Pilot Study on Treatment of Wastewater from an Ethylene Plant with Membrane Bioreactor Technology

Jian-Jun Qin,Kiran Arun Kekre,Eberhard Tao,Bryan Cashion,Robert Wenta,Maung Htun Oo,Guihe Dutková

doi:10.2174/1874123100802010119

Abstract

Pilot studies were conducted with an anoxic/aerobic concept membrane bioreactor (MBR) technology and a hollow fiber Petro® MBR system with capacity of 12 m3/d was operated continuously (24-hour) during the study. Trials on different membrane fluxes were conducted to obtain the sustainable flux while mixed liquor suspended solid (MLSS) was maintained at 9-11 g/L. The results of the MBR pilot trials showed that no obvious fouling of the membrane was found when the plant was operated at the flux of 12 L /m2/h (LMH) over 3 months and 15 LMH over one month during the pilot study. Design guidelines such as hydraulic retention time (HRT), sludge retention time (SRT), anoxic and aeration volume ratio, re-circulation flow rate and air scouring were obtained for a full-scale plant. It was concluded that treatment of wastewater from an ethylene plant without addition of any chemicals using MBR technology is feasible. The product quality consistently met the requirement for discharge and was suitable for the feed of further reverse osmosis (RO) post-treatment.

Highlights

IntroductionAdvanced membrane bioreactor (MBR) which is a combination of the conventional activated sludge process (ASP) and Microfiltration/Ultrafiltration membrane separation has been widely used in treatment of domestic sewage as MBR has advantages of consistently high quality of effluent, small footprint, reduced sludge production and simple system operation and facility management over ASP [1,2,3,4,5,6,7,8,9,10,11,12,13,14]
Denitrification happens and nitrate is converted to nitrogen in the anoxic tank, and nitrification takes place and ammonium is converted to nitrate in the aeration tank while biological oxygen demand (BOD) and chemical oxygen demand (COD) are biologically digested in both tanks
When the operation started at the flux of 6 L /m2/h (LMH), the initial membrane relative permeability was 1.0 with mixed liquor suspended solid (MLSS) concentration of 4512 mg/L in the aeration tank

Summary

Introduction

Advanced membrane bioreactor (MBR) which is a combination of the conventional activated sludge process (ASP) and Microfiltration/Ultrafiltration membrane separation has been widely used in treatment of domestic sewage as MBR has advantages of consistently high quality of effluent, small footprint, reduced sludge production and simple system operation and facility management over ASP [1,2,3,4,5,6,7,8,9,10,11,12,13,14]. Gander et al [4] have studied different types of commercial MBRs for domestic wastewater treatment with cost considerations and indicated that the submerged configuration with sucking the product from the inside of membranes would be more cost effective in operation than the side-stream configuration with pressuring the product from the inside to outside of membranes. Tao et al [12,13] have investigated different types of submerged MBRs under the tropical conditions and demonstrated the advantages of MBR technology for reclamation of the domestic sewage

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Conclusion