Total Dissolved Solids (TDS) in Recycled Water

<...will this TDS level will cause any deposition in pipelines at normal temp? ...>

Total Settleable Solids might, depending on particle size and pipeline velocity. Total Dissolved Solids probably won't unless there is a hot surface somewhere, in which case expect calcium and magnesium carbonates and sulphates together with a little silica - assuming these are already in the water: a water analysis would help to evaluate it.

<...will this TDS level will cause any scale problem in vacumme pumps if used as seal water? ...>

Read the vacuum pump manufacturer's manual.

<...How to lower this TDS level? is RO the only option?...>

Nope. Ion exchange, electrolytic deionisers, evaporation......

That would depend on several factors such as what salts constitute the TDS, what the water temperature is, and what the water pH is. Highly soluble salts such as sodium or potassium nitrate normally would not cause deposits at such concentrations. Water at ambient temperatures should also not cause deposits unless the salts are only weakly soluble and close to the maximum concentration level. Likewise, copper salts may precipitate out at pH > 8.5. Please provide more data if you wish to know more.

Check the Calcium hardness of the recycled water. LSI to assess scaling tendency. You have not mentioned what is the TDS of recycled water. Whether RO or Demineralization to be considered depends on the usage of the recycled water.

It depends on which ions are in the water, it may cause deposition of carbonate scaling inside the pipeline if CO3(2-) available in water. however, there are various methods to eliminate the possibility of scale formation. using chemicals to increase the concentration factor of the water, periodic cleaning with chemicals to remove deposits, lower the water temperature to lower the potential of carbonate formation, reducing LSI factor of the water which itself could be carried out in different ways and so on. for a better conclusion, you need to have the chemical composition of dissolved solids in water and the quantity of each one.

good luck

*Insufficient data presented.

*in feed water from 20 to 300 ppm levels. What is the use and inputs into feed water?

*What is the current settling treatment, Mere gravity settling or coagulants are used?

Now coming to your enquiry

*TDS if present as sodium salts should not do much harm.

*If this TDS is inclusive of HARDNESS, then go for a scientific analysis of gravity settled water. If hardness is present, the answer is there will be scaling problems.

*Domestic lines operating with around 500 TDS are frequently prone to scaling.

*In that case you got to check the raw water inlet also for true estimation.

*One option is the 280 ppm from 20 to 300, can you alternate this or modify your process ?

*If you happened to use lime, ferrous and inorganic pH Adjusters, then you got to rethink your treatment system.

All depends on your further inputs to the queries so that we can work on it.

* The recycling process of the same water will cumulate further more for every cycle and surely will add to serous scaling problems on a progressive fashion. That means the recycling water should be free from or minimum of TDS.

At "normal" ambient temperatures, that TDS will not plate out on piping, so no problem with item 1.

I would be very concerned about damage to seals (due to elevated temperature from friction, and risk of scratching seal surfaces, if used per item 2.

In addition to earlier suggestions, why not add low level acids to convert TDS into solution with PH between 6.8 and 7.0 buy converting dissolved TDS materials.

Another option may be flocculants and bubbler blower to allow skimming of no-longer dissolved solids to allow recycle of water.

What is the desired er-use of the water? Under either of options suggestions, could be introduced (or re-introduced) to cooling towers as make-up.

Hello all CR4 members,

Thanks for your valuable inputs.

I would be getting water analysis data for better understanding of the problem.

As one of reply says, any treatment is depend upon the end use of recycled water. I shall talk more in detail with my customer and get back to you.

regards

Hi Sharadmandale,

Have an idea what is the composition of your TDS, and see separately organic as particles of emulsions, detergents, etc..., minerals as Sodium, Calcium cations, and anions as Sulfates, Carbonates,..., and other salts,.... The pH of your liquid must be controlled before recycling operation starts and maintain it the same if the incoming water is the same origin all the time. Deposits in the pipe lines is due to slow flow rate, and too long horizontal pipings.

Make analysis, note incoming ingredients, and act following obtained data. Good luck by using simple but efficient judgement, and if you need cleaning, use mild acid as Sulfamic to eliminate what's accumulated, Gil.

TDS 300 itself is not very high. TDS os 20 is better than most municipal water. Unless chemically treated how does the 300 TDS precipitate out? 20 TDS should be safe at ambient temperatures.

Hi Bioamani,

You are absolutely right that 20 ppm impurity is much lower than our tap water. However, we are not the user of this clean water. Best weekend, Gil.