valuable for land application
by Brian R. Hook
The Hampton Roads Sanitation
District (HRSD) – which provides service for 3,100 square
miles around Virginia Beach, Virginia, with nine wastewater-treatment
facilities – estimates it is saving money, by the tons,
by not dumping its biosolids in a landfill.
Rhonda Bowen, recycling manager
at the district, estimates that putting the biosolids in a landfill
costs around $315 per dry ton compared with $225 a dry ton for
the land application of the biosolids. She said that about 11
percent of the biosolids that the district generates are used
for land applications. Another 11 percent of the biosolids generated
in the district is composted and sold back to the general public
“We have several different
processes (for disposing of biosolids) to give us diversification.
We are not dependent on one method.” Bowen said. The district
incinerates the remaining biosolids and only sends it to a landfill
as a last option.
HRSD has been recycling biosolids
through land application on farmland since 1984. The district
first tested the program on a 310-acre farm next door to one of
its wastewater treatment facilities. The district still owns and
operates the working farm.
“We feel the recycling
of our biosolids, both for land application and composting, are
the most environmentally sound ways to manage these materials,”
Bowen said “There is a huge a benefit received by the farmer
who receives these materials.”
HRSD defines biosolids as a nutrient-rich
organic material resulting from the natural biological and physical
treatment of wastewater. Solids are first separated from the wastewater
during the treatment process. These separated solids contain primarily
organic material, sand, nutrients, microorganisms, and trace amounts
HRSD said the solids are further
processed by several biological, chemical or physical methods,
depending on the end usage. The resulting biosolids are either
liquid or a moist to dry soil-like material that generally have
a mild organic odor that dissipates after application. The treatment
process takes the biosolids to what’s classified as a Class
A level, used for composting, or a Class B level, used for farmland
Bowen said Class B biosolids
have not been processed quite to the extent as Class A material.
Therefore there are additional site restrictions that prevent
the general public from being in direct contact with the Class
B material. She said that both classes of biosolids meet all quality
standards established by federal, state, and local regulators.
Landscapers and home gardeners
use Class A biosolids compost to enhance lawns and gardens. Farmers
can take advantage of the many plant nutrients and soil enhancement
properties provided by Class B biosolids. The HRSD estimates that
farmers can save anywhere from $75 to $100 per acre by using biosolids,
increasing crop yields, reducing erosion and reducing runoff associated
with the use of inorganic fertilizers.
Biosolids are rich in nutrients,
containing nitrogen and phosphorus along with other supplementary
nutrients such as potassium, sulfur, magnesium, calcium, copper,
zinc and iron, according to the HRSD. Bowen said that since most
of the nutrients are in the organic form, biosolids acts as a
slow release fertilizer and soil conditioner.
“It adds a lot of micro-nutrients
that are essential to crops. But the farmers don’t generally
apply these micro-nutrients because the costs are extensive. They
have added benefit by adding the biosolids and receiving these
additional micro-nutrients,” Bowen said. “We are also
keeping a valuable resource out of landfills and not using up
Bowen said that composting and
land application of biosolids also helps to offset operating costs
at the district. “In our situation we are not in this business
to make a profit. Our ultimate goal is to clean wastewater. We
have to manage those materials in whatever way is available and
we feel that composting and land application and other recycling
alternatives are the best way to manage those materials,”
Cal Sawyer, director of the Division
of Wastewater Engineering at the Virginia Department of Health,
said that Virginia is among the top in the amount of biosolids
applied across the country annually. He said that 250,000 dry
tons of biosolids are applied to a little over 50,000 thousand
acres in 20 to 30 counties in Virginia each year.
“It’s the most economical
method of the three management options that are addressed in the
federal and state regulations,” Sawyer said. The three options
include incineration with the disposal of the ash to a landfill,
co-disposal mixed with solid waste in a landfill and land application,
including pasture, cropland and forestland.
“I think it can be as much
as half of the cost for incineration and two thirds of the cost
for landfill. It also depends on the availability of landfill
space,” Sawyer said.
Sam Hadeed, communications director
at the National Biosolids Partnership, said that about 60 percent
of the biosolids across the country are used for land application
purposes. The not-for-profit based in Alexandria, Virginia is
an alliance of the National Association of Clean Water Agencies,
Water Environment Federation and the U.S. Environmental Protection
Agency. Its goal is to advance environmentally sound and acceptable
biosolids management practices. About 80 agencies participate.
Hadeed said some agencies are
facing controversy in regards to land application of biosolids,
especially in places like Southern California. “They don’t
want human waste on farmland. So you have legalities that sometime
make it difficult,” he said.
But he said that as agencies
start looking at managing their biosolids and realize that landfills
are filling up, it is becoming more costly to put biosolids in
a landfill. Therefore, he said land application of biosolids becomes
a more attractive option.
“It’s going to be
more economical and more environmentally friendly if we can recycle
this byproduct somewhere in our community,” Hadeed said.