To dry solids and liquids, where should we place them?
There is no specific "one size fits all" answer to this question. The choice of drying technique will depend on the source of solids and liquids and the final use of the dried products.
For example, while analyzing solid and liquid samples, a chemist or environmental scientist will generally dry them in an oven. Measurement of solids in water samples is an example of this type of drying. In a microbiological lab, solid and liquid samples (including cleaned glassware) are kept in an autoclave to disinfect them, and there is an option of a drying cycle to dry the load before taking it out.
In a waste water treatment plant, we dry the sludge (semi-solid mass) in centrifuges or by sunlight (by spreading it over large land area).
There are a number of other methods of drying the solids and liquids, including the use of hot air, hot surfaces, freeze drying (or lyophilization), etc.
It is the specific purpose and source that will determine the method appropriate for your particular case.