Regeneration of water treatment substrates

A method for eliminating anionic and cationic species from waste streams produced in regeneration of an ion exchange column, comprising:

• feeding to a waste treatment vessel a first waste stream including a cationic species to be eliminated, which first waste stream is the waste stream generated from a water-softening treatment;
• feeding to the waste treatment vessel a second waste stream which comprises a regenerant solution including an anionic species to be eliminated that reacts with said cationic species, which anionic species has been eluted from the ion exchange column by the regenerant solution;
• allowing said cationic and anionic species to react to form a precipitate;
• and
• separating and removing the precipitate.

A method of regenerating an ion exchange column containing a nitrate-selective ion exchange material loaded with nitrate ions, in which the loaded ion exchange column is subjected to a regeneration sequence comprising:

• passing through the column a dilute brine solution;
• collecting the solution effluent containing at least one anion other than nitrate;
• passing through the column a second, and optionally a third, brine solution, the second, and if present the third, solution having a higher concentration than the first;
• and
• collecting the second, and optional third, solution effluent containing nitrate ions,
• passing water through the column and collecting the effluent wash water;
• and
• using the effluent wash water in a further regeneration cycle.