Produced Water Treatment Improvements in Facing Indonesian Government Regulation on Onshore Disposed Waste Water

摘要

Produced water is the largest byproduct generated by the oil and gas industry. Water injection, considered as the best answer for produced water disposal, is not always possible due to reservoir constraints. The secondary produced water treatment facility in Mutiara Central Plant, VICO Indonesia, is a phenol treatment plant (PTP). It is processing approximately 8000 BPD produced water before being released to the Dondang River. A biologically activated sludge process is applied to reduce the pollutant content so the disposed water complies with onshore waste water disposal regulation for oil and gas production industry on Permen LH 04/2007. The process reduces chemical oxygen demand (COD), ammonia, phenol, sulfide, and oil and grease content in the produced water. Frequently since 2008, high COD and ammonia content above the regulated thresholds (200 mg/L for COD and 5 mg/L for ammonia) in disposed produced water has been observed. A field investigation was conducted to collect integrated data of recent process parameters. The field data were then compared to design conditions, industrial practices, and literature to a determine root cause tree. In addition, a feed batch activated sludge pilot was constructed and study on inlet COD source was performed for comprehensive study. The field investigation revealed that root causes limiting the phenol treatment performance were higher oil content and COD in the inlet stream, highly fluctuating inlet debit, lack of oxygen supply, and inadequately designed and maintained clarifier and return sludge system. Following minor mitigation actions in January 2010 such as chemical process optimization, adjusting nutrient doses, adding sugar, fresh microbes, and routine maintenance, the effluent quality data has improved to just bellow the threshold. Six major improvements were proposed to improve PTP performance and effluent quality; e.g. repair pre-heater, construct new secondary clarifier, replace existing return sludge pump with proper capacity, install three more aerators, utilize K1 as equalization pond, and repair existing drying bed. VICO Indonesia has committed to commissioning the first four recommendations by the end of 2011.