Water. desalination + reuse

| 20 | Desalination & Water Reuse | August-September 2014 projects _________ Carlo Zaffaroni, Bernardino Ciongoli, Kar Munirathinam, Mauro Marinettie CH2M Hill, Ali Redha Awadh, A Jabbar, A Karim BAPCO ___ Editor's note: the Bahrain Oil Refinery is located on the east coast of Bahrain, a few kilometers from the island of Sitra. The 267,000-barrels-a-day plant includes facilities for the primary treatment of process wastewater but more recently the company that operates the facility – the Bahrain Petroleum Company (BAPCO) – has implemented innovative methods in secondary treatment. In 2006, BAPCO began testing wastewater for secondary treatment which indicated that biological treatment was necessary to meet the projected wastewater treatment requirements of Bahrain's Supreme Council for the Environment. Biological treatment of refinery wastewaters is common practice but BAPCO's refinery wastewater has abnormal characteristics that complicate treatment, including: • refractory total Kjeldahl nitrogen (TKN), especially in view of stringent discharge limits of 5 mg/l TKN in the receiving body of water, the Persian Gulf; • high salinity - up to 30,000 mg/l of total dissolved solids (TDS) with 18,000 mg/l chlorides - and temperature of wastewater at up to 48°C in summer which limits bacterial activity and biological treatment performance; and • low concentration of degradable organic carbon in the wastewater - revealed by chemical oxygen demand (COD) - which limits the capacity for nitrogen removal. A study was completed to identify available treatment technologies, management strategies and achievable treatment performance. Due to the low total suspended solids (TSS) and TKN discharge limits and the wastewater's high salinity (TDS) and temperature, a membrane bioreactor (MBR) was selected as the preferred treatment technology. Although MBR plants are becoming more accepted; until now, they have not been used for refinery wastewater treatment. This has been due mainly to the potential risk related to the wastewater's oil content and MBRs' lack of a proper track record for large, similar industrial applications. Innovative Technologies Implemented at Bahrain Petroleum Company to Treat Refinery Wastewater Wastewater at the Bahrain Oil Refinery required special treatment.

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