Low Flow Design of Package Membrane Bioreactor Systems for Total Nitrogen Removal

Valued qualities such as portability, small footprint, fast start up, and high effluent quality have made package membrane bioreactor (MBR) systems a preferred technology for decentralized wastewater treatment applications. Package MBR systems have many advantages which make them ideal for decentralized wastewater treatment applications, particularly those looking for high effluent quality including total nitrogen removal. However, the selection of a package MBR system can be overwhelming for decision makers given the wide variety in available package MBR systems today and if not evaluated properly can lead to selection of a system that cannot meet the low flow challenges often encountered by decentralized wastewater treatment applications. Therefore it becomes important for decision makers to recognize whether the package MBR system is designed with features that allow it to maintain treatment conditions during low flows. This includes a properly designed flow equalization system capable of handling low influent flows which can be done using multiple pumps with VFDs or an influent flow splitter configuration. The package MBR system should also be designed with system turndown through the use of multiple treatment trains and/or use of multiple pumps and blowers. Lastly the package MBR system must be able to maintain control of oxygen delivery during low flows. Selecting a system which incorporates these low flow design methods into the design of the package MBR system will lead to selection of a system that will reliable meet total nitrogen limits at low flow conditions. Source: WEFTEC 2009 Proceedings