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H20 Pure Plus ® BioClean -
the science & technology of the Zeta RodTM

H20 Pure Plus ® BioClean is the description we use for an extraordinary variety of natural, non-chemical water treatment applications where there is a specific need for the ultimate control of scaling, corrosion and biofouling.

The use of ionizers have become increasingly important in the treatment of water in many industrial and commercial situations. Potentially toxic microorganisms such as algae and bacteria cannot survive. BioClean ionizing rods are easily applied to domestic water cleansing needs. In other words the slimy green biofouling film and scale that collects on the inside walls of rainwater tanks disappear completely with the electronic ionizing rods. Coupled with the Rainfresh natural treatment unit, tank water has never been so pure.


H20 Pure Plus has joined with the Zeta Corporation of the United States to introduce the world's most effective water quality systems.

And the reason H20 Pure Plus® has joined with Zeta RodTM is explained below.

The science & technology of the Zeta RodTM

Many of the problems associated with water systems such as scaling, corrosion, and biofouling are largely governed by interactions between materials suspended in the water and the wetted surfaces of the system.

The Zeta Rod works by altering the natural surface charge of suspended particles. The results of this fundamental physical alteration are profound: particles that would normally stick to surfaces or agglomerate into scale or biofilms remain separated in stable suspension.


The stability of the suspension is enhanced by increased electrostatic repulsion between particles due to the "double layer" of ions that surround particles and wetted surfaces.

The formation of the double layer is shown in the figure below. In the illustration below the particle (blue) is shown to have a net negative surface charge. The particle is surrounded by a layer of ions (red) that remain tightly bound to the particle surface.


The bound layer is in turn surrounded by a layer (light blue) that is much more diffuse and is not tightly bound. Forces acting upon the particle can cause distortion or separation of the particle from the diffuse layer at the "shear plane" but the tightly-bound layer is considered to remain attached to the particle as it moves.

Particles exposed to the powerful electrostatic field of the Zeta Rod electrode experience an elevation in surface charge that increases the density of the bound layer. The stronger bound layer serves to prevent the approach of the charged particles to each other.

Wetted surfaces also form a strong bound layer, which prevents particles from attaching. The cleanliness of wetted surfaces preserves heat transfer efficiency and interferes with the metabolic processes that lead to biofouling by microorganisms.

Zeta Rod electrodes are designed to generate the powerful field required to ensure stable particle dispersion in a wide variety of applications.

How the Zeta RodTM works

The Zeta Rod forms a capacitor when placed in the vicinity of a grounded conductive surface such as a metal water pipe, storage tank, or sump


For a cylindrical capacitor, the total capacitance of the system is given by the equation above, where:

C is capacitance,
q is charge,
v is voltage,
I is length, and
a and b are the radii of the electrodes forming the capacitor.

The primary field of the Zeta RodTM (potentials above about 5 kV) extend for about 20 feet in either direction from the electrode surfaces.

Applications & industries

Because the Zeta RodTM affects the fundamental physical properties of particles in water, there are numerous applications of the technology in diverse industries, including:


Cooling Towers
Industrial and Commercial HVACR - heating and cooling: the Zeta RodTM eliminates the requirement for chemical pH control, corrosion inhibitors, and biocides, maintains heat transfer efficiency, and reduces water and sewer costs.
Chillers

Metal Working Fluids
Metal working: the Zeta RodTM prevents biofouling of lubricant and coolant mixtures without the necessity for chemical biocides that can adversly affect lubricant and coolant performance.

Reverse Osmosis
Reverse osmosis and membrane filtration: the Zeta RodTM extends membrane life by interfering with the attachment of microbes and suspended solids to membrane and other wetted surfaces.
Agriculture

Evporative Condensers
Glass production: the Zeta RodTM prevents biofouling of shear lubricants and plugging of spray systems without chemical biocides that deteriorate lubricant performance.

Evaporative Coolers
Pulp and paper processes: the Zeta RodTM improves the cleanliness and efficiency of many water-based processes inclduing showers, heaters, evaporators, and paper machines.

Paper Machines
Brewery and beverage pasteurization and processing: the Zeta RodTM can replace chemical biocides in pasteurizers, and improves the performance of refrigeration systems and heating and cooling equipment.

Eliminate chemical usage in water treatment for heating and cooling systems

The Zeta RodTM system represents a powerful, robust, and elegant means of eliminating scale, deposits, and biological fouling in water-based heating and cooling systems.

By stabilizing the dispersion of suspended and colloidal substances in water, the Zeta Rod permits operation at high cycles of concentration without scaling heat transfer surfaces.

