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ARRoGANT CoURiERS WiTH ESSaYS
Grade Level: Type of Work Subject/Topic is on:
[ ]6-8 [ ]Class Notes [Process of Disposing of ]
[x]9-10 [ ]Cliff Notes [Toxic Waste ]
[ ]11-12 [x]Essay/Report [ ]
[ ]College [ ]Misc [ ]
Dizzed: 07/94 # of Words:723 School: ? State: ?
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Abstract: Aluminum sulfate reacts with phosphates to create aluminum
phosphate and a sulfate. The conversion of the phosphate to aluminum
phosphate is very important because this allows the phosphate to be easily
extracted. This manipulation is used today in industrial waste treatment
sights. The removal of phosphates is very important for if phosphates are
not removed, they plague bodies of water by feeding algae which clog the
surface waters and eventually effect every living and nonliving thing in
that environment. Chemical Process: The reactions which occur are the
following:
Aluminum sulfate(alum) in combination with wastewater can flocculate
phosphorus. The Flocculation that happens with aluminum sulfate addition
is the formation of aluminum phosphate particles that attach themselves
to one another and become heavy and settle to the bottom of a clarifier.
The aluminum sulfate and phosphorus mixture can then be withdrawn,
thereby removing the phosphate or phosphorus from the wastewater flow.
Industrial Applications: The application of this reaction to the
industrial world consists of a set of processes to filter out the
phosphate. The setup is the following: Purpose: Restrict phosphates to
aluminum phosphates for easier disposal of phosphorus.
The first step in phosphorus removal is the Rapid Mix. In this stage,
alum and waste or water runoff(known as effluent) is blended together
as rapidly as possible with the use of a highФ speed mixer called a
"flash mixer." After this instant mixing, a slower moving process
called coagulation and flocculation follows to allow the formation of a
floc. These processes occur in a Flocculation Chamber. This floc
consists of suspended and colloidal matter, mainly including the
aluminum phosphate. Next, the effluent travels to a clarifier in which
sedimentation occurs. The heavier aluminum phosphate settles to the
bottom then pumps at the bottom of the clarifier pump out the aluminum
phosphate via pipes. This aluminum phosphate is then disposed.
Currently, there are no economical uses for aluminum phosphate. Also,
this chemical process is similar to the process used by laundry
detergents. Many detergents contain synthetic phosphates, called
tripolyphosphates(TTPs). These chemicals cling to grease and dirt
particles(alum in the previous example), keeping them in suspension
until the wash water is flushed out of the washing machine.
Impact on Society: This reduction in phosphorus is very important. This
added phosphorus disrupts the natural cycle of phosphorus. One result of
this is an algal blooms, or exponential growth in algae. When algal blooms
occur, the surface of a freshwater lake is clouded with an almost finite
amount of bacteria because of an increase in a nutrient. In this case an
increase in phosphate, a favorite for algae. This deprives the bottom of
the lake by cutting off light. A dense mat of algae choke off the lake.
Also, phosphates are nutrients for plantlife. When fall approaches, or when
phosphate levels are decreased, the algae die and fall to the bottom,
changing the bottom from a silt, sand and clay bottom to a sand gravel and
rock bottom. When the plants die, they are degraded by aerobic bacteria,
which can deplete dissolved oxygen, killing aquatic organisms. As oxygen
levels drop, anaerobic bacteria resume the breakdown and produce noxious
products. All of this impairs navigation, fishing, swimming and
recreational boating. Total phosphorus removal through filters after using
alum as a filtering aid achieves 70 to 95 percent efficiency. Phosphates
must be filtered out before the water or wastes are dumped back into bodies
of water. Glossary
Flocculation: The gathering together of fine particles to form larger particles.
Effluent: Wastewater or other liquid -- raw, partially or completely
treated -- flowing from a basin, treatment process, or treatment plant.
Coagulation: The use of chemicals that cause very fine particles to clump
together into larger particles. This makes it easier to separate the
solids from the liquids by setting, skimming, draining or filtering.
Floc: Groups or clumps of bacteria and particles or coagulants and
impurities that have come together and formed a cluster.
Colloidal: Very small and finely divided. Referring to solids. Does not
dissolve and remains dispersed in a liquid for a long time due to small
size.
Algal blooms: Rapid growth of algae in surface waters due to increase in
inorganic nutrients.
Bibliography
Kerri, Kenneth D. Advanced Waste Treatment. Sacramento, Ca.: CSU,
Sacramento, 1987.
Adams, Melinda. Environmental Science. Redwood City, Ca.: The
Benjamin/Cummings Publishing Company, Inc., 1991.