Evaluation of different polymeric coagulants for the treatment of oil refinery wastewater

E K Tetteh,S Rathilal,Harvey Arellano-Garcia

doi:10.1080/23311916.2020.1785756

Abstract

Wastewater from oil refinery industries has major pollution potentials with mutagenic and toxic compounds. Due to water scarcity in South Africa, oil refinery industries are compelled to find appropriate technology to treat their wastewater for reuse. With regards to this, most of the chemo-physical treatment processes are inadequate and are faced with major environmental and economic challenges. Therefore, this study aimed to find replaceable and cost-effective coagulants to the conventional coagulant for the treatment of a local South Africa oil refinery wastewater using dissolved air flotation (DAF) Jar tests. Three polymeric coagulants for the removal of turbidity, total suspended solids, chemical oxygen demand, and soap oil and grease (SOG) were investigated. At defined experimental conditions of recycle ratio (10%), air saturator pressure (350 kPa) and pH at 5, each coagulant was evaluated from a dosage of 10 mg/L to 50 mg/L. Above 80% of the aforementioned oily pollutants were removed at the coagulant dosage of 50 mg/L. Among the coagulants evaluated, PASS was found as the most suitable alternative coagulant to alum, to enhance and aggregate the air bubble–oil droplet interface for easy separation by the DAF. From the results, PASS is foreseen as promising and economical for pre-treatment of industrial wastewater, which is due to its lower cost and easy degradability.

Highlights

The rise of industrialization and extensive utilization of petrochemical products, makes the processing of crude oil a major pollution potential by generating large volumes of wastewater posing a threat to human health and the ecosystem (Sun et al, 2020)
This study aimed to investigate three different polymeric coagulants viz. poly alumi nium chloride (PAC-10 LB), Polyferric sulphate (PFS) and Polyaluminium silicate sulphate (PASS) for the treatment of a local South African oil refinery wastewater (ORW) to an acceptable discharge limit of 50 mg/L
dissolved air flotation (DAF) performance DAF being a separation process works on the following principles: (i) air bubbles encapsulating the insoluble particles, (ii) agglomeration of air bubble–insoluble particles to form flocculent structures and (iii) chemical adsorption of the air bubbles to the insoluble particles (Atamaleki et al, 2020; Tetteh & Rathilal, 2020)

Summary

Introduction

The rise of industrialization and extensive utilization of petrochemical products (oil-related fuels), makes the processing of crude oil a major pollution potential by generating large volumes of wastewater posing a threat to human health and the ecosystem (Sun et al, 2020). Interfering with the crude oil processing can lead to enormous human health risk and economic deformation (Kweinor Tetteh et al, 2017; Shikwambana & Kganyago, 2020; Tetteh et al, 2020). To curb this issue as an effort of achieving the united nations (UN) sustainable development goal of clean water and sanitation for all before 2030 (UN, 2018), the treatment of oil refinery wastewater (ORW) for reuse comes in handy (Sharma et al, 2020: Sun et al, 2020)

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Conclusion