Toxic metals removal from dilute solutions by biosorptive flotation

1995 ◽  
Vol 32 (9-10) ◽  
pp. 211-220
Author(s):  
A. I. Zouboulis ◽  
P. Solari ◽  
K. A. Matis ◽  
G. A. Stalidis
Keyword(s):  
Toxic Metal ◽  
Separation Process ◽  
Dissolved Air Flotation ◽  
Metals Removal ◽  
Dilute Aqueous Solutions ◽  
Flotation Technique ◽  
Solid Liquid ◽  
Solid Liquid Separation ◽  
Digested Sewage Sludge ◽  
Dissolved Air

Toxic metal ions (cadmium, nickel and zinc), considered as priority pollutants, were removed from dilute aqueous solutions by sorption onto non-living (sterilized) anaerobically digested sewage sludge. The desorption of cadmium from metal-laden sludge was also examined. Flotation was subsequently applied as an effective solid/liquid separation process. The dissolved-air flotation technique was applied for the generation of fine bubbles and, in parallel, electrokinetic measurements were carried out. Promising results were succeeded from the combined process of biosorption/flotation (termed biosorptive flotation).

Removal of Toxic Metal Ions from Solutions Using Industrial Solid Byproducts

1993 ◽  
Vol 27 (10) ◽  
pp. 83-93 ◽  
Author(s):  
A. I. Zouboulis ◽  
K. A. Kydros ◽  
K. A. Matis
Keyword(s):  
Toxic Metals ◽  
Toxic Metal ◽  
Industrial Wastes ◽  
Mineral Particles ◽  
Solid Adsorbent ◽  
Metals Removal ◽  
Environmental Considerations ◽  
Solid Liquid ◽  
Solid Liquid Separation ◽  
By Products

Nowadays the problem of industrial wastes handling and disposal is increasing continuously, as more strict environmental considerations have to be taken into account. In this paper, selected experimental results are presented from our current research in toxic metals removal (e.g. Cu, Pb, As), related to the applications of mineral particles as by-products (red mud, pyrite, dolomite, etc.) for the induced removal of toxic metals from aqueous solutions. These by-products, existing in finely divided form and considered rather as solid industrial wastes, have been used as a cheap solid adsorbent or substrate. Appropriate methods for the subsequent solid/liquid separation were examined, among them flotation. Different parameters were tested and high removals of toxic metals were achieved. In this way, a useful application may be realized for the waste mineral particles.

scholarly journals Solid–liquid Separation of Activated Sludge by Flotation Using Microporous Ceramic Diffuser

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
S. W. Hong ◽  
C. Park ◽  
T. H. Chung ◽  
Y. S. Choi
Keyword(s):  
Activated Sludge ◽  
Porous Ceramic ◽  
Operating Cost ◽  
Experimental Results ◽  
Solid Loading ◽  
Dissolved Air Flotation ◽  
Pressure Water ◽  
Solid Liquid ◽  
Solid Liquid Separation ◽  
Dissolved Air

Dissolved air flotation (DAF) is the most widely used to separate particles from liquid. However, the main disadvantage of DAF systems is the increased operating cost due to the energy requirements for the high pressure water recycling and air compressing. In this study, alumina–based porous ceramic diffusers which can produce microbubbles at low pressure regions have been developed in order to separate and thicken activated sludge solids. No bubble was generated at lower pressure (< 0.2 bar), whereas too large bubbles were generated at higher than 2.0 bar. At 1.8 bar, more than 70% of the bubbles had a diameter ranged from 20 to 60 μm. According the experimental results, the separation and thickening efficiency was mainly dependant on solid loading rate (SLR) and air to solid (A/S) ratio. When the sludge with a concentration of exceeding 5,000 mg/L was continuously fed into the flotation tank, the thickened concentration was measured to be higher than 20,000 mg/L, while SS concentrations in the clarified effluent were ranged from 5 to 10 mg/L. The experimental results revealed that the use of microporous ceramic diffusers could provide an economical, easy and reliable means of separating suspended solids (e.g., biological flocs) from liquid.

