Drug – bio-affecting and body treating compositions – Inorganic active ingredient containing – Heavy metal or compound thereof
Reexamination Certificate
1998-04-06
2001-06-19
Pak, John (Department: 1616)
Drug, bio-affecting and body treating compositions
Inorganic active ingredient containing
Heavy metal or compound thereof
C424S630000, C424S632000, C424S633000, C424S634000, C424S635000, C424S638000, C424S646000, C424S647000, C424S648000, C424S682000, C424S698000, C504S151000, C504S152000, C514S499000, C514S500000, C514S502000, C210S705000, C210S723000, C210S724000, C210S728000, C210S732000, C210S735000, C210S749000, C210S753000, C210S764000
Reexamination Certificate
active
06248369
ABSTRACT:
BACKGROUND OF THE INVENTION
Fresh water from rivers or lakes is treated in a water plant to convert the raw water into water for human consumption meeting accepted purity standards. The processes used have been honed over the years to produce high quality potable water from raw water at surprisingly low costs.
The primary treatment in a water plant occurs in a clarifier where a flocculant is added to raw water. A water plant clarifier is a large sized, round or rectangular concrete structure. The flocculent causes particles suspended in the water to coagulate, subsequently growing in size and weight. The clarifier is sized to provide sufficient residence time for the majority of the solids to drop out of suspension. Water is then passed through sand filters, perhaps treated with activated carbon, chlorinated and possibly fluoridated before being delivered to water supply mains which transport the treated water to residences, businesses and industries.
One of the recurrent problems in water treatment plant operations is the growth of algae in the clarifier and sand filters. Algae come in many types including filamentous algae, such as Cladaphora and Spirogyra, planktonic algae such as Microcystis and Anabaena, branched algae such as Chara vulgaris and Nitellam, swimming pool algae commonly referred to as black, brown and red algae and algae found in ponds such as Dictyosphaerium, Spirogyra, Oedogonium, Chlorococcum, Pithophora, Hyudrodictyon and Lyngbya. It is not uncommon to see a municipal water plant clarifier with a beard of algae around its peripheral walls and filamentous algae growths several feet long.
As used herein, the term municipal water plant is intended to mean a water plant used in treating raw water and converting it to potable water for human consumption, regardless of whether the entity doing so is public or private.
Algae blooms have been noted to appear literally overnight under the right temperature and sunlight conditions and, if left untreated, will cause taste and odor problems in the finished waters. The problems caused by algae in municipal water plants are handled in a variety of ways by current treatment methods. The odor and taste problems which typically recur during periods of high summer temperatures and long daylight hours occur from detritus thrown off by algae in the clarifier. Not all of this detritus is removed by sand filters. Any detritus passing through the sand filters is converted in the final chlorination process to a family of chloro-organic compounds which cause the objectionable smell and taste that consumers complain about.
The standard treatment for controlling algae in municipal water plants is to scatter crystals of cupric sulfate pentahydrate, CUSO
4
.5H
2
O, which is also known by its common name blue vitriol, into the clarifier. Blue vitriol is commercially available in 50 pound bags having crystals ranging in size from fine (⅛″) to large (1″). Scattering is done with a shovel, a scoop, or by hand. Ideally, the crystals dissolve in the water so the copper ion is present in the water. The soluble or active copper (II) ion kills algae because of its effect on chlorophyll which is a large porphyrin structure occurring either as blue-green chlorophyll-a or yellow-green chlorophyll-b. Both molecules have four centrally placed nitrogen atoms which complex a single magnesium atom. The magnesium removes carbon dioxide from the water and delivers it to the algae thus allowing photosynthetic growth. The soluble copper (II) ion replaces the magnesium by forming a stronger porphyrin complex, which does not bond with carbon dioxide. The algae dies by virtue of its growth mechanism being squelched by a lack of carbon dioxide, in a process analogous to the chemical poisoning of hemoglobin in mammals. A small part of the algicidal copper exits the treated water stream in the clarifier sludge and not with the finished water because it has been intimately bonded to the algae chlorophyll. A large part of the copper sulphate is believed to remain undissolved and drops into the clarifier sludge as copper hydroxide coated pellets. One of the inherent advantages of copper algicides is that algae cannot mutate or evolve to avoid its effect. No amount of evolution can prevent copper from displacing magnesium in the chlorophyll and no amount of evolution can cause the copper porphyrin to absorb carbon dioxide.
Disclosures of some interest are found in U.S. Pat. Nos. 3,844,760; 4,012,221; 4,505,734 and 5,541,150.
SUMMARY OF THE INVENTION
The above description of the prior art is an idealized situation but which has a number of practical problems and disadvantages, some subtle and some not so subtle. A substantial part of the blue vitriol does not dissolve because it is difficult to dissolve in water which is not acidic. Plainly put, blue vitriol crystals do not dissolve very well in pH 7, or more alkaline, water. Thus, much of the copper sulfate is wasted because it ends up in the clarifier sludge as blue vitriol pebbles with a thin copper hydroxide coating. In addition, scattering blue vitriol crystals in the clarifier does not produce uniform dosages of copper sulfate in the water. Instead, very high dosages will be found immediately down current from the crystals and little copper sulfate will be found elsewhere.
In this invention, a water soluble copper salt is dissolved in an aqueous solution of an acidic flocculant. It is fortuitous that the selected flocculants are quite acidic because many water soluble copper salts, and the preferred copper sulfate, are much more soluble in low pH water than in neutral to high pH water. The resultant algicide-flocculant solution is commonly delivered in a tank truck or by a tank rail car and off loaded into storage tanks.
The solution is then metered into the clarifier, thus delivering a reliable, predictable quantity of flocculant and copper algicide. This technique operates to deliver a uniform low dose of copper algicide in a very simple, efficient and trouble free manner because flocculant metering pumps deliver a controlled amount of flocculant in a manner which mixes the flocculant into the raw water in a thorough and uniform manner. It is this liquid injection that thoroughly and uniformly mixes the algicide with the water, as contrasted to the prior art technique scattering of blue vitriol crystals with a shovel into the clarifier. Efficient mixing of the copper algicide with the water provides low, uniform dosages of copper which is very desirable because little copper is wasted.
The copper solution provides copper (II) ions that displace the magnesium ion in chlorophyll to kill the algae in the clarifier. The amount of copper in the algicide-flocculant solution is controlled; thus the amount of copper in the clarifier is also controlled and is maintained at low levels. The copper reacts with the magnesium in the chlorophyll molecules and, along with the dead algae, collects in the sludge in the bottom of the clarifier.
When using this invention, no blue copper crystals will be found in the clarifier sludge which means that more of the copper has been put to its intended use of killing algae rather than wasted in the clarifier sludge. In addition, the amount of soluble copper ion passing through the clarifier into the finished water will normally not exceed 0.1 ppm which is well below the 1.3 ppm standard required by the Lead and Copper Rule of the Environmental Protection Agency.
It is difficult to overstate the importance of low, uniform dosages of copper. For the algicide to be effective, copper (II) ions must come intimately close to the magnesium ion in the chlorophyll complex of substantially all of the algae cells. Although there is moderate circulation in the clarifier, it is hard to imagine copper ions in concentrations on the order of less than 1 ppm reacting with enough magnesium atoms in chlorophyll to control an algae bloom. However, this can be done with improved mixing and distribution of the algicide when it is combined with the flocculant as in this invention. Uni
Linn Tosby L.
Nier Thomas J.
Bay Chemical and Supply Company
Moller G. Turner
Pak John
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