Design more flexibility into wastewater treatment

Several case histories illustrates how to design a refinery wastewater treatment system (WWTS). The heart of WWTS, the biological oxidation (BIOX) process, is the main focus. The design case history shows how to calculate BIOX parameters such as system flow, hydraulic retention time, sludge age, destruction/removal efficiency, reactor loading, etc. Tighter control on equipment size prevents overdesign and minimizes capital and operating costs. A BIOX system that is too large can cause as many problems as one that is too small. Improved WWTSs specification allows cost-effective operations at extreme flow and contaminant conditions. The paper describes the complex and variable scheme, WWTS design concepts, waste water biodegradability, destruction/removal efficiency, food-to-microorganisms, mixed liquor suspended solids, hydraulic retention time, sludge age, BIOX reactor loading, aeration, temperature, clarifier, discharge permit limits, operating diagram, operability review, and three case histories.