## DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

## DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

(OP)

Hi folks,

I need help and it will be great from your experience to help me, I appreciate that.

I work on design DAF Dissolved Air Flotation product. I have input parameters and with input parameters I calculated A/S ratio, Air solubility, Solid loading ratio, Hydraulic loading ratio etc, the next step when I know calculations and what is required DAF plate area , I need to find what will be Length, Height and Width for my DAF plate pack (Dissolved air Flotation).

How do I find that informations ?

Also for Height of the DAF - is it standard height required for the air bubble motion upward.

King Regards,

Andreas

I need help and it will be great from your experience to help me, I appreciate that.

I work on design DAF Dissolved Air Flotation product. I have input parameters and with input parameters I calculated A/S ratio, Air solubility, Solid loading ratio, Hydraulic loading ratio etc, the next step when I know calculations and what is required DAF plate area , I need to find what will be Length, Height and Width for my DAF plate pack (Dissolved air Flotation).

How do I find that informations ?

Also for Height of the DAF - is it standard height required for the air bubble motion upward.

King Regards,

Andreas

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Most applications do not use a plate pack.

The height of the DAF is more or less standard.

The information that you are seeking will have to come from a manufacturer. It is not something that the manufacturers are interested in providing for free.

http://purac.se/wp-content/uploads/2013/09/en_pura...

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

My DAF Flow ratio is for 25 m3/hr . It is for wastewater and for plate pack . I mean modern DAF system like this one from huber on picture - is that type of DAF - plate pack?

Manufacturer --Company is Manufacturer where I work , all concept from idea to final concept, I am responsible and I decide, as I am new with this kind of product and this is hard from me and in same time and work on this, I need help how to determine Length, Height and Width after when I have all input design key parameters , to start design DAF in Solid Works example.

Pleas provide me with next steps what should I do, as I am here on forum to get help of you guys

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Finally I found input parameters but I still can't find way how to get information to obtain from my input parameters what will be Length, Width, Height. Is there possibility to ask any company like this one you provide me with their webpage "Purac".

I need advice, suggestions,consultancy from someone what will be dimnesions with my input parameters.

Of course I would pay for that consultancy,suggestion that is not problem

Or who do I ask for this ?

Thanks,

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Lamella systems are typically designed with a hydraulic flow pattern that divides the flow equally between the plates. This design does not do that that and one would not expect it to work. Lamella units do not work or wastewaters with grease and organics as the lamellas will clog.

Would not recommend that you copy this product as it may not work.

Purac is an expert on flotation. GEWE invented the lamella process. Purac may be able to assist you.

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

There is plenty of information out there on the general parameters you are looking for , but ultimately you as the designer decide what the relative dimensions are based on the water you are dealing with.

You could build a pilot plant to trial your design.

Alternatively you could obtain a working unit , reverse engineer it then try to improve on the design.

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

clean water

That water is not for drink, with very low solids, very low chemicals,

oils and grease .

I can find all input parameters except Design Solids Loading - ( lb/sq/= ft/hr or ( kg /m2/hr ) , I don;t know how to obtain Design Solids Loading input parameter for calculation, Also Influent Oil and Grease ___mg/L I will get that from customer

Could you guys help me with my input parameters what I have like : Air Required, Air to Solid ratio A/S Hydraulic Loading ratio, Soldi Loading ratio, = I can get all that parameters and need opinion from someone with this for suggestion what will be Length, Height and Width for my DAF input parameters.

Or is it this all input parameters what I learning every day and trying to understand them for DAF with wastewater mainly. Or If I have input parameters will that influce more on my DAF design.

My DAF is not with wastewater , it is clean water ( not for drink) but water with oil and grease, hydrocarbons

Please guys help me as I need help

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

There is no absolute design procedures for DAF units but many have rise rates of about 15m/hr(this will depend on bubble size and particle density) and detention times of around 20 minutes. This would dictate a depth of about 5 meters and the area would then depend on the flow rate.

