scholarly journals Dissolved air flotation (DAF) for biomass recovery from algal ponds

2017 ◽  
Vol 12 (3) ◽  
pp. 534-540 ◽  
Author(s):  
Dayana Melo Torres ◽  
André Luís Calado Araújo ◽  
Rui de Oliveira ◽  
André Câmara de Brito
Keyword(s):  
Suspended Solids ◽  
Sewage Treatment ◽  
Random Factor ◽  
Dissolved Air Flotation ◽  
Sample Characteristics ◽  
Biomass Recovery ◽  
Air Flotation ◽  
Final Effluent ◽  
Flocculation Time ◽  
Dissolved Air

This work evaluated the performance of a dissolved air flotation (DAF) system for biomass recovery from the effluent of algal ponds used for sewage treatment in Northeast Brazil. Two different coagulants and effluent samples were tested following a random-factor experimental design (34–1–4 factors and 3 levels), in triplicate. Factor analysis showed that coagulant dose was the most important factor, independently of the type of coagulant and sample characteristics. For polyaluminium chloride it is possible to work with the original sample pH at the lower recirculation rate (10%) and flocculation time (10 minutes), being able to recovery an algal masses (dry basis) of around 1,200 kg/day and 550 kg/day from the primary facultative and second maturation pond (final effluent), respectively. DAF was more efficient for ferric chloride, however a pH correction to the value of 5.0 was necessary, leading the process to generate masses of solids (dry basis) of about 1,150 kg/day for the facultative pond and 830 kg/day for the maturation pond. Removals of suspended solids, turbidity, and chlorophyll-a were above 60%, reaching at optimal conditions removals up to 90%.

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.

A bioflocculant-supported dissolved air flotation system for the removal of suspended solids, lipids and protein matter from poultry slaughterhouse wastewater

2018 ◽  
Vol 78 (2) ◽  
pp. 452-458 ◽  
Author(s):  
C. Dlangamandla ◽  
S. K. O. Ntwampe ◽  
M. Basitere
Keyword(s):  
Steady State ◽  
Suspended Solids ◽  
Total Suspended Solids ◽  
Bacillus Sp ◽  
Dissolved Air Flotation ◽  
Slaughterhouse Wastewater ◽  
Air Flotation ◽  
Dissolved Air

Abstract In this study, two previously identified isolates, i.e. Comamonas aquatica (BF-3) and Bacillus sp. BF-2, were determined to be suitable candidates to utilise in a bioflocculant-supported dissolved air flotation (Bio-DAF) system as a pretreatment system for poultry slaughterhouse wastewater (PSW). A 2% (v/v) (bioflocculant:PSW) strategy was used for the DAF to reduce total suspended solids (TSS), lipids and proteins in the PSW, by supplementing the bioflocculants produced and the co-culture (C. aquatica BF-3 and Bacillus sp. BF-2) directly into the DAF. The Bio-DAF was able to reduce 91% TSS, 79% proteins and 93% lipids when the DAF system was operating at steady state, in comparison with a chemical DAF operated using 2% (v/v) alum that was able to only reduce 84% TSS, 71% proteins and 92% lipids. It was concluded that the Bio-DAF system worked efficiently for the removal of suspended solids, lipids and proteins, achieving better results than when alum was used.

Pretreatment considerations for dissolved air flotation: water type, coagulants and flocculation

1995 ◽  
Vol 31 (3-4) ◽  
pp. 63-71 ◽  
Author(s):  
Donald Q. Bunker ◽  
James K. Edzwald ◽  
Jan Dahlquist ◽  
Lars Gillberg
Keyword(s):  
Chemical Properties ◽  
Water Type ◽  
Raw Water ◽  
Dissolved Air Flotation ◽  
Mixing Intensity ◽  
Flotation Performance ◽  
Air Flotation ◽  
Favorable Conditions ◽  
Flocculation Time ◽  
Dissolved Air

