A method of separating a mixture of liquid and insoluble solids in a
filter press may comprise: pumping the mixture into a chamber between two filter plates in the
filter press to form a
filter cake, wherein the chamber is lined by filter cloths, and wherein, during the pumping, filtrate is forced through the filter cloths and out of the chamber; heating the
filter cake in the chamber, wherein, during the heating, filtrate is forced through the filter cloths and out of the chamber, and wherein the heating is by
radio frequency irradiation of the
filter cake in the chamber; and releasing dried filter cake from the chamber. A
filter press system for separating a mixture of liquid and insoluble solids may comprise: a frame; a plurality of filter plates configured to form a stack of parallel plates, each of the plurality of filter plates being movably attached to the frame, the plurality of filter plates further being configured to form a multiplicity of chambers, each of the multiplicity of chambers being lined by filter cloths, wherein the plurality of filter plates, the multiplicity of chambers and the filter cloths are configured to allow filtrate to escape from the chambers while retaining solids from the mixture to form a filter cake; and a
radio frequency heater, for directly heating the filter cake in the multiplicity of chambers. The
radio frequency heating may include
microwave heating, or
dielectric heating by lower frequency radio
waves in the range of 1 to 100 MHz.