Induced Air Flotation Research Articles

Optimization of floc-flotation process in the removal of suspended particles from wastewater in a Jameson cell using central composite design

In removing of suspended particles from wastewater, settling methods becomes insufficient when the suspensions are diluted and contain fine/ultrafine and colloidal particles. In that case, floating of suspended particles by applying floc-flotation is faster than settling methods and the floated sludge contains higher solid content. In this study, the Jameson flotation cell which is an improved version of induced air flotation was used to remove suspended particles. Flocculation-flotation (Floc-flotation) methods were applied together to increase the efficiency of wastewater treatment. Some of the critical variables (Feed flow rate, flotation duration, and conditioning time) that directly impact flotation performance were examined. One of the most popular response surface methodologies (RSM), Central Composite Design (CCD), which has three parameters and five levels, was utilized to plan and conduct the experiments. By measuring the residual turbidity of clarified water and particle removal recovery, the efficacy of the floc-flotation process in the Jameson cell was assessed. The results showed that flotation time and feed flow rate have a significant impact on both residual turbidity and flotation recovery than conditioning time. Interaction effects between feed flowrate and flotation time and between flotation time and conditioning time were also found significant in both responses. The optimal condition that aiming the lowest turbidity while maximizing flotation recovery was identified. The results of this study indicate that floc-flotation applied with Jameson cell is an effective method for removing very fine particles from extremely diluted concentrations.

Induced air flotation for fat, oil, and grease recovery in urban wastewater: A proposed methodology for system optimization and case study

Induced air flotation (IAF) is a well-known technology that is widely applied in urban wastewater treatment plants (WWTP) for fat, oil, and grease (FOG) removal. However, most IAF systems are not optimized and typically operate with fixed parameters, regardless of inflow variations. Furthermore, the optimization of IAF systems is limited by the lack of equipment in WWTP laboratories to determine FOG concentrations in wastewater. In this study, an adapted sulfo-phospho-vanillin method for FOG quantification in wastewater is proposed for optimization and automation of the IAF system. The proposed methodology requires simple equipment that is widely available in WWTP laboratories, paving the way for in situ FOG determination. The method was successfully employed to determine the optimal operating conditions of the IAF system in terms of hydraulic retention time and organic loading rate. Furthermore, a full-scale IAF system was optimized using this methodology and its energy demand was reduced by 40 %.

Improving the Separation of PS and ABS Plastics Using Modified Induced Air Flotation with a Mixing Device

A dramatic increase in plastic waste has resulted in a strong need to increase plastic recycling accordingly. A selective flotation has been highlighted due to its outstanding efficiency for the separation of mixed plastics with analogous physicochemical characteristics. In this study, the effects of design and operational factors on the bubble’s hydrodynamic and mixing parameters in induced air flotation (IAF) with a mixing device were investigated through a design of experiment method (DOE) analysis for improving the plastic separation efficiency (i.e., PS and ABS). As a result of DOE analysis, the increase in the induced air tube diameter together with the rotational speed could generate a smaller bubble size. This led to the enhancement of the ratio of interfacial area to velocity gradient (a/G), which was interestingly found to be a significant factor affecting plastic recovery apart from the chemical agents. It demonstrates that operating IAF with a mixing device at a greater a/G ratio improved the plastic separation performance. These findings suggest that operating an IAF process with a mixing device at suitable a/G conditions could be a promising technique for separating plastic wastes, which have similar physicochemical characteristics as PS and ABS.

Optimization of Floc-Flotation Process in the Removal of Suspended Particles from Wastewater by Induced Air Flotation

Optimization of Floc-Flotation Process in the Removal of Suspended Particles from Wastewater by Induced Air Flotation

Induced Air Flotation for Fog Recovery in Urban Wastewater: A Proposed Methodology for System Optimization and Case Study

Induced Air Flotation for Fog Recovery in Urban Wastewater: A Proposed Methodology for System Optimization and Case Study

Biorefining of spruce TMP process water: Selective fractionation of lipophilic extractives with induced air flotation and surface active additive

Lignocellulose biomass plays an important role in reducing the dependency on fossil fuels and ameliorating the dire consequences of climate change. It is therefore important that all the components of lignocellulose biomass are exploited. These components include hemicelluloses and extractives that are liberated and sterically stabilized during the thermomechanical pulping and that form the dissolved and colloidal substance (DCS) in the process water. Biorefining of this process water can extract these substances, which have a number of promising applications and can contribute to the full exploitation of lignocellulose biomass. This paper presents a simple treatment of unbleached Norway spruce (Picea abies) process water from TMP (thermomechanical pulping) production using induced air flotation (IAF) and cationic surfactant, dodecyl trimethylammonium chloride (DoTAC) to refine the extractives and prepare the waters so that hemicellulose could be easily harvested at a later stage. By applying 80 ppm of DoTAC at a pH of 3.5 and 50 °C before induced air flotation, 94% of the lipophilic extractives were recovered from process water. Dissolved hemicellulose polysaccharides were cleansed and left in the treated process water. The process enabled efficient biorefining of lipophilic extractives and purification of the process water to enable more selective harvesting of hemicelluloses in subsequent steps.