And because the Zeta Rod interferes with the ability of microbes to attach to wetted surfaces, it prevents the proliferation of biofilm and slime that can clog equipment, interfere with efficient heat transfer, and cause corrosion and foul odors.

You can obtain more information regarding the benefits of the Zeta Rod system in various types of heat exchangers:
  • Evaporative coolers: treat many coolers with a single cost-effective Zeta Rod system.

  • Cooling towers and chillers: water, energy, chemical, and maintenance savings without corrosion, scaling, and biofouling.

  • Evaporative condensers: operation at elevated cycles of concentration without scaling, corrosion, and biofouling.

  • Air washers: elimination of scale and foul odors.

Disease and biofouling in water systems

Biofilm is a slick coating on wetted surfaces produced by many types of microbes. A thin layer of biofilm usually coats the interior of piping and other water handling equipment. This material provides both habitat and food supply for a range of bacteria including Legionella.

Legionella bacteria, according to the Centers for Disease Control, are ubiquitous in nature but rarely present a problem to humans. The danger exists when humans inhale tiny droplets of water containing Legionella. A normal healthy person might not be affected, where a person already ill or recovering from a severe medical procedure is especially susceptible and is more likely to develop Legionaires Disease.

Biofilm is highly resistant to cleansing by chemical and mechanical action. Biofilm durability is demonstrated by its resistance to penetration by biocides. Sheltered inside the biofilm, Legionella and other bacteria reproduce, protected from biocides such as chlorine or ozone. Areas of piping that have been treated to kill the bacterial population are often quickly reinfected by bacteria that have survived the treatment chemicals. Full sanitizing of water systems and equipment is virtually impossible without controlling the development of the host biofilm and scale.

The Zeta RodTM prevents microscopic particles from sticking together. When particles of mineral matter stick together the product is scale. When bacteria join together and multiply the product is slime or biofilm. Legionella are known to live in, and take nutrition from, both scale and biofilm deposits. When the deposits are no longer present, biocidal agents are able to attack directly and destroy the harmful microbes.

Biofouling & Biocorrosion

Corrosion in iron water pipe. It is now reported that up to 70% of all corrosion in water systems is caused or accelerated by microbes.

There is increasing recognition that microbes such as bacteria play an even larger role in all forms of corrosion than previously thought. [Refs here] The widely-accepted model for bacterial fouling in water systems involves the following steps:
  1. Attachment of organisms to a surface.
  2. Absorption and metabolism of simple organic molecules that fuel further metabolic action (below left).


  3. Generation of the glycocalyx, a polysaccharide that serves to further anchor the organism and protect it from adverse environmental factors such as changes in temperature, flow, pH, or the action of biocides (above right).



Through water channels in the glycocalyx the thriving bacterial colony is able to absorb nutrients and oxygen from the water. However, as growth continues and the depth of the slime layer increases, there is little penetration of oxygen in the layers against the pipe or vessel surface.

Effects of biofouling

Anaerobic bacteria can propagate in the deeper layers of the biofilm where little oxygen reaches. Some of these anaerobes are capable of metabolizing carbon from stainless steel, and some produce nitric, sulfuric, or other organic acids that further accelerate corrosion.

The depletion of oxygen in the wetted surfaces under bacterial colonies can result in the formation of "differential aeration cells" that can lead to galvanic corrosion.

By interfering with the ability of microbes to attach to wetted surfaces, the Zeta RodTM stops the microbial surface fouling at the source.

Corrosion

Most metals in their refined form (except for a few noble metals such as gold) are inherently unstable. The tendency of refined metals to revert to their natural mineral states is a driving force behind corrosion processes.

There are a number of different types of corrosion, including:
  • General or overall corrosion: a uniform attack over the entire exposed area of a surface across a wide range of temperatures.
  • Pitting corrosion: high localized corrosion rates with little or no general corrosion to the areas surrounding the pits.
  • Galvanic corrosion: when two dissimilar metals are electrically connected in the presence of an electrolyte, the more electrochemically active metal corrodes by giving up electrons and corrodes an increased rate.
  • Microbiologically-induced corrosion (MIC): Microorganisms form colonies on surfaces, leading to corrosive conditions.
  • Stress-corrosion cracking (SCC): when a stressed metal is exposed to certain types of environments it may become susceptible to stress-corrosion cracking at stress levels that may be significantly below the yield strength of the material.