Solid/liquid separation behavior of alum and polyaluminium chloride coagulation flocs

2006 ◽  
Vol 6 (1) ◽  
pp. 87-93 ◽  
Author(s):  
B. Gorczyca ◽  
G. Zhang
Keyword(s):  
Liquid Separation ◽  
Dissolved Air Flotation ◽  
Gravity Settling ◽  
Mean Size ◽  
Air Flotation ◽  
Solid Liquid ◽  
Solid Liquid Separation ◽  
Separation Behavior ◽  
Polyaluminium Chloride ◽  
Dissolved Air

Properties of alum and polyaluminium chloride (PACl) flocs were analyzed in order to explain solid/liquid separation behavior of these aggregates in dissolved air flotation and gravity settling. PACl flocs settle better and are less sensitive to changes in water temperature than alum flocs. Therefore, PACl flocs may be more suited for gravity separation, especially in cold waters, and alum flocs may be preferred for flotation. At an optimum coagulant dose for dissolved air flotation the logarithmic mean size of alum flocs was close to the size of the air bubbles (30 μm) and the proportion of flocs smaller than 20 μm was about 30.5%.

Removal of cadmium from dilute solutions by flotation

1995 ◽  
Vol 31 (3-4) ◽  
pp. 315-326 ◽  
Author(s):  
Anastasios I. Zouboulis ◽  
Konstantine A. Matis
Keyword(s):  
Sodium Dodecyl ◽  
Toxic Metal ◽  
Dilute Solutions ◽  
Water And Wastewater Treatment ◽  
Dissolved Air Flotation ◽  
Bubble Generation ◽  
Flotation Technique ◽  
Air Flotation ◽  
Ph Range ◽  
Dissolved Air

Cadmium constitutes a priority pollutant existing in waste streams from metal plating and various other industries. The removal of this toxic metal employing the dissolved air flotation technique was investigated in laboratory batch experiments; the mechanism of precipitate flotation as the respective hydroxide was followed. Main examined parameters include: recycle ratio, pH of the solution, concentrations of added surfactant (sodium dodecyl sulphate), frother (ethanol) and cadmium. Promising results have been obtained, at the pH range between 10 and 11 approximately, showing the significance of flotation as a separation process in water and wastewater treatment for dilute solutions (around 10 mg/l of metal). Under the optimum conditions removal of cadmium was near to 100%, while the remaining concentration in the solution after flotation was less than 0.10 mg/l. A comparison was also attempted between two flotation techniques applying different bubble generation methods, i.e. dissolved air and dispersed air flotation. These experiments run in parallel and under the same conditions.

Removal of suspended substances by coagulation and foam separation from municipal wastewater

2002 ◽  
Vol 46 (11-12) ◽  
pp. 183-188 ◽  
Author(s):  
Y. Suzuki ◽  
T. Maruyama ◽  
H. Tegane ◽  
T. Goto
Keyword(s):  
Suspended Solids ◽  
Municipal Wastewater ◽  
Treatment Time ◽  
Separation Process ◽  
Foam Separation ◽  
Suspended Substances ◽  
Milk Casein ◽  
Short Time ◽  
Solid Liquid ◽  
Solid Liquid Separation

A new method for solid-liquid separation for wastewater incorporating simple operation and shortened treatment time is necessary for improvement of sewage systems. In this study, removal of suspended solids from municipal wastewater by coagulation and foam separation using coagulant and milk casein was examined. By adding casein before the foam separation process, the removal of suspended substances was dramatically improved. The optimum condition for treating sewage was 20 mg-Fe/L of FeCl3, 3 mg/L of casein, and pH 5.5, which resulted in a removal rates of over 98% for turbidity and SS. A removal of 96-98% was also possible for phosphate and anionic surfactant. When PAC was used, the floc was also efficiently recovered in foam by the addition of casein. It became clear that coagulation and foam separation using casein as the collector is an effective method for removing suspended solids in municipal wastewater in a short time (within 10 min).

scholarly journals Enhancing Bioenergy Yields from Sequential Bioethanol and Biomethane Production by Means of Solid–Liquid Separation of the Substrates

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3683 ◽  
Author(s):  
Lisandra Rocha-Meneses ◽  
Jorge A Ferreira ◽  
Nemailla Bonturi ◽  
Kaja Orupõld ◽  
Timo Kikas
Keyword(s):  
Flue Gas ◽  
Cost Effective ◽  
Separation Process ◽  
Energy Output ◽  
Bioethanol Production ◽  
Liquid Separation ◽  
Lignocellulosic Feedstock ◽  
Transportation Sector ◽  
Solid Liquid ◽  
Solid Liquid Separation

