title: COD fractionation and biological treatability of mixed industrial wastewaters.
abstract: This study was conducted at a centralized wastewater treatment plant that receives discharges from nearly 160 industries. The chemical oxygen demand (COD) was fractionated for two objectives: delineation of the limits of the activated sludge process being used at the plant, and evaluation of the potential environmental impact of the treated effluent. Physico-chemical analyses, respirometric and biodegradation tests, as well as COD fractionation were carried out. Molasses-wastewaters were determined to be the major contribution to the plant. The influent was dark brown in color, with a relatively high content of both organics (2503 mg/L COD) and salts (5459 μS/cm conductivity), but a low biochemical oxygen demand (568 mg/L BOD(5)) and BOD(5)/COD ratio (0.24). The degradability of the organics was limited by the high content of inert soluble COD (S(I)). The COD fractionation pattern was 40-20-40% for S(I), X(I) (inerts) and S(H) (soluble hydrolyzable), respectively. More than 90% BOD(5) removal was obtained, which was sufficient for the plant to meet the national Standards. However, the effluent discharged into the river was intensely colored and polluted (>1000 mg/L COD, >5000 μS/cm), emphasizing the need for legislation regulating COD, color and salinity, and for upgraded treatment methods worldwide for molasses wastewaters.
authors.affiliation: Centro Interamericano de Recursos del Agua, Universidad Autónoma del Estado de México, Apartado postal 367, CP 50091 Toluca, Mexico. c-fa-ll@hotmail.com
authors.forename: C
authors.initials: C
authors.lastname: Fall
authors.forename: E
authors.initials: E
authors.lastname: Millán-Lagunas
authors.forename: K M
authors.initials: KM
authors.lastname: Bâ
authors.forename: I
authors.initials: I
authors.lastname: Gallego-Alarcón
authors.forename: D
authors.initials: D
authors.lastname: García-Pulido
authors.forename: C
authors.initials: C
authors.lastname: Díaz-Delgado
authors.forename: C
authors.initials: C
authors.lastname: Solís-Morelos
mesh_terms: D001673:Biodegradation, Environmental; D057919:Biological Oxygen Demand Analysis; D007220:Industrial Waste / Q000032:analysis*; D012722:Sewage / Q000382:microbiology; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000032:analysis*
chemical_list: D007220:Industrial Waste; D012722:Sewage; D062065:Wastewater