US20170211191A1

US20170211191A1 - Systems and methods to prevent contamination of potable water with lead and/ or iron, and to extend the useful life of the potable water system, while reducing maintenance and capital costs

Info

Publication number: US20170211191A1
Application number: US15/428,102
Authority: US
Inventors: Frank Seth Gaunce
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-07-28
Filing date: 2017-02-08
Publication date: 2017-07-27

Abstract

Provided are systems and methods for preventing corrosion, and lead and iron contamination in potable water piping systems comprising lead, non-electrically conducting, and/or iron pipes. A sacrificial/potential anode, made of a material, such as a metal or metal alloys less noble than iron, e.g., zinc, aluminum, magnesium, and/or alloys thereof, is electrically attached to the potable water piping system. Alternatively, an active cathodic corrosion prevention system may be used. The active cathodic corrosion protection system comprises an independent source of DC power, a voltage controller and a non-sacrificial or a sacrificial/potential grounding anode. The negative terminal of the voltage controller is connected to the potable water piping system. The interior surface of the lead and/or iron pipe is maintained at a voltage and/or potential above the reduction potential of the redox reactions between the disinfection chemicals and the interior surfaces of the lead and iron pipes.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims to priority to U.S. Provisional Utility Application Ser. No. 62/388,798 filed Feb. 8, 2016, the contents of which are incorporated herein by this reference. This Application is also a Continuation-in-Part of application Ser. No. 15/177,770, filed Jun. 9, 2016, and a Continuation-in-Part of application Ser. No. 14/811,629, filed Jul. 28, 2015 the contents of both applications are incorporated herein by this reference.

TECHNICAL FIELD

This invention relates to potable water delivery systems, and more specifically, systems and methods for preventing lead and iron contamination of potable water by the lead and iron delivery system. The method controls the internal corrosion by controlling the chemical redox reaction between the protective concentration of disinfection chemicals and the iron and lead metal pipes. The internal corrosion is prevented by maintaining the redox reaction in cathodic mode by impressing a cathodic potential on the system equivalent to, or higher than the cathodic potential of the redox reaction. External corrosion is prevented by the cathodic corrosion protection method, employing a sacrificial anode. Depending on conditions, this sacrificial anode may provide a high enough potential to control the internal redox reaction in cathodic mode. In such case, the anode is referred to as a sacrificial/potential anode.

BACKGROUND

During the late 19th century and early part of the 20th century, building codes required that cast iron pipe be used for mains, and lead pipe be used from the mains to the point of delivery of potable water. Many of these systems remain in use today, but over time, some pipe components have failed. By mid-century, failed components had been replaced with plastic components, which resulted in unintended and undesirable consequences, including contamination of the potable water with iron and lead.
The potable water is delivered to the distribution system (which includes the mains and the other piping components from the mains to the point of delivery) essentially lead and iron free. A small excess of disinfectants (chlorine, bleach, ozone, and/or other oxidants) referred to as a protective concentration, is left in the purified water to assure its purity at point of use, should the water become contaminated during delivery. This 1-4 ppm of chlorine or other oxidants can react with the interior of the iron mains and the lead piping, causing corrosion.by a redox reaction between the excess disinfectants and the lead and iron. However, the amount of iron corroded from the iron pipes is not enough to exceed permissible concentrations of iron in potable water, nor is it great enough to reduce its service life by an unacceptable amount.
Regarding lead, so long as the lead and iron pipes remain in electrical contact the lead does not corrode because it is at the reduction potential of iron, which is considerably higher than the reduction potential of lead. Additionally, should lead be present in the water, some would be plated on the iron.
However, the ageing iron and lead potable water distribution systems can no longer reliably deliver potable water that meets the current regulatory standard for lead content. Corroded iron mains are being repaired with plastic, thus breaking the electrical conductivity of the distribution system, which in turn negates the cathodic potential protection of the lead pipes. Consequently, the protective concentration of purification chemicals left in the potable water is corroding the interior of the lead pipes in a redox reaction, thus adding unacceptable amounts of lead to the water. This redox chemical reaction is generally not recognized by the potable water suppliers, or consumers as a source of lead contamination. Consequently, the lead contamination is ascribed to different sources. As a result, inappropriate, ineffective, and costly actions are taken in an attempt to correct the lead contamination.
Lead poisoning is a serious health concern, and even small amounts of lead can cause serious health problems. Infants and children under the age of 6 are especially vulnerable to lead poisoning, which can severely affect mental and physical development. At very high levels, lead poisoning can be fatal. As a result of the corrosion of the lead pipes, children may be physically and/or mentally damaged before the lead contamination is discovered and corrective action taken. The intelligence deficit and the tendency toward violent behavior is carried into adult life resulting in undesirable consequences, such as poverty and crime.
Corrosion inhibiting reagents are being used to mitigate this problem of iron and lead corrosion to a limited success. In some cases, to solve the problem, the lead pipe is being removed and replaced with copper or plastic piping. This is costly, and although this may solve the lead problem, it introduces a similar problem of copper corrosion and leaves the failing iron mains to be dealt with at a future date.
Other corrective actions can be very costly and may range from a few million dollars to supply bottled water for an extended period of time, or to complete replacement of the potable water distribution system at a cost of perhaps several billion dollars and the bankruptcy of a community.
There is, therefore, a need for potable water systems and methods that preemptively prevent or reduce the corrosion of iron and lead pipes in potable water systems.

