The document describes the design of internals for a rectangular clarifier. It includes: - Key internals like inlet baffles, drive units, effluent weirs, scum troughs, and sludge hoppers. - Design parameters calculated for a clarifier treating 3,000 cubic meters of wastewater per day, including flow velocity, Reynolds number, detention time, and weir loading rate. - Design of V-notch weirs based on a calculated flow rate, with a notch height of 1.2 cm and width of 7.2 cm, requiring 605 notches around the perimeter. - Recommended slope range of 1:100 to 1