A rotary disc filter device includes a rotary drum and one or more disc-shaped filter members secured about the drum. Each disc-shaped filter member includes a filter disposed on opposite sides thereof and each disc-shaped filter member includes a modular frame made up, in part at least, by a series of interconnected modules. One module of the modular filter frame includes a base that is secured to the rotary drum and a support projecting outwardly from the base. A series of these modules are interconnected to form a modular filter frame.