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Recycle flow ratio = 25 m3/hr

recycle temperature = 10-12 C

Influent TSS = 100-120 mg/L

Chemical addition = 0 mg/L ( without chemical addition)

Influent Oil and Grease = is not on high level ( have to find that from customer)

could you suggest me with this what will be , how do I find best for bubble size and particle density with flow ratio 25 m3/hr and what will be approximatelz detention times.

as this is not typically DAF for waste treatment separation , here is focus on separate oil and hydrocarbons but there are not on high percentage ( what I will get from influent oil and grease)

what should I do with this .

Also I found on internet this spreadsheet for calculation :

http://www.engineeringexcelspreadsheets.com/2017/0...

will that help?

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

because this DAF is not for wastewater ,

It is for water : that water is not for drink, with very low solids, very low chemicals,

oils and grease .

______________

or should I design approximately something and then from your suggestion to see how test unit work and then make new design parameters from that.

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Typically the recycle is a lot lower than 100%. 10% is more normal.

A chemical coagulant is typically used but perhaps not always.

The bubble sizing is one of the key problems and can mean success or failure. The required bubble size is related to the particle size and density and the rise rate of the conjoined bubble and particle. The bubble size is influenced e size/type of the injector, air pressure and the saturation tank. Determination of particle density in the field is difficult apart from whether it will float unassisted or not.

Large amounts of oil and grease will often act differently to discrete particles and may float in large chunks or sheets.

You seem to think that your required parameters are somewhat outside the normal. If they are then i would suggest that you build something based on what you know/want and then modify or improve on it based on operations and further research.

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

In terms of physical size that determination should follow after you have determine the factors above.

But just to give you a ball park estimate using the data you have provided.

Flow rate 25m3/hr

Recycle 25mm3/hr.

Total flow through unit =50m3/hr.

Using a conservative vertical linear velocity of 10m/hr means that you need 5m2. Whether you make it 1 metre wide by 5 long or some other dimension will depend on your equipment layout, how you take off the float etc . Generally i would think at least a 2 to 1 length to width ratio but i ammm sure opinions will vary.

In an earlier post i told you that typical detention time is 20 mins. This depends on many factors which you are either going to have to make assumptions on or do some investigation. If you assume 20 mins detention time and you have a linear vertical velocity of 10m/hr assumes that the liquid will travel upwards 3.33metres in 20 minutes. Using all these assumptions gives you a tank of 5m2 and 3.33 metres usuable depth.

I would not use those dimensions though until you confirm the assumptions that i have made are correct , but it gives you some idea of the physical size of the machine you are looking at.

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

How I can measure particle density and look at bubble sizing and rise rates.

I will going next week on trial unit on training of DAF product , should I ask commisioning Engineer for this and ask him how to measure this to get some assumptions on this for dimension DAF ?

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Bubble sizing is related to operating pressure , airflow and system design. Saturator pressure impacts significantly below about 350-400kpa.

Rise rates can be calculated theoretically but often you can get a good idea by looking at what is going on in the actual unit.

If the commissioning Engineer is well experienced he may be able to help you.

Experienced unit operators may also have somme useful information on operation and design.

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

The Commissioning Engineers are there but they will not give any informations.

This your answer are very good and helps me to think about air bubble more and what parametres influence on design.

Just put anything what you think is important, as your informations are welcome and that helps me more with confidence on this.

For measure bubble size :

Is this good step 1 : I can ask company who will provide pump for DAF and ask them what microns size of bubbles I need for pump, is that also good factor for bubble sizing, and then see what is operating pressure too?

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

You will probably need to copy the basics of an existing design and look at the impacts of different operating parameters.

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Now I have this

Influent flow ratio = 25 m3/hr

Recycle flow ratio = 25 m3/hr

Total flow through unit 50m3/hr

recycle temperature = 10-12 C

Influent TSS = 120 mg/L , 2305 lb/day

Efficiency factor , f = 0.5

Design loading rate = 10 m

Solving for the tank area, A = 5m2

Loading per Area = 1.78 lb/ft2h

1. I can ask company who provide Pump for DAF unit – what microns size of bubbles I need for pump – with that answer what I can measure next to get data which are necessarily for dimensions of DAF tank?

2. How do I calculate rise rates, as you mention it can be calculated theoretically –

• For water

• For air bubble

is that come from assumption , or can I get that from informations what I have above

With your experience any information is welcome , and please put all what you think from your experience is good for this, I appreciate any kind of your answers ,big respect

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

The water rise rate is the flow in cubic metres per hour divided by the surface area of the flotation tank.

