Modelling aerobic 4-chlorophenol and 2,4-dichlorophenol biodegradation-effect of biogenic substrate concentration

Şahinkaya, Erkan
Aerobic biodegradation kinetics of 4-Chlorophenol (4-CP) and 2,4-Dichlorophenol (2,4-DCP) by acclimated mixed cultures were examined separately and in mixture using batch and sequencing batch reactors (SBRs). Biodegradation abilities of acclimated mixed cultures were also compared with those of isolated pure species. Complete degradation of chlorophenols and high COD removal efficiencies were observed throughout the SBRs operation. During the degradation of 4-CP, 5-chloro-2-hydroxymuconic semialdehyde, (the -meta cleavage product of 4-CP), accumulated but was subsequently removed completely. Chlorophenol degradation rates increased with increasing chlorophenols concentration in the feed of the SBRs. Gradually decreasing feed peptone concentration did not adversely affect chlorophenol degradation profiles in SBRs. Only competent biomass was thought to be responsible for chlorophenol degradation due to required unique metabolic pathways. It was assumed that the fraction of competent biomass (specialist biomass) is equal to COD basis fraction of chlorophenols in the feed of the reactors as competent biomass grows on chlorophenols only. Models developed using this assumption agreed well with experimental data. The performance of a two stage rotating biological contactor (RBC) was also evaluated for the treatment of synthetic wastewater containing peptone, 4-CP and 2,4-DCP at 5 rpm. High chlorophenols (>98%) and COD (>94%) removals were achieved throughout the reactor operation up to 1000 mg/L 4-CP and 500 mg/L 2,4-DCP in the feed. Results showed that RBC is more resistant than suspended growth reactors to high chlorophenols load. The change of dominant species during the operation of SBRs and RBC was also followed using API 20NE identification kits.


Kinetic analyses of the effects of temperature and light intensity on growth, hydrogenm production and organic acid utilization by rhodobacter capsulatus
Sevinç, Pelin; Gündüz, Ufuk; Department of Biotechnology (2010)
Effects of temperature and light intensity on photofermentative hydrogen production by Rhodobacter capsulatus DSM1710 by use of acetic and lactic acids as substrates were studied. Experiments were conducted at 20, 30 and 38oC incubator temperatures under light intensities in the 1500 – 7000 lux range. pH of the medium and quantity of hydrogen forming together with quantity of biomass, and concentrations of acetic, lactic, formic, butyric and propionic acids in the medium were determined periodically. Growth...
Kinetics of riboflavin production by Brewers' yeasts
Tamer, I.M.; Özilgen , Mustafa; Ungan, Suat (Elsevier BV, 1988-12)
The kinetics of riboflavin production by Saccharomyces cerevisiae and Saccharomyces carlsbergensis in synthetic media and wort were studied. The results indicated that riboflavin was produced by growing cells only. Riboflavin production rate was proportional to growth rate of the yeasts in the exponential phase. Riboflavin was depleted in the stationary phase. The depletion rate was expressed with a first-order kinetic expression in yeast concentration. The kinetics of substrate utilization and ethanol prod...
Modeling chlorophenols degradation in sequencing batch reactors with instantaneous feed-effect of 2,4-DCP presence on 4-CP degradation kinetics
ŞAHİNKAYA, Erkan; Dilek, Filiz Bengü (Springer Science and Business Media LLC, 2007-08-01)
Two instantaneously fed sequencing batch reactors (SBRs), one receiving 4-chlorophenol (4-CP) (SBR4) only and one receiving mixture of 4-CP and 2,4-dichlorophenol (2,4-DCP) (SBRM), were operated with increasing chlorophenols concentrations in the feed. Complete degradation of chlorophenols and high-Chemical oxygen demand (COD) removal efficiencies were observed throughout the reactors operation. Only a fraction of biomass (competent biomass) was thought to be responsible for the degradation of chlorophenols...
Molecular cloning and co-expression of Thermoplasma volcanium proteasome subunit genes
Kocabıyık, Semra; Zwickl, Peter; Ozdogan, Seda (Elsevier BV, 2010-10-01)
In this study we describe, the construction of a co-expression vector allowing simultaneous production of Thermoplasma volcanium 20S proteasome alpha- and beta-subunits in Escherichia coli. This heterologous expression system provided high level production of fully active 205 proteasome that can be purified easily by using a conventional two-step chromatographic technique. The recombinant proteasome was purified to homogeneity 12-fold with a specific activity of 26.5 U/mg. Sodium dodecyl sulfate-polyacrylam...
ARIKAN, O; OZILGEN, M (Elsevier BV, 1992-09-01)
Settling kinetics of champagne yeast were studied with 0.01, 0.05, and 0.10 m NaCl, CaCl2, AlCl3, and 1.00 +/- 0.01 OD660 (optical density at 660 nm) initial yeast concentration at pH 1. In the suspensions with 0.01 M NaCl, the pH of the medium varied between 1 and 3, and the initial yeast concentration changed between 0.74 and 1.25 OD660. Analysis of the data showed that the settling phenomena occurred in two steps: (i) establishment of the diffuse double layer to overcome repulsion, hence achievement of c...
Citation Formats
E. Şahinkaya, “Modelling aerobic 4-chlorophenol and 2,4-dichlorophenol biodegradation-effect of biogenic substrate concentration,” Ph.D. - Doctoral Program, Middle East Technical University, 2006.