Water and Wastewater.com Help Forums - please help me to making a DAF systerm

Andy Vu YaBB Newbies Offline I love Water and Wastewater.com Posts: 4 Company or Organization: Song Duong	please help me to making a DAF systerm Aug 23^rd, 2008, 9:30am Hi every body, I'm from VietNam. My factory make tissue paper. We are going to instal a DAF after paper machine. Please, help me : technology, equiment, chemical ... Thanks Andy Vu
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Andy Vu YaBB Newbies Offline I love Water and Wastewater.com Posts: 4 Company or Organization: Song Duong	Re: please help me to making a DAF systerm Reply #1 - Aug 23^rd, 2008, 11:46am waste water = 60 m3/min C = 0.03%
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Dan Keys

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Re: please help me to making a DAF systerm
Reply #2 - Aug 23^rd, 2008, 9:08pm

Welcome to the help forum, Andy

Are you sure you have 60m3/min? That is a very large flow. Also, I am not sure what you mean by C=0.03% What is "C" refering to?

1. Please check your data and provide us with:

flow
mg/L TSS

2. Have you already selected a DAF manufacturer? The DAF manufacturer should be able to provide you with all the detailed requirements. If you have not selected a DAF manufacturer, be very careful that the one you chose has previous experience with pulp and paper. Be very careful to install a DAF large enough to treat the flow and solids you have. The size of the DAF should be based on BOTH the flow and the solids.

Get a little more detail and we will help you every way possible. There is plenty of DAF in the paper industry and it will be fairly easy to get you more information. Best of luck with your project.

Dan Keys

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Dan Keys
KeysTec Environmental

Dissolved Air Flotation Design, Waste Treatment Process Control Design, Primary Pretreatment Consulting

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Andy Vu YaBB Newbies Offline I love Water and Wastewater.com Posts: 4 Company or Organization: Song Duong	Re: please help me to making a DAF systerm Reply #3 - Aug 24^th, 2008, 6:41am Thanks for your help! C = Concentration of pulp in waste water = 0,03%, sometime = 0,09%. I have had a mistake, flow rate only 60 m3/hour. TSS is about 600 ppm We stilll don't choose any DAF systerm. I think size of DAF will about 10,5 m2. And DAF type rectangle. Andy Vu
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Dan Keys

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Re: please help me to making a DAF systerm
Reply #4 - Aug 24^th, 2008, 4:32pm

Thank you for your prompt response.

First, let's consider the design of the DAF. Most modern DAFs are based on recycle pressurization for air bubble generation. The size of the DAF must accomodate both the throughput flow and the recycle flow. For many decades, a basic principle for size has always worked well. Recently, some manufacturers have claimed higher flows in smaller DAFs. Don't fall in that trap. The cost may be lower, but the performance will be lower as well. When selecting the DAF, use the following calculations and you will not have a problem.

The following is based on the surface area of the DAF where solids float. Do not include the inlet area where there is high turbulence.

Flotation Surface Area = 2 GPM / Sq. Ft. or 5 m3/hr / m2 (metric)

This means you will need a minimum of 14 square meters of flotation surface area for your flow. If you will be growing or might have higher flows, make the DAF bigger acording to the formula above. The biggest mistake I have found in 30 years of working with DAF is selecting a DAF that is too small because some sales person said his was different. Don't make that mistake. It isn't worth it.

Some manufacturers will try to sell you a "plate" style DAF which will provide higher flows in a smaller DAF. The principle is sound, but the DAF is more difficult to maintain and work with. So, if possible, stay with a simple "open" design unless you must have a smaller DAF due to space constraints.

There are many DAF manufacturers and suppliers, but I suggest you study the valuable information provided on www.ptecserve.com. I am not associated with that company, but I did design the DAFs they manufacture and sell, so I am very familiar with them. Any well designed DAF will be based on the same principles. Click on the button on the left for "HS MacroDAF". It will take you to a copy of their literature. Go to the second page and look at their size charts for the most reliable sizing information I am aware of. The sizes and flows listed are based on principles that are proven over decades of application. Compare those size/flow charts with similar information from any other DAF supplier. The chart is in English Units and you will either have to convert or contact them for a copy with Metric which I'm sure they will provide. If you are offered a smaller DAF for the same flow, be very cautious.

As to the chemicals, your application is common in DAF use and good chemical suppliers are familiar with pulp and paper. Have several companies come in and do jar testing with recommendations. They will gladly do that, hoping for future business. If you have any problem getting honest testing, contact me privately and I will direct you to someone that can help in your area.

There is much more to installing a well designed DAF system and I will help as much as possible with any more questions you have. Keep it as simple as possible and it will be most reliable. Do not depart from proven principles and equipment. Make sure you have a constant flow to the DAF. Install a properly sized flow equalization tank ahead of the DAF to provide the conastant flow if necessary.