SUMMARY

It is an object of this invention to limit the lifelong loss of intellectual capacity and tendency to violent behavior due to lead poisoning, particularly of infants, young children, and to a lesser extent, of adults.
It is a further object of this invention to reduce the level of violence and criminal activity in older sections of our cities that requires additional policing to maintain order by reducing lead poisoning by potable water of children and adults.
It is also a further object of this invention to provide a relatively inexpensive way to control the lead content of potable water to regulatory standards, and to extend the useful life of the existing potable water distribution systems.
In accordance with the foregoing objectives and others, exemplary systems and methods are disclosed herein that can be used to prevent or reduce the corrosion of iron and lead pipes in potable water systems.
Each electrically isolated section of lead pipe is electrically connected to a grounded zinc or zinc alloy mass or other more cathodic metal or metal alloy, which serves as an electrode. This type of metal mass is commonly referred to as a sacrificial anode, and the process, as cathodic corrosion prevention. This method is commonly used to prevent the exterior corrosion of metals in contact with an electrolyte that is shared with the sacrificial anode. However, in this case, there are two purposes for the anode; firstly, to protect the iron pipe from exterior corrosion resulting from contact with soil or water electrolyte; secondly, to prevent the interior of the iron and lead pipes from corrosion by their redox reactions with the protective concentration of disinfectant chemicals, left in the potable water. This later objective is achieved by raising the internal potential of the pipes to, or beyond, the cathodic potential of their respective redox reaction potentials. It is recognized that so long as the lead is electrically connected to the iron, the lead is protected by the reduction potential of the iron. Alternatively, or in addition to, each electrically isolated section of iron or lead pipe is electrically connected to a grounded mass of zinc metal, zinc metal alloy, or a lesser noble metal such as aluminum or magnesium, or alloys thereof, or other source of appropriate electrical potential.
Alternately, the potential of the iron and lead pipes can be raised above their reduction potentials by connecting them to a source of DC power of appropriate potential above ground.
Because the sacrificial anode and the iron and lead pipes share a connection through the ground which acts as an electrolyte, the sacrificial anode and the external surfaces of the iron and lead pipes create an electrolytic cell which generates an electrical current that corrodes the anode and prevents corrosion of the exposed surfaces of the iron and lead cathodes. Because metallic iron has a higher reduction potential than lead, and because the iron and lead are electrically connected, and because the impressed DC voltage required to assure that the redox reaction between the iron and the protectant concentration of disinfectant chemicals is cathodic and at least equivalent to the reduction potential of iron, both the exterior and interior, the entire distribution system is protected from corrosion. By this method, all electrically connected metallic system components with reduction potentials more noble than the impressed cathodic voltage are protected from corrosion.
The details of one or more embodiments of the subject matter of this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are illustrated by way of example and not limited to the figures of the accompanying drawings, in which like references indicate similar elements and in which:

FIG. 1 illustrates a passive corrosion prevention system according to one embodiment of the invention.