Treatment of produced water by induced air flotation: effect of both TWEEN 80 and ethanol concentrations on the recovery of PAHs

Abstract The present study investigates the application of induced air flotation (IAF) technique on PAHs (PAHs) removal performance from a real oilfield produced water of a separator cell. The quantification of total PAHs (PAHtot) was done using ultraviolet-visible spectrometry (UV-Vis) according to the naphthalene calibration curve. The UV-Vis spectra of naphthalene dissolved in a mixture of the binary solvent (water-ethanol) and the Tween 80 showed stability in the molecular orbital of C10H8. The use of small concentration of Tween 80 was revealed to be discrete in the quantification of PAHtot. The flotation process was improved at the critical micelle concentration of Tween 80 (CMC) of 2 % and the critical coalescence concentration of ethanol (CCC) of 0.5 mL/L for the PAHtot recovery of 49.76 % and the PAHtot content in the pulp of 50.24 %. At these concentrations, half of PAHtot was removed from produced water PW. Above the CMC and the CCC, the PAHtot recovery decreased and the PAHtot content in the pulp increased. It was found that there is a collector concentration at which the amount of water carrying from the pulp to the concentrate was increased and in parallel, the PAHtot recovery increased and the PAHtot content in the pulp decreased. Both of the CMC and the CCC have promoted the decrease on the conditioning time from 30 to 10 min and the flotation time from 20 to 6 min. Since the impeller speed and air flow rate were constant, the flotation of PAHs was limited. The flotation kinetics of PAHtot was described by the Higuchi model.

Recovery of manool from evaporator condensate by induced air flotation in a kraft pulp mill based integrated biorefinery

The conversion of conventional pulp and paper manufacturing processes into an integrated forest products biorefinery has great potential in the context of sustainable development. In this paper, we present a process concept which uses induced air flotation technology for recovery of manool, a valuable bioproduct, from the condensate of the multi-effect evaporation system in the kraft pulping process. The results showed that approximately 70% (purity of approximately 35%) recovery of manool was achieved from crude manool when the aeration time was about 7 min. The glass microbeads were effective in preventing sticking, due to their hydrophobic nature, and facilitating froth collection. Also, the use of a silicone defoamer at a dosage of approximately 40 ppm mitigated excessive foaming in the process.

Prediction Model for the Treatment of Stabilized Oily Wastewater by Modified Induced Air Flotation (MIAF)

The objective of this study is to propose a prediction model for characterizing stabilized oily-wastewater that has been treated using Induced Air Flotation (IAF) and Modified Induced Air Flotation (MIAF), which is a combination of coagulation and flotation. Wastewater samples containing an anionic surfactant at the critical micelle concentration (CMC) were prepared as the stabilized oily-emulsion. The amount of oil as well as the amount removed was measured using COD. The study shows that the coagulant dosage (CAlum), interfacial area (a), and velocity gradient (G) are the important factors that affect flotation performance. Therefore, the proposed model is based on these parameters in terms of the CAlum and a/G ratio. The maximum removal efficiency and the reduction of the COD values can be predicted for any of the operating conditions. It was found that predicted oily wastewater efficiency and removal kinetic fit reasonably well with those obtained from experiments.

ファインバブルの資源・環境分野への活用

In order to synthesize methane hydrate at high formation rate, finebubbles were utilized. The finebubble generator consisted of a liquid pump and a special line mixer. Finebubbles shortened an induction time of hydrate formation because the nucleation of hydrate was enhanced. With increasing liquid circulation flow rate, the induction time of hydrate formation shortened and the formation rate of hydrate increased because the number of finebubbles increased. The induced air flotation of oil droplets was conducted by the finebubble generator for oil-in-water emulsion separation. Compared with millibubbles, the dispersion of finebubbles effectively separated oil droplets. This was because finebubbles had high efficiency of collision with droplets and it was difficult to detach droplets because of the low rising velocity of finebubbles. The oil separation was largely enhanced at the solution pH below 4.5 because the electrostatic attraction between oil droplets and finebubbles was generated.

