Ion exchange for ammonia removal in drinking water
Ion exchange for ammonia removal in drinking water
(OP)
I run a small municipal water plant that has sand filters, ion exchange softeners, and chlorination.
The problem is we have too much ammonia, over 2 parts, which causes problems in disinfection, nitrites, and copper problems. The softeners do not currently remove ammonia. I would like to use ion exchange to remove ammonia rather than going to RO or nanofiltration because of cost. Any ideas on the cheapest, effective alternatives? We only pump at 200 gpm about 8 hours a day. The water after the softeners is also agressive and needs some treatment.
The problem is we have too much ammonia, over 2 parts, which causes problems in disinfection, nitrites, and copper problems. The softeners do not currently remove ammonia. I would like to use ion exchange to remove ammonia rather than going to RO or nanofiltration because of cost. Any ideas on the cheapest, effective alternatives? We only pump at 200 gpm about 8 hours a day. The water after the softeners is also agressive and needs some treatment.





RE: Ion exchange for ammonia removal in drinking water
RE: Ion exchange for ammonia removal in drinking water
If you want to remove the ammonia with ion exchange, you can achieve that by operating water softeners in series. Unfortunately, that is not a practical solution as water that has been completely softened will be very corrosive. Therefore, for your application, ammonia removal with ion exchange is probably not practical from a corrosion standpoint.
Rather than breakpoint chlorination, you should consider chloramination. Chloramination uses 3:1 to 4:1 chlorine to ammonia feed ratio by weight. Breakpoint chlorination uses 10:1 chlorine to ammonia feed ratio by weight.
The least expensive method to make the water less corrosive is to raise the water pH. Not sure why you are using water softeners in the first place, maybe radium removal? From what you have presented, water softeners do not seem to be practical.
RE: Ion exchange for ammonia removal in drinking water
Good luck,
karbone
RE: Ion exchange for ammonia removal in drinking water
Air stripping will also work but is usually only economic when other VOC's are present.
RE: Ion exchange for ammonia removal in drinking water
RE: Ion exchange for ammonia removal in drinking water
Again, the least expensive method to make the water less corrosive is to raise the water pH. I would suspect that your copper problem is more a result of corrosion from the lack of hardness than from ammonia. The ammonia should be tied up with chlorine.
Air stripping the ammonia is probably also not practical because of the cost of chemicals to raise and lower the pH.
Why don't you post the complete water analysis?
RE: Ion exchange for ammonia removal in drinking water
As to the aggressive nature of the softened water, have you considered blending soft water with hard water? Ten States standards recommends blending to around 85 mg/L hardness for drinking water.
S. Bush
www.water-eg.com
RE: Ion exchange for ammonia removal in drinking water
Have you looked into the arsenic removal process where you co-precipitate the arsenic with iron and filter the resulting floc? You already have the filter, you would only need to install the chemical feed.
And as sbush suggests, you should not be softening the entire water flow. Municipal water is not usually softened to lower than 120 mg/l.
RE: Ion exchange for ammonia removal in drinking water