Scum Handling Methods at Large Wastewater Treatment Plants and Implications for Biosolids Handling

Scum is a notoriously difficult wastewater residual to handle and treat. This is particularly true for large wastewater treatment plants where scum volumes can be especially high. Because of the difficulty of treating large volumes of scum, treatment processes are numerous and varied. This paper describes the results of two separate surveys of large U.S. wastewater treatment plants that employ various means of scum treatment. The first survey focussed on ultimate scum disposal methods and the second survey examined methods of scum volume reduction. This paper will present an overview of the survey findings as well as a brief discussion of the potential implications of scum handling practices on biosolids handling.