Removal of COD and SO42− from Oil Refinery Wastewater Using a Photo-Catalytic System—Comparing TiO2 and Zeolite Efficiencies

Emmanuel K Tetteh,Sudesh Rathilal,Dennis Asante-Sackey,Elorm Obotey Ezugbe

doi:10.3390/w12010214

Emmanuel K Tetteh, Sudesh Rathilal + Show 2 more

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https://doi.org/10.3390/w12010214

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Journal: Water	Publication Date: Jan 12, 2020
Citations: 36	License type: CC BY 4.0

Affiliation: Durban University of Technology

Abstract

Advanced oxidation processes (AOPs) have many prospects in water and wastewater treatment. In recent years, AOPs are gaining attention as having potentials for the removal of different ranges of contaminants from industrial wastewater towards water reclamation. In this study, the treatability efficiencies of two photo-catalysts (TiO2 and zeolite) were compared on the basis of the removal of chemical oxygen demand (COD) and SO42− from oil refinery wastewater (ORW) using photo-catalytic system. The effects of three operating parameters: catalyst dosage (0.5–1.5 g/L), reaction time (15–45 min), mixing rate (30–90 rpm) and their interactive effects on the removal of the aforementioned contaminants were studied using the Box–Behnken design (BBD) of response surface methodology (RSM). Statistical models were developed and used to optimize the operating conditions. An 18 W UV light was incident on the system to excite the catalysts to trigger a reaction that led to the degradation and subsequent removal of contaminants. The results obtained showed that for almost the same desirability (92% for zeolite and 91% for TiO2), TiO2 exhibited more efficiency in terms of mixing rate and reaction time requirements. At the 95% confidence level, the model’s predicted results were in good agreement with experimental data obtained.

Highlights

IntroductionThere is continuous aggravation of water pollution due to population growth and its corresponding effects on industrialization, agriculture, and domestic activities
Issues of water scarcity and how it can be curbed continues to be a challenge to the world.There is continuous aggravation of water pollution due to population growth and its corresponding effects on industrialization, agriculture, and domestic activities
The findings showed that the efficiency of the TiO2 photo-catalysis time, and concentration of TiO2 in media on the removal of chemical oxygen demand (COD), total phenols, and color from black increased with increasing contact time, catalyst dosage, and decreasing initial organic load

Summary

Introduction

There is continuous aggravation of water pollution due to population growth and its corresponding effects on industrialization, agriculture, and domestic activities. This has led to radical exploration of alternative and sustainable means of obtaining water from unconventional means, such as water re-use through wastewater treatment [1]. Large volumes of oily wastewater is generated during transport and refinery of oil [2]. High levels of chemical oxygen demand (COD), total suspended solids (TSS), total dissolved solids (TDS), soap oil and grease (SOG), and traces of metals are found in the oily waste streams, which make their treatment problematic and cause huge pollution problems [4]

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