Pretreatment considerations of coagulant selection, flocculation time and flocculation mixing intensity were studied for two different water supply types, aquatic humic and non-aquatic humic waters of low turbidity. Alum, ferric salts, and various polyaluminium chlorides (PACs) with different chemical properties were all effective in dissolved air flotation (DAF) when used under favorable conditions of dosage, pH, and flocculation time. A stoichiometry was found for the aluminium coagulants between coagulant dose and raw water DOC. Si and sulfate PACs were effective in treating cold waters with short flocculation times of 2.5 to 5 minutes. Flotation performance improved slightly with increasing flocculation mixing intensity. The results suggest that flocculation tanks be designed to produce strong, “pinpoint” size floc particles.

Influence of flocculation conditions in the performance of an experimental domestic sewage treatment plant consisting of an anaerobic expanded bed reactor followed by dissolved air flotation

2003 ◽  
Vol 48 (6) ◽  
pp. 285-293
Author(s):  
R.G. Penetra ◽  
M.A.P. Reali ◽  
J.R. Campos
Keyword(s):  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Domestic Sewage ◽  
Expanded Bed ◽  
Mean Velocity ◽  
Dissolved Air Flotation ◽  
Anaerobic Reactor ◽  
Air Flotation ◽  
Dissolved Air

This paper presents the results of a study performed with an experimental domestic sewage treatment plant (240 m3.d-1 flow) consisting of expanded bed anaerobic reactor (EBAR) followed by dissolved air flotation (DAF) unit. For the flotation step, the anaerobic reactor effluent was previously coagulated with 50 mgFeCl3.l-1 and flocculated under different conditions (mean velocity gradient, Gf, and flocculation time, Tf). The Gf values were from 60 to 100 s-1 associated with 13 and 20 min Tf values. During the tests, the following operational conditions of the flotation unit were maintained: chemical addition (50 mgFeCl3.l-1), 18% recirculation rate associated with a pressure of 450 ± 10 kPa in the saturation chamber and overflow rate of 180 m3.mÐ2.d-1. Temperature ranged from 23.8¡C to 30.01/4C. Best results were achieved for Gf = 80 s-1 and Tf = 20 min. For these conditions, the DAF unit removal efficiencies were: 94.4% for chemical oxygen demand (with 53 mg.l-1 COD residual), 87% for phosphorus (with 0.80 mgP.l-1 residual), 96.7% for total suspended solids (with 9 mg.l-1 TSS residual) and 96.4% for turbidity (with 12.9 NTU residual), when the anaerobic reactor effluents have worst quality during the whole day.

Plywood Mill Water System Closure by Dissolved Air Flotation Treatment

1999 ◽  
Vol 40 (11-12) ◽  
pp. 33-41 ◽  
Author(s):  
P. Jokela ◽  
P. Keskitalo
Keyword(s):  
Heat Recovery ◽  
Occupational Safety ◽  
Suspended Solids ◽  
Water System ◽  
Raw Material ◽  
Surface Load ◽  
Dissolved Air Flotation ◽  
Treated Water ◽  
Air Flotation ◽  
Dissolved Air

In plywood industry water is mainly needed for soaking the logs. Dissolved air flotation with chemical precipitation was found to be a suitable treatment method for the soaking basin overflow of a plywood mill using birch as raw material. According to pilot treatment studies over 90% reductions of the suspended solids are possible with a hydraulic surface load of 6.5 m3/(m2h). In subsequent experience in full scale following reductions have been achieved: suspended solids 93%, BOD7 50%, CODCr 57%, P 92% and N 52%. Two-thirds of the flotation treated water is led to flue gas scrubbers and circulated back to the soaking basin. Optionally water can be led to the heat recovery, too. One-third of the flotation treated water is disposed of as the mill effluent. Concentrations of organic matter in the system have been reduced after the addition of flotation indicating the possibility of further closure. However, due to the use of aluminium sulphate in coagulation, aeration is needed for sulphate reduction prevention. Further closure of the water system is possible in the future if the heat recovery is renovated, preventing the increase of the water temperature (now 37°C) which otherwise might cause occupational safety hazards.

