Unfortunately much of what ...

Unfortunately much of what is done to maximize water use or reuse uses an old mindset and usually have divergent plans or processes. in 1994 we made a slight but significant change to the way in which a High cycle power plant operated. It was a bold change on the surface since it went opposite traditional thought. However it was based on improving mass balance and not staying with the way things have always been done.

The plant used cold lime/soda softening and was a zero liquid discharge plant. To minimize total solids build up (dissolved and suspended) they used a brine concentrator. This worked but they still needed large evaporation ponds. There were numerous clarifier upsets and as the previous post indicated large evaporites hung from the CT slates. These would actually get so heavy they would cause structure to fail.

The change was to take cooling tower blowdown and run it to the lime/soda softener instead of make up water.  It was far easier to treat a constant 4,000gpm of flow and drop 160+ppm SiO2 to 10ppm, than to take 16,000gpm of water with 21ppm SiO2 to 9ppm SiO.

As with all things, time judges success. Within weeks, the SiO2 dropped to never going above 120ppm. The sulfate dropped to under 6,000ppm (had run closer to 16,000ppm), sulfuric acid use dropped to 1/3 of previous (lots of logical reasons for that). The water in the evap ponds was able to be recovered. The BC could be run at less that maximum and its fouling decreased with longer run cycles (much lower SiO2 BC feed). This plant ran under this mode until it was decommissioned and leveled.

This was a case of not looking at the dynamics of what was desired today but staying with "how things have always been done."  Progress only comes with change.