Microalgal Harvesting by in situ Autoflotation

1987 ◽  
Vol 19 (12) ◽  
pp. 385-387
Author(s):  
E. Sandbank ◽  
L. J. van Vuuren
Keyword(s):  
Open Channel ◽  
Photosynthetic Activity ◽  
High Rate ◽  
Dissolved Air Flotation ◽  
Polyelectrolyte Solution ◽  
Rapid Mixing ◽  
Removal Efficiencies ◽  
Slow Mixing ◽  
Dissolved Air

Dissolved Air Flotation (DAF) principles were applied to harvest microalgae from high rate algal pond (HRAP) effluents in a highly simplified system which consisted of an open channel and a dosing pump only. Polyelectrolyte solution is dosed into the channel through a diffuser in the vicinity of a paddle wheel, where rapid mixing occurs. Slow mixing takes place in the channel. While flocs grow, oxygen bubbles resulting from algae photosynthetic activity are entrapped. Floating flocs are removed manually at the end of the channel. Removal efficiencies of 90% were obtained at a 10 mg polyelectrolyte dose. The float had 4 to 6% solids which dewatered easily to 10% solids.

High-rate dissolved air flotation for water treatment

2001 ◽  
Vol 43 (8) ◽  
pp. 43-49 ◽  
Author(s):  
M. A. P. Raeli ◽  
M. Marchetto
Keyword(s):  
Reynolds Numbers ◽  
Pilot Scale ◽  
Water Velocity ◽  
High Rate ◽  
Raw Water ◽  
Parallel Plates ◽  
Dissolved Air Flotation ◽  
Removal Efficiencies ◽  
Air Flotation ◽  
Dissolved Air

This paper presents the results of an experimental investigation about the performance of a horizontal flow high-rate pilot scale Dissolved Air Flotation (HRDAF) unit containing inclined parallel plates for treating a coloured and low turbidity raw water. Experiments were performed with the DAF unit in order to verify the influence on flotation of : (i) the water velocity (Vh) between the plates, in the range 18 to 96.5 cm.min−1 with corresponding Reynolds numbers between 240 and 1060; (ii) the supplied air (S*) value ranging from 2.2 to 8.5 g of air/m3 of water ; (iii) the angle of the plates (60° or 70°). The best pilot plant operational condition was obtained applying only 4.0 g/m3 (S*) with Vh around 18 cm.min−1 for treatment of water coagulated with a Al2(SO4)3 dosage of 40 mg.l−1. In these conditions, the unit presented very good removal efficiencies of colour (90%, residual of 10 uC), turbidity (88%, residual of 0.8 NTU ) and TSS (94%, residual of 1.8 mg.l−1). Furthermore, the unit could operate at higher Vh values up to 76 cm.min−1 and still present good results. The DAF unit thus behaved as a high rate unit presenting good performance with low air requirement.

Harvesting of Algae from High-Rate Ponds by Flocculation-Flotation

1987 ◽  
Vol 19 (12) ◽  
pp. 257-263 ◽  
Author(s):  
E. Sandbank ◽  
G. Shelef
Keyword(s):  
High Rate ◽  
Dissolved Air Flotation ◽  
Aluminium Sulfate ◽  
Algae Removal ◽  
Solids Concentration ◽  
Slow Mixing ◽  
Oxidation Ponds ◽  
Solids Removal ◽  
Suspended Algae ◽  
Dissolved Air

Microalgae grown in stabilization ponds and in high rate oxidation ponds (HROP) treating wastewater, were harvested by flocculation with aluminium sulfate and floated in a laboratory electro-flotation unit, where bubbles were produced electrolytically. It was shown that the higher the solids concentration, the lower is the air: solids ratio needed to achieve 90% algae removal. The simultaneous flocculation of suspended algae and release of bubbles while flocs grow, give equal suspended solids removal as the classical flush mixing flocculation followed by slow mixing-flotation stage. Air : solidsratios between 0.009 and 0.013 were sufficient for flocs flotation by dissolved air flotation (DAF) and electro flotation. Continuous flocculation-flotation in a DAF pilot plant unit showed that flush mixing can be replaced by injection of chemicals in-line provided a retention of 15 sec is given before the inflow to the flotation tank. Slow mixing could be eliminated altogether when bubbles were generated simultaneously with the flocculation stage. DAF was further simplified, replacing the air compressor used for pressuring air into water by a venturi suction at the under pressure side of the pump in the pressurised line. DAF in its simplified version is preferred for algae harvesting in fresh water algae cultures and in HROP systems, while it is recognized that electroflotation may be preferred in harvesting marine microalgae.

