Wastewater Gathering and Oil Separation Design: Optimizing Air and Water Quality Performance

摘要

Critical to the effective, efficient treatment of refinery wastewater is the removal of oil prior to treating dissolved organics with aerobic biological treatment. Refinery industry best practices include initial treatment of the oily wastewater (i.e., desalter wastewater and oily sewer water) using API oil/water separators (API). Depending on refinery topography, one or more lift stations may be required to pump oily wastewater to the API. Several federal air quality rules and state rules/permits apply overlapping emissions standards. Water quality rules and permits apply standards to the treated effluent. Prudent emissions estimates and efficient design are vital for informing the design of individual refinery wastewater projects to meet both air quality and water treatment objectives. This paper presents the latest design options for wastewater gathering and oil separation systems with associated emissions and operating implications. Emission estimates are provided for an example wastewater lift station and an example API separator unit. These estimates are based on case study project designs, established calculation methods, and evaluation of actual system operations. The effects of the process design on emissions and compliance programs are summarized. For example, the effects of using a nitrogen conservation approach are shown to reduce both nitrogen consumption and hydrocarbon emissions based on actual systems in operation. Recommended practices are also presented.