The use of integrated flotation and ceramic membrane filtration for surface water treatment with high loads of suspended and dissolved organic matter

In this work, we present results of surface water treatment pilot testing of ceramic MF/UF membranes using surface water from the River Spree in Berlin, Germany. The river water is characterized by high fluctuations in quality parameters with recurring spikes in dissolved organics, turbidity and microalgae concentration. The goal of this study was to evaluate the techno-economic applicability of a novel integrated treatment process using coagulation, flocculation, induced air flotation and ceramic membrane filtration based on a 12m3/d pilot system. It was shown that flotation serves as an effective pre-treatment for membrane filtration, allowing a flux of 112l/m2h with only limited and controllable fouling. Different parameters were tested in the pilot including chemical dosings, air supply, filtration fluxes etc. Turbidity and TOC levels of both the feed and the product water were continuously monitored. Finally, using an economic analysis (net present value) it is shown that ceramic membranes are comparable in overall costs to polymeric membranes or even lower when high fluxes (150l/m2h or higher) are implemented.

Separation of Oil Droplets from Oil-in-Water Emulsion Using a Microbubble Generator

The induced air flotation of oil droplets was performed using a microbubble generator to develop a simple and energy saving method for oil-in-water emulsion separation. The microbubble generator, which consisted of a liquid pump and a special line mixer, was set at the bottom of a bubble column. The effects of operation conditions on the oil separation performance were investigated. A sintered glass gas sparger was also used to disperse millibubbles. Oil-in-water emulsions were prepared from soybean oil and water. Compared with millibubbles, the dispersion of microbubbles effectively separated oil. This was because microbubbles had high efficiency of collision with droplets and it was difficult to detach droplets because of the low rising velocity of microbubbles. Millibubbles were difficult to attach to oil droplets and easy to detach droplets because of the high velocity movement of bubbles. The oil separation ratio was a maximum at the gas velocity of 0.2 mm/s because the amount of millibubbles increased as the gas velocity became higher above 0.4 mm/s. The oil separation was largely enhanced at the solution pH below 4.5. The zeta potential of droplets was negative in the pH range from 3 to 11. However, as the solution pH became lower, the zeta potential of microbubbles changed from negative to positive at the solution pH of 4.5. In addition to the hydrophobic attraction, the electrostatic attraction between oil droplets and microbubbles was generated since the zeta potentials of droplets and microbubbles had negative and positive values, respectively.

Oil removal from produced water by conjugation of flotation and photo-Fenton processes

The present work investigates the conjugation of flotation and photo-Fenton techniques on oil removal performance from oilfield produced water. The experiments were conducted in a column flotation and annular lamp reactor for induced air flotation and photodegradation steps, respectively. A nonionic surfactant was used as a flotation agent. The flotation experimental data were analyzed in terms of a first-order kinetic rate model. Two experimental designs were employed to evaluate the oil removal efficiency: fractional experimental design and central composite rotational design (CCRD). Overall oil removal of 99% was reached in the optimum experimental condition after 10 min of flotation followed by 45 min of photo-Fenton. The results of the conjugation of induced air flotation and photo-Fenton processes allowed meeting the wastewater limits established by the legislations for disposal.

Oil removal of oilfield-produced water by induced air flotation using nonionic surfactants

Oil separation from produced water is commonly carried out at oilfields for resource recovery as well as environmental reasons. In this work, the separation of oil by induced air flotation was studied in a batch unit. A series of nonionic surfactants with different hydrophile–lipophile balance (HLB) values were used as a flotation agent. The effects of different HLB values and surfactant concentration on the oil removal of oilfield produced water were investigated. The removal rate constant (k) was determined and the flotation process followed first-order kinetics. The maximum oil removal obtained was approx. 80% after 4 min of flotation.

TPH removal from oily wastewater by combined coagulation pretreatment and mechanically induced air flotation

The objective of this study was to combine coagulation and mechanically induced air flotation in order to determine the optimum operational condition for the removal of total petroleum hydrocarbons (TPHs) from oily wastewater. A mixture of water, gas oil, and emulsifier was used to generate a stable emulsion as the simulated wastewater. Aluminum sulfate, ferric chloride, and polyaluminum chloride were employed as coagulants to destabilize the emulsions, and the subsequent separation of hydrocarbons was carried out in a mechanical flotation cell. Considering the multiplicity of factors in both stages of coagulation and flotation, the effects of each factor were studied using Taguchi design of experiments technique, and the optimum conditions were revealed. The results showed that at the optimal conditions, about 93% TPH removal was achieved by addition of 50 mg/l aluminum sulfate at pH 4, flotation time of 10 min, impeller speed of 1,000 rpm, and airflow rate of 4.5 l/min.

