Tertiary Treatment of Wastewater Using a Rotating Biological Contactor System

摘要

The use of rotating biological contactors (RBCs) to upgrade sewage treatment plants is relatively new in the United States, and only a few full-scale RBC secondary plants have been in operation for more than 1 year. RBCs appear to be simple to operate and maintain, cost competitive, reliable, economical, and compatible for retrofitting existing Department of Army (DA) sewage treatment plants without extensive renovation. However, data are scarce regarding RBC retrofitting strategies for upgrading existing secondary trickling-filter sewage treatment plants for additional biochemical oxygen demand (BOD) and nitrogen removal to meet current and anticipated National Pollution Discharge Elimination System (NPDES) requirements. In addition, because of differences in manufacturers' inherent design philosophies, nowell-defined theory of design and operation is accepted by all manufacturers. The overall objective of this investigation was to evaluate the performance of an RBC wastewater treatment process as an upgrading-retrofit unit process for BOD reduction and nitrification. Using a 0.5-m RBC plant at an existing full-scale trickling-filter plant, the flexibility, feasibility, and characteristics for BOD reduction and nitrification potential were determined under a variety of hydraulic, organic, and ammonia-loading regimes. The design procedure is presented, along with design calculations for 1.0, 5.0, and 7.5 mgd plants. Capital costs and energy requirements for these plants at various options were listed for comparison. These results indicate that DA sewage treatment plants can be effectively upgraded.