Abstract

The wastewater produced from the oilfield is chemically corrosive due to high salinity in combination with high temperatures. It is also rich in contaminants, such as oil, polyacrylamide, emulsions, suspended solid, etc. The density difference between the oil and water in the wastewater is low, which makes separation via gravity difficult. In this study, a combined pilot treatment is studied, which includes Fenton oxidation, settlement, activated carbon adsorption, and ultrafiltration (UF). The operational conditions of Fenton oxidation are optimized based on alleviating the fouling of the UF membrane. When the Fenton oxidation was operated at the molar ratio of H2O2 to FeSO4 3:1 and pH 2.2–2.5, the UF membrane could operate continuously for 20 h without cleaning. The membrane was fouled by the organics (oil/grease) and polymer, which can be effectively removed by composite cleaning reagent consisting of 0.1% NaOH and 0.1% sodium dodecylbenzenesulfonate (SDBS). With the UF treatment, the chemical oxygen demand (COD) of the effluent was less than 50 mg/L, which could meet the upgraded standard.

Highlights

  • The oil exploitation industry is the foundation of almost all modern economic sectors

  • The membrane was fouled by the organics and polymer, which can be effectively removed by composite cleaning reagent consisting of 0.1% NaOH and 0.1% sodium dodecylbenzenesulfonate (SDBS)

  • The denitrified effluent from the intermediate tank flows into the activated carbon unit for the adsorption procedure to further remove the dissolved organics and by-produce from the Fenton oxidation, which will reduce the fouling potential to the UF membrane

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Summary

Introduction

The oil exploitation industry is the foundation of almost all modern economic sectors. The wastewater produced from the oilfield is chemically corrosive due to high salinity in combination with high temperatures It is rich in oil emulsion, grease, suspended solids, bacterial content, and polymeric content, which could cause serious membrane fouling [3]. Since large volumes of the produced water are being generated in many countries with oilfields, there are increasingly focused efforts to find efficient and cost-effective treatment methods to remove pollutants. Biological treatment is a cost-effective method for removing dissolved and suspended compounds from onshore oilfield wastewater. Alkhudhiri et al [12] tested air gap membrane distillation in treatment of the produced water All those methods could achieve the targeted COD of less than 50 mg/L. The capability of the UF membrane in COD removal and cleaning strategy of the fouled membrane were studied

Pretreatment
Fenton
UF Membrane
Investigation
Addition is
H2 O2 and FeSO4 Addition
O2newly
O2 ratio
Figure
Settlement and Intermediated Units
Activated Carbon Adsorption
UF Membrane Challenge Tests
Effect
Chemical
Treatment Capacity Challenge for the Combined Process
Cost Analysis
Findings
Conclusions

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