3.2. Database contents
The LWDB includes 68 sites with a total of 135
separate systems. The higher number of systems
reflects the presence of multiple systems (separate
inflow and outflow points) at a single site. Allsites in the LWDB are constructed wetlands.
Eighty-three percent of these systems are SF, and
the rest are SSF or other. Ninety percent of these
systems have marsh vegetation; the remainder are
open water, or dominated by floating aquatic
plants, shrubs, or of unknown vegetation types.
Seventy-two of these systems are research facilities.
Many of the others are larger-scale demonstration
systems. Most of the systems included in
the database are being used for some form of
research and technology development.
Of the treatment wetland sites in the LWDB,
38 receive dairy farm wastewaters, 19 receive
wastewaters from swine operations, eight receive
cattle feeding wastewaters, two are aquaculture
systems, and one is a poultry farm operation.
Livestock wastewater treatment wetlands occur
throughout the USA in most EPA regions (all but
regions 2, 8 and 9) and throughout Canada. Region
4 (southeastern USA) has the largest number
of sites and systems, followed by Canada.
The LWDB includes design information for
135 systems with a total of 278 individual treatment
cells. Multiple cells in a system may function
in series or in parallel.The LWDB includes operational data from 48
treatment wetland systems at 22 sites with a total
of 1390 individual records that include data for
multiple parameters. Table 1 summarizes the wetland
long-term and annual average operational
performance data.
The LWDB includes 89 citations to scientific
journal articles, system design and data reports,
and other documents related to the wetland systems.
These literature citations, listed and sorted
by site number, should be consulted for more
detailed information on each system in the
database.
In some cases, no published information is
available for operating treatment wetland systems.
For these systems, the best sources of more
information are (1) the operator or system manager,
(2) a researcher working with the system, or
(3) the system engineer who will know design
considerations and may be involved in performance
assessment. The LWDB provides contact
information for 37 researchers knowledgeable
about the design and operation of these systems.