Page 122 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

Part II

Particulate Separations

Screening and gravity settling are the topics of Part II. The precipitates, biological flocs, organic solids, etc. Solid objects
former includes intake cribs, bar screens, and fine screens. include refuse items and natural debris, that is, objects larger
The latter includes settling basins, flocculent settling, plate than those that would be considered particles. All such par-
settlers, oil separators, flotation, and grit chambers. These ticles may be removed by either of these processes by apply-
treatment technologies may be employed to remove a wide ing the appropriate technology. As a note, centrifuging
variety of particle types that occur in different categories of belongs with gravity settling, that is, the force acting on a
water (e.g., rivers and lakes for drinking water and various given particle occurs within a force field.
kinds of wastewaters).
Particles found in water include clay, silt, sand, algae,
bacteria, viruses, chemically coagulated colloids, chemical