COD fractionation of tannery wastewaters—Particle size distribution, biodegradability and modeling

• Published in: Water research (Oxford) Vol. 42; no. 4; pp. 1083 - 1092
• Main Authors: Karahan, Ö., Dogruel, S., Dulekgurgen, E., Orhon, D.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2008; Elsevier Science
• Subjects: Applied sciences; ASM3; biodegradability; Biodegradation, Environmental; calibration; cell respiration; Chemical Fractionation; chemical oxygen demand; COD fractions; Computer Simulation; Exact sciences and technology; filtration; hydrolysates; Industrial Waste; mathematical models; microbial growth; Modeling; Models, Biological; Other industrial wastes. Sewage sludge; Oxygen - metabolism; Oxygen uptake rate; Particle Size; particle size distribution; particulates; Pollution; simulation models; Size distribution; tannery effluents; Tannery wastewater; Tanning; Ultrafiltration; Waste Disposal, Fluid; Wastes; wastewater treatment; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - metabolism; Water treatment and pollution; Tannery wastewater; Size distribution; COD fractions; Modeling; ASM3; Oxygen uptake rate; Biodegradation; Activated sludge; Filtration; Biodegradability; Pollutant behavior; Segregation; Calibration; Tannery; Biological purification; Hydrolysis; Membrane separation; Pore size; Particle size distribution; Ultrafiltration; Industrial waste water; Leather industry; Waste water purification; Speciation
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2007.10.001

This study aims to establish the scientific link between particle size distribution (PSD) and biodegradability of different COD fractions of tannery wastewater, by means of sequential filtration/ultrafiltration, respirometric analysis and model evaluation. PSD profiles were determined in physical segregation experiments, using eight membrane discs, each with different pore sizes between 2 and 1600 nm. Biodegradability-related COD fractionation was determined at each size interval by model simulation and calibration of the corresponding oxygen uptake rate (OUR) profiles. Activated Sludge Model No. 3 (ASM3), modified for direct growth on hydrolysis products, was adopted for evaluation. PSD analyses defined a COD fingerprint with two significant portions at the two ends of size distribution, with 60% of the total COD at the particulate range, 25% at the soluble range and the remaining 15% well distributed among the colloidal range. Comparative evaluation of the sequence of OUR profiles yielded values of applicable model coefficients. It also enabled the assessment of size distribution for each major COD fraction, as an original tool for better interpretation of specific biodegradation characteristics of the selected tannery wastewater. Results also revealed a very slowly biodegradable/residual particulate COD component with a significant inhibitory effect. Model-based evaluation of the OUR profiles enabled quantifying the impact of inhibition in terms of changes in rate coefficients for growth, hydrolysis of soluble COD and endogenous decay.