Acidogenic activity: Process of carbon source generation for biological nutrient removal

In this study, a sequencing batch reactor (SBR) connected with a two step a naerobic digestion system is proposed in order to investigate the possibili ty of simultaneous C, N and P removal from wastewater. The system was studi ed using synthetic wastewater. In this system, the effluent of nitrate from the SBR reactor is added to the acidogenic reactor influent. Nitrate elimi nation and VFA production are then achieved together in the acidogenic reac tor. The performances of three lab-scale reactors, operated for C, N and P biological removal are analyzed. The removals of TOC, TN and TP-PO4 were gr eater than 96%, 75% and 86%, respectively. The results show that the combin ation of anaerobic digestion in two step-SBR treatment is effective for sim ultaneous C, N and P removal. The benefits from this process are the saving of carbon source for denitrification and phosphorus removal. Reactor arran gement made possible the existence of zones where the different bacterial p opulations involved could coexist. Complete denitrification occurs in acido genic reactor and hence the methanogenic activity is not reduced nor inhibi ted by N-NO3 presence, allowing greater TOC removal. A stable P-release and P-uptake took place after coupling of the three reactors. Furthermore, a f ast settling, compact sludge is generated in the SBR with the operational c onditions applied. (C) 1999 Published by Elsevier Science Ltd on behalf of the IAWQ. All rights reserved.