Comparison of Fenton and Ozone Oxidation for Pretreatment of Petrochemical Wastewater: COD Removal and Biodegradability Improvement Mechanism

Abstract

Cost-effective pretreatment of highly concentrated and bio-refractory petrochemical wastewater to improve biodegradability is of significant importance, but remains challenging. This study compared the pretreatment of petrochemical wastewater by two commonly used chemical advanced oxidation technologies (Fenton and ozone oxidation), and the mechanisms of biodegradability improvement of pretreated wastewater were explored. The obtained results showed that in the Fenton oxidation system, the COD removal of petrochemical wastewater was 89.8%, BOD5 decreased from 303.66 mg/L to 155.49 mg/L, and BOD5/COD (B/C) increased from 0.052 to 0.62 after 60 min under the condition of 120 mg/L Fe2+ and 500 mg/L H2O2, with a treatment cost of about 1.78 $/kgCOD. In the ozone oxidation system, the COD removal of petrochemical wastewater was 59.4%, BOD5 increased from 127.86 mg/L to 409.28 mg/L, and B/C increased from 0.052 to 0.41 after 60 min at an ozone flow rate of 80 mL/min with a treatment cost of approximately 1.96 $/kgCOD. The petrochemical wastewater treated by both processes meets biodegradable standards. The GC–MS analysis suggested that some refractory pollutants could be effectively removed by ozone oxidation, but these pollutants could be effectively degraded by hydroxyl radicals (•OH) produced by the Fenton reaction. In summary, compared with ozone oxidation, petrochemical wastewater pretreated with Fenton oxidation had high COD removal efficiency and biodegradability, and the treatment cost of Fenton oxidation was also lower than that of ozone oxidation.

Application of advanced oxidation processes for domestic and industrial wastewater treatment

“…The compound commonly used in several studies as a supplier of ferrous ions (Fe 2+ ) for the Fenton process is ferrous sulfate heptahydrate (FeSO 4 •7H 2 O) [46][47][48].…”

Pre-treatment of composite industrial wastewater by Fenton and electro-Fenton oxidation processes

“…The obtained results were similar to that recorded (89% COD) by Younes & Al-Sa`ed 24 at pH 3, H 2 O 2 /Fe +2 (w/w ratio 10:1) and initial COD as15400-18200 mg/L for pretreatment of mixed wastewaters. Cheng et al 25 pretreated petrochemical wastewater at pH 3 and achieved 89.8% COD removal, BOD 5 /COD increased from 0.052 to 0.62 after 60 min, 120 mg/L Fe 2+ and 500 mg/L H 2 O 2 .…”

“…This can be interpreted as the over dosage of Fe 2+ not only increases economic costs and iron sludge generation, but also promotes the scavenging effect of OH radical 6 . Therefore, the optimum concentration of ferrous ion that enhances maximum removal of COD was adopted as 1 mg/L which more less than that applied (60 mg/L Fe +2 ) by Delil and Gören 26 with maximum COD removal of 76% (initial COD 6200 mg/L) at pH 2, and 250 mg/L H 2 O 2 in treatment of sugar industry wastewater; and 120 mg/L Fe +2 by Cheng et al 25 who used Fenton process to pretreat petrochemical wastewater and achieved 89.8% COD removal after 60 min and 500 mg/L H 2 O 2 .…”

Integrated Process of Immediate One-Step Lime Precipitation, Atmospheric Carbonation, Constructed Wetlands, or Adsorption for Industrial Wastewater Treatment: A Review

“…Recently, several pretreatment technologies have been evaluated to treat and improve the biodegradability of industrial wastewater for suitable biological treatment. Some examples of wastewater treatment technologies that improve the biodegradability of wastewater include advanced oxidation processes (AOP) and electrochemical treatments [29][30][31][32], and constructed wetlands [28]. AOP (e.g., ozonation, UV/O 3 , ozonation coupled with H 2 O 2 , O 3 /UV/H 2 O 2 , sonification, photocatalytic oxidation, Fenton, and other processes) are effective in the treatment of various wastewaters.…”