Treatment of Oily Wastewater by Induced Air Flotation

Treatment of Oily Wastewater by Induced Air Flotation

Selective purification of bleached spruce TMP process water by induced air flotation (IAF)

Abstract The environmentally benign closure of water systems in paper mills leads to the problem of accumulation of dissolved and colloidal wood substances (DCS) in process water. Notably, pitch affects the pulp and paper production negatively and increases the demand for additional treatment of the process water. In the present article, the purification of thermomechanical pulping process water from the alkaline peroxide bleaching stage has been investigated, with the induced air flotation (IAF) in focus. The following parameters were considered concerning the IAF efficiency to remove detrimental substances: concentration of cationic foaming agent, pH value, calcium concentration, and temperature. The amounts and characteristics of residual DCS were determined by gas chromatography and turbidity measurements. Residual concentrations of the foaming agent dodecyltrimetylammonium chloride were determined by electrospray ionization mass spectrometry. Up to 90% of pitch was removed, whereas hemicelluloses, which are important in preventing pitch problems, remained in the waters. Up to 70% of the pectic acids accounted for the high cationic demand of the process waters were removed by optimization of the IAF parameters. The presented separation process gives new opportunities to a selective purification of the process waters.

Integration of processes induced air flotation and photo-Fenton for treatment of residual waters contaminated with xylene

Produced water in oil fields is one of the main sources of wastewater generated in the industry. It contains several organic compounds, such as benzene, toluene, ethyl benzene and xylene (BTEX), whose disposal is regulated by law. The aim of this study is to investigate a treatment of produced water integrating two processes, i.e., induced air flotation (IAF) and photo-Fenton. The experiments were conducted in a column flotation and annular lamp reactor for flotation and photodegradation steps, respectively. The first order kinetic constant of IAF for the wastewater studied was determined to be 0.1765 min −1 for the surfactant EO 7. Degradation efficiencies of organic loading were assessed using factorial planning. Statistical data analysis shows that H 2O 2 concentration is a determining factor in process efficiency. Degradations above 90% were reached in all cases after 90 min of reaction, attaining 100% mineralization in the optimized concentrations of Fenton reagents. Process integration was adequate with 100% organic load removal in 20 min. The results of the integration of the IAF with the photo-Fenton allowed to meet the effluent limits established by Brazilian legislation for disposal.

Impact of Coagulation Agents on the Performance of Flotation Unit for the Treatment of Industrial Waste Water

The performance of a batch laboratory scale induced air flotation (IAF) unit in controlling fat, oil, and Grease (FOG) and five days biological oxygen demand (BOD5) in effluents of a meats processing & packing industry, was tested using two types of coagulation agents (Alum and Bentonite clay) and three air flow rates. Prior to coagulation, air flow rates of 3 and 5 l/min were the best for having FOG removal efficiencies of 60% and 62%, respectively. Significant improvements in these were measured (94.5% and 96.2% for the mentioned air flow rates respectively) after the addition of 0.5 g/l Alum, while extra 0.2 g/l bentonite clay as coagulation aid had achieved efficiencies of 96.3% and 99.3% for these air flow rates respectively. Also, the addition of 0.5 g/l Alum had improved the BOD5 reduction efficiency from 54% to 65% and from 63% to 71%, for air flow rates of 3 l/min and 5 l/min respectively, as compared with no Alum cases. Higher BOD5 removal efficiencies of 73% and 78% were measured for the two air flow rates respectively, by aiding the coagulation with 0.2 g/l bentonite clay. At least 25% saving of flotation time was proved by the addition of bentonite clay to achieve final results, similar to these with Alum only for both FOG and BOD5, which in turn may save part of the operational costs.Author would like to acknowledge the logistic and technical support of the Ins. of International Education IIE, Scholars Rescue Fund SRF and Russ College of Eng. / OU.

Development of a Method for the Extraction of Oil from Clay by Friendly Phase Transfer Catalyst

The separation of waste oil from clay was studied using benzyl triethanol ammonium chloride as phase transfer catalyst. The study showed that the surface tension has an effect on oil recovery. An induced air flotation process was used and polymeric decyl phenol formaldehyde ethoxylate was used as the collector. The effects of various parameters including concentration of catalyst, collector, time of flotation, contact angle, and zeta potential on oil extraction were studied. The results show that oil recovery increases with time of flotation up to a maximum and then levels off. Oil recovery is marginal if the flotation time is extended beyond 12 min. For example, oil recovery increases by only 4% for 25 g oil and 20 g surfactant in the feed when flotation time increases from 12 to 15 min. Oil recovery also increases with surfactant dosage. Furthermore, oil recovery was enhanced by controlling the interfacial tension at the oil–water and water–air interfaces. The mechanism of oil separation was discussed according to micelle composition and the calculated oil recovery obtained was 87%. Furthermore, the kinetic study proved that the process is first order and depends on catalyst concentration. Oil recovery follows a Gibbs adsorption equation. The molecular interaction parameter at the aqueous solution–air interface was also calculated. The results proved that the extraction of oil from solid phase can be conducted by adding phase transfer catalyst. Moreover, the article suggests a model of oil separation from soil according to specifications of adsorbed oil, including isoparaffin and n-paraffin that were analyzed by gas chromatography technique.