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OVERVIEW OF PHOSPHATE TECHNOLOGY

AS CORROSION CONTROL TREATMENT FOR DRINKING WATER
DISTRIBUTION SYSTEMS

Phosphate Raw Materials

There are basically 18 known phosphate raw materials that are manufactured today with two more special commercial phosphate blends, one for oil field drilling mud and the other as a fire retardant.

It also is commonly known that a number of these phosphates have ability to sequester divalent metals (including the softer metals calcium and magnesium). However, the level of sequestration for each phosphate varies considerably with pH and differs between hard divalent metals (iron, manganese, etc.) and soft divalent metals (calcium, magnesium). That is, a phosphate that sequesters hard metals at a specific pH will sequester considerably less soft metals at the same pH, and vice versa. At the pH of drinking waters, between pH of 6.5 to 9.0, there are severe limitations on the sequestering ability of the phosphates.

PHOSPHATE CHEMISTRY

The uniqueness of phosphates to sequester at all and the fact that their use for almost 100 years in food chemistry for human consumption, make them the prime candidate raw material for corrosion control use in drinking water systems.

1) The first challenge becomes which raw materials to use and in what proportions. It also is well known that polyphosphates revert to orthophosphates under time, pH changes, and particularly temperature changes.

2) Because of this, it becomes a second challenge to find a way to slow or stop this reversion process in order to maximize the performance of these raw materials for drinking water corrosion control use. In fact, there have been some AWWA studies pointing to the fact that because of reversion, polyphosphates actually increase toxic lead and copper levels. The problem with such products noted in the studies is a combination of disproportionate poly/ortho ratios, the wrong combination of specific orthophosphates and polyphosphates, and reversion of the polyphosphate portions.

3) The third challenge becomes finding the right combinations of different polyphosphates and different orthophosphates to lower toxic metals (i.e. lead and copper) coming from distribution piping and tap fixtures without the presence of calcium (or magnesium) in the water (normally required to form a calcium phosphate coating), as well as making the blend resistant to reversion...which is the real key to optimizing performance.

All three challenges can be solved using a singular approach. That is, focusing on the correct raw materials in the correct proportions along with SQ 547 proprietary technology. This singular solution considerably slows or stops the reversion process of polyphosphates to orthophosphates. For example, the reversion of a polyphosphate follows the reaction below:



Even though this reaction is reversible, the major tendency is left to right. When the proper combination of “common ion” phosphate components are found, than these “common ion” phosphate components, in combination with other indigenous factors within distribution piping, force the reaction to go back to the left until a steady state equilibrium is reached and the system enters into a relative apparent static state. That is, reversion takes place in both directions. Polyphosphates revert to pyrophosphate intermediate and then to orthophosphates while orthophosphates reform into pyrophosphate intermediates and back to polyphosphates (these later steps require an energy source that is part of SeaQuest’s proprietary SQ 547 technology). Once the steady state equilibrium is established, the formula called SeaQuest becomes very resistant to changes in pH, time, and temperature within the drinking water distribution system. Because the reaction is in a constant state of movement back and forth, even though it is in an apparent static condition, the specific ingredients no longer become pH dependent with respect to sequestration so that;

a. sequestration of both hard and soft metals occurs at the same pH levels,

b. reversion no longer throws the reaction out of balance so stability rules,

c. Temperature no longer dramatically speeds up reversion so sequestration stabilizes even at higher temperatures,

d. And all the other positive aspects of phosphates with respect to drinking water treatment are magnified.

SeaQuest’s proprietary SQ 547 technology does not involve any change in phosphate chemistry. Such compounds are readily used in numerous common grocery store foodstuffs including baked goods, dairy goods, meats, drinks, eggs, cereals, etc. The SQ 547 proprietary technology does involve how the blended ingredients are put together under a unique environment that results in all the listed product claim benefits. Just as Coca Cola formulation and recipe is proprietary and made in Atlanta, Ga., so to SeaQuest formulation and recipe is proprietary and made in Atlanta, Ga. Both products enjoy a long history of safe human consumption.

Phosphate Performance Characteristics

Once the proper blend of appropriate raw materials is found, then two inherent phosphate characteristics become very magnified. One is the ability to remove corrosion/scale deposits that is nothing more than slowly sequestering pre-existing deposits built up within water piping distribution systems, and two is the ability to phosphatize (forming an iron phosphate coatingindependent on the absence or presence of calcium) on metal surfaces.

The process of slow sequestration of pre-existing deposits within a piping distribution system starts with sequestration of these deposits on the inside surface of a pipe at the interface layer of the water and deposit surface. It is believed that this sequestration involves a precursor stage of hydrogen bonding with the deposit oxide and the phosphate entity of the SeaQuest molecular structure. As a result, deposits are only slowly taken into solution (sequestered) causing an increase in metals in the water. At the same time the corrosion protective-phosphate-coating is formed on bare metal surfaces causing a decrease in metals in the water normally coming from the mechanical force of flow. The net effect is deposit removal with little to no change in the water quality at the tap.

As more and more of the deposit oxide is sequestered and more and more of the hydrogen bonding precursor stage develops, the overall integrity of the deposit mass changes its color (chemistry) and becomes softened. Once softened enough, this mass can be flushed out by hydrant flushing or simply disappears in the normal course of flow without any negative effects to water quality at the tap.

The fact that a proper blend of phosphate raw materials--SeaQuest--indeed can phosphatize metal surfaces at ambient temperatures and very low treatment rates (in the >1 ppm range) is a tremendous magnification of inherent phosphate characteristics. The process can be visually demonstrated more rapidly by placing a steel coupon into a jar of SeaQuest Liquid (3.9 active pounds in a gallon) heated to 180°F for 30 seconds, rinsing the coupon and allowing the coupon to air dry. Once dry, a very continuous monomolecular irridescent phosphate coating is very visible. The formation of the iron phosphate coating on water carrying pipes is what optimizes lead and copper corrosion control as well as overall corrosion control.

Inside this Newsletter

1. Zebra mussels

2. Plastic piping & rubber gaskets

3. How do biofims form and how do we fight them?

4. On line

5. Thought of the month

6. Anyone know the answers?

7. The ice man cometh

8. Desal and RO

9. Overview of Phosphate
Technology

10. Phosphate Performance vs. New Drinking Water Regulations