Design and Performance of Early Massachusetts Intermittent Sand Filters

Location

Andover

Brockton

Concord

Farmington

Gardner

Leicester

Natick

Spencer

Year Started

1902

1899 1891

1897

Loading Rate (gal/d/ac)

35,000

83,000

122,000

61,000

Filter Depth (in.)

48-60

70 60

Sand Size (mm)

Ammonia Removal

Influent

40.7

12.4 16

Effluent

BOD5 Removal

Influent

139 321

Effluent

Source: Data from the Massachusetts Board of Health (1912) and Mancl and Peeples (1991).

FIGURE 5.1 Cross-sectional and plan views of typical intermittent sand filter. (From Middlebrooks, E.J. et al., Wastewater Stabilization Lagoon Design, Performance, and Upgrading, Macmillan, New York, 1982. With permission.)

treated raw or primary effluent wastewater and produced an excellent effluent. A typical intermittent sand filter is shown in Figure 5.1. Intermittent sand filtration is capable of polishing pond effluents at relatively low cost and is similar to the practice of slow sand filtration in potable water treatment. Intermittent sand filtration of pond effluents is the application of pond effluent on a periodic or intermittent basis to a sand filter bed. As the wastewater passes through the bed, suspended solids and other organic matter are removed through a combination of physical straining and biological degradation processes. The particulate matter collects in the top 2 to 3 in. (5 to 8 cm) of the filter bed; this accumulation eventually clogs the surface and prevents effective infiltration of additional effluent. When this happens, the bed is taken out of service, the top layer of clogged sand is removed, and the unit is put back into service. The removed sand can be washed and reused or discarded.

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