DECISION TREE FOR TROUBLESHOOTING BIOLOGICAL PHOSPHORUS REMOVAL

Biological phosphorus removal is being used successfully at many wastewater treatment facilities. In recent years, effluent phosphorus permits that require phosphorus removal beyond 95 percent have become more commonplace and in some cases removal efficiencies of more than 99.5 percent are required. Such treatment requirements elevate the importance of biological phosphorus removal performance reliability.This paper is an extension of a Water Environment Research Foundation (WERF) funded study on the reliability of enhanced biological phosphorus removal (EBPR). This study showed many plants do not maintain consistent phosphorus removal for more than a few months between excursions. From these results and observations at other EBPR facilities, it appears that even with the best process control EBPR will remain a sensitive process and occasional process upsets can occur. However, the response and corrective actions are very much in the hands of the operators, engineers and the process designers. Few plants have strategies in place to troubleshoot EBPR and identify the source of plant upsets.This paper provides general guidelines for operators and engineers on how to troubleshoot biological phosphorus removal problems as well as help anticipate problems and avoid EBPR upsets. Known common causes for EBPR problems are discussed alongside with descriptions of diagnostic tests and procedures. The troubleshooting strategy suggested in this paper relies on a combination of data collection, diagnostic tests, and process monitoring to identify and, if possible, eliminate the source or EBPR problems.