not known is whether water quality would have been degraded even more if remedial
measures had not been instituted. Dierberg et al. [40] point out that evaluation of
restoration practices in Florida lakes has been hampered by the lack of long-term
data and the consequent limitation on the use of robust statistical approaches in
evaluating effectiveness.
9.4 Water Treatment from Lake DeForest in Clarkstown,
NY, USA
United Water New York draws about 80% of its water supply from wells throughout
Rockland County. The remaining 20% is supplied from a surface source, Lake
DeForest in Clarkstown, NY [41].
The process of Lake Water treatment begins by pumping the water from the Lake
DeForest Reservoir into the treatment plant. During the pumping process chemical is
added to oxidize inorganic material, and the water passes through screens which
remove large objects prior to entering the pumps. The water then proceeds to the new
DAF (dissolved air flotation) system. A coagulant (aluminum sulfate) is added as the
water enters the DAF system. This allows smaller particles to form larger flocs,
getting the water ready to enter the final step of the DAF process. In this step,
millions of microbubbles are added to the water floating the flocs to the top. The float
(residuals) is removed and the clean water proceeds to the filters. It is during this step
that chlorine is added. Chlorine destroys bacteria and viruses in the water. The water
passes through the filters (layers of coal, sand, and gravel) to remove the smallest
remaining particles. Next, the water receives another small dose of chlorine to be
sure that the water remains pure and safe. Finally, corrosion control chemicals are
added. This step helps prevent corrosion of the water pipes and plumbing. It also
reduces the chance of lead dissolving in the water from plumbing.
10 Summary
A major factor in the death of a lake is eutrophication, which is the result of increased
biological growth within the lake, or acidification, which is the result of increased
release of sulfur dioxide and nitrogen oxides from industrial plants, or acid mine
drainage waters from mines. Biological life may be controlled by limiting the
nutrients or pH in the lake.
Reduction or elimination of external pollutant sources certainly is important for
lake restoration and water quality improvement. Many eutrophic and hypereutrophic
lakes, however, exhibit a very slow improvement in water quality even several years
after major external pollutant sources were eliminated.
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L. K. Wang et al.
measures had not been instituted. Dierberg et al. [40] point out that evaluation of
restoration practices in Florida lakes has been hampered by the lack of long-term
data and the consequent limitation on the use of robust statistical approaches in
evaluating effectiveness.
9.4 Water Treatment from Lake DeForest in Clarkstown,
NY, USA
United Water New York draws about 80% of its water supply from wells throughout
Rockland County. The remaining 20% is supplied from a surface source, Lake
DeForest in Clarkstown, NY [41].
The process of Lake Water treatment begins by pumping the water from the Lake
DeForest Reservoir into the treatment plant. During the pumping process chemical is
added to oxidize inorganic material, and the water passes through screens which
remove large objects prior to entering the pumps. The water then proceeds to the new
DAF (dissolved air flotation) system. A coagulant (aluminum sulfate) is added as the
water enters the DAF system. This allows smaller particles to form larger flocs,
getting the water ready to enter the final step of the DAF process. In this step,
millions of microbubbles are added to the water floating the flocs to the top. The float
(residuals) is removed and the clean water proceeds to the filters. It is during this step
that chlorine is added. Chlorine destroys bacteria and viruses in the water. The water
passes through the filters (layers of coal, sand, and gravel) to remove the smallest
remaining particles. Next, the water receives another small dose of chlorine to be
sure that the water remains pure and safe. Finally, corrosion control chemicals are
added. This step helps prevent corrosion of the water pipes and plumbing. It also
reduces the chance of lead dissolving in the water from plumbing.
10 Summary
A major factor in the death of a lake is eutrophication, which is the result of increased
biological growth within the lake, or acidification, which is the result of increased
release of sulfur dioxide and nitrogen oxides from industrial plants, or acid mine
drainage waters from mines. Biological life may be controlled by limiting the
nutrients or pH in the lake.
Reduction or elimination of external pollutant sources certainly is important for
lake restoration and water quality improvement. Many eutrophic and hypereutrophic
lakes, however, exhibit a very slow improvement in water quality even several years
after major external pollutant sources were eliminated.
304
L. K. Wang et al.