So for your example you have a tank with a flow of 50m3/hr and it has a 5m2 surface area. 50m3hr/5m2 =10m/hr

Bubble rise rate is the travel time from the release point until they reach the surface of the liquid. This is related to bubble size, viscosity of the liquid, density size and shape of the attached particle/s etc.You could attempt to mathematically model this according to Stokes law but there may be too many variables , so it probably comes down to some observation as much as anything. Heavy particles may require many small bubbles to attach before it will rise, whereas a large buuble may lift several attached particles. Bubble rise rate varies of course but 20m/hr is not unusual so with a 3 metre deep tank a bubble might take 10 minutes to rise to the top.

I have attached a presentation that gives some general performance parameters and other useful information

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

this hydraulic loading rate : 10, was from - drinking water for conventional rate DAF it is 10-15 cubic m per sq m-h

with this input parameters what I have, and from your informations ( thanks so much, I respect that) , can I obtain hydraulic loading rate, or is that some assumption / or based on experience for the DAF unit standard number?

I know that : Hydraulic loading refers to the flows (MGD or cu m/day) to a treatment plant or treatment process. Detention times, surface loadings, and weir overflow rates are directly influenced by flows

How do I find calculation to obtain this

what parameters I need to use to get Hydraulic loading rate

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

I put this parameters from previous your suggestion here , and here is my DAF -Sketch.

Thank you ashtree for powerpoint, I am trying to understand all, and here is something what I need to know exsctly :

From Powerpoint you attached file, do I need calculate

this Contact zone or is that desired length.

Also for my DAF, I want DAF design without bottom skimmer or Auger.

Example of DAF is like this one : Huber-Siltb

Here on Picture My_DAF_ dimensions are : Length 4.5 m, Width 1.1 m Height 3.33 m

for this dimension do I need put also dimension Length for separation zone as on this picture Contact Zone is showed from Powerpoint you gave me.

All technologies inside for DAF I don't need that ,as I only need to design this DAF.

Please provide me with information for this Contact zone - : is that desired length ?

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

You have chosen a high recycle rate so your contact zone will need to be bigger than normal or your velocities and detention times lower.

With a flow of 50m3/hr 100m/hr contact zone vertical velocity you will need 0.5m2 of contact zone area or half that if you want 200m/hr.

Use a detention time of 1-2 minutes to work out the volume.

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

detention time : I don't know what is,

water rise rates : I can say it is 10 m/hr

but I don't know exactly how do I measure all this parameters, or get direct from commisioning engineer as they will not say (of course)

I am now on site this days .

How do I measure water rise rates, could I do that by stopwatch from start machine , /something like that.

As I am there this days,

they use https://www.toroequipment.com/products/dissolved-a...

- FRC 10 Toro DAF

but material is different (our material - clean water , with low solid concentration, low chemicals, oil and grease) that is just what I hired for one month from them to use their DAF for testing materials.

I want to measure this parameters when feed materials ( liquid/solid) comming inside their DAF and how to behave in DAF ( to obtain : detention time, water rise rates). Can I do that with stopwatch anything or analysis from PLC monitor??

_________________________________________________________________________

you mention 100 m/hr , how did you get 100 m /hr

Total flow = Q + recycle flow: 25 + 25 = 50 m3/hr

and with assupmtion water rise rates (vertical velocity) 10 m/hr

how did you get 100 m/hr

Also here on this picture where lamlella packs start and hopper bottom - is that all one size for height of DAF or from lamella packs to top ;

Kind Regards,

Sebastian

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Detention time= volume /flow.

If the volume of the tank is 100m3 and the flow is 100kl/hr(100m3/hr) the detention time is one hour.

In the contact zone you want a detention time of 1-2 minutes. At 50m3/hr the volume of e contact zone should be 0.8 to 1.6 m3. At 100m/hr velocity in the contact zone only the area will have to be 0.5m2 or less.

If you are going to put a lamella pack in the design is totally different. A lamella is for settling so if you have no solids you do not use a lamella pack in the DAF.

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

There are some solids but not in way to clog Lamella packs, they will be in some low percentage . I will know clearly what is percentage of solids after I collect samples of material for testing.

do you have fb or some other contact where we can talk private? and also you will have benefits of this ,as you can be in this project.

