How to Increase Calcium ion in RO Water with High Capacity (1500 m3/d)

Published on by in Technology

How can I increase calcium ion (Increase from 1 ppm to 20 ppm) in RO water using natural things or water soluble calcium salt?

This is for a 1500 m3/d  capacity of RO plant.

The goal is to produce drinking water.

Thanks for your guidance.