ORGANIC CARBON BIODEGRA-DABILITY and HETEROTROPHIC BACTERIA along a COMBINED SEWER CATCHMENT during RAIN EVENTS M. Seidl(1), P.Servais(2), M.Martaud(3), C.Gandouin(3) and J.M.Mouchel(1) (1) CERGRENE, ENPC Cit‚ Descartes, Champs/Marne,
77455 Marne-la-Valle France (2)GMMA, ULB Campus de la Plaine, CP
221, B-1050 Bruxelles, BELGIQUE (3) SAFEGE, Parc de l'Ile, BP 727,
92007 Nanterre, FRANCE ABSTRACT The aim of this study was the evaluation of fluxes of organic carbon and biodegradability of waste waters during rain events in order to better predict the impacts of combined sewer overflows (CSO). The combined sewer system studied was located in a densely populated urban catchment adjacent to Paris. Five subcatchments of different size, have been monitored during several rain events for suspended solids, conductivity, ammonium, chemical and biological oxygen demand. In addition, two of these subcathments have been evaluated for dissolved and particulate organic carbon, their biodegradable fractions, and the total bacterial biomass. Several indexes, indicate a lower degradability of waste water during dry weather at the downstream stations, accompanied by an increase of bacterial size and bacterial biomass. A further decrease of biodegradable organic carbon related to rain intensity can be seen at all stations. Our results show a higher proportion of refractory organic carbon during rain events than during dry weather with a possible contribution of the in-sewer sediments to the bacterial wet weather flux. KEYWORDS Bacteria, combined sewer, organic carbon, urban runoff, waste waters
ACKNOWLEDGEMENT This study was funded by the Inter-Agence program and coordinated by Agence de l'Eau Rhin-Meuse, and Agence de l'Eau Seine Normandie. Hauts-de-Seine Council and AESN also contributed to the study conducted by SAFEGE Consulting Engineers. REFERENCES AFNOR (1986). Eaux, méthodes d'essai. AFNOR, Paris. APHA (1989). Standard methods for the examination of water and wastewater.17th edition. APHA, Washington. Clesceri L.S. Ed. Even S., Billen G., Mouchel J.M. & Poulin M. (1996). Simulating the impact of CSO's from greater Paris on the river Seine using the model prose. Proceedings of 7th IUCSD September 1996 Hanover Gromaire -Mertz, C.Chebbo & M.Saad (1997) Origins and characteristics of urban wet weather pollution in combined sewer systems Proceedings of 2nd Int.Conf. on Sewer , Aalborg Denmark, May 1997 Harremoes, P. (1988). Overflow quantity, quality and receiving water impact. Proceedings of 14th IAWPRC Conf. On Urban discharges July 1988 Brighton, Great Brittain, Adv. in Wat. Pol. Control Pergamon Kaijun W., G. Zeeman & G. Lettinga (1994). Alternation in sewage characteristics upon aging. Proceedings of Proceedings of 1st Int.Conf. on Sewer , Aalborg Denmark, May 1994 Mouchel J.M., M. Seidl & P. Servais (1997) Measure of biodegradation of waste waters during rain events by means of micro respirometry; in preparation SAFEGE (1996) Etude des flux de pollution par temps de pluie sur un bassin versant test du département des Hauts-de -Seine: 1, 2 & 3. SAFEGE, Conseil Géneral des Hauts-de-Seine & AESN, Nanterre Seidl M., P.Servais, A.Anzil & J.M.Mouchel (1996a). Dégradation des matières organiques dans le milieu naturel après les rejets urbains - Etude et quantification des processus. Cergrene ENPC Paris, Gmma ULB Bruxelles & Agence de l'Eau Rhin-Meuse. Seidl M., G.Belhomme, P.Servais, J.M.Mouchel & G. Demortier (1996b). Biodegradable organic carbon and heterotrophic bacteria in combined sewer during rain events. Proceedings of 7th IUCSD Hanover, Germany September 1996 Servais P., Barillier A. & Garnier J., (1995). Determination of the biodegradable fraction of dissolved and particulate organic carbon in waters. Annls. Limnol. 31:75-80 Servais, P., Garnier, J., Demarteau, N., Brion, N. & Billen, G. (1994) Caractérisation des apports de matières organiques, nutriments et micro-organismes par les rejets d'eau usées. IN: Rapport CNRS PIREN Seine 1994/III - Bassins versants urbains" GDR Analyse et modélisation des sustèmes fluviaux anthropisés. LGA Univ Paris VI - Jussieu, Paris |