Flushing and Dechlorinating Large Diameter Pipe 1

[sjsiok]

I am installing a 48" diameter water main and the needed flow rate to flush the line is about 15,000 gpm. I was told by the State DEP that we need to dechlorinate this water before sending to the stream. Does anyone know of any dechlorination systems that can handle these types of flows. The only ones i found only go up to 6000 gpm.

 

[cub3bead]

You can custom design one for the flow or buy 3 of the 6000 gpm systems and throttle back on the bisulfite flow.

 

[dicksewerrat]

Why not pump to a sanitary system and pay them to deal with it.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[sjsiok]

There is no sanitary sewer in the area....plus, what sanitary sewer line do you know that could handle 15,000 gpm.

 

[Bjegovic]

large qty of chlorine (water is super-chlorinated for flushing, right) will adversely affect most of biological waste water treatment plants!

bisulfite ('scavanger') is commonly used on RO plants to remove active chlorine and protect membranes. this sounds like the best option to me!

 

[waterexpert]

Alternatively, you could use activated carbon filters...

Seán

http://www.expertise-limited.co.uk

 

[rconner]

This is perhaps a stupid suggestion/idea, as I don't work specifically in this field; however, I wonder if it might not be possible to get disinfection as per standard procedures, but then undertake a different though perhaps arguably reasonable flushing/cleaning of such a large main not by rapidly discharging huge volumes of super-chlorinated water into the environment as worried about, but instead maybe by the use of some sort of a controlled cleaning or swabbing pig propelled by a lesser volume of water (e.g. from a hydrant or smaller separate main source nearest the insertion point etc.)?
Is it possible that such a pig cleaning/flushing operation, with a smaller (pig) propelling velocity through the large main could however effectively keep even some quite sizeable objects and debris ahead of the pig and additionally maybe allow at least a small volume though at maybe even very high velocity of clean water forward past the pig (right where it is needed continually jetting around the periphery of the pig to maybe even more thoroughly clean the walls), with an added benefit that a much smaller discharge rate to the environment might be better handled by now existing/avaialble dechlorinators where this is necessary etc.? Perhaps it could thus be argued some sort of well-designed pigging operation might thus do the job, be feasible, and if no means is available now for required dechlorination be better for the environment or downstream waste water treatment?
This suggestion of course would require at least some sort of pig insertion devices/plans etc. Perhaps those certainly more expert in these fields (the pig manufacturers and/or those on standards committess or regulatory folks?) could comment on the potential of such alternative approach?

 

[blueoak]

Would they let you send it to a detention pond? A little aeration and you could dechlorinate pretty quick.

Or alternatively, this also might be a good opportunity just to dilute the water prior to discharge to the stream. Unlike other pollutants, there shouldn't be any reason to expect that the chlorine will accumulate in the environment.

 

[maxxl28]

Note using the slug method for disinfection, requires a concentration of 100mg/l, and needs a contact time of 3 hours, with the slug not dropping below 50mg/l concentration. I have been told one method was to pump the water to a significant height, and with a carefully designed nozzel, spray the water and allow, I guessing here, a combination of sunlight, aeation and evaporation to reduce chlorine concentrations. In asmush as I hava 24" water line with the same requiremnets, I am very interested in this topic.

 

[maxxl28]

Do anyone know of an elegant way of pulling the chlorinated water from our new 24”water line and pumping it into the adjacent raw water line which feeds the city’s water treatment plant?

 

[bimr]

Here is information on the environmentally friendly dechlorination product Vita-d-chlor that may of help to you. People with fish tanks use this product to avoid harming the fish as may occur with other chlorine reduction methods.

In addition, the paper will answer all of your other questions regarding chlorine removal as well.

http://www.vita-d-chlor.com/specs/AWWARFDechlorGuides.htm

 

[bimr]

maxxl28,

The elegant method is simply called flushing. You should have normal system water pressure in the water main to push out the chlorinated water.