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

and detention time in contact zone : V/Q = in my case : 50/25 = 2 min.

How do I measure time for detention time to obtain 10 - 20 min , is there any possibility to find that as I am face to face with DAF system and every day looking on DAF. ( like on PLC monitor or stopwatch

Also for conventional DAF is 10 -20 min detention time( is that from experience, some standard for all DAF , or assumption from Engineers experience.

Here on my picture : I put orange colour - is that contact zone ?

- are they start from Lamella packs or from hopper bottom ( I can't find this informations in any book)

can I calculate detention time Separation zone like : Total flow / area , in my case 50 / 5 = 10 ?

Thanks

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

It will depend on a lot of variables but you will need to have the required detention time above the lamella. The lamella is really there to settle and collect heavier solids so is almost working independantly of the DAF. If you have many solids you may need to consider a collection auger because as soon as you open the withdrawal valve in the bottommm of the hopper you may cause all sorts of undesired flow paths.

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

What is difference between conventional and high rate DAF design -

Is it conventional DAF without Lamells packs?, and is it DAF with Lamella packs - related to high rate DAF ?

When you say water rise rates ( vertical linear velocity ) is that related to contact zone or in separation zone , and is it water rise rate same number for contact zone and separation zone.

and what is maximum velocity volume inside the tank

For calculation detention time for contact zone : total flow / Q

How do I find calculation detention time for separation zone? Is that: Total flow / area

Example if total flow is 50 m3/hr and area is 5 m2 - in that case : 50/5 = 10 , and use in case that height is 3 m , 10/3 = 3.33333 ( 60 min /3.33 = 20 min , is it about 20 min correct detention time

Or there is standard like for conventional DAF and High rate DAF , which you suggest me from powerpoint slide .

For conventional DAF : detention time is 10 – 20

And for High Rate 10 – 15 min

If you can put here email, or number on which I can call you for futher informations, that will be great

Kind Regards,

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Detention time is : Volume/flow

Vertical velocity is : Flow (m3/hr)/area

There is no definitive separator between standard and high rate DAF units. High rate units are an evolution of earlier DAF units and then tend to have shorter detention times and higher vertical velocities.

It is against forum policy to post our email or phone numbers as this can attract nuisance spam etc.

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

IN SEPARATION ZONE : detention time :(volume of separation zone)/(volumetric flow rate through separation zone.) Is that this : 50/25 = 2, ( 60min /2 = 30 min

what is maximum velocity volume inside the tank

Here on picture is data : if I use small area then that is big vertical velocity, big area then that is small vertical velocity.

Also what confuse me : Is it conventional DAF without Lamells packs?, and is it DAF with Lamella packs - related to high rate DAF ?

That is not in case important, but I have to see in what percentage is outlet sludge on bottom if is in high level then I will not use Lamella, is is not , then Lamella. Someone told me also If is to much sludge , then option is DAF should be bigger without lamella, but now I can find (thanks to you ) Area and understand that, ( area depends from Hydraulic loading rate ; Area = Q/Hydrauling loading rate (5 m3/m2h ) , 25/5 = 5 m2

Still I have problem how to find Height, if I have area,design loading rate, Hydraulic loading rate ( from table: from 5 to 15 ) . from your suggestion :

If you assume 20 mins detention time and you have a linear vertical velocity of 10m/hr assumes that the liquid will travel upwards 3.33metres in 20 minutes. Using all these assumptions gives you a tank of 5m2 and 3.33 metres usuable depth.- is that from calculation : 60 min / 20 min detention time = around 3 min , 3.33 metres

If I have from this calculation (if it is correct) 30 min detention time, and vertical velocity of 10 m/hr - liquid will travel upward : 60 min / 30 detention time = 2 min (so liquid will travel upward around 2 min in 30 min? , is this correct or not?? So Tank will be 5m2 and about 2 or more about 2.5-3 m usable depth from this calculation ?

