green algae particles through zeta potential and particle size distribution in the dissolved air flotation process

2006 ◽  
Vol 6 (1) ◽  
pp. 95-103 ◽  
Author(s):  
D.H. Kwak ◽  
S.J. Kim ◽  
H.J. Jung ◽  
C.H. Won ◽  
S.B. Kwon ◽  
...  
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Green Algae ◽  
Dissolved Air Flotation ◽  
Flotation Process ◽  
Clay Particles ◽  
Blue Green Algae ◽  
Dissolved Air

The raw water characteristics of a water treatment plant in Korea are mainly dependent on two major factors: the clay particles attributed to rainfall and blue-green algae in reservoirs. In this work, zeta potential and particle size distributions of clay and algae particles, which are the important parameters affecting their removal efficiency, were measured to investigate the behavior and removal characteristics of particles under various conditions. The results showed that the zeta potential of blue-green algae was more sensitive to treatment conditions than clay, and it fluctuated highly with coagulant dosage, suggesting that the control of zeta potential is important for effective removal of algae particles. On the other hand, the range of particle size distribution that remained from the preliminary sedimentation tank was generally smaller than for flotation. However, the zeta potential of the remaining particles was either close to the isoelectric point or positive, and the particles were not so hard to remove for that reason. In the final analysis, for simultaneous removal of clay and algae particles, a sufficient zeta potential difference must be formed not only for algae particles but also for small clay particles from the sedimentation tank in the dissolved air flotation process.

Significance of pressure and recirculation in sludge thickening by dissolved air flotation

1997 ◽  
Vol 36 (12) ◽  
pp. 223-230 ◽  
Author(s):  
Hak Chung Tai ◽  
Yeon Kim Doo
Keyword(s):  
Separation Efficiency ◽  
Reliable Operation ◽  
Dissolved Air Flotation ◽  
Efficient Operation ◽  
Recirculation Flow ◽  
Operating Variable ◽  
Solids Separation ◽  
Air Flotation ◽  
Sludge Thickening ◽  
Dissolved Air

An experimental study was conducted to identify the effect of each operating variable on the liquid-solids separation efficiency using a bench scale batch flotation system and waste activated sludge. Interpretation of the experimental results was performed by use of the characteristic constants of an empirical equation proposed. Minimum A/S ratio for reliable operation of dissolved air flotation should be greater than 0.009. However, unstable sludge rising took place at the initial clarification stage due to excessive shear and turbulence when the pressure was high in spite of high A/S ratio. The efficiency increased as the A/S ratio increased except a case of high pressure coupled with high A/S ratio. High recirculation flow with a saturator pressure less than 5 atm is recommended for stable and efficient operation. The pore size of a diffuser did not affect the thickening efficiency significantly. Concentration gradient of the float solids became larger as flotation continued. Skimming of a top layer or a long skimming interval is desirable for high thickening efficiency.

scholarly journals An Improved Configuration of Vertical-Flow Mesh Tube Filters for Seawater Pretreatment: Performance, Cleaning, and Energy Consumption

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2804
Author(s):  
Dong-Ho Kim ◽  
Changkyoo Choi ◽  
Chulmin Lee ◽  
Rusnang Syamsul Adha ◽  
Thanh-Tin Nguyen ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Water Reuse ◽  
Minimum Energy ◽  
Specific Energy Consumption ◽  
Pilot Scale ◽  
Dissolved Air Flotation ◽  
Removal Experiments ◽  
Filter Bed ◽  
Better Than ◽  
Dissolved Air

Roughing filters are types of porous media filter used in pretreatment systems where the raw water contains a large amount of suspended particles (SPs) and organic matter. Mesh tube filtration (MTF) media are roughing-filter media composed of low-density polyethylene used for SP removal during wastewater treatment. In this study, we present an improved MTF design—a porous filter bed (PFB), which exhibits superior SP removal performance compared to conventional MTF media. We then compare the applicability of MTF and PFB to both the primary pretreatment process for seawater desalination and the water reuse process. In bench-scale SP removal experiments, PFB shows removal rates of 46.7%, 68.0%, 67.6%, and 68.4% at hydraulic retention times of 15, 20, 30, and 60 min, respectively, which are better than those of MTF. The specific energy consumption (SEC) of batch dissolved air flotation (DAF) was known to range from 0.035 to 0.047 kWh/m3, whereas the SEC calculated for pilot-scale MTF and PFB is 0.027 kWh/m3 and minimum energy for influent supply, respectively. This suggests that PFB can compete with DAF as a primary pretreatment process. MTF predominantly removes SPs by sedimentation, whereas SP removal in PFB typically occurs via deposition of SPs on the mesh tube media.

