INVESTIGATING DISSOLVED AIR FLOTATION FACTORS FOR OIL REFINERY WASTEWATER TREATMENT

Emmanuel Kweinor Tetteh; Sudesh Rathilal

doi:10.12955/cbup.v6.1311

Emmanuel Kweinor Tetteh Faculty of Engineering and the Built Environment, Durban University of Technology
Sudesh Rathilal Faculty of Engineering and the Built Environment, Durban University of Technology

DOI: https://doi.org/10.12955/cbup.v6.1311

Keywords: Dissolved air flotation, DAF, flotation, oil refinery wastewater, oil from water

Abstract

The global demand for petrochemical and petroleum industry products unavoidably generates large volumes of oil refinery wastewater (ORW). The complete treatment, reclamation and disposal of the ORW to an acceptable environmental limit is currently a challenge to most of the petroleum industries. With the current development in conventional treatment methods viz. coagulation, dissolved air flotation (DAF), and biological and membrane separation processes. DAF, which is well-established separation process, effectively employs microbubbles as a carrier phase for separation. Although, DAF is frequently used in combined water and wastewater treatment plants, its fundamental characteristics and operational parameters have not yet been fully investigated for the treatment of ORW. In this study, the correlation and effects of the parameters understudy (coagulant dosage, air saturator pressure, air-water ratio and rising rate) on chemical oxygen demand, soap oil and grease, turbidity and total suspended solids removal from ORW were examined experimentally using a laboratory DAF system. The results showed that increasing the saturator working pressure and the rising rate had less effect on the system, than increasing the air-water ratio. The agglomeration of the oil droplets was found to depend solely on the polyaluminum sulphate (PAS) dosage to destabilize the oil droplets. The DAF treatability performance showed over 80% removal of the contaminants at optimum conditions of pH of 5, PAS dosage of 10 mg/L, rising rate of 15 minutes, air saturator pressure of 300-500 kPa, and air-water ratio of 5-15%. The PAS dosage was found to be the most significant factor. Therefore, a moderate increase of the PAS dosage under these optimum conditions will increase the DAF efficiency in the treatment of ORW.

References

Aliff Radzuan, M. R., Abia-Biteo Belope, M. A., & Thorpe, R. B. (2016). Removal of fine oil droplets from oil-in-water mixtures by dissolved air flotation. Chemical Engineering Research and Design, 115, 19–33. https://doi.org/10.1016/j.cherd.2016.09.013

APHA/AWWA/WEF. (2012). Standard Methods for the Examination of Water and Wastewater. Standard Methods, 541. https://doi.org/ISBN 9780875532356

Diya’Uddeen, B. H., Daud, W. M. A. W., & Abdul Aziz, A. R. (2011). Treatment technologies for petroleum refinery effluents: A review. Process Safety and Environmental Protection, 89(2), 95–105. https://doi.org/10.1016/j.psep.2010.11.003

Edzwald, J. (1995). Principles and applications of dissolved air flotation. Water Science and Technology, 31(3–4), 1–23. https://doi.org/10.1016/0273-1223(95)00200-7

El-Naas, M. H., Alhaija, M. A., & Al-Zuhair, S. (2014). Evaluation of a three-step process for the treatment of petroleum refinery wastewater. Journal of Environmental Chemical Engineering, 2(1), 56–62. https://doi.org/10.1016/j.jece.2013.11.024

El-Naas, M. H., Surkatti, R., & Al-Zuhair, S. (2016). Petroleum refinery wastewater treatment: A pilot scale study. Journal of Water Process Engineering, 14, 71–76. https://doi.org/10.1016/j.jwpe.2016.10.005

Guo, S., Li, G., Qu, J., & Liu, X. (2011). Improvement of acidification on dewaterability of oily sludge from flotation. Chemical Engineering Journal, 168(2), 746–751. https://doi.org/10.1016/j.cej.2011.01.070

Karhu, M., Leiviskä, T., & Tanskanen, J. (2014). Enhanced DAF in breaking up oil-in-water emulsions. Separation and Purification Technology, 122, 231–241. https://doi.org/10.1016/j.seppur.2013.11.007

Pintor, A. M. A., Martins, A. G., Souza, R. S., Vilar, V. J. P., Botelho, C. M. S., & Boaventura, R. A. R. (2015). Treatment of vegetable oil refinery wastewater by sorption of oil and grease onto regranulated cork - A study in batch and continuous mode. Chemical Engineering Journal, 268, 92–101. https://doi.org/10.1016/j.cej.2015.01.025

Sahu, O. P., & Chaudhari, P. K. (2013). Review on Chemical treatment of Industrial Waste Water Review on Chemical treatment. Journal of Applied Science Environmental Management, 17(2), 241–257. https://doi.org/http://dx.doi.org/10.4314/jasem.v17i2.8

Tetteh, E. K., & Rathilal, S. (2018). Evaluation Of The Coagulation Floatation Process For Industrial Mineral Oil Wastewater Treatment Using Response Surface Methodology (rsm). International Journal of Environmental Impacts, 1(4), 491–502. https://doi.org/10.2495/EI-V1-N4-491-502

Tetteh, E. K., Rathilal, S., & Robinson, K. (2017). Treatment of industrial mineral oil wastewater – effects of coagulant type and dosage. Water Practice and Technology, 12(1), 139–145. https://doi.org/10.2166/wpt.2017.021

Welz, M. L. S., Baloyi, N., & Deglon, D. A. (2007). Oil removal from industrial wastewater using flotation in a mechanically agitated flotation cell. Water SA, 33(4), 453–458.

Yan, L., Wang, Y., Li, J., Ma, H., Liu, H., Li, T., & Zhang, Y. (2014). Comparative study of different electrochemical methods for petroleum refinery wastewater treatment. Desalination, 341(1), 87–93. https://doi.org/10.1016/j.desal.2014.02.037

Yavuz, Y., Koparal, A. S., & Öǧütveren, Ü. B. (2010). Treatment of petroleum refinery wastewater by electrochemical methods. Desalination, 258(1–3), 201–205. https://doi.org/10.1016/j.desal.2010.03.013