Low potable water greenhouse system

Greenhouses are known to reduce water use while simultaneously increasing plant yield. The reduced water demand presumably comes from a local increase in humidity.

Increased humidity reduces water loss by transpiration - that is, evaporation through the plant leaves. (Plant leaves have internal surfaces for gas exchange, because they need to acquire carbon dioxide and release oxygen.)

However, greenhouses are generally not completely air-tight, exchanging air with the environment at some rate. Even if carbon dioxide is supplied from a concentrated source, oxygen must escape, and sometimes windows are opened to maintain a suitable internal temperature. Therefore, water is still lost to the atmosphere.

In many places, water pure enough to be suitable for irrigation is at a premium, yet there may be a ready supply of low-quality water, contaminated by non-volatile solutes. For example, coastal regions have access to copious sea-water, containing sodium and chlorine ions, amongst others.

I propose that in these situations, an evaporator system could productively be used to transfer water demand away from the high-quality supply. The precise embodiment of this depends on the water source and other local considerations.
In some cases, complete evaporation may be used to produce a solid product, which may have its own commercial value. In others, all precipitation may be avoided; a more concentrated outflow would then be necessary.