Reducing the effect of cyanobacteria in the microfiltration of secondary effluent

2010 ◽  
Vol 62 (7) ◽  
pp. 1682-1688 ◽  
Author(s):  
Y. T. Goh ◽  
J. L. Harris ◽  
F. A. Roddick
Keyword(s):  
Organic Matter ◽  
Sewage Treatment ◽  
Cyanobacterial Blooms ◽  
Secondary Effluent ◽  
Dissolved Air Flotation ◽  
Algal Organic Matter ◽  
Alum Coagulation ◽  
Pre Treatment ◽  
The Impact ◽  
Dissolved Air

Cyanobacterial blooms in the lagoons of sewage treatment plants can severely impact the performance of membrane plants treating the effluent. This paper investigates the impact of Microcystis aeruginosa in a secondary effluent on the microfiltration filterability and cleaning of the membrane. Alum coagulation and dissolved air flotation (DAF) were investigated to remove the algae and so enhance the volume of effluent processed, and their influence on reversible and irreversible fouling. Degree of fouling due to the algal components was found to be in decreasing order of algal cells, algal organic matter and extracellular organic matter. Alum coagulation with 5 mg L−1 as Al3 +  led to a substantial increase in permeate volume, an increase in dissolved organic carbon removal, and a foulant layer which protected the membrane from internal fouling but which was hydraulically removable resulting in full flux recovery. Pre-treatment by DAF or 1.5 μm filtration following alum coagulation enhanced the flux rate and permeate volume but exposed the membrane to internal irreversible fouling.

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.

scholarly journals The role of algal organic matter in the separation of algae and cyanobacteria using the novel “Posi” - Dissolved air flotation process

2018 ◽  
Vol 130 ◽  
pp. 20-30 ◽  
Author(s):  
Narasinga Rao Hanumanth Rao ◽  
Russell Yap ◽  
Michael Whittaker ◽  
Richard M. Stuetz ◽  
Bruce Jefferson ◽  
...  
Keyword(s):  
Organic Matter ◽  
The Novel ◽  
Dissolved Air Flotation ◽  
Flotation Process ◽  
Algal Organic Matter ◽  
Air Flotation ◽  
Dissolved Air

Pre-treatment with dissolved air flotation considering an integrated process design

2001 ◽  
Vol 1 (2) ◽  
pp. 115-122
Author(s):  
J. Dahlquist ◽  
M. Kulesza
Keyword(s):  
Organic Matter ◽  
Process Design ◽  
Treatment Plant ◽  
Integrated Process ◽  
Raw Water ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Pre Treatment ◽  
Treatment Step ◽  
Dissolved Air

The raw water from Lake Zegrzynski is difficult to treat and requires a high chemical dosing rate of coagulant for the reduction of organic matter in order to comply with EU standards. The high degree of reduction calls for an efficient coagulant, but also an optimal chemistry such as correct dosing amount and an optimal flocculation-pH. The paper describes different removal efficiencies of organic matter, particularly with respect to pH in flocculation. During the warm season, the raw water can also suffer from large amounts of plankton that are difficult to remove to a satisfactory degree. In a two-step chemical treatment concept, with Dissolved Air Flotation (DAF) and the pulsator process, the plankton content in the final outlet water is reduced to very low levels. It follows that eventual peaks of plankton in the raw water cannot be detected in the final outlet water. Ozone is added for removal of taste and odour originating from the presence of plankton. In the pre-treatment step prior to the ozonation, a great deal of the organic matter is removed, which reduces the necessary ozone dosage. The Municipal Water Company of Warsaw City has decided to consider an additional pre-treatment step to the existing water treatment plant at Wieliszew. For that purpose, and bearing in mind an integrated process design, the company has performed pilot-scale experiments with DAF installed prior to a process line identical with the existing full-scale plant. The experimental flow is about 10 m3/h.

