Frequent Questions

What is a sludge and what is its regulatory status when reclaimed?

A sludge is any solid, semi-solid, or liquid waste generated from a wastewater treatment plant, water supply treatment plant, or air pollution control device (40 CFR §260.10). Examples of sludges include filters and baghouse dust (Memo, Petruska to Monz; December 20, 1994, RCRA Online #11933). The regulatory status of a secondary material when reclaimed depends on the type of material reclaimed. Listed sludges are regulated as solid wastes when reclaimed but characteristic sludges are not. Both kinds of sludge are regulated as solid wastes when used in a manner constituting disposal; burned for energy recovery, used to produce a fuel,or contained in fuels; or accumulated speculatively (Section 261.2, Table 1). There are two types of sludge categories, sludges listed on the F or the K lists and sludges exhibiting a hazardous characteristic.The treated effluent from a wastewater treatment plant is not a sludge.

Additional guidance on sludges is available in the following documents: 

Memo, Fields to Wolfe; August 15, 1997 ( RCRA Online #14158)
Memo, Bussard to Defour; January 21, 1997 ( RCRA Online #14017
Memo, Bussard to Weisjahn; July 21, 1994 ( RCRA Online #11857
Memo, Shapiro to Directors; March 24, 1994 (RCRA Online #11822
Memo, Lowrance to Grant; April 6, 1988 ( RCRA Online #11338
Monthly Call Center Report Question; June 1986 ( RCRA Online #12656
Memo, Straus to Bzura; June 6, 1985 (RCRA Online #11083

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