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Coagulant Clogged Pipes

01/13/2019 2:57 PM

Hello everyone, I work at a Water Treatment plant and about 9 months ago we closed off one of our clarifiers. We forgot to flush the Alum line that fed the clarifier the coagulant (Alum). Now it has hardened in the line. We began to dig it up and cut it at the first couple 90s but we found out it was cemented the whole way to the clarifier from our plant

My question is how do we unclog this pipe? We tried warm water and Muriatic acid. It seems to work a little but very slow going. Is there anything we can use to change it back into a liquid. FYI it's a 1 inch pipe at about 900 ft which is all buried and we have no idea how much of it is hardened.

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#1

Re: Coagulant clogged pipes

01/13/2019 3:30 PM

To put it in technical terms, you're pretty much screwed.

The most widely used alum is potassium alum.

Material Safety Data Sheet - Spectrum Chemical

Where was your shut-down check list?

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#6
In reply to #1

Re: Coagulant clogged pipes

01/13/2019 5:18 PM
  1. That's what we're using. Thanks for the pdf file and links.
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#11
In reply to #6

Re: Coagulant clogged pipes

01/14/2019 5:41 AM

Are you sure it's potassium alum? Though the link says it's used for water treatment, I've not heard of it. Most of the aluminium settles out with the flocs, but my guess is the potassium would stay in solution, maybe raising an issue with water quailty if it's for drinking. The "alum" used at WTPs in UK is aluminium sulphate, shipped in solid form (kibbled, slabs) and dissolved on site, or as a solution. It's not an alum in chemistry terms.

I know that doesn't help with your problem. It might be worth talking to the supplier, but I'm not sure anything will dissolve it quicker than water. How about running a separate pipe, eg PE or PP, maybe overground, at least as a stop-gap solution?

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#15
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Re: Coagulant clogged pipes

01/14/2019 10:47 AM

"To put it in technical terms, you're pretty much screwed"

I reckon you're well and truly flocked!

But seriously, you could just try an 'almost unsafe' pressure to the line, for a week or two, or month/s

Or drill a small loooong hole, & keep feeding water into it -

& as Code M suggests, run a temp poly line interim.

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#16
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Re: Coagulant clogged pipes

01/14/2019 10:49 AM

P.S. you can tank and use any washout - should still flock well, AFAIK -

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#2

Re: Coagulant clogged pipes

01/13/2019 3:51 PM

I dunno, since it's soluble in water, can you direct the jet from a pressure washer into the end of the straight sections?

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#3

Re: Coagulant clogged pipes

01/13/2019 5:02 PM

<...We...> might be working somewhere else very soon, then.

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#5
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Re: Coagulant clogged pipes

01/13/2019 5:15 PM

"We" as in collectively the "water plant", otherwise I probably would be looking for a new job. Thankfully it was our previous boss who did this. I'm just stuck with the issue. Really not looking forward to busting concrete and ton of digging.

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#4

Re: Coagulant clogged pipes

01/13/2019 5:11 PM

I guess it depends on how much time you have....

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#7

Re: Coagulant Clogged Pipes

01/13/2019 8:10 PM

How much of the 900' is a straight run, hopefully with a few elbows only near the end(s)? If you're lucky, maybe you can do a short dig to the straight part. Then flush with a high pressure water hose with high velocity nozzle on the end.

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#8

Re: Coagulant Clogged Pipes

01/13/2019 8:49 PM

The company were I used to work at, dealted with somewhat non-Newtonian fluids... that solidifies after while.

to clean out our process equipment we had them jetted out. There are various type of companies that do this, like the like shown, we also have even higher waterjet to do out heat exchangers. The process lines we literally dismantled them and modified a drill and drilled them out.

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#9

Re: Coagulant Clogged Pipes

01/14/2019 12:02 AM

your conundrum is much like the cable company and electric company laying lines.

1. Their underground contractor can drill 4 inch diameter and continue for 300 feet.

2. Their contractor can direct the auger head to turn left or right or up or down, even when that mechanical auger is out 50 or 100 feet.

3. I know sewers, and I know sewer plant managers, so I will not comment on whether it would be judicious to couple that auger with a chemical to solubilize or/and soften the target alum.

4. Even if you bought the machine (due to stress and damage) you would be more than $150 thousand ahead of a pipe change out.

Good hunting!

