The development of the treatment wetland technology
for the agricultural industry reflects the
collective efforts of scientists and engineers who
have designed and studied pilot and full-scale
wetland treatment systems. Historical studies, fullscale
projects, published literature, and conferences
have been key to providing a scientific basis for the
technology’s development.
Constructed and natural wetlands are being used
to treat wastewaters from a variety of types of
concentrated livestock operations. This technology
is relatively new for these applications; however, at
least 68 separate sites are currently using treatment
wetlands and more are being constructed each year.
The livestock industry has the distinct advantage of
being able to draw upon the considerable data
available from other treatment wetland applications.
The development and analysis of the LWDB
and the NADB have indicated that a number of the principal pollutants typical of livestock wastewaters
are removed in treatment wetlands at about the
same rate as these constituents in other wastewater
types. Thus, recently published design methods
described by Kadlec and Knight (1996) can be
applied with some confidence to the preliminary
design of wetlands treating livestock wastewaters.
Considerable published data exist for the design,
construction and early years of operation of many
livestock wastewater treatment wetlands. Increasing
knowledge about removal rate constants, background
concentrations and temperature effects on
removal should be a goal of ongoing and future
research in this field. As these systems mature and
steady-state data become available, findings should
be re-analyzed and published to provide further
design and operational guidance. Also, more complex,
multi-parameter models should be developed
to incorporate apparent effects of dissolved oxygen,
pH, plant populations and other environmental
factors on treatment wetland performance.