Enhanced rapid gravity filtration and dissolved air flotation for pre-treatment of river thames reservoir water

1998 ◽  
Vol 37 (2) ◽  
pp. 35-42 ◽  
Author(s):  
M. J. Bauer ◽  
R. Bayley ◽  
M. J. Chipps ◽  
A. Eades ◽  
R. J. Scriven ◽  
...  
Keyword(s):  
Water Treatment ◽  
Water Supply ◽  
21St Century ◽  
Reservoir Water ◽  
Dissolved Air Flotation ◽  
Lowland Rivers ◽  
Air Flotation ◽  
Pre Treatment ◽  
Counter Current ◽  
Dissolved Air

Thames Water treats approximately 2800Ml/d of water originating mainly from the lowland rivers Thames and Lee for supply to over 7.3million customers, principally in the cities of London and Oxford. This paper reviews aspects of Thames Water's research, design and operating experiences of treating algal rich reservoir stored lowland water. Areas covered include experiences of optimising reservoir management, uprating and upgrading of rapid gravity filtration (RGF), standard co-current dissolved air flotation (DAF) and counter-current dissolved air flotation/filtration (COCO-DAFF®) to counter operational problems caused by seasonal blooms of filter blocking algae such as Melosira spp., Aphanizomenon spp. and Anabaena spp. A major programme of uprating and modernisation (inclusion of Advanced Water Treatment: GAC and ozone) of the major works is in progress which, together with the Thames Tunnel Ring Main, will meet London's water supply needs into the 21st Century.

Removal and fate of Cryptosporidium in dissolved air drinking water treatment plants

2001 ◽  
Vol 43 (8) ◽  
pp. 51-57 ◽  
Author(s):  
J. K. Edzwald ◽  
J. E. Tobiason ◽  
H. Dunn ◽  
G. Kaminski ◽  
P. Galant
Keyword(s):  
Natural Organic Matter ◽  
Drinking Water Treatment ◽  
Spring Water ◽  
Water Production ◽  
Dissolved Air Flotation ◽  
Model Predictions ◽  
Particle Counts ◽  
Recycle Rate ◽  
The Impact ◽  
Dissolved Air

In the first part of the paper, data from pilot plant studies are used to evaluate Cryptosporidium removal by dissolved air flotation (DAF) clarification and dual media filters under challenge conditions. Oocyst removals were investigated for design detention times and hydraulic loadings for winter and spring seasons. Coagulation was optimized for turbidity and removal of natural organic matter. DAF performance was better for spring water temperatures achieving 2.5 ± 0.3 log removal of oocysts compared to 1.7 ± 0.3 log removal in the winter. Cumulative log removal across DAF and filtration exceeded 5.4, and was not affected by water temperature. Low turbidities and particle counts are indicators of good treatment and good removals of Cryptosporidium. The second part of the paper uses a mathematical model to predict the fate of Cryptosporidium through a DAF plant and the impact of filter backwash recycle on oocyst build-up in the plant influent. Model predictions show that the fate of Cryptosporidium and the build-up of oocysts in the plant influent depend on: DAF performance, the percent of filtered water production used for backwashing, and the percent of filter backwash recycle flow. A DAF plant with 2.5% filtered water production for backwashing and that achieves 1.6 log removal or greater of oocysts by DAF clarification will not have a build-up of oocysts in the plant influent regardless of the recycle rate. This is because the oocysts are concentrated in the DAF floated sludge and not within granular filters.

The impact of interactions between algal organic matter and humic substances on coagulation

2015 ◽  
Vol 84 ◽  
pp. 278-285 ◽  
Author(s):  
Martin Pivokonsky ◽  
Jana Naceradska ◽  
Tomas Brabenec ◽  
Katerina Novotna ◽  
Magdalena Baresova ◽  
...  
Keyword(s):  
Organic Matter ◽  
Humic Substances ◽  
Algal Organic Matter ◽  
The Impact

scholarly journals Dissolved air flotation of surface water for spiral-wound module nanofiltration pre-treatment

Desalination ◽  
2008 ◽  
Vol 228 (1-3) ◽  
pp. 191-199 ◽  
Author(s):  
Vítor Geraldes ◽  
Aykut Anil ◽  
Maria Norberta de Pinho ◽  
Elizabeth Duarte
Keyword(s):  
Surface Water ◽  
Dissolved Air Flotation ◽  
Air Flotation ◽  
Pre Treatment ◽  
Dissolved Air ◽  
Spiral Wound
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