Abstract: A modular plate settler for use in a liquid clarifier system having one or more inlet ports for receiving an influent flow of liquid, a settling tank for settling and collecting solids separated from the influent flow of liquid and outlet weirs for discharging an effluent flow of clarified liquid. The modular plate settler comprises a parallelogram shaped enclosure provided with a full bottom opening for receiving the influent flow of liquid from the settling tank, and a plurality of inclined parallel gravity settling plates within the enclosure and over which the influent flow of liquid passes toward a full top opening, whereby the solids settle on the plates and slide downwardly under gravitational force into the tank. The flow of liquid is thus clarified of solids and flows through the top opening and effluent trough toward the outlet weirs.