If you need recommendations for specific vendors, contact me privately and I will help. I try to avoid using this great forum to promote one vendor or another. Water and Wastewater.com has a good list of vendors accessable on the home page.

Very best regards,
Dan Keys

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Dan Keys
KeysTec Environmental

Dissolved Air Flotation Design, Waste Treatment Process Control Design, Primary Pretreatment Consulting

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Andy Vu YaBB Newbies Offline I love Water and Wastewater.com Posts: 4 Company or Organization: Song Duong	Re: please help me to making a DAF systerm Reply #5 - Aug 25^th, 2008, 10:57am Thank you very much, Mr Dan Keys. Your instruction is very useful with me. I'll design and sent it to you. Could you show me more about the form : Flotation Surface Area = 2 GPM / Sq. Ft. Sq and Ft are unit that not common in Viet Nam Very best regards, Andy Vu
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Corb YaBB Newbies Offline Water and Wastewater.com is the best! Posts: 9 Company or Organization: BioprocessH2O	Re: please help me to making a DAF systerm Reply #6 - Aug 25^th, 2008, 3:27pm Sq. ft. refers to square feet. 1 square meter = 10.76 square feet He also converted to the metric. 5 m3/hr / m2
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Dan Keys

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Re: please help me to making a DAF systerm
Reply #7 - Aug 27^th, 2008, 8:54am

Thank you, Corb, for answering the question while I was away (trying to make a living Wink

)

There are many arguments about the size of DAF, but the most reliable and proven flow capacity formula is (in metric) 5 m3/hr / m2. This means you can safely expect to treat 5 cubic meters per hour for each square meter of the DAF surface. Some DAF manufacturers claim much more flow per square meter (or square foot) than the standard, but they rely on chemistry and design techniques that are not proven to be reliable in the broad base of applications. So, to be absolutely sure, stick with the proven formula unless the DAF manufacturer is able to prove their claims with pilot equipment at a realistic scale in your site on the water you need to treat.

For those interested, the parallel plate DAF will treat higher flows in a smaller DAF based on the known principle of laminar flow between closely spaced plates which effectively increase surface area. If anyone is ever interested, I'll gladly provide the most reliable formula for calculating flow rates for that design as well, but for smaller flows, it is better to stick with the most simple, open surface area DAF with the least maintenance required.

Dan Keys

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Dan Keys
KeysTec Environmental

Dissolved Air Flotation Design, Waste Treatment Process Control Design, Primary Pretreatment Consulting

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MNPunjabi

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Re: please help me to making a DAF systerm
Reply #8 - May 14^th, 2012, 3:42pm

Dan,

Thank you for your guidance. I am working on a DAF installation project and would like your input. Flow rate is 200 GPM, TSS on the influent can be as high as 1000 mg/L.

A vendor has pitched the plate design and I'm not sure if that is required. You mentioned the KISS principle, which I fully support. Space is tight where this new DAF is to be installed.

Questions:
1. Can you provide your opinion of plate vs open? If you recommend plates, what is the formula to design?
2. Can you recommend some vendors? There are many different players out there and I need a solid product that is proven.

Thank you.
MnPunjabi

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aditya_2281

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Re: please help me to making a DAF systerm
Reply #9 - May 15^th, 2012, 9:37am

Dear MNPunjabi,

If there are plates, there are many advantages like the surface area of inside the DAF increases.

Also there is a theory called Boycott effect. You can see the link below.

http://www.youtube.com/watch?v=CFtteE5TuhI

If you have the plates in certain angle (we prefer 60 deg) the sludge settles down through the walls of the plates thereby the water can come up easily with very minimum blockage with the help of micro bubbles.

Formula :

Length of the plate * Width of the plate * Number of plates * Number of rows you install the plates * Corrugation factor (1.25) * Cos 60

This gives you the effective plate surface area and you will have to add the top surface area of the DAF which gives you the total effective surface area.

We are a premier DAF manufacturing company and if you have any further questions please let me know. yanamandra@worldwaterworks.com

Best Regards,
Aditya,
Projects Engineer,
World Water Works Inc.,
Oklahoma City, OK.

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WasteH2ODave

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Re: please help me to making a DAF systerm
Reply #10 - May 22^nd, 2012, 8:00am

Andy Vu wrote on Aug 23^rd, 2008, 9:30am:

Hi every body,
I'm from VietNam. My factory make tissue paper.
We are going to instal a DAF after paper machine.

Please, help me : technology, equiment, chemical ...

Thanks
Andy Vu

Andy Vu,

In Vietnam there is a company called Wock Oliver. There are on the homepage of W&WW as well. The DAF that they make was originally designed for paper effluent. I have done some work with them here in the United States. I would recommend them.
www.wockoliver.com
Contact: Shellay Virk

For us, they designed, engineered, and implemented a full waste water treatment program and has been absolutely wonderful. They have both rectangular and circular DAF's.

Kind Regards

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