When treating municipal wastewater, there are two choices to be made that determine which treatment system will be utilized; will the effluent be discharged to a stream or will it be reused for beneficial purposes such as growing agricultural crops by land application. For land application systems, the effluent quality is less stringent, usually 2-3 times higher than that required for stream discharge. In addition, the public tends to be more supportive when it comes to the reuse of wastewater in irrigation rather than the reuse in households. A simple, low cost, low energy pond treatment system has been widely used for reuse systems. However, there is a lack of specific design guidelines for pond treatment systems, and selection of a design procedure is difficult to ascertain. This study examines various pond design approaches and recommends the use of a Pond-In-Pond (PIP) approach as the more appropriate design layout for reuse purposes, where PIP is the integration of two types of ponds - anaerobic and aerobic. The results from the Computational Fluid Dynamics (CFD) analysis of a flow-diversion mechanism in recent studies and performance data from existing PIP systems show that the PIP is a promising concept for wastewater reuse systems. The PIP system under study produced an average annual effluent BOD of approximately 40 mg/L.
- Land application
- Pond design