Pond-In-Pond (PIP) - An Upgraded Pond Design Towards Water Sustainability

Waste stabilization ponds (WSP) are recommended to treat wastewater in small communities, which make up to 85% of the cities in the U.S. Thus, a novel design, the Pond-in-Pond (PIP), was proposed to promote an efficient and sustainable nature-based solution for wastewater treatment and agricultural reuse. This presentation summarizes the previous studies on this design, its current state-of-the-art, and the future research under development. The PIP consists of a deeper anaerobic pit, surrounded by berms, that outflow into a larger pond. Monitoring of existing systems’ data show how the PIP treatment system outperforms a traditional pond system in terms of both consistent effluents and increased organic removal for similar sized units so that it can be sustainably applied to cropland. At present, the most up-to-date research on this technology focused on the pond’s hydrodynamics, using computational fluid dynamics (CFD). For comparison purposes, two equally sized ponds were modeled with a design flow of 1 MGD (0.044 m3/s). The particle settling was significantly higher on the PIP compared to the traditional pond configuration. Since most of the solids settled in the pit, this portion was analyzed comparing different length-to-width ratios (LWR), 1:3, 1:1 and 3:1, and number of outflowing sides. The CFD simulations demonstrated that the 1:1 shaped pit was the most appropriate design for the anaerobic pit, outperforming the other LWR in all aspects. Future analysis will focus on how to improve overall organic matter removal, and preliminary research point to the LWR as the main factor in pond’s efficiency.