Avaliação do Desempenho da Decantação Secundária em Estações de Tratamento de Águas Residuais: Caso de Estudo de Frielas

Miguel Branco dos

Key information

Authors:

Miguel Branco dos (Miguel Branco dos Santos)

Supervisors:

Paulo Jorge Inocêncio (Paulo Jorge Inocêncio); Eduardo Augusto Ribeiro de Sousa (Eduardo Augusto Ribeiro de Sousa)

Published in

11/23/2007

Abstract

At Frielas WWTP, discharge values for TSS generally surpass those established in D.L. n.º 152/97 as limits. The strategy traced by the operation team to solve the situation consists in the placement of two baffles in one of the secondary clarifiers (nº 12). If good results are obtained, these modifications will be extended to all the clarifiers. The present work has as objective to test the viability of the proposed strategy, comparing the results of the efficiency of the clarification obtained during a period of 3 days, for the situations of the absence and the presence of the baffles. The state of the art concerning the plant was elaborated, surveying monthly average values of TSS on the effluent and average removal efficiencies of the several steps of the treatment. The diagnosis was carried through by analysing thoroughly the most conditioning parameters of secondary clarification. Water modeling system MOHID and results from sample collecting were used to validate the solutions proposed to correct the referred problems. The results show that the hydrodynamics of the secondary clarifier is significantly enhanced by the presence of the baffles: 1st - a 45% improvement was achieved in the quality of the clarified effluent from carifier n.º 12, in what TSS are concerned; 2nd - the over-carriage of sludge didn?t occur in this situation.