Application of dissolved air flotation for treatment of wastewater from meat processing industry

1995 ◽  
Vol 31 (3-4) ◽  
pp. 341-344 ◽  
Author(s):  
J. Wasowski
Keyword(s):  
Rational Design ◽  
Meat Processing ◽  
Waste Waters ◽  
Processing Industry ◽  
Dissolved Air Flotation ◽  
Technological Factors ◽  
Air Flotation ◽  
The Given ◽  
Dissolved Air

The paper concerns the application of dissolved air flotation for treatment of waste water from the meat processing industry. The main aim of the study was identification of the flotation mechanism aided by the coagulation in the layouts with and without recycling, and finding and defining the role of the technological factors influencing flotability of pollutants found in the given waste waters. The results of the studies, supported by the mathematical analysis, form the basis of rational design and conduction of flotation in practice.

Use of dissolved air flotation in potable water treatment in Finland

1995 ◽  
Vol 31 (3-4) ◽  
pp. 225-238 ◽  
Author(s):  
J. Heinänen ◽  
P. Jokela ◽  
T. Ala-Peijari
Keyword(s):  
Water Treatment ◽  
Drinking Water Treatment ◽  
Dissolved Air Flotation ◽  
Unit Process ◽  
Air Bubble ◽  
Special Cases ◽  
Air Flotation ◽  
Practical Experiences ◽  
Dissolved Air

The basic concepts of treating humic waters with dissolved air flotation are discussed emphasizing the important role of zeta potential in the forming of floc-air-bubble-agglomerates. Then practical experiences from Finnish drinking water treatment plants are presented. When surface water is used as a raw water, it is more or less humic. Thirty-six such plants have dissolved air flotation as a clarification process, the oldest one dating from 1965. They serve about one million people. All of them are working well proving that dissolved air flotation is a suitable method in humic water treatment. Some special cases are discussed in detail. These are cases where sufficient data about design, operation and costs are available and which it is hoped can help other designers. The last plant referred to is an example of an advanced treatment process where dissolved air flotation is an integrated unit process.

Separation characteristics in dissolved air flotation - pilot and full-scale demonstration

2003 ◽  
Vol 48 (3) ◽  
pp. 89-96
Author(s):  
M. Ljunggren ◽  
L. Jönsson
Keyword(s):  
Particle Size ◽  
Contact Zone ◽  
Separation Efficiency ◽  
Particle Separation ◽  
Full Scale ◽  
Particle Sizes ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Practical Implications ◽  
Dissolved Air

This study presents practical implications for particle separation in Dissolved Air Flotation (DAF). The objectives were to localise where particles are separated from the water phase and to determine what particles, in terms of size, are removed by the DAF-process. Both pilot- and full-scale plants were investigated. Particle sizes were analysed with a light-blocking particle counter and an optical borescope was used for visualisation of particle-bubble aggregates. It was found that particles are preferably separated upstream in the process, i.e. close to the contact zone. Furthermore, separation efficiency for particles increased with increasing particle size.

Collision efficiency factor of bubble and particle (abp) in DAF: theory and experimental verification

2001 ◽  
Vol 43 (8) ◽  
pp. 139-144 ◽  
Author(s):  
M. Han ◽  
W. Kim ◽  
S. Dockko
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Bubble Size ◽  
Efficiency Factor ◽  
Collision Efficiency ◽  
Turbidity Removal ◽  
Dissolved Air Flotation ◽  
Accepted Practice ◽  
Bubble Sizes ◽  
Dissolved Air

The collision efficiency factor of bubble and particle (αbp) in dissolved air flotation (DAF) can be calculated theoretically by trajectory analysis, which takes into account both hydrodynamics and inter-particle forces. To determine the theoretically optimum particle size for any given bubble size, a collision efficiency diagram for DAF was developed where collision efficiency is contoured on a plane of particle and bubble sizes for different conditions of particle zeta potential. A set of experiments tested the validity of the suggested collision efficiency diagram, and examined whether pretreatment is important and why slight coagulant overdosing and shorter flocculation times are generally preferred in DAF, both current accepted practice. Batch DAF reactors were used and kaolin samples were prepared from jar tests using different alum dosages and flocculation times. The particle size distribution, particle zeta potential, and turbidity removal in each experiment were measured, as were bubble size and zeta potential. The results agreed well with the predictions of the collision efficiency diagram and explained current practices. A collision efficiency diagram identifies the pretreatment goal, i.e., tailoring of the optimum characteristics required of particles (zeta potential and size) under existing operational bubble characteristic.

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