COMBINED BIODEGRADATION OF CARBON, NITROGEN AND PHOSPHORUS FROM WASTEWATERS

The objective of this study was to develop an integrated system for si multaneous removal of carbon, nitrogen and phosphorus from industrial wastewaters. The system consisted a two step anaerobic digestion react or for carbon removal coupled with a sequencing batch reactor (SBR) fo r nutrient removal. In the proposed system, carbon is converted into b iogaz by methanogenic activities. The volatile fatty acids (VFA) produ ced during the first step of anaerobic digestion were used as electron donors for biological dephosphatation in the SBR in which anaerobic a nd aerobic phases were cyclically applied. It was shown that nitrifica tion of ammonia took place in the SBR reactor, during the aerobic phas e. Furthermore, denitrification and VFA production were achieved toget her in the acidogenic reactor, when the efflux of nitrate from the SBR is added to the acidogenic influx. The proposed process was fed with a synthetic wastewater with composition characteristics: Total Organic Carbon (TOC) = 2200 mg l(-1); Total Kjedahl Nitrogen (TKN) = 86 mg l( -1); Phosphorus under phosphate form (P-PO4) = 20 mg l(-1)). In these conditions, the removal of carbon, nitrogen and phosphorus were 98%, 7 8% and 95%, respectively. The benefits from the system are the saving of (i) an external carbon source for denitrification and dephosphatati on, (ii) a reactor for the denitrification step. (C) 1998 Elsevier Sci ence B.V. All rights reserved.