Evaluation of Treatment Efficiency of Processes for Petroleum Refinery Wastewater

1994 ◽  
Vol 29 (8) ◽  
pp. 47-50 ◽  
Author(s):  
Kee Kean Chin
Keyword(s):  
Petroleum Refinery ◽  
Refinery Wastewater ◽  
Residual Oil ◽  
Oil And Grease ◽  
Dissolved Air Flotation ◽  
Petroleum Refinery Wastewater ◽  
Aeration System ◽  
Air Flotation ◽  
Final Effluent ◽  
Dissolved Air

Processes used in the treatment of a petroleum refinery wastewater included initial API oil separator to be followed by dissolved air flotation and an extended aeration system. The API oil separator removed most of the settleable solids and oil. The residual oil varied from around 680 mg/l to 104 mg/l and was further treated with chemical coagulation, flocculation and dissolved air flotation which remove more than 80 % of the oil and grease. Mean COD after dissolved air flotation was around 970 mg/l and it was lowered to around 378 mg/l using the extended aeration biological system at 15-day HRT. The final effluent COD/BOD ratio was high indicating the presence of a high percentage of refractory organic compounds.

Dissolved air flotation clarification of activated sludge and wastewaters from chemical industry

2003 ◽  
Vol 47 (1) ◽  
pp. 205-210 ◽  
Author(s):  
P. Jokela ◽  
J. Immonen
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Animal Feed ◽  
Paper Industry ◽  
Dissolved Air Flotation ◽  
Jar Test ◽  
Air Flotation ◽  
Carry Over ◽  
Winter Time ◽  
Dissolved Air

Wastewaters from separate chemical factories are treated together in an extended aeration activated sludge plant. The factories produce chemicals for paper industry (e.g. starch), latexes and animal feed. The components of the wastewaters include styrene, tertiary butanol and vinyl acetate. Activated sludge is clarified by sedimentation. During winter time, when the water temperature was 3-12°C, the clarification deteriorated causing carry over of suspended solids containing COD. Enhancement of suspended solids and COD removals was studied in a dissolved air flotation jar test unit. Flotation trials were conducted for activated sludge, sedimentation treated final effluent (tertiary treatment) and separate wastewater fractions. The need for chemicals, flocculation and amount of recycle water were judged according to the achieved removals. Dissolved air flotation was found well suited for the clarification of activated sludge, but not technically and economically feasible for the clarification of the wastewater streams before the activated sludge treatment.

Optimization of Fenton's reagent coupled to Dissolved Air Flotation to remove cyanobacterial odorous metabolites and suspended solids from raw surface water

2011 ◽  
Vol 64 (8) ◽  
pp. 1668-1674 ◽  
Author(s):  
Jorge A. Elías-Maxil ◽  
Fotis Rigas ◽  
María Teresa Orta de Velásquez ◽  
Rosa-María Ramírez-Zamora
Keyword(s):  
Water Treatment ◽  
Suspended Solids ◽  
Advanced Oxidation Process ◽  
Treatment Plant ◽  
Drinking Water Treatment ◽  
Fenton’S Reagent ◽  
Fenton's Reagent ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Dissolved Air

Ferrous salts are commonly used as coagulants in Water Treatment Plants (WTPs). When these salts are combined with hydrogen peroxide in acidic conditions – besides coagulation – an additional Advanced Oxidation Process (Fenton's reagent) can take place. Using a response surface methodology, this paper presents the optimization of a novel treatment system constituted by Fenton's reagent (FE) and Dissolved Air Flotation (DAF) for removing 2-Methylisoborneol (MIB), geosmin and Total Suspended Solids (TSS) from raw water. FE was proven able to remove completely both micro pollutants found in the influent of a drinking water treatment plant. Moreover, higher clarification rate was achieved by coupling FE-DAF with respect FE-Sedimentation.

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