Evaluation of flocculation and dissolved air flotation as an advanced wastewater treatment

2001 ◽  
Vol 43 (8) ◽  
pp. 83-90 ◽  
Author(s):  
A. C. Pinto Filho ◽  
C. C. Brandão
Keyword(s):  
Wastewater Treatment ◽  
Domestic Wastewater ◽  
High Rate ◽  
Advanced Treatment ◽  
Dissolved Air Flotation ◽  
Anaerobic Reactor ◽  
Treatment Processes ◽  
Domestic Wastewater Treatment ◽  
Air Flotation ◽  
Dissolved Air

A bench scale study was carried out in order to evaluate the applicability of dissolved air flotation (DAF) as an advanced treatment for effluents from three different domestic wastewater treatment processes, namely: (i) a tertiary activated sludge plant ; (ii) an upflow sludge blanket anaerobic reactor (UASB); and (iii) a high-rate stabilization pond.

scholarly journals In situ treatment of metalworking wastewater by chemical addition-dissolved air flotation coupled with UV, H2O2 & ZnO

Heliyon ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. e03091 ◽  
Author(s):  
Mohammad Mehdi Golbini Mofrad ◽  
Hamidreza Pourzamani ◽  
Mohammad Mehdi Amin ◽  
Iman Parseh ◽  
Mohammadreza Alipour
Keyword(s):  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Dissolved Air

Emerging investigator series: control of membrane fouling by dissolved algal organic matter using pre-oxidation with coagulation as seawater pretreatment

2020 ◽  
Vol 6 (4) ◽  
pp. 935-944 ◽  
Author(s):  
Bhaskar Jyoti Deka ◽  
Jiaxin Guo ◽  
Sanghyun Jeong ◽  
Manish Kumar ◽  
Alicia Kyoungjin An
Keyword(s):  
Organic Matter ◽  
Membrane Fouling ◽  
Chemical Oxidation ◽  
Dissolved Air Flotation ◽  
Algal Organic Matter ◽  
Wet Chemical ◽  
Air Flotation ◽  
Dissolved Air

High AOM removal achieved by pre-oxidation with coagulation–flocculation-dissolved air flotation. In situ ferrate was formed by wet chemical oxidation of NaOCl-Fe3+. Membrane fouling was significantly alleviated and assessed by OCT technique.

High Rate Dissolved Air Flotation (DAF) for the Removal of Algae Species

2017 ◽  
Vol 31 (5) ◽  
pp. 415-419
Author(s):  
Woosik Jung ◽  
◽  
Ju-Suk An ◽  
Keun-Won Song ◽  
Hyun-Je Oh
Keyword(s):  
High Rate ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Dissolved Air

High rate settler in biological system for oil and soap wastewater treatment

1995 ◽  
Vol 32 (11) ◽  
pp. 39-44 ◽  
Author(s):  
S. I. Abou-Elela ◽  
A. Ashmawy ◽  
H. I. Aly ◽  
H. M. Ahmed
Keyword(s):  
High Rate ◽  
Nile River ◽  
Aeration Tank ◽  
Activated Sludge Process ◽  
Biological Degradation ◽  
Inorganic Pollutants ◽  
Dissolved Air Flotation ◽  
Biological Unit ◽  
Untreated Wastewater ◽  
Dissolved Air

Wastewater from an oil and soap company provided the material of this study. The company discharges 31,000 m3/d of untreated wastewater into the Nile River. The wastewater was highly contaminated with organic and inorganic pollutants. An end-of-pipe treatment scheme was devised of dissolved air flotation with/without alum followed by biological degradation. The biological unit was compact and comprised an aeration tank based on a completely mixed activated sludge process followed by a high rate settler. The unit was operated at two organic loads, namely 1.44 and 2.88 kg BOD5/m3/d. The results obtained showed that this scheme of treatment produced a high quality effluent suitable for disposal into surface water or reuse. Also, the high rate settler acted as a biological reactor as well as a settler for finely divided organic matter.

Long-term Comparison Testing with Sand Ballasted Flocculation (SBF) and High-rate Dissolved Air Flotation (DAF).

2008 ◽  
Vol 3 (4) ◽  
Author(s):  
J. Van Cappellen ◽  
J. Clement ◽  
S. Kempeneers ◽  
G. Budd ◽  
W. Bossaerts ◽  
...  
Keyword(s):  
High Rate ◽  
Operational Experience ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Water Companies ◽  
Technology Comparison ◽  
Dissolved Air

This paper reports on the investigation conducted by Antwerp Water Works (AWW) in Belgium to make a long term (12 months) comparison between SBF and high-rate DAF to determine which process would be optimal. Three major objectives where put forward at the beginning of the study: technology comparison, gain operational experience and conduct coagulant testing. This paper discusses the result obtained with respect to these objectives. Overall this paper clearly points to the value this type of piloting can bring to water companies.

scholarly journals High-rate activated sludge systems combined with dissolved air flotation enable effective organics removal and recovery

2019 ◽  
Vol 291 ◽  
pp. 121833 ◽  
Author(s):  
Cristina Cagnetta ◽  
Bart Saerens ◽  
Francis A. Meerburg ◽  
Stijn O. Decru ◽  
Eddie Broeders ◽  
...  
Keyword(s):  
Activated Sludge ◽  
High Rate ◽  
Dissolved Air Flotation ◽  
Organics Removal ◽  
Air Flotation ◽  
Removal And Recovery ◽  
Activated Sludge Systems ◽  
Dissolved Air
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