Galvanic corrosion

Galvanic corrosion is a form of electrochemical corrosion that occurs when two dissimilar metals in the presence of an electrolyte form an electrical circuit, known as a galvanic cell.

In a galvanic cell, an exchange of electrons takes place,that causes one of the metals to corrode at an accelerated rate (compared to its corrosion rate without the presence of the other metal). The active, corroding metal, called the "anode" gives up electrons to the less active, non-corroding metal called the "cathode". After the anode corrodes completely away, the cathode will again begin to corrode as reflected by its position in the Galvanic Series.

By preventing the attachment and proliferation of microbes, and stabilizing the dispersion of colloidal particles, the Zeta Rod eliminates two major sources of corrosion in water systems.

Scale

Scaling is the deposition from solution onto a wetted surface. In many water systems, metal salts such as calcium carbonate and calcium sulface naturally present in the water can be deposited, reducing the efficiency of on heat transfer, and eventually leading to occluded piping and failure of the system.

The Zeta RodTM keeps these potential deposit formers in stable dispersion, preventing them from agglomerating or adhering to wetted surfaces.


Reverse Osmosis

Reverse Osmosis ("RO") is a process whereby water is forced through a membrane which prevents the passage of contaminants. The resulting pure product water, called "permeate," is then used in a wide variety of processes including:
  • Semiconductor and microelectronics manufacturing,
  • Production of pure water and beverages for human consumption,
  • Pharmaceuticals, drugs, and other health products,
  • Many different industrial products.
In RO and other filtration applications, the Zeta RodTM extends the life of filter media and membranes, greatly reduces downtime for cleaning, and stabilizes permeate production at a high level.

By preventing the attachment of particles including microbes, to wetted surfaces and membranes, the Zeta RodTM stops membrane fouling.

Membrane fouling is the principal problem faced in reverse osmosis operations. Fouling has been labeled as unavoidable by many sources. The origin of fouling varies from one location to another. It can be of a mineral origin, biological origin or a combination of both.

The Zeta RodTM system effect in preventing membrane fouling comes from the alteration of surface charge densities both on waterborne particle as well as wetted surfaces; membranes are included among these wetted surfaces.

Membrane fouling will manifest itself by one or several of the following signs:
  • Increase in feed pressure to maintain permeate flow.
  • Reduction in permeate flow at constant feed pressure.
  • Increase in pressure differential.
  • Increase in salt rejection rate and decrease in recovery rate.
  • Reduction of permeate quality.
  • Variations in the fouling matrix indicated by high fluctuations in pressure feed and pressure drop.
The fouling rate can be determined by establishing the time it takes for a clean set of membranes to drop their productivity by a given percent (usually at a 10% loss in permeate, membrane cleaning is performed).

A Zeta RodTM application to a clean membrane system will produce:
  • Significantly reduced fouling rate
  • Stable permeate rate at constant feed pressure
  • Low transmembrane pressure drop
  • Stable salt rejection rate
  • Stable recovery rate.
On a fouled system, application of the Zeta RodTM will produce:
  • Increase in normalized permeate flow rate at a constant pressure
  • Significant decrease in pressure feed to maintain constant permeate flow rate
  • Reduction in transmembrane pressure drop
  • Increase in recovery rate
The conditions listed above represent effects that have been consistent in Zeta RodTM RO applications. Specific results vary from system to system depending on the age of the membranes, membrane condition, water quality, and operating conditions. The performance of an RO system will improve in cases where the membranes are fouled, and the system will operate closer to the design parameters for much longer periods of time when the Zeta RodTM is installed before significant fouling has occurred.


Process leaching

Although the Zeta RodTM does not alter the chemistry of water it does reduce the surface tension of water, affecting how water interacts at surfaces. Improved wetting at surfaces has benefited numerous process applications, including micropore sponge production, and soil penetration in irrigation. There may also be improved leaching action by preventing the aggregation of colloids that would otherwise fill and block pore spaces in the material being leached.

Flocculation

The performance of polyelectrolytes can be modified to suit the nature of the colloidal material that is to be removed from a water, by altering the molecular weight and ionic nature of the polymer. Some of these modified polyelectrolytes are rather expensive and are very sensitive to changes in the chemistry of the water being treated.


Above, a pictorial representation of the action of polyelectrolyte chains upon particles suspended in water.

The elevated particle charge produced by the Zeta RodTM causes enhanced reactivity of synthetic polyelectrolytes, allowing the use of a less expensive, less sensitive, or less specific formulation in some applications with increased efficiency.

