Zdjęcie1298 (4)

Sludge (błwwWs) ii composed mostly of solids generated during wastewater treatment pruce*>ev Slodgc treatment and disposaf arc prohably ihe most costly operations in w aste-u-aier treatment pbnts. The U.S. Environmental procection Agency (l^!.S. EPA) ha* reported that appro,\imaiely 7 niillion dry tons of sludge arc produced annttally in the United State*, and sludge production is espected to inercase in the futurę. Memher States of the Eiirapean Conraiunitj produee approximalely 5i million dn tons of hioso-lids per yeąr (Bowden, 1987). France produee* a linie less than 900,000 dry tons of sludge year (Sachon et al.. .1997).

•    Grit Grit is a muturc of coarse and dense nmlerials such as sand, bonę chips, and glass. These materials arc collected in the grit chamber and arc dircctly disposed intffi

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| Primary sludge. This is the sludge generated by primary treatment of wastewater and accumulated in the primary clarilier. Il contains 3-8 percent solids.

•    Secmlan sludge. Secondary sludge is generated by biological treatment processeaj (c.g., actisated sludge, trickling tilier). The solids arc mostly organie and rango from U5 to 2 percem for activaied sludge and up to 5 percent for trickling filter sludge. , MMjS&fj This sludge rcsults from tertiary (Chemical) treatment of wastewater.,