
Read: a
story on the algal scrubber system in Agricultural Research. From the Nation's Attic to the
Nation's FarmBy Don Comis July 21, 2000An Agricultural Research Servicemicrobiologist has gone to the nation's attic for inspiration in designing an
algal scrubber system to clean waste from dairy barns. ARS scientist Walter Mulbry redesigned and moved a device out of the
darkness of the Smithsonian Institution's living coral reef exhibit into the
daylight outside 300-cow dairy barns at a research center about 15 miles away
in Beltsville, Md. Mulbry teamed up with Walter Adey, director of the Marine Systems Laboratory
at the Natural History Museum in
Washington, D.C., to see if Adey's invention would clean dairy waste as well as
it cleaned fish waste. He began with one of the scrubbers that Adey kept in a
behind-the-coral-reef exhibit attic space. The scrubbers were algae-lined tanks
that filtered water flowing out of, and back into, the coral reef aquaria on
public view. The scrubber did such a good job of removing nitrogen and phosphorus from
liquid dairy manure in the lab, that Mulbry recently moved the experiment
outdoors. Instead of the scrubber tank, Mulbry used a series of four parallel
water troughs, or raceways, each 50 meters long by 1 meter wide. He lined these
with plastic mesh for growing algae. Mulbry dilutes the liquid manure from the dairy barns into tanks at the ends
of each raceway, and the diluted manure is then pumped down the raceways in
waves. The algae use the manure as fertilizer. Each week, the algae will be
harvested by rolling up the mesh mats. The algae will then be dried for testing
as a high-protein feed supplement for cattle on the farm and as an aquaculture
feed. The algae will also be tested as a green manure fertilizer to grow corn,
soybeans and wheat. Possible commercial uses in the future include high-value
chemicals made from the algae. A brief story on the algal scrubber system appears in the July issue of
Agricultural Research. ARS is the chief scientific agency in the U.S. Department of Agriculture. Scientific contact: Walter Mulbry, ARS Soil Microbial Systems
Laboratory, Beltsville, Md., phone (301) 504-6417, fax (301) 504-7976,
[email protected]. Story contacts Walter W Mulbry U.S. Department of Agriculture |