What are the design requirements for equipment and process redundancy for a wastewater treatment plant?
• The requirements for equipment and process reliability and redundancy are defined within the various chapters of the Arizona Department of Environmental Quality’s (ADEQ) Engineering Bulletin No. 11, “Minimum Requirements for Design, Submission of Plans and Specifications of Sewage Works”. The bulletin essentially requires that two or more of all essential treatment units or items shall be provided. With one unit or item out of service, the remaining units or items shall meet the design capacity of the plant. Reliability and redundancy requirements can usually be met by using redundant treatment process trains or designing a single treatment process with parallel piping and equipment which provides full redundancy (i.e. main and standby process unit(s) or equipment). An engineering analysis should be performed when designing a new or modifying an existing wastewater treatment plant to determine what process units and types of equipment require redundancy and increased reliability. The
