Luxury Swimming Pool Sand Filter Specification

Sand filter media are beds of granular material, or sand, drained from
underneath so that pretreated wastewater can be treated, collected and
distributed to the land application system. They are normally used
to polish effluent from septic tanks or
other treatment processes before it is
distributed on the land. All on-site
systems are no-discharge, meaning
the wastewater must stay in the
system and not leave the property.The wastewater cannot enter surface
water, streams, ditches or any water
resources. After the filtrate is collected
by the sand filters under drains, it is
then disposed of by a soil absorption
system.

Intermittent sand filters provide biodegradation or decomposition of wastewater constituents
by bringing the wastewater into close contact with a well developed aerobic biological
community attached to the surfaces of the filter media. This process requires unsaturated
downward flow of the effluent through a filter media which may be a mineral sand or
equivalently sized crushed glass meeting one of the media.

The Sand filter media is contained in a watertight vessel either below the surface of the ground or wholly
or partially elevated in a containment vessel. Proper function requires that the influent to the
filter be distributed over the media in controlled, uniform doses. In order to achieve accurate
dosing, these systems require a timer controlled pump with associated pump tank, electrical
components, and distribution network to deliver a minimum of 12 doses per day spread evenly
over a 24 hour period. The effluent is collected in the bottom of the sand filter and discharged
either by gravity or pressure to a suitable disposal component, usually a sub-surface drainfield.
This technology is used on sites with high groundwater levels and/or shallow soil conditions
where treatment must be accomplished before disposal. Intermittent sand filters are also used
as part of a mitigation strategy when horizontal separations are reduced.

Media Specifications -- The filter media must meet either the Coarse Sand Media or
the Sand Filter Media specifications for particle size gradation detailed in Appendix
A. Filter media used in constructing a sand filter must be accompanied with a written
certification from the supplier that the sand fully conforms to one of the media.

Treated Wastewater (Filtrate) Collection and Discharge -- Filtrate may be collected and
discharged from the bottom of the sand filter by either a gravity flow underdrain, or pumped
from a pump basin. When sand filters are membrane-lined, gravity flow underdrains must exit
through a boot. The boot and exit pipe must be watertight.

Sand filter media Filteration

Filtration is the last unit process in pretreatment of
water
Water flows either by gravity or under pressure
through a filter media like sand or anthracite
Suspended solids and flocs formed previously by
coagulation and flocculation are retained on the
filter surface
Once the pressure drop exceeds the set limit, the
filer bed is cleaned by back washing the media
by reversal of flow of water
The filter is now ready for use.