Catalytic ozonation of an industrial textile wastewater in a heterogeneous continuous reactor

Abstract

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 the treatment of industrial WWs. In this study, catalytic ozonation of industrial textile WW obtained from AKSA Textile Plant in Yalova/Turkey has been examined in a three phase reactor where the solid catalyst phase was fluidized at different experimental conditions. The effects of inlet chemical oxygen demand (COD) value, pH, different catalyst types [perfluorooctylalumina (PFOA) and alumina] and gas to liquid flow rate ratios (QG/QL) have been determined. Pseudo-first order degradation rate constants for the dyes in the real industrial textile WW were determined in terms of COD, by taking samples at different heights along the reactor during an experimental run at steady state. Moreover, “absorbance vs. concentration” calibration correlations were developed to estimate the concentrations of colored dyes in the sample. This provided the opportunity to measure the dye concentrations and estimate the percent removals of each dye in the samples, separately. Besides COD removals, also total organic carbon (TOC) removals and ozone consumptions were measured and discussed by comparing the results obtained in both sole and catalytic ozonation experiments.