A sewage treatment apparatus comprises a first stage equipment for treating sewage feed to obtain a first effluent and a second stage equipment for treating the first effluent to obtain a second effluent. The second stage equipment comprises a mixer (VI) for mixing the first effluent and a flocculation agent to obtain the first effluent containing the flocculation agent and a flocculation-clarification equipment (VII) comprises a first flocculation reaction chamber (A), into which the first effluent containing the flocculation agent is entered and subjected to flocculation reaction to form a mixture of water and dreg; a first separation chamber (C), into which the mixture of water and dreg from the first flocculation reaction chamber (A) is entered and separated to obtain a first part of the second effluent and a first dreg; and a second separation chamber (D), into which part of the first dreg is entered and separated to obtain a second part of the second effluent and a second dreg.