ASCE 18-18

Prepared by the Oxygen Transfer Standards Committee of the Standards Development Council of the Environmental and Water Resources Institute of the American Society of Civil Engineers.

Prepared by the Oxygen Transfer Standards Committee of the Standards Development Council of the Environmental and Water Resources Institute of the American Society of Civil Engineers

Standard Guidelines for In-Process Oxygen Transfer Testing provides proven techniques for use by engineers, owners, and manufacturers for measuring oxygen transfer and evaluating the performance of aeration devices under process conditions.

Standard ASCE/EWRI 18-18, which was first developed by ASCE in 1996, provides updated information on nonsteady-state, off-gas, and inert gas tracer methods, as well as a brief comparison among methods. The methods presented are considered to be well developed and provide satisfactory precision for a wide range of aeration processes in suspended-growth biological systems. Because the range of process variables and wastewater characteristics that affect the precision and accuracy of these methods are difficult to control, the methods are offered as standard guidelines and are not recommended for compliance testing of aeration equipment. Since the original publication in 1996, the procedure that has gained the widest acceptance and use is the off-gas method. Although still considered an accurate and reliable method for measuring oxygen transfer in process systems, the tracer technique has not been used in recent years. The technology remains dynamic, however, and modifications and/or new procedures are likely to occur in the future.

These procedures may also be applicable to testing oxygen transfer devices in lakes and streams; however, they are not applicable to ?xed-?lm reactors, although modi?cation of some of the methods might serve to provide data on these processes as well.

In-process testing does provide the engineer with useful information that can be used in future design. It provides the owner with data that can be used for operation and maintenance of the aeration equipment and provides manufacturers with a useful research and development tool for equipment development and design