Effect of biological treatment on psd-based cod, toc and color profiles in textile wastewaters

As the industrialization has rapidly increased, the production of wastes accelerates and threatens the environment as well as the existence of many living forms. In raw wastewaters, organics forms a typical and significant fractionation of the pollution. There are processes such as activated sludge systems in treatment plants to reduce organic pollutants to meet the disposal regulations. This study offers particle size measurement by sequential filtration/ultrafiltration as an alternative method for wastewater characterization in order to determine appropriate treatment technology. Moreover, the correlation between particle size distribution (PSD) and chemical oxygen demand (COD) fractionation provides an insight into biological treatability. In this study, wastewater samples were obtained as two sets from the influent and effluent streams of wastewater treatment plant located in an organized industrial district, Bursa, Turkey. The influent wastewater sample was characterized by a COD level of around 711 mg/L, with 185 mg/L of TOC and 1034 Pt-Co of color. Apart from the characterization experiments, COD fractionation was determined. Particle size distribution method was used for COD, TOC and color profiles. Especially, PSD-based COD fractionation by sequential filtration/ultrafiltration serves as fingerprints for industrial wastewater. PSD-based COD fractionation profiles identify that the bulk of the COD both for influent and effluent flow is in the soluble form (< 2nm). Moreover, treatment efficiencies were determined by comparing the profiles of the influent and effluents. The study shows that biological treatment is effective, especially in soluble part. The TOC experiments were used as a tool for wastewater characterization. The results show that COD and TOC profiles exhibit similar trends with regard to the particle size distribution. The studies on color profiles in wastewater reveals that the biological treatment process is not very effective on removing color from the wastewater. PSD-based fractionation also complemented the results of respirometric analyses and provided supporting information for the interpretation of biodegradation characteristics.