Flow structures in a dissolved air flotation pilot tank and the influence on the separation of MBBR floc

2002 ◽  
Vol 2 (2) ◽  
pp. 69-76 ◽  
Author(s):  
M. Lundh ◽  
L. Jönsson ◽  
J. Dahlquist
Keyword(s):  
Flow Structure ◽  
Removal Efficiency ◽  
Pilot Plant ◽  
Suspended Solids ◽  
Short Circuit ◽  
Flow Structures ◽  
Dissolved Air Flotation ◽  
Air Content ◽  
Air Flotation ◽  
Dissolved Air

The objective of the study was to find ways of improvement of the dissolved air flotation process by studying the flow structure. The paper presents experimental data on flow structures and the relation between the flow structure and the removal efficiency. Measurements have been performed in a pilot plant with an Acoustical Doppler Velocimeter. The water velocity was measured in a grid net, giving insight into the flow structure. The removal efficiency was analysed at Malmö wastewater treatment plant in Sweden. The pilot plant separated biological floc from a Kaldnes Moving Bio-Bed Reactor (MBBR). The efficiency of the separation was analysed by measurements of suspended solids in the influent and the effluent. Air content was measured inside the tank and in the re-cycle. The result showed that basically two flow structures existed; the stratified and the short-circuit flow structure. The stratified flow structure seemed correlated to efficient separation of particles while the short-circuit flow structure seemed to have a negative effect, especially when the flow structure was affected by varying the re-cycle rate, i.e. the air content. Conclusively, the flow structure seemed to be correlated to type of flow structure. However, studies with higher concentration of suspended solids for verification were suggested.

The flow structure in the separation zone of a DAF pilot plant and the relation with bubble concentration

2001 ◽  
Vol 43 (8) ◽  
pp. 185-194 ◽  
Author(s):  
M. Lundh ◽  
L. Jönsson ◽  
J. Dahlquist
Keyword(s):  
Flow Structure ◽  
Water Body ◽  
Pilot Plant ◽  
Experimental Studies ◽  
Flow Structures ◽  
Return Flow ◽  
Dense Layer ◽  
Dissolved Air Flotation ◽  
Air Content ◽  
Measured Flow

Fluid dynamics is believed to be of crucial importance for the removal mechanism in Dissolved Air Flotation. The paper is a presentation of experimental studies on velocity and air-content profiles in a DAF pilot plant. The correlation between air content and flow patterns is discussed. Two flow structures are detected. A stratified flow structure is defined by a horizontal transport of the water in a upper, less-dense layer, and a lower, downwards-vertical transport in the lower, dense layer. Between the layers a return flow is found. The short-circuiting flow is defined as an immediate downward deviation towards the outlet arrangement at the bottom of the tank, probably causing decreasing effluent quality. Density gradients, caused by differences in air content in the tank, are believed to generate a stratification of the water body, thus causing the water to be transported in layers. Measurements of air-content profiles correlate to the measured flow structures, also indicating a separation ofthe water body in two layers with a distinct boundary.

Optimising dissolved air flotation/filtration treatment of algae-laden lagoon effluent using surface charge: a Bolivar treatment plant case study

2012 ◽  
Vol 66 (8) ◽  
pp. 1684-1690 ◽  
Author(s):  
Russell Yap ◽  
Michael Holmes ◽  
William Peirson ◽  
Michael Whittaker ◽  
Richard Stuetz ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Surface Charge ◽  
Wastewater Treatment Plant ◽  
Pilot Plant ◽  
Treatment Plant ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
A Charge ◽  
Dissolved Air

Dissolved air flotation (DAF) incorporating filtration (DAFF) is used at the Bolivar wastewater treatment plant (WWTP) to polish lagoon effluent for reuse. Elevated algal populations are frequently experienced and can lead to increased coagulant requirements and process control issues. Streaming current detectors (SCDs) and a charge demand analyser (CDA) were used to monitor the full-scale plant. This was followed by an optimisation study using a pilot plant with a CDA. It was found that the normal operational charge demand range for DAF at Bolivar was between −46 and −40 μeq L−1. Decreasing the pH of coagulation reduced coagulant consumption and facilitated more sensitive CDA responses to changes in alum dose.

Effects of Al3 +  and hydraulic characteristics on the removal and behaviour of particles in dissolved air flotation

2006 ◽  
Vol 6 (3) ◽  
pp. 89-95
Author(s):  
Jungsoo Mun ◽  
Sungwon Park ◽  
Mooyoung Han
Keyword(s):  
Turbulent Flow ◽  
Removal Efficiency ◽  
Operating Conditions ◽  
Point Of Zero Charge ◽  
Hydraulic Characteristics ◽  
Dissolved Air Flotation ◽  
Floc Size ◽  
Saturated Water ◽  
Air Flotation ◽  
Dissolved Air

The removal efficiency of the dissolved air flotation (DAF) process to separate particles from water and wastewater depends on the size and zeta potential of bubbles and particles, the solution and operating conditions, hydraulic characteristics, etc. The effects of aluminium ions and turbulent flow-produced when air-saturated water was spouted into the reactor in the DAF process, on removal and, particle behaviour were on investigated. When bubble size was similar to particle size (10–50 μm), the maximum removal efficiency was 92% in a Kaolin solution of 10−3 M Al3 +  without pre-treatment for flocculation process, and, as time passed, the floc size was observed to increase at a pH of 8, which was the condition of high removal efficiency as seen through image analysis. When the air-saturated water was spouted into the reactor, the size of particle at p.z.c. (point of zero charge) seemed to increase to form a floc due to collision effects caused by turbulent flow. Consequently, floc formation by turbulent flow in the reactor seemed to positively affect removal efficiency.

scholarly journals Automation and Control of a Dissolved Air Flotation Pilot Plant

2017 ◽  
Vol 50 (1) ◽  
pp. 3911-3916 ◽  
Author(s):  
Rodolpho R. Fonseca ◽  
José P. Thompson, Jr. ◽  
Ivan C. Franco ◽  
Flávio V. da Silva
Keyword(s):  
Pilot Plant ◽  
Dissolved Air Flotation ◽  
Automation And Control ◽  
Air Flotation ◽  
And Control ◽  
Dissolved Air

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.

Disturbances and Inhibition in Biological Treatment of Wastewater from an Integrated Refinery

1988 ◽  
Vol 20 (10) ◽  
pp. 21-29 ◽  
Author(s):  
N. Galil ◽  
M. Rebhun ◽  
Y. Brayer
Keyword(s):  
Pilot Plant ◽  
Biological Treatment ◽  
Suspended Solids ◽  
Biological Process ◽  
Oil Refinery ◽  
Process Rate ◽  
Inhibitory Effects ◽  
Dissolved Air Flotation ◽  
Mixed Liquor ◽  
Dissolved Air

Biological treatment of wastewater from an integrated oil refinery, containing hazardous contaminants, was studied in an on site pilot plant. The wastewater is pretreated by gravity separation, flocculation and dissolved air flotation. Biotreatment of such wastewaters poses several problems which have to be considered in planning, design and operation of the treatment system. The process rate is relatively slow, due to the inhibitory effects. The mixed liquor volatile suspended solids (MLVSS) could not be maintained at concentrations higher than 2000 mg/l. Sudden discharges of concentrated phenolic wastes disrupted the process first by impairing bioflocculation, followed by complete inhibition of the biological process.

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