Recycling Wastewater from DM Plant

What does "DM" stand for here?

DM means DEMINERALISATION Plant which is used to produce DM water which is feed to boiler.

The regeneration wastewater has a very high mineral content. To recycle it, you need to remove the dissolved minerals, and depending on what type of minerals are dissolved in it, it can be very costly to do so. For example, if it is mostly carbon bicarbonate i.e. hardness, simply using waste heat or solar heat will drive off dissolved CO₂ and precipitate out most of the calcium. On the other hand, removing sodium chloride will require costly methods such as distillation or reverse osmosis. One thing to consider: if your waste regenerant water has an extremely high concentration of pure NaCl, you may want to consider using it to regenerate your softener bed.

Dear kohil jayesh, Dt'12/02/2009

Your enquiry regarding economic recycling of DM plant regeneration,regarding which I suggest the following options.

1]Regeneration water is saturated with hardness metal ions ,mineral acids& alkalies used for individual resin beds regeneration.This water is full of hardness and Total Dissolved solids that,it is useless anywhere.

2]If it is to be recycled,for maximum permeate fresh water ,membranes [r.o/nano] can be used to to further segregate saline water and fresh water,you know membranes are costlier and saline reject needs evaporation,all adding to cost.

My simple and best suggestions are

a]Try roof solar panels and slow diffusion evaporation of regenration water and possible glass condensers for fresh water recovery.

b]Try flue gas heats/condensate steam energy to heat evaporate and condense.

3]For speedy solar eveporation contact me,so that I can I will share my technical views based on information of your plant and processes.

S.Udhayamarthandan,Ankha Kaizen Technologies

sumarthandan@gmail.com

G.A. From Dvader1000 it really just depends on the water! My question would be how much water are we talking about? what is the quality you need ? If it is sodium chloride we are talking about I have seen it placed into tanks slightly cooled at the bottom and had it build up in the bottom of the tank to an acceptable quality to be used. There is also electronic ion exchange, WHICH CAN BE COSTLY!

It seems like you must be considering very small volumes of waste water if you believe resin is a solution. The acid/alkali waste from regeneration is likely more of a environmental hazard that would then need special handling than the waste water itself. The thing with this type of waste water is to consider the value of the water against the cost of regenerating it to useable state. Also, consider partial regeneration and blending with a better quality of water to get within the contaminant levels acceptable for the process usage. For this ion exchange resins tend to be the most expensive solution, when you consider all the other environmental costs, additional facilities and materials to operate. Could you concentrate the waste stream, and blend the regenrated water? Also, is your priority more to try to reduce the volume of the waste stream or recover water cheaply to offset import cost, or both? You really should contact a consultant who specializes in such wastewater regeneration, and try to determine the cost effectiveness. It will be a dead end project if in the end you determine the regenerated water is much more expensive then other sources.

2 possibilities spring to mind, depending on the composition of the waste stream.

1. Use solar evaporation and reclaim the salts/minerals. With the right design it is even possible to reclaim the water, although rarely economic to do so.

It is unlikely that this will pay unless you have both plenty of spare land and lots of sunshine.

2. Grow spiraluna or a similar algae. It could also feed a small fish farm if there was sufficient of it.

If the waste water quality makes this feasible, this could be reasonably profitable.

Again, this presupposes you have sufficient spare land available to do this as a fair pond area is required.

All of the above is heavily dependent on the actual composition of your waste stream.

I assume you have already looked into using it as cooling water for some other process (depends on hardness among other things), or some other use in your processes where the mineral content would not be a problem.

Good luck.