Water Reuse
Almost a decade of research sponsored by the Florida
Institute of Phosphate Research has produced a system that uses mined
land to clean surface water well enough to meet drinking water standards
and potentially be pumped into the aquifer, which would act as a natural
pipeline, allowing the water to be pumped out at the point where it
is needed.
The Southwest Florida Water Management District recognized
the promise of the research in 1999 and agreed to co-fund the pilot
test of the system at Progress Energy's Hines Energy Complex in Polk
County. Though there are still questions to be answered, SWFWMD has
put the concept of using natural water treatment into its long-range
water management plans.
"The concept is good and from what I've seen
I see reason to continue to investigate how the concept can be used,"
said Mark Barcelo, Manager of the SWFWMD Hydrologic Evaluation Section.
A section of SWFWMD's Regional Water Supply Plan dated
August 2001 addresses "Aquifer Recharge and Conveyance"
as "a major component of some of the proposed surface-water and
reclaimed water options." Later the plan refers to flowing water
through wetlands built on clay settling areas and a sand filtration
area to condition raw water and suggests several future projects.
Recognizing the potential of using mined phosphate
land to capture storm and surface water is not new, nor is the idea
of using wetlands to clean water, Barcelo said. What is new, he said,
is the concept of constructing a natural water treatment system on
mined land instead of a water treatment plant. That stems from SWFWMD
learning about the FIPR project that Peter Schreuder was conducting
and becoming involved in the pilot-test phase of the research.
Schreuder's project studied the feasibility of flowing
wastewater or stormwater through a clay settling area wetland and
then filtering it through sand tailings. Phosphate mining leaves both
clay settling areas and sand tailings behind. The goal: to produce
water pure enough to be pumped into the aquifer -- Florida's natural
reservoir -- to supplement river and stream flow, or be put to immediate
public use.
Bench-scale results of several studies that considered
factors such as how well the system would take care of disease-causing
micro-organisms, showed the concept had great promise. The demonstration
project at Progress Energy Florida tested the idea in the real world.
It ran secondary treated effluent from the City of Bartow's Waste
Water Treatment Plant, water from PEF's cooling pond, and surface
water from the PEF facility through a wetlands treatment area and
sand filtration system. The water was then tested to assess if the
system safely and effectively reconditioned the different surface
waters to meet primary and secondary water standards.
As of March 2004, the final report for the pilot test
had not yet been released but Peter Schreuder, President of the hydrogeology
firm Schreuder, Inc. and the principal investigator in this research,
said that the demonstration phase data shows the water meets all primary
drinking water standards. The water also meets the vast majority of
secondary drinking water standards, which apply only to aesthetics,
not health effects. He added that he is already working on ways to
modify the system to meet the standards that are not completely satisfied.
"Because of the pilot test, we have a good idea
where the few remaining problems are and we believe we can make the
necessary adjustments," he said. "It is all part of research."
It is research that Schreuder describes as imperative
in an area where water managers are searching for new ways to produce
the 200 to 300 million gallons of water per day they say they need
to meet demand expected by 2020.
Barcelo said he has not seen the final data, but thinks
the system may be close to being able to clean surface water, but
more testing will be needed to determine if it can clean treated wastewater
well enough for aquifer recharge.
Streamflow
Peter Schreuder is also completing another FIPR-funded
study: Evaluation of Impacts of Phosphate Mining on Streamflow, which
compares stream flow in a mining-impacted sub-basin of the Peace River
(Payne Creek) with an unmined sub-basin (Joshua Creek).
The primary goal of the research program is to answer
the question of how mining and reclamation of the land to recover
phosphate ore have permanently affected the flow of surface water
in the river basins where these activities took place.
Stream flow over time will be related to potential
factors such as rainfall per unit area; changes in acreages of various
mined and reclaimed landforms; changes in soils and vegetation; other
changes in land use and import or export of water (e.g., irrigation
water from deep wells).
The final report has not yet been completed, but Schreuder
has said that the study indicates that phosphate mining and reclamation
initially cause an increase in streamflow.
