Catalytic ozonation of industial textile wastewaters in a three phase fluidized bed reactor

Download
2010
Polat, Didem
Textile wastewaters are highly colored and non-biodegradable having variable compositions of colored dyes, surfactants and toxic chemicals. Recently, ozonation is considered as an effective method that can be used in the treatment of industrial wastewaters; catalytic ozonation being one of the advanced oxidation processes (AOPs), is applied in order to reduce the ozone consumption and to increase the chemical oxygen demand (COD) and total organic carbon (TOC) removals. In this study, catalytic ozonation of industrial textile wastewater (ITWW) obtained from AKSA A.Ş. (Yalova, İstanbul) textile plant has been examined in a three phase fluidized bed reactor at different conditions. The effects of inlet chemical oxygen demand concentration (CODin), pH, different catalyst types [perflorooctyl alumina (PFOA) and alumina] and catalyst dosage on ozonation process were determined. Moreover, the changes in the organic removal efficiencies with gas to liquid flow rate ratio were investigated. The dispersion coefficients (DL) and volumetric ozone-water mass transfer coefficients (kLa) were estimated at various gas and liquid flow rates in order to observe the effect of liquid mixing in the reactor on ozonation process. It was observed that increasing both gas and liquid flow rates by keeping their ratio constant provided higher organic removal efficiencies due to the higher mixing in the liquid phase. The dyes present in ITWW sample were known to be Basic Blue 41 (BB 41), Basic Red 18.1 (BR 18.1) and Basic Yellow 28 (BY 28). The “absorbance vs. concentration” calibration correlations were developed to estimate the amounts of these colored dyes in the ITWW sample. This provided the opportunity to examine the degradation of each dye in this wastewater separately. While PFOA catalyst was found to increase the removal efficiency of BY 28 at an acidic pH of 4, alumina yielded highest color removals for BB 41 and BR 18.1 at a pH of 12. The highest TOC and COD reductions being 24.4% and 29.5%, respectively, were achieved in the catalytic ozonation of the ITWW using alumina as the catalyst at a pH of 12 and at a gas to liquid flow rate ratio of 1.36 (QG = 340 L/h, QL = 250 L/h). At the same conditions, also the highest overall color removal in terms of Pt-Co color unit, namely 86.49%, were obtained due to the lower BY 28 concentration in the WW sample than those of the BB 41 and BR 18.1. In addition, the oxidation of BB 41, BR 18.1 and BY 28 dyes were investigated in a semi-batch reactor by sole and catalytic ozonations with alumina and PFOA catalyst particles. The sole and catalytic ozonation reactions followed a pseudo-first order kinetics with respect to dye concentration. The highest TOC and COD removals being 58.3% and 62.9%, respectively, were obtained at pH of 10 for BB 41 and 55.2% and 58.8%, respectively, for BR 18.1 with alumina catalyst. On the other hand, for BY 28 PFOA catalyst yielded highest TOC and COD reductions being 61.3% and 66.9%, respectively, at pH of 4.

Suggestions

Catalytic Ozonation of Dye Solutions in a Semi-Batch Reactor
Pirgalıoğlu, Saltuk; Özbelge, Ayşe Tülay; Department of Chemical Engineering (2008)
Treatment of textile wastewaters containing dye materials using the conventional methods based on biological treatment is not possible. In order to overcome this problem, ozonation based on the oxidation of organic pollutants with ozone gas dissolved in aqueous phase have been studied widely. Catalytic ozonation and advanced oxidation processes (AOP) are also used in order to increase the efficiency of sole ozonation In this work, catalytic ozonation processes in the presence of Copper Sulfide (CuS) powder ...
Catalytic ozonation of an industrial textile wastewater in a heterogeneous continuous reactor
Polat, Didem; Balci, Irem; Ozbelge, Tulay A. (2015-09-01)
Textile wastewaters (WWs) are highly colored and non-biodegradable having variable compositions of colored dyes, surfactants and toxic chemicals. Discharge of these WWs to the environment is very detrimental for ecosystems, therefore new methods have been investigated in order to meet the quality criteria of water and the discharge standards of the partly treated WWs. Recently, catalytic ozonation being one of the advanced oxidation processes (AOPs), is considered as an effective method that can be used in ...
Dynamic Behavior of continuous flow stirred slurry reactors in boric acid production
Yücel Çakal, Gaye Ö; Eroğlu, İnci; Department of Chemical Engineering (2004)
One of the most important boron minerals, colemanite is reacted with sulfuric acid to produce boric acid. During this reaction, gypsum (calcium sulfate dihydrate) is formed as a byproduct. In this study, the boric acid production was handled both in a batch and four continuously stirred slurry reactors (4-CFSSR̕s) in series system. In this reaction system there are at least three phases, one liquid and two solid phases (colemanite and gypsum). In a batch reactor all the phases have the same operating time (...
Study of adsorption characteristics of long chain alkyl amine and petroleum sulfonate on silicates by electrokinetic potential, microflotation, FTIR, and AFM analyses
ÖZÜN, Savaş; Atalay, M. Umit; Demirci, Şahinde (Informa UK Limited, 2019-05-19)
The long-chain alkyl amines and petroleum sulfonates are mostly used to remove unwanted minerals from feldspar ores in acidic pHs. In this study, their adsorption characteristics on pure albite and quartz were investigated by electrokinetic potential measurements, microflotation tests, Fourier transform infrared spectroscopy, and atomic force microscopy studies. According to the results, amine had strong influence on zeta potentials of both albite and quartz turning them positive and resulting over 90% flot...
Dissolution of colemanite and crystallization of gypsum during boric acid production in a batch reactor
Erdoğdu, Anıl; Eroğlu, İnci; Department of Chemical Engineering (2004)
One of the most commonly used boron compounds, boric acid, is produced by dissolving colemanite (2CaO₉3B2O3₉5H2O) in aqueous sulfuric acid whereby gypsum (CaSO4₉2H2O) is formed as a byproduct and must be separated from the main product. This process consists of two steps, dissolution of colemanite and formation of gypsum. The amount of boric acid formed depends on the first step, dissolution of colemanite. In the latter step, gypsum crystals are formed and stay in the reaction mixture to grow up to a size l...
Citation Formats
D. Polat, “Catalytic ozonation of industial textile wastewaters in a three phase fluidized bed reactor,” M.S. - Master of Science, Middle East Technical University, 2010.