FIG. 2 illustrates an active corrosion prevention system according to one embodiment of the invention Note that an electrical conductor is used to bridge a non-conducting section such as a break and/or a plastic repair.

FIG. 3 illustrates the use of fire hydrants and /or other above ground metal components as points of electrical connection to the distribution system.

DETAILED DESCRIPTION

The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show illustrations in accordance with example embodiments.
The systems and methods disclosed herein for preventing corrosion of lead and/or iron piping comprise electrically attaching a dedicated cathodic corrosion protection system to the lead and/or iron pipes. The passive cathodic protection system may comprise a sacrificial anode or multiple anodes made of, zinc metal, zinc alloy, or a lesser noble metal such as aluminum or magnesium, or alloys thereof. The sacrificial/potential anode is in contact with the ground and electrically connected to the lead and/or iron pipes. The sacrificial/potential anode maintains the lead and/or iron pipes at a voltage above the pipes' respective reduction potentials, thus preventing the external corrosion of the lead and/or iron pipes. If the sacrificial/potential anode creates a cathodic potential high enough to make the redox reaction between the protective concentration of disinfection chemicals cathodic, then the interior of the pipes will be protected from corrosion.
Alternatively, an active cathode corrosion protection system supplied by an independent electrical energy source may be used. The positive terminal of the active system is connected to ground by either a conducting non-sacrificial anode or a sacrificial anode. The negative terminal is connected to the lead and/or iron pipes. The voltage between the grounding anode and the lead and/or iron pipes is maintained at a level at, or above, the pipes' respective reduction potential, and the cathodic potential of the redox reaction between the pipe interior surface and the disinfectant chemicals. It must be understood that the necessary cathodic potential to make the redox reaction between the pipe interior and the disinfectant chemicals is dependent on the concentration of the chemicals and the temperature of the system.
FIG. 1 shows an example embodiment of a lead pipe corrosion prevention system according to the present invention. Iron main 110 provides potable water from a water source. Lateral 120 provides water from iron main 110 to a lead pipe 170, possibly through service connection 130. The delivery system is comprised of iron main 110 and lateral 120, and is generally underground, as indicated by the cross hatches. If lateral 120 is plastic, a conducting jumper 140 is used between the iron main 110 and lead pipe 170 in order to maintain electrical continuity throughout the delivery system. Note that, for clarity, only a portion of the ground is shown crosshatched.
The present invention adds sacrificial anode 180, which is electrically connected to the lead piping by, e.g., electrical conductor 190 and clamps 200. While electrical conductor 190 and clamps 200 are provided as an example, any means of electrically connecting sacrificial/potential anode 180 to the lead piping may be used, and one of ordinary skill in the art will recognize other such connections. At least part of sacrificial/potential anode 180 is grounded, as indicated by the cross hatches in FIG. 1. Furthermore, while FIG. 1 only shows one sacrificial anode 180, more than one sacrificial anode may be used. Sacrificial anode 180 is comprised of zinc, a zinc metal alloy, or a more cathodic metal or alloy. One of ordinary skill in the art will recognize other materials that may be used. Sacrificial anode 180 maintains the lead pipe at a voltage above the reduction potential of iron and thus the reduction potential of lead and the reduction potential of the redox reaction between the disinfectant chemicals and lead and iron. Consequently, both the exterior and the interior, of both the iron and the lead pipes are protected from corrosion Thus, both the iron and the lead in the deliver water, added from the delivery system are reduced to a level of little concern, perhaps ppts. Thus, the health problems caused by lead contamination of potable water by the delivery pipes are prevented.
The ground medium provides the electrical return leg of the electrolytic circuit. The required size of sacrificial anode 180 depends on the size and length of the distribution system. The required number and location of sacrificial anodes 180 is dependent on, whether, or not, the lead pipe is electrically connected to the iron main. The iron main acts as a sacrificial/potential anode for the lead pipe. If the lead pipe is not electrically connected to the iron main, a separate sacrificial/potential anode connected to the lead pipe is required to protect the lead pipe from both external and internal corrosion.
