ANTHRACITE

Although its potential for water treatment has been recog-nized since ancient times, anthracite coal was not used forthat purpose until the beginning of this century. Crushedanthracite makes an excellent medium density filtrationmedia. Anthracite has been manufactured from the finestPennsylvania coal since 1932. It is specifically selected forwater treatment, and during its production goes through sev-eral sizing inspections. Random samples are chosen for acomplete laboratory quality control analysis for effective size,uniformity coefficient, specific gravity acid solubility and hard-ness.Because of its fractured shape, some sediment penetratesdeeper into the bed. When compared to equivalent filtersands, this means longer filter runs and less head loss.Backwash rates are also reduced.Anthracite, because of its unique density, can be used inmulti-media filters. At 56 lbs./ft.3 it will hydraulically classifyand remain above heavier medial such as Filter Sand orManganese Greensand providing a prefiltration layer.

Advantages:

• Higher service flows and longer filter runs than equivalent sand filters.
• Close attention to gradation, hardness and purity assurescon sis tent and reliable performance.
• Unique density allows Anthracite to be combined with other filtration media in multi-media filters.

Physical Properties:

• Color - Black
• Density - 50 lbs./cu. ft.3
• Effective Size - #1 (0.6-0.8 mm), #1-1/2 (0.85-0.95 mm), #2 (1.7-2.0 mm)
• Uniformity Coefficient - #1 (1.5), #1-1/2 (1.6), #2 (1.5)
• Mesh Size - #1 (14 x 30), #1-1/2 (10 x 20), #2 (14 x 12)
• Sphericity - 0.6
• Hardness - 3.0-3.8 (Moh's Scale)
• Acid Solubility - <1%
• Caustic Solubility 0 <1%
• Apparent Specific Gravity - 1.65
• Meets American Water Works Association Standard -B100-89

Conditions for Operation:

• Bed Depth - 24 - 36 in.
• Backwash Rate - #1 (12-18 gpm/ft.2), #1-1/2 (18-25 gpm/ft.2), #2 (use air scour)
• Backwash Bed Expansion - 30-50% of bed depth
• Service Flow Rate - 5 gpm/sq. ft. or higher dependingupon local conditions.