Enhanced flocculation with the Zeta RodTM has been demonstrated in process water clarification, centrifugation of sanitary sewer sludge, flocculation of metal hydroxides in a planetary wastewater, and enhanced flocculation of fines in a secondary fiber papermill wastewater system.

Wastewater Recycle And Reuse With The Zeta RodTM

Shown is one excellent application of the Zeta Rod to water re-use. The briney reject from a reverse osmosis unit, high in dissolved solids, is used as make-up for a Zeta Rod-equipped cooling tower. The Zeta Rod allows the tower to operated at elevated cycles of concentration with a very high solids load without scaling.


Not only does this arrangement eliminate a source of high-solids effluent from the RO into the outside environment, it replaces cooling tower make-up water that would otherwise have to be purchased.

Cooling towers



Cooling towers receive significant benefits from application of a Zeta RodTM system:
  • Elimination of chemical water treatment,
  • Reduced blow-down and operation at higher cycles of concentration without scaling,
  • Elimination of biofouling, and
  • Excellent corrosion protection.
Airborne dust, pollutants, chemicals, and organic materials such as pollen, leaves, spores, and microorganisms that continuously innoculate the cooling tower water system with potentially troublesome agents.

The water circulating in the tower typically contains inorganic salts such as calcium carbonate, calcium sulfate, silica, and other components that can form scale, interfering with the passage of air and water in the tower.

As water evaporates from the tower, these contaminants become more and more concentrated, increasing the likelihood of deposit formation.

Installation of a Zeta Rod system in the water system of a cooling tower prevents deposit formation and stops the proliferation of algae, fungi, bacteria and other microbes.

Because particulate and suspended material does not attach to wetted surfaces, and because biological activity is suppressed, corrosion rates are typically less than 2 mils/year for mild steel and less than 1 mil/year for copper. The figure below shows corrater (electronic corrosion measurement) data for the cooling tower of a glass bottle manufacturing facility with a Zeta Rod system installed in the tower sump.


Enhanced Cooling Tower Performance With The Zeta RodTM


Continuous operational integrity


The Zeta Rod system power supply model ZRPGM is equipped with a local alarm system to report any fault or failure of the energy level of the system before it becomes a problem. The ZRPGM has a "local alarm" which provides 100 VAC for activation of audible or visible annunciators if a system fault is detected. The ZRPGM also incorporates an arc detector with manual reset, and electrode voltage reporting by 4 to 20 mA proportional output for digital equipment communication.

Scale detection

Scale formation is not observed in Zeta RodTM systems as long as the physical and electrical integrity of the power supplies and electrodes and their connectors are intact. The Zeta RodTM system is self-monitoring in this respect.

Inspection for any deposits should be done on a monthly to quarterly basis. Scale is seen early in the tower fill and deck and system condition can be determined by periodic observations coupled with the annual condenser inspections. Other data relative to heat transfer are provided by the system efficiency readings commonly reported in central energy management and equipment monitoring systems.


Heat exchangers

The Zeta RodTM system prevents scaling of heat exchange surfaces that can reduce energy efficiency and damage equipment. Examples of applications where the Zeta RodTM has improved the performance of heat exchangers include:
  • air handlers: improved cleanliness preservation of media
  • evaporative coolers: reduction in scale on pads, reduced corrosion of structural parts, with less blow-down
  • cooling towers and chillers: operation at higher cycles of concentration without scaling.
Process deposit control
Virtually all industrial processes that utilize large flows of water experience heavy fouling of process equipment and piping, as well as heat exchange equipment.



Water-based processes often exhibit aggressive fouling by reactions secondary to the basic process.

The modular design of the Zeta RodTM system allows installations to be made accommodating unique process system design problems. Large vessels or piping, high flow volumes, and complex process chemistry are all amenable to Zeta RodTM deposit control applications.

The Zeta RodTM has successfully solved fouling or deposit problems in the following applications:
  • heavy calcium sulfate interference in a protein synthetic process,
  • solvent extraction sludge problems in copper processing,
  • surface film prevention,
  • specialty leach processing,
  • ice-making equipment,
  • mine tailing water recycle,
  • acid mine drainage iron oxide control,
  • multiple effect evaporator scale prevention,
  • membrane filter fouling,
  • bacterial contamination of cutting/milling fluids,
  • paint spray booth build-up, and
  • can and bottle pasteurization.

H2O Pure Plus® is wholly owned by H2O World Wide Water Solutions Pty Ltd, an Australian company based on Queensland's Gold Coast. The H2O Pure Plus® BioClean system incorporates the Zeta Rod technology under agreement with




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