FIG. 2 illustrates an alternate embodiment of the present invention, an active cathodic corrosion protection system for both the iron and lead pipes. This system is substantially the same as the system described in FIG. 1, but with a DC voltage from an independent power source controlled at a voltage above the reduction potentials of the iron and the cathodic redox potential of the iron and disinfectant chemicals, is impressed on the lead or iron pipes. In this system, iron main 110 and lateral 120 are substantially the same as described with respect to FIG. 1. In this system, however, either an electrically conducting insoluble anode or a sacrificial/potential anode 210 is used to contact ground. Insoluble anode 210 may be made of an insoluble material, such as graphite. One of ordinary skill in the art will recognize other suitable materials for insoluble anode 210. Insoluble anode 210 is electrically connected to a DC power source 220 and voltage controller 230. DC power source 220 is electrically connected to the variable voltage controller 230. The DC power source 220 may be any source of direct current power, of appropriate voltage, including but not limited to a storage battery or an AC/DC rectifier converter. The variable voltage controller's 230 negative terminal is electrically connected to the lead or iron pipe, for example, the negative terminal of variable voltage controller 230 may be electrically connected to the lead pipe. Variable voltage controller 230 will permit the cathodic voltage to be raised or lowered to control the concentration of lead and/or iron in the potable water at point of delivery. The cathodic voltage may be increased to protect greater areas of the distribution system, as well as for changes in the protective concentration of disinfecting chemicals
Multiple sacrificial/potential anodes and/or DC voltage sources may be connected to any part or parts of the electrically connected potable water distribution system so as to, maintain a desired uniform voltage throughout the entire potable water distribution system.
Fire hydrants, control valves, and flow meters are above ground components that can be utilized as connection points; FIG. 3 to diagnose the electrical continuity of the distribution system, to bridge electrical breaks with surface jumper cables, and to install this cathodic corrosion protection system. By utilizing above ground surface components, the corrosion protection can be installed without excavating to gain access to the underground pipes of the distribution system. This is of major significance when the water mains are located under streets or, other infrastructures.
Similar systems may be used to limit or prevent corrosion of iron pipes. A passive corrosion prevention system for iron pipes includes the components described in FIG. 1, but the sacrificial/potential anode is comprised of zinc metal, zinc metal alloy, or a lesser noble metal such as aluminum or magnesium, or alloys thereof.
An active corrosion prevention system for iron pipes includes the components described in FIG. 2, but the voltage is controlled at a voltage above the reduction potential of iron.
The present invention prevents the excessive lead and/or iron contamination of the potable water, while extending the service life of the iron mains and lead laterals by using cathodic corrosion protection techniques for protecting the exterior surfaces of the lead and iron pipes and potential to control the reaction protect at great savings over the
Additional benefits of this invention include: 1) the cathodic potential will prevent pinhole corrosion of any copper tubing in the distribution system and in the final plumbing; 2) water loss will be reduced; 3) the cost to maintain the potable water distribution system will be reduced; and 4) the use and cost of water purification chemicals will be reduced by eliminating the need for corrosion inhibitors, and less disinfection agent.
Additional Notes:
The protection methods are implemented by electrically connecting to a fire hydrant or multiple hydrants, valves, or flow meters.
Bypass breaks and non-conducting repairs to the iron mains by installing electrical conductors between hydrants located on opposite ends of the break, thus restoring electrical continuity of the underground system without disturbing the ground surface.
Bypass electrical continuity breaks in lead laterals by installing metallic jumpers between a fire hydrant and a water meter on the lateral.
Detect the local level of cathodic corrosion protection by measuring the electrical potential between a hydrant and the ground
Connect the protective power source to a hydrant to boost a decayed protective voltage to protection levels.
Reduce maintenance and capital costs and extend the useful life of the potable water system by implementing these claims that also reduces the iron and lead contamination in the delivered potable water to regulatory levels. (we are assuming that the water purification plant is delivering water with lead content that meets regulatory specifications.)
The corrosion protection system prevents the potable water from being contaminated with lead and iron by the existing water distribution system when this process is implemented. The system maintenance and capital costs are reduced by using surface components such as fire hydrants to electrically detect and correct existing underground electrical faults. Further, fire hydrants are conveniently available throughout the system and can be used to monitor the system's protective voltage, and to provide a local connection to the distribution system to boost any decayed protective voltage. Once preexisting conditions are corrected, my method will deliver potable water without adding lead or iron for a very long time. My methods rejuvenate existing systems and protect new and future systems from decay due to corrosion.
Although the invention has been described in terms of particular embodiments, one of ordinary skill in the art, in light of the teachings herein, will be able to generate additional embodiments and modifications without departing from the spirit of, or exceeding the scope of, the claimed invention. This invention is not limited to using the particular elements, materials, or components described herein, and other elements, materials, or components will be equivalent for the purposes of this invention. Accordingly, it is understood that the drawings and the descriptions herein are proffered only to facilitate comprehension of the invention and should not be construed to limit the scope thereof.

