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New collectors for Co(II) and Ni(II) removal from aqueous systems by flotation (DAF)
Published in Gülhan Özbayoğlu, Çetin Hoşten, M. Ümit Atalay, Cahit Hiçyılmaz, A. İhsan Arol, Mineral Processing on the Verge of the 21st Century, 2017
L. Stoica, C. Constantin, O. Micu, A. Meghea
Flotation is a complex separation process, whose achievement depends on physical-chemical properties, hydrodynamic factors, and interface mass-transfer, correlated with the species structure.Dissolved Air Flotation (DAF) is a depollutant separation process and its main advantages are: high efficiencies (%R > 95), rapidity, accessibility, the possibility of removal and recovery organic and inorganic species.The present work established the optimum separation conditions for Co(II) and Ni(II) ions removal from aqueous systems by applying DAF technique, in I.F. and PP.F. variants.Alkylhydroxamic acid (C7-C9) have tensioactive properties and chelating action for the transitional metallic ions (Co, Ni). These properties related by experimental researches demonstrate the possibility of using alkylhydroxamic acids as collector reagents in ion flotation (I.F.) and precipitate flotation (PP.F.) at understoichiometrical consumption (cc:cM(II) ^ 10High separation efficiencies offer and the possibility of decreasing the metallic ions concentrations under the allowable limits and the recovery of valuable compounds.The proposed method appears to be cost effective and environmentally acceptable.
Zero Liquid Discharge
Published in Ashok K. Rathoure, Zero Waste, 2019
Ashok K. Rathoure, Tinkal Patel, Devyani Bagrecha
A dissolved air flotation (DAF) system is a water treatment equipment used to disperse water and contaminants in the wastewater. DAF System works with a two-step process, the first being the pre-treatment process and the second being a flotation process. The system works by the following method: during the pre-treatment process, chemicals are combined with the contaminant in the water to create a light, floatable floc in the mixing tank. After pre-treatment process, air (in micro bubble form) are introduced into the pre-treated water in the DAF unit. The air then will float the floc so it can be divided from the water with a skimmer.
Water Pollution
Published in M. Brett Borup, E. Joe Middlebrooks, Pollution Control in the Petrochemicals Industry, 2018
M. Brett Borup, E. Joe Middlebrooks
Dissolved Air Flotation (DAF) is commonly used in petrochemical waste treatment plants to enhance oil and suspended solids removal. DAF units, while not as economical as API separators and tilted plate separators, produce a better quality effluent which is often required to meet effluent oil limitations. If a significant portion of the oil is emulsified, chemical addition with flocculation chambers may be a part of the flotation unit. Coagulation-flocculation processes are effective in removing suspended solids, some nutrients and heavy metals from petrochemical wastestreams (Ford and Tischler, 1974).
A two-stage dissolved air flotation saturator configuration for significant microbubble improvement
Published in Environmental Technology, 2023
Mohamad Hosein Nikfar, Hesam Parsaeian, Ali Amani Tehrani, Alireza Kouhestani, Hamidreza Masoumi Isfahani, Alireza Bazargan
Dissolved Air Flotation (DAF) is widely used in separation and purification processes for the removal of colloidal particles, oil droplets, and suspended matter [1]. According to previous studies [2], DAF can be used for both industrial and domestic wastewater applications. However, DAF is not the only viable flotation method, and there are other systems for bubble generation as well [3]. In traditional DAF systems, the water is sent to a saturator where it comes into contact with pressurized air, leading to its dissolution. Then, as the water passes through a pressure-releasing nozzle, hundreds of millions of small bubbles are formed as dissolved air diffuses out of the solution [4]. When released, the bubbles attach to the suspended particles in the water and bring them to the surface, where they are collected and/or removed [5]. Henry’s law determines the maximum amount of soluble air that can be obtained at a given saturator pressure and temperature. Bubble size and number are very important [6] since according to the literature, smaller bubbles have better efficiency for the separation of particles from the water or wastewater, and in some cases the best separation is obtained when bubbles and particles are approximately the same sizes [7]. Elsewhere [8], bubble-floc interaction has been investigated, and it has been shown that the highest removal efficiency of a system can be achieved when the floc size is 5–10 times larger than the bubble size.
Analysis of culturable and non-culturable bacteria and their potential to form biofilms in a primary treated dairy wastewater system
Published in Environmental Technology, 2018
Michael Dixon, Steve Flint, Jon Palmer, Richard Love, Patrick Biggs, Abraham Beuger
The treatment of dairy wastewater varies depending on the location of the manufacturing plant, as it is partly mandated by local legislation, the local receiving environment and any discharge limits placed upon the particular factory. Biological treatment systems such as aerated lagoons, anaerobic biofilm reactors or activated sludge are common. A widely used treatment system is a dissolved air flotation (DAF) tank, to remove suspended solids such as fats and protein [3] followed by irrigation onto pasture. However, bacteria present in this system will grow, leading to biofilm formation on any surface within the wastewater system. If this biofilm formation becomes extensive, blockage of the wastewater system could occur, which would prevent the release of wastewater and increase cost in terms of both cleaning and lower processing volumes. Biofilm formation in a drip irrigation system using secondary treated and tertiary treated wastewater was shown to reduce discharge by 50% when the biofilm covered up to 80% of the flow channel [4]. Yan et al. [5] showed that in drip irrigation systems the flow path (emitter heads) influenced the biofilm community structure and diversity. Scanning electron microscopy revealed both particles present in the biofilm and the extracellular polymeric substances (EPS) structure caused blockages in the emitter heads with phospholipid fatty acids exhibiting the best correlation coefficient between the amount of biomass and discharge reduction.
Removal of flocculated TiO2 nanoparticles by settling or dissolved air flotation
Published in Environmental Technology, 2021
H. A. Oliveira, A. Azevedo, J. Rubio
Dissolved air flotation (DAF), or flotation with micro and nanobubbles, is widely utilized for water and wastewater treatment, because of the efficiency as a solid-liquid separation process. Nowadays, DAF constitutes a worldwide theme as presented periodically in special international congresses dealing with its use in removal of colloids, fine and ultrafine suspended particles, organic and inorganic precipitates, ions, microorganisms, proteins, dispersed and emulsified oils in water, among others [34–39].