Thanks

Sebastian (Jasmin Babic)

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

IN CONTACT ZONE : detention time : Volume/Flow : 50/25 = 2 min

IN SEPARATION ZONE : detention time : (volume of separation zone)/(volumetric flow rate through separation zone.) Is that this : 50/25 = 2, ( 60min /2 = 30 min

If I have from this calculation (if it is correct) 30 min detention time, and vertical velocity of 10 m/hr - liquid will travel upward : 60 min / 30 detention time = 2 min (so liquid will travel upward around 2 min in 30 min? , is this correct or not?? So Tank will be 5m2 and about 2 or more about 2.5-3 m usable depth from this calculation ?

Kind Regards,

Sebastian

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

So Flow is 50 m3/hr

Flow Q = 25 m3 /hr

Recycle Flow = 25 m3 / hr

_______________________________

Total Flow through unit = 50 m3/ hr

TSS = 120 mg/L

Efficiency factor, f = 0.5

Recycle Temperature T = 10 – 12 C

Hydraulic loading rate = 10 m3/ m2h

Solving for the tank area for separation zone, A = Flow/Hydraulic loading rate , A : 50/10 = 5 m2

Design loading rate = Q/A , Design loading rate : 50/5 = 10

Detention time for contact zone = volume / flow , Detention time : 5 m2/50 m3hr = 0.1 min

IN SEPARATION ZONE : detention time :(volume of separation zone)/(volumetric flow rate through separation zone.) Is that this : 5/50 = 0.1

Contact zone Area : 0.8 to 1.6 m3 ( your suggestion thanks)

The Contact zone is generally quite small with velocity of about 100 m/hr and detention time of 1-2 minutes (your suggestion thanks so much)

Contact Zone : velocity about 100m/hr, detention time 2 min

Water rise rates (vertical velocity) for separation zone = total flow / area , 50m3 per hr / 5 = 10 m/hr

Water rise rates (vertical velocity) for contact zone = total flow / area , 50m3 per hr / 0.8 = 62.5 m/hr , 50 m3 per hr / 0.5 = 100 m/hr

The only problem is

Hydraulic loading rate: m3/m2h - this m2h - is that mean separation area , or all tank, and how to calculate area of plates, is that refer to area of plates - m2h?From table : conventional DAF 5 - 15 m3/m2h( That is ok, but what that refers to

Also If I have Solid loading rate : 3 kg /hr , is it same calculation for all of this , using flow 50 m3/hr

I think I am confused little bit, it is this ok , please

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"

## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Calculation process is it same as for hydraulic loading rate like :

Solving for the tank area, A = Flow/solid loading rate

Design loading rate = Q/A , Design loading rate

Detention time for contact zone = volume / flow

Water rise rates (vertical velocity) for separation zone = total flow / area

Or is it everthign different with Solid loading rate

http://frcsystems.com/daf-system-design-plate-pack...

So including all information ( thanks to you) and Hydraulic loading rate 10 m3/m2h, Area : 5m2

Height : from your assumtion , but I am type of Engineer who's going in detail how to find exactly all that, and air bubble motion upward ( but I think it's not possieble to obtain that information direct on site, how measure their start from start point to top, This Version on picture 1 :

Hydraulic loading rate : m3/m2h [m3/

m2h-this m2h is that refer to area of plates?Sorry I was confused, probably tired as I work on this without break all day all night ,

when they say : Detention time = volume / flow , so Volume is in m3 ( in that case all time I was wrong? that is not area m2 in my case 5 m2 ?

Volume = L x H x W in this case is it , height where is assumption 3.33 m

What is volume (m3) of this separation area

If area is 5 m2 = L x W

Is it Volume whis = L x W x H ?

Volume = 4.5 x 1.12 x 3 = 15 m3

Just to be clear

In that case from your calculate :

If you assume 20 mins detention time and you have a linear vertical velocity of 10m/hr assumes that the liquid will travel upwards 3.33metres in 20 minutesSo Volume for tank area V = L x W x H , V : 4.5 x 1.12 x 3 = 15 m3

Detention time = Volume/Flow , Detention time : 15 / 50 = 0.3 , 0.3 x 60 min = 18 ( around 20 min) and 60 min / 18 (around 20 min ) = 3.33 m is

this correct?## RE: DAF Dissolved Air Flotation how to get Length ,Height and Width after input parameters

Regards

Ashtree

"Any water can be made potable if you filter it through enough money"