Help: Mixing/ agitate an Open Pond 2

[msangabriel]

Hello,

can you help me find a solution on how to mix/ agitate an open pond with dimensions of 72m x 72m and depth of 6.5meters?

If i am about to use an agitator, our problem is the mounting and support for the drive train and motor.

The fluid is a mixture of oil and water with fluid density close to that of water. Purpose of the agitator is to dilute the solution of water and oil.

Will it suffice to use aerator? because manufacturers have floating aerator designs which is ideal for our case.

thanks everyone!

 

[LittleInch]

Your post raises more questions than answers.

1) This is a big "pond" - what access / sides does it have to mount anything - a sketch or photo would help a lot
2) More importantly, why are you trying to mix oil and water. They famously don't mix very well and most of the time people want to skim the oil off and then dispose of clean water. What is the purpose of this "pond". An agitator won't dilute anything. Aerators aerate - introduce air into the liquid to increase oxygen levels. The floating ones work by using jets of water taken from the water in the pond, but will mix the surface, but not the whole tank depth.

3) If it's ideal, what is your question?

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[msangabriel]

@littleinch sorry for creating confusions, I think i phrase it wrong on mixing water and oil. Honestly i am not very familiar with the purpose of this project. As i was told, we need to install agitator on this big lagoon, an impounding basin. I'll get back to you when i've gathered enough information. For the mean time,just want to know if with this size of impounding basin, would it be possible using only agitators? and what are my possible options.

Thanks!

 

[AWloo]

Something like this would be beneficial to contact the manufacturer of agitation equipment. Giving them the pond dimensions, required mixing information and the contents in the pond would be a good start. You may need several mixing equipment because the pond is so large.

Other considerations are submersible to floating stations.

Best Regards,

AWloo

 

[vti]

Do a google on "manure lagoon agitation". Lot's of info.

 

[zdas04]

I've seen projects that wanted to transport a small amount of oil in a very large amount of water. Generally the most economic way to do it is to shear the oil/water mixture to create an emulsion that is a small enough percentage of the total pumped volume (something like 5% of the volume being an emulsion to avoid the Bingham-Plastic emulsion dominating the stress/strain behavior). Typically you do this with an aerator whose suction is very close to the surface.

David Simpson, PE
MuleShoe Engineering

Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat

 

[msangabriel]

Thank you for your inputs.

I would to correct my first statement, liquid to be mix are water from different sources, storm drain, RO reject and treated waste water. Density of mixture is close to that of water.

Side entry for mixer is not possible. what are my possible options for us to arrive with desirable mixture of liquids?

Thanks Everyone!

 

[Artisi]

Mixing in ponds is nothing new or difficult, contact a few mixer manufactures for advice.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[TenPenny]

There are some companies that use a submersible pump to circulate the liquid and agitate the pond that way, I would consider that concept.

 

[StoneCold]

You might be able to pump the water at the edge of the pond and shoot it back in below the surface of the pond with a liquid eductor unit.
Like the one attached below. Just float the eductor using a anchor/bouy system in the middle of the pond.

Regards
StoneCold

 

[LittleInch]

msangbriel, Your info is just way too vague toge t any sort of decent response. Your volume is significant - 34,000 m3, but "mixing" means different things to different people and without any idea of what you are actually trying to mix (what is actual solid content and density of the solid content?) and why - are you trying to pump this dirty water out or what? - it is difficult to provide much advise or assistance. Similarly there are no details of your "pond" - Is it all below ground but square? are the sides earth, concrete, metal, lined, unlined, sloped, what?

Do you need to pick up sludge from the base and try and mix it with the rest of the water? Do you need to jet the bottom of the "pond" to stir up material? What do you do now?

I think you will be surprised by the size of the units required for such a large sized pond Some sort of submersible sounds like a good idea, but do you want it provide a moving jet? I think you'll need a lot more than one....

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[gerhardl]

Still missing info here: for what purpose is the mixing necessary? (What are you doing with the mixed component?) Cheapest way, and very cheap to test, is areation as used for for keeping freezing harbours for small vessels free from ice, by submerged, holed pipelines.

 

[MikeHalloran]

Simple aeration may help, but you will probably get better circulation with a few sparge pumps, which are simple and cheap to build.


Mike Halloran
Pembroke Pines, FL, USA

 

[moltenmetal]

What are you doing: mixing, aeration, or attempting to emulsify floating oils? Or a combination of these? The right solution depends ENTIRELY on those missing details.

 

[geesamand]

Floating aerators usually don't do much for bulk fluid circulation. Take a look at aerial photos of a paper mill lagoon with donut-style aerators - you will eventually find a mud field with a few wet spots around the donut aerators.

Mixers designed for bulk fluid circulation might not have enough effect to break apart the oil droplets and form the emulsion that I assume is desired.

Submersible pumps might work but the maintenance on them is much worse than mixers that have their motors and drives above water.

I guess the question is: is the performance of this mixing application important? If you don't care about wasting power, leaving throughput on the table, stagnant zones in the pond, or overall reliability of the system then buy what you think will work. For non-critical applications that usually works and you can focus on other things. If you do care, call a mixing company, and do it early in the design process. Ask them for their experience with your process, and if direct experience does not exist, how they plan to size for it or what scale testing they can perform. Ask for an NDA if your situation is to be kept private. There are far more mixing situations than there are formulas in the books and the research in mixing is moving faster than the bound literature anyway.

David

 

[msangabriel]

Hello Everyone,

Big Thanks to your responses! Regarding the confusion i made, please let me clarify some queries.

The purpose of the agitator is to mix the impounding basin. Ideally the basin is a mixture of water from different sources. So basically the mixture component qualities are similar to that of clean water. Our impounding basin should only contain water from storm drain, clean water drain and RO reject from Power Plant but the current situation shows presence of oil in our basin. This problem will be address separately. For the record, our current project assumes that the impounding basin will operate on ideal scenario, only clean water present at the impounding basin. No sludge to mix and no oil to emulsify.

Regarding the basin, it is a sloped basin, square area with dimensions of 72.2 m x 72.40 m and depth of 6.5 m. The bottom is HDPE lined over compacted soil.

We have initial responses from our suppliers and the best option i think is to used a floating mixer with mooring. Any idea on this matter?

Thanks!

 

[racookpe1978]

The "oil from power plant" ought to be less than 1 - 2 liters per day. MUCH less than that.

 

[moltenmetal]

OK, now you can take that information to someone like Flygt and they can specify a mixer for you. Generally mixing is most efficiently accomplished by a mixer rather than a pump, with or without mixing venturies. With a volume that large, energy efficiency is going to matter a lot.

If there's oil, you need to find it and intercept it at source- or if the source is a person, fire them!

 

[LittleInch]

HDPE liner won't stand much in the way of direct jet forces so for something that size I suspect you will always get some settlement of dirt and material from something that big. A fixed pipework with jets at about 1m from the floor would get you a system that could be cycled to reduce the pump load and divide the pond into three or four and then pump each in turn to mix up any settled material.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way