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#10

Re: Coagulant Clogged Pipes

01/14/2019 12:27 AM

Try flushing strong sulfuric acid through the pipe. It should dissolve away the Al(OH)3 & polymer, loosening the clog. Then you can waterjet the blockage away

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#12
In reply to #10

Re: Coagulant Clogged Pipes

01/14/2019 6:09 AM

So long as it doesn’t dissolve the pipe as well! The forum doesn’t know what the MOC of the pipe is yet.

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#13

Re: Coagulant Clogged Pipes

01/14/2019 7:02 AM

You don't say what the pipe is made of, but if I were doing the job I would dig up the old pipe and replace with polypipe, if it's not in concrete, a contractor should be able to pull the old pipe out whilst feeding a new one back in using the old one as a towline.

Bazzer

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#14

Re: Coagulant Clogged Pipes

01/14/2019 7:08 AM

This will be of no help at all but is offered in sympathy with your problem. Years ago I went to inspect a lined GRP aluminium sulphate tank, the name below might indicate where the tank was. Looking in from the top I could see up to a metre's depth of rock hard solid product which had dropped out of solution over many years and collected on the base. Obviously inspection was not possible so it was agreed I would return a week or so later while they tried to remove the build up. Sure enough when I got back I was assured that 'Paddy is in the tank now breaking up the solids - he should be done by lunchtime'. When we got to the tank Paddy was indeed breaking up the solids - with a jack hammer! Jack hammers and glass fibre tanks are not a good combination and as well as breaking up the solids Paddy was putting holes in the tank. It was very easy inspection after that! Good luck but I suspect you will find it easier and safer to replace the line.

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#17

Re: Coagulant Clogged Pipes

01/14/2019 6:44 PM

Very hot water will dissolve almost anything.I suggest directing a small stream,1/4" or so,into the pipe at 60 PSI or more.The water must be very hot,160F +

As the coagulant dissolves,move the stream deeper into the pipe.It may take a while.but it will eventually dissolve it.

Good luck.

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#18

Re: Coagulant Clogged Pipes

01/16/2019 6:45 AM

Hello,

A 1" line will be a problem, but if you talk with the guys in the sewer division, they might have a "jetter" that could be used. These work by the action of the high pressure water passing through the head driving "attachments". The water flow then displaces the debris and blows it back along the pipe interior.

You might need to fabricate an attachment, maybe 3/4" size and 1' long with a "gummy" leading point where the water exits. The gummy point stops you drilling through the side of the pipe, the length maintains axial alignment and the 3/4" will allow displaced material to blow back around the head. Personally, I'd not attempt anything longer than 100' in a run, so you need to pothole your line each 180' and at each bend.

The head also needs to have water jets facing "backwards". The flow from these assists the pipe and attachment to advance since there is no way that you could push it from the outside.

Note to moderators: If the following is inappropriate, then it's OK to remove or modify. I'm just naming companies and models of devices that I am aware of. It is not an endorsement.

Alternatively their equipment supplier might have a specialist unit for hire. In Aus I would contact SECA and I believe they have representation in Europe and USA. Alternatively contact the local agent for "sewer serpent" as they work inside remote pipe on cables and connections up to 5,000m from entry point.

Long term, I'd consider moving the batching/dosing system a little closer to the point of use.

Good luck!

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#19

Re: Coagulant Clogged Pipes

01/21/2019 11:05 PM

if it is 900 ft pf 1" pipe the best thing you could do is call a commercial (not residential) pipe cleaning contractor and discuss your problem with them. They would be the outfit that cleans industrial pipes, water mains, water company main lines, etc. They would have the equipment to clean it such as a rotary snake with many different heads for it.

A company I worked for made a toxic product that was used as a biocide for latex paint. If it was allowed to cool or the flow was stopped in the piping it would solidify. After others tried many ridiculous attempts to clean it, I devised two different successful methods.

1. A ships auger welded to a long rod. The rod was chucked into a portable drill and the material was broken up and forced out when the auger was withdrawn from the pipe.

2. For longer runs we used a small but long flexible rotary snake, such as used to snake out small diameter drain pipes. RIGID makes several models of these which have numerous types of removable heads for the forward end of the snake. The most aggressive head was used and the piping was cleaned very good.

Regretfully the EPA shut the plant down years ago.

Good Luck, Old Salt

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