Low pressure membranes continue to be the preferred technology for large water and wastewater treatment plants, as they provide a verifiable barrier, small footprint and superb water quality. The increasing demand for larger capacity,low-pressure membrane systems, has catapulted as the preferred solution. Reflecting this push toward submerged plants is the fact that most of the largest drinking water and wastewater membrane plants in the United States, both in operation and under contract, are submerged. Submerged membranes offer lower operating costs and a reduced equipment footprint over pressure systems.

But what configuration is most economical for smaller systems? Itis often believed that for smaller capacity plants, pressure systemscontinue to be the most economically viable solution. Pressure systems are typically skid mounted, easy to install, and do not require heavy construction. Submerged systems for smaller capacities are perceived as being more expensive and as having higher installations costs, although this is often not the case.

Using data from plants currently in operation and those presently under contract, this presentation will illustrate a financial and size comparison between pressure and submerged membranes. The goal is to provide information showing that submerged membranes are a viable option for both large and small systems.

This analysis will focus on drinking water system comparing the following factors:

This presentation will use information from one manufacturer in an effort to provide as much supporting data as possible. The comparisons made are not intended to be used as a cost estimating tool, but rather to provide information on the market from the stand point of one supplier.

Copyright 2003, American Water Works Association. All rights reserved.