Reuse of RO water in the Cooling Tower
Reuse of RO water in the Cooling Tower
(OP)
Has anyone reused the rejected water from a RO plant as make-up for the cooling tower in an air-conditioning system? How does this affect the chemical treatment of the condenser water system?





RE: Reuse of RO water in the Cooling Tower
RE: Reuse of RO water in the Cooling Tower
A hospital client of mine uses the RO plant to generate pure water for use in dialysis.
It is my intention to reuse the water rejected from the RO plant. I understand this rejected water has approximately twice the concentration of dissolved solids as scompared to the potable water fed to the RO plant. At present this rejected water is drained away. I am hoping to use this rejected water in the cooling tower substituting for the potable make-up water currently used, thereby saving water. I would appreciate your help.Thanks
RE: Reuse of RO water in the Cooling Tower
Generally high pH, silicates, Mg and Ca(which slip from the softener) in the RO reject characterize the scale forming tendency of RO water. Either you have to reduce COC of cooling water or increase chemical dosage.
Regards,
RE: Reuse of RO water in the Cooling Tower
Since as you well note RO rejected water has much more dissolved solids, you can expect a little bit more scaling. Furthermore, since RO water is also chlorine free, you should also expect a little increase on the chlorine consumption for bio control.
RE: Reuse of RO water in the Cooling Tower
Youc could also try and recover condesate from the air handlers and use it as make up water for the towers.
RE: Reuse of RO water in the Cooling Tower
RE: Reuse of RO water in the Cooling Tower
If the RO inlet isn't softened, then I wouldn't re-use it in the cooling tower. There would also be a reject water stream from the DI plant. This has low TDS and should be re-usable if mixed with some mains water.