The production of second-generation ethanol using lignocellulosic feedstock is crucial in order to be able to meet the increasing fuel demands by the transportation sector. However, the technology still needs to overcome several bottlenecks before feasible commercialization can be realized. These include, for example, the development of cost-effective and environmentally friendly pretreatment strategies and valorization of the sidestream that is obtained following ethanol distillation. This work uses two chemical-free pretreatment methods—nitrogen explosive decompression (NED) and synthetic flue gas explosive decompression—to investigate the potential of a bioethanol production sidestream in terms of further anaerobic digestion. For this purpose, samples from different stages of the bioethanol production process (pretreatment, hydrolysis, and fermentation) and the bioethanol sidestream went through a separation process (involving solid–liquid separation), following which a biomethane potential (BMP) assay was carried out. The results show that both factors being studied in this article (involving the pretreatment method and the separation process) served to influence methane yields. Liquid fractions that were obtained during the process with NED gave rise to methane yields that were 8% to 12% higher than when synthetic flue gas was used; fermented and distillation sidestream gave rise to the highest methane yields (0.53 and 0.58 mol CH4/100 g respectively). The methane yields from the liquid fractions were between 60–88% lower than those that were obtained from solid fractions. Samples from the bioethanol sidestream (solid fraction) that were pretreated with NED had the highest methane yield (1.7 mol CH4/100 g). A solid–liquid separation step can be a promising strategy when it comes to improving the energy output from lignocellulosic biomass and the management of the ethanol distillation sidestream.

Oil Removal from Refinery Wastes by Air Flotation

1974 ◽  
Vol 9 (1) ◽  
pp. 328-339 ◽  
Author(s):  
B. Volesky ◽  
S. Agathos
Keyword(s):  
Suspended Solids ◽  
Suspended Solid ◽  
Oil Removal ◽  
Dissolved Air Flotation ◽  
Physical Separation ◽  
Sedimentation Technique ◽  
Flocculation Aid ◽  
Flotation Technique ◽  
Air Flotation ◽  
Dissolved Air

Abstract Air flotation as a physical separation process for removing oily products and suspended solid matter from refinery wastewaters achieves removal efficiencies from 65% to more than 90%. Demonstrated capacity of the process for COD and BOD removal ranges up to 90%. With addition of flotation and flocculation aid chemicals better performance is achieved. Current results are presented and critically reviewed. It appears that the pressure dissolved-air flotation system employing recycle-flow operation can produce effluent containing consistently less than 15 p.p.m. of oil and suspended solids. Its performance and capacity of handling overload situations makes it superior to the conventional flocculation-sedimentation technique. Oil removal limitations of the process and current research trends are stressed including an electro-flotation technique. Some aspects of process optimization are also discussed.

Optimization of Solids Separation in Dissolved Air Flotation

2008 ◽  
Vol 43 (2-3) ◽  
pp. 239-247 ◽  
Author(s):  
Beata Gorczyca ◽  
Paul Klassen
Keyword(s):  
Bubble Formation ◽  
Particle Removal ◽  
Dissolved Air Flotation ◽  
Particle Counter ◽  
Floc Size ◽  
Treated Effluent ◽  
Air Flotation ◽  
Average Size ◽  
Solid Liquid ◽  
Dissolved Air

Abstract Sizes of flocs were analyzed to identify characteristics of the particle size distribution optimal for separation by dissolved air flotation (DAF). Optical microscopes and two particle counters were used for floc sizing. A Brightwell Technologies particle counter was found to provide floc size measurements in agreement with improved microscopic methods. The particle counter provided distribution of flocs with sizes down to 1 micron (µm). This allowed for inclusion of flocs with size ranging from 5 to 1 µm, which were excluded from the analyses in the earlier study. Four alum dosages were applied: 15, 25, 40, and 60 mg/L. The turbidity and colour of the DAF effluent at alum dosages of 25, 40, and 60 mg/L were very similar. However, the analysis of the flocs in the treated effluent revealed that, at the alum dose of 60 mg/L, particle removal was the best. Therefore, this dosage was selected as optimal for the solid/liquid separation process. The average size of coagulation flocs at 60 mg/L was approximately 30 µm, and was equal to the estimated size of air bubbles produced by the saturator. Therefore, this study confirms the finding of the earlier work claiming that the optimum DAF performance is attained when the mean floc size and the bubble size are equal. Similar size of floc and bubble indicates that flocs act predominantly as nuclei for bubble formation. This finding contributes to the knowledge of mechanisms of floc air bubble attachment in DAF.

Sign in / Sign up

Export Citation Format

Share Document