for the benefit of the environment and which other area is to be maintained for the
benefit of society?
These are not simple questions to answer. Each individual has a personal concept
that has some validity. This will require a considerable amount of discussion and
cooperation among individuals and obviously will result in various pressure groups
trying to get a little more for themselves or a special cause. However, we must look
at the total picture, not just at what affects a few individuals here and now.
Considerations must be made for the future so that humankind can coexist with
the environment on earth for many years to come. With an educated society, logical
thinking, and good information, human beings can make good decisions about what
efforts must be expended both now and in the future in order to improve and preserve
the environment for the best use of all for now and for time to come.
14 Dissolved Air Flotation Boat Plant for Lake Restoration
One of the primary causes of the death of a lake is excessive biological growth,
called eutrophication. Biological growth is limited primarily by the availability of
the nutrients necessary for growth. It has been shown that phosphorus is most
frequently the limiting nutrient to control biological growth in a lake, but nitrogen
is also commonly limiting. Phosphorus may be permanently removed from a lake by
various processes, whereas nitrogen is difficult to remove permanently due to the
fact that certain blue-green algae can fix atmospheric nitrogen as a nitrogen source.
Thus, emphasis has been placed on the removal of phosphorus. There are various
methods for the treatment of wastewaters to remove the nutrients before being
discharged to a body of water. Once in a lake, phosphorus removal is most frequently achieved by producing an insoluble aluminum salt of the phosphorus, but
iron salts are effective under aerobic conditions. Calcium salts are effective in
removing phosphorus, but they generally adversely increase the pH of the lake.
Precipitated aluminum phosphate salts may be allowed to settle to the bottom of the
lake, or they may be removed from the water column. A study showed that removing
the phosphate-rich hypolimnetic waters from a summer stratified temperate climate
lake, precipitating the phosphorus as either aluminum or iron salts, separating the
precipitate by dissolved air flotation (DAF), and returning the phosphate reduced
water to the lake were very effective in controlling the phosphorus nutrient content in
Devil’s Lake, WI, USA.
Figure 6.27 shows a dissolved air flotation boat plant designed by Dr. Lawrence
K. Wang of the Lenox Institute of Water Technology (LIWT) and Dr. Milos Krofta
of Krofta Engineering Corporation (KEC) [44]. The readers are referred to the
authors’ other article [30] for the detailed technical information of lake restoration
using dissolved air flotation process.
6 Basic Hydrology, Water Resources, and DAF Boat Plant for Lake Restoration
293
benefit of society?
These are not simple questions to answer. Each individual has a personal concept
that has some validity. This will require a considerable amount of discussion and
cooperation among individuals and obviously will result in various pressure groups
trying to get a little more for themselves or a special cause. However, we must look
at the total picture, not just at what affects a few individuals here and now.
Considerations must be made for the future so that humankind can coexist with
the environment on earth for many years to come. With an educated society, logical
thinking, and good information, human beings can make good decisions about what
efforts must be expended both now and in the future in order to improve and preserve
the environment for the best use of all for now and for time to come.
14 Dissolved Air Flotation Boat Plant for Lake Restoration
One of the primary causes of the death of a lake is excessive biological growth,
called eutrophication. Biological growth is limited primarily by the availability of
the nutrients necessary for growth. It has been shown that phosphorus is most
frequently the limiting nutrient to control biological growth in a lake, but nitrogen
is also commonly limiting. Phosphorus may be permanently removed from a lake by
various processes, whereas nitrogen is difficult to remove permanently due to the
fact that certain blue-green algae can fix atmospheric nitrogen as a nitrogen source.
Thus, emphasis has been placed on the removal of phosphorus. There are various
methods for the treatment of wastewaters to remove the nutrients before being
discharged to a body of water. Once in a lake, phosphorus removal is most frequently achieved by producing an insoluble aluminum salt of the phosphorus, but
iron salts are effective under aerobic conditions. Calcium salts are effective in
removing phosphorus, but they generally adversely increase the pH of the lake.
Precipitated aluminum phosphate salts may be allowed to settle to the bottom of the
lake, or they may be removed from the water column. A study showed that removing
the phosphate-rich hypolimnetic waters from a summer stratified temperate climate
lake, precipitating the phosphorus as either aluminum or iron salts, separating the
precipitate by dissolved air flotation (DAF), and returning the phosphate reduced
water to the lake were very effective in controlling the phosphorus nutrient content in
Devil’s Lake, WI, USA.
Figure 6.27 shows a dissolved air flotation boat plant designed by Dr. Lawrence
K. Wang of the Lenox Institute of Water Technology (LIWT) and Dr. Milos Krofta
of Krofta Engineering Corporation (KEC) [44]. The readers are referred to the
authors’ other article [30] for the detailed technical information of lake restoration
using dissolved air flotation process.
6 Basic Hydrology, Water Resources, and DAF Boat Plant for Lake Restoration
293