Petrochemical condensate treatment by membrane aerated biofilm reactors: A pilot study

•MABR pilot in series was successfully applied to treat real petrochemical condensate.•Total RE of TOC, phenol, NH3 of > 80%, ~98%, 70–90% were achieved, respectively.•Simultaneous C/N removal and nitrification/denitrification were established.•High resistance to shock loads and process fluctuations was observed.•Potential for high OTR, OTE, and SAE was noted. An OxyMem membrane aerated biofilm reactor (MABR) pilot of two ~ 54 L reactors in series with a hydraulic retention time (HRT) of 10 h each was successfully applied for the treatment of real petrochemical condensate with a total organic carbon (TOC) concentration of ~ 100 mg/L. The main aim was to (i) evaluate the removal efficiency (RE) of main petrochemical pollutants and (ii) to examine the operational performance of the two on-site pilot-scale MABR units. The start-up/inoculation of the reactors in batch mode, followed by continuous pilot operation on synthetic feed, and the transition from synthetic to an actual petrochemical feed were covered. At stable operational conditions on the actual feed, the pilot in series achieved an overall RE for TOC, biological oxygen demand (BOD5), organic acids, phenol, and ammonia of 80–85%, ~95%, >98%, ~98%, and 70–90%. The system in series demonstrated high resilience to process fluctuations, high treatment efficiency of the complex feed, and the ability to develop a diverse biofilm. In terms of oxygen transfer rate (OTR), oxygen transfer efficiency (OTE), and specific aeration efficiency (SAE) values of > 1.5 g/m2/day, > 21%, and > 6.5 kg O2/kWh were achieved. Such values outcompete the aeration efficiency (AE) of conventional activated sludge (CAS) processes and demonstrate the potential of MABRs to achieve higher OTE. Based on the collected data, the MABR concept in series can be considered highly effective for treatment of petrochemical streams.