High Head Low Flow WWTP Effluent

[lauren8miller]

I'm confused on when a Turbine pump can be used. Its the only pump I've found that can handle the amount of head (500 ft) and flow I'm looking for. But I would be placing it in a more typical wet well for the effluent of a wwtp, not a water supply well. Is this ok? The wet well would end up being pretty deep. Would it be better to do a series of booster stations? It looks like this would require at least 5 booster stations, at least from the pumps I've found. Any help or info would be much appreciated. Thank you!

 

[Artisi]

If other than clean water and with the limited info given, I would say unusable.

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.)

 

[bimr]

what is the flow capacity?

 

[lauren8miller]

It is clean water (tertiary treated effluent from a wwtp). The max flow is about 230 gpm and relatively steady as it follows an EQ basin.

 

[Artisi]

there is no reason why a vertical turbine pump can't be installed in a wet well - a common everyday event. Sketch what you are thinking for more discussion.

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.)

 

[ashtree]

Turbine pumps are regularly used in tertiary treated wastewater effluent. To be tertiary treated generally implies a filtration stage so that the amount of solids should be negligible, and therefore should pose no problem for a turbine.

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

 

[bimr]

Would think that the turbine pump could be mounted on top of the wetwell. This will be a multistage pump but the pump length should not be overly long because of the low number of stages.

The vertical turbine will not be a complicated pump arrangement, unlike a system with multiple booster pumps.

 

[lauren8miller]

Thanks for the responses! The pumps I'm looking at have column lengths of 5 or 10 ft (

http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/2016/08/BRDIDISCH.pdf).

This gives me to wet well options- one about 11 ft deep with a minimum diameter of 6 ft or alternatively one about 11 ft deep and 6 feet in diameter. I I haven't seen a wet well that is wider than it is deep, is this an issue? I would assume the shorter column would be less expensive and easier to install. Also, is there a standard minimum distance between lineshaft pumps for the wet well? The second pump is a redundant and the two would not be running simultaneously. Thoughts? Thanks again for the help!

 

[ashtree]

If everything else was equal you would go with the deep well, so that you have the maximum amount of water above the suction. There will be some level down near the pump intake below which you may not be able to pump because of vortices induced by the intake.

In a deeper pump station , for a given volume there will be less % of total volume in that "unpumpable" portion of the well.

Maintenance access will be the likely decider of the minimum spacing between pumps. Likewise the pipe work configuration on the discharge particularly if the two pumps come together into a common tee will also be a decider on minimum distances apart. Ideally you would have not less than 6 feet or 2 metres to enable a decent space for working.

I am sure the pumps you have selected would be okay but they would also seem to be relatively complicated for the application. Have you considered submersible turbines?



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

 

[lauren8miller]

I was also looking at this submersible turbine pump (

http://goulds.com/turbine-pumps/5-1...ersible-turbine-pumps/#product-tab-overview),

but had ruled it out previously because the intake is above the motor, increasing the "unpumpable" portion of water and increasing the wet well depth required. Do you think this would be a better pump?

 

[ashtree]

What you are saying is true and the submersible would need a flow shroud around its motor for cooling purposes.

You can mount the submersible horizontally near the bottom but this needs to be approached cautiously to avoid creating further maintenance issues.

The other option is to use a bottom intake submersible. These are rare but they are available.

It would seem that you have considered the submersible turbine option so your original solution may be most suitable.

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

 

[Artisi]

Lauren, I would put the cart before the horse in this case, assume you are happy with the Goulds pump, I would give them the flow / head etc a description the use and ask for a hydraulic selection, min. submergence required and min. base mount to pump inlet length. Given this I would then look at sump size to accommodate the 2 pumps with sufficient clearance under the pump inlet to sump base.
It is a very straight and easy application - 10 minutes and it's all over.


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]

Use the standard vertical turbine pump as mentioned in your first link. It's done every day. Note that the column length can be whatever you want it to be; it will come in sections of 5 or 10 feet, with the upper section whatever is required to make the appropriate tpl (total pump length). You are not limited to 5 or 10 or 15 feet. There is a minimum length, about 1 ft longer than the 'bowl assembly' length, ie the length of the 5 impeller sections and the suction inlet.

There are suggestions in the Hydraulic Institute guidelines for sump sizing based on pump flows, start about page 4 in this document

http://turbolab.tamu.edu/proc/pumpproc/P16/P16161-169.pdf

 

[bimr]

Agree with Artisi.

Note that submersibles will have greater maintenance costs over the life of the pump system.