Claims

What is claimed is:

1. A corrosion prevention system for a potable water piping system, wherein the potable water piping system comprises at least one iron main, possibly one section of non-conductive pipe, and at least one section of lead pipe, the corrosion prevention system comprising:

a. iron mains and at least one sacrificial/potential anode electrically connected to at least one section of lead pipe,

b. whereby an interior surface of the section of lead pipe is maintained at a voltage above the reduction potential of the redox reaction between iron and the protective concentration of disinfection chemicals, wherein the lead pipe is electrically connected to the iron main.

2. The corrosion prevention system of claim 1, wherein the sacrificial/potential anode is comprised of a metal less noble than iron.

3. The corrosion prevention system of claim 2, wherein the sacrificial/potential anode is comprised of zinc, an alloy thereof, or a metal or metal alloy less noble than zinc.

4. The corrosion prevention system of claim 1, further comprising a DC power source electrically connected to at least one section of iron main connected to a lead pipe.

5. A corrosion prevention system for a potable water piping system, wherein the potable water piping system comprises at least one iron main, possibly one section of non-conductive pipe, and at least one section of lead pipe, the corrosion prevention system comprising:

a. at least one insoluble anode, and/or a sacrificial/potential anode

b. a power source electrically connected to the insoluble anode, and/or sacrificial/potential anode

c. a voltage controller electrically connected to the insoluble anode, the power source, and the lead pipe,

d. whereby an interior surface of the lead pipe is maintained at a voltage above the reduction potential of iron, wherein the lead pipe and the iron main are electrically connected

6. The corrosion prevention system of claim 5, wherein the insoluble anode is comprised of graphite.

7. The corrosion prevention system of claim 5, wherein the power source comprises a battery or a solar cell and a voltage controller.

8. The corrosion prevention system of claim 5, wherein the power source comprises an AC/DC rectifier-converter.

9. A method for preventing corrosion of a lead pipe in a potable water piping system, wherein the potable water piping system comprises at least one iron main and possibly a section of non-conductive pipe, electrically bypassed by an electrical jumper, comprising:

a. electrically connecting means for corrosion protection to the lead pipe;

b. whereby the interior surface of the lead pipe is maintained at a voltage above the reduction potential of iron.

10. The method of claim 9, wherein the means for corrosion protection comprises at least one sacrificial/potential anode.

11. The method of claim 10, wherein the sacrificial/potential anode is comprised of a metal less noble than iron.

12. The method of claim 11, wherein the sacrificial/potential anode is comprised of iron, zinc, or an alloy thereof.

13. The method of claim 9, wherein the means for corrosion protection comprises a voltage controller, a DC power source, wherein the voltage controller is electrically connected to the power source and the iron and lead distribution system. x

14. The method of claim 13, wherein the power source comprises an AC/DC rectifier converter