OLIVEIRA, R.; OLIVEIRA, Rui de.
Abstract:
The objective of this work.is to evaluate the performance of a two chamber septic tank operating under constant flow and load conditions and receiving raw sewage of the City of Campina Grande North East Brazil for hydraulic retention times between 0.72 and 1.47 d. Also the effect of passing the septic tank effluent through an anaerobic upflow filter was observed. A full scale experimental model of the septic tank-upflow f i l t e r was operated for a period of about sixteen months. It was observed that the f i r s t chamber of the septic tank behaves as the main biological reactor in which about 70 per cent of BOD and 80 per cent of the feacal coliforms of the influent are eliminated. The second chamber contributes to raise the overall efficiency of the septic tank. The anaerobic functions as a unit to polish the septic tank effluent and increases the overall BOD and feacal coliform removal e f fi ciency to 85 and 90 per cent respectively. From the experimental results it was concluded that the efficiency of the experimental model under the used operating conditions is quite high. This conclusion i s believed to be important as it indicates the applicability of small anaerobic units in individual excreta disposal systems.
