CES Commentary to CDC (Center Of Disease Control)

The problems caused be a terror attack on a city water supply are as follows:

1.      People will die, panic and buy all the bottled water they can find.

2.      The US EPA has no practical solutions to an attack on our drinking water.

3.      Chlorinated solvents are toxic and will eat through most RO (Reverse Osmosis membranes).

4.      There is no way to clean the poison from a large drinking water plant or the thousands of miles of underground pipes.

5.      If the local water is turned off there will be no way to put out fires in the area affected.

6.      The proposal by Parsons Engineering to truck in bottled water for an entire city is ridiculous and extremely costly.

7.      It is easy to poison a city water supply and the poison will remain in the pipes for months

Solution:

1.      Contract CES to place RF-100m and RF-700m mobile drinking water plants in strategic

      locations in 1,700 cities.

2.      Create a plan to train and deploy mobile units during an emergency. These units will be

      capable of purifying any type of non-salty water in large volumes and bottling it onsite.

3.      Other units will be used to systematically clean poison from miles of drinking water pipes.

4.      Boiling tap water will not remove antifreeze and metals poison.

5.      Chlorine will not remove most poison.  

6.      Large amounts of poison is easy to purchase or steal.  

This following research onlya general guide. CES has more extensive research and the technical knowledge to counter bio and chemical terrorism. The CDC has agreed to test our technology for countering bio-terrorism.    

Note:  The CDC has agreed to test our mobile emergency drinking water system.

EPA ACTIONS TO SAFEGUARD THE NATION'S DRINKING WATER SUPPLIES   October 2001

Environmental Protection Agency (EPA) is working with other government agencies and water suppliers to ensure that the Nation's drinking water continues to be safe, even from terrorist attack. EPA is providing local water utilities with the best scientific information as well as technical training on conducting vulnerability assessments and enhancing emergency response plans should an attack occur. To further protect the Nation's drinking water supplies, EPA has set up a special task force to enhance protection efforts already underway. The task force will consider how EPA can support efforts by utilities to accelerate local vulnerability assessments and mitigation actions. The goal is to ensure that water utilities are undertaking the steps to understand vulnerable points and to mitigate the threat from terrorist attacks as quickly as possible. The task force will work to speed up the availability of new advanced materials being prepared by EPA and other federal agencies and private sector partners, that will be used in preparedness efforts......... 

For your information, we have compiled the most frequently asked questions concerning the security of the Nation's drinking water.

Water Quality Association (WQA) Press Release on Bio-terrorism

WQA issued a press release on October 16, 2001 concerning possible bio-terrorist threats to our

nation's water supply and POU/POE products' capabilities in meeting those threats. It is important to note that since the release was issued the size of anthrax spores is being re-evaluated; they may actually be smaller than declared by this release....  The FBI has just extended its terrorist threat advisory to water utilities through December 11. Although the FBI knows of "no specific credible threats" to water supplies, they encouraged utilities to maintain security at "critical nodes" such as tunnels, pumping and storage facilities, and distribution systems.  WQA home page

AWWA JOINS WHITMAN IN CALLING TERRORIST THREATS TO NATION'S DRINKING WATER SUPPLY REMOTE - Water Utilities Have Nevertheless Heightened Security Measures,  October 18, 2001

(Denver, Colorado) - The American Water Works Association, an organization that represents America's water treatment utilities and drinking water professionals, joins U.S. Environmental Protection Agency Administrator Christine Todd Whitman in assuring the public that the nation's drinking water is safe and highly unlikely to be compromised in the event of a terrorist attack. Ms. Whitman spoke today about potential threats to the nation's water supply at a press conference in the Washington, D.C., area. American Water Works Association home page

Hotlist is a collection of Web sites grouped around specific topics.  It appears each Tuesday in the Houston Chronicle's Business section and is written by Cay Dickson.  In the weeks since September 11, Cay has written two columns that focus on links that explore various aspects of terrorism. 

Whitman underscores water safety

Citing dilution and treatment barriers as well as stepped-up security measures at water systems across the country, Whitman said, "We believe it would be very difficult for anyone to introduce the quantities needed to contaminate an entire system."

POU and terrorism: An interview with Peter Beering

Peter Beering is the terrorism preparedness coordinator in Indianapolis, IN, and is one of the experts who trains officials in terrorism preparation and response in cities across the country for the US Department of Defense. (from WaterTech.ONLINE)

One on One with J. Allen Rose

J. Allen Rose is vice president of Black & Veatch Special Projects Corp. and a nationally recognized expert in the areas of security. (from WaterTech.ONLINE)

POU industry should educate consumers about bio-terrorism

Security has increased at water treatment plants and water storage facilities since the tragic events of 11 September, but manufacturers and dealers of POU/POE water treatment equipment should be prepared for the possibility of a biological or chemical threat. (from WaterTech.ONLINE)

Consumer Information, Web Links for Information on Bio-terrorism

NSF International, a public health and safety company, said its consumer affairs office has been deluged with questions about bioterrorism, so it has established a special Web site that can be used to garner information.  (It is instructive that NSF International, the premier organization for independent testing of water purification devices, does not provide information about the best technologies for dealing with possible contamination of our drinking water by terrorists - RJ)

Terrorism targeted by world's tap water suppliers

6/19/2001  Water utilities band with law enforcement to protect public health resources

Counterterrorism efforts between the federal government and the drinking water community have been under way since a presidential directive in 1998 established the National Infrastructure Protection Center (NIPC). Since then, through the Critical Infrastructure Protection Advisory Group (CIPAG), a group of representatives from several water utilities around the country focused on better protecting America's drinking water infrastructure from terrorist attack.

NPR, Morning Edition, October 19, 2001 - List of the program's stories for the day.

Dam Security - Listen to the report with Real Audio

NPR's Howard Berkes reports that managers at America's dams and reservoirs are beefing up security to prepare for possible biological and chemical attacks. Sixty-one million people depend on dams and reservoirs for their water -- making the structures a tempting target. (5:06 min.)

Attack on Water Systems Seen As Improbable, But Not Impossible,    October 19, 2001

The potential for terror attacks that target water and wastewater systems was a major topic of discussion during WEFTEC, the Water Environment Federation's annual conference held this week in Atlanta. Security was the focus for speakers during the conference's opening session and at two technical sessions that attracted standing room only audiences. Most speakers, and those commenting from the audience during the question-and-answer sessions, agreed that the current threat to water infrastructure was minimal but that additional precautions were justified in the wake of September 11 and the more recent anthrax incidents.  Water Environment Federation

DrinkingH2O.com - On Line Information System for the Drinking Water Community

DrinkingH2O.com delivers the latest news and resources for drinking water professionals, as well as information for the public about water treatment and conservation.

Industry Security Roundup - CNBC and the Wall Street Journal - 10/28/01, click Energy, Industrial and Utilities option:

In the lobbies of office towers, the check-in desks at airports, the rampways of hydro-electric dams and the research labs at universities, suspicions are heightened and security has been tightened. Sept. 11 jolted Americans out of their not-in-the-USA complacency about random acts of terrorism and put the country on an alert never before seen. Click a category for a description of some measures U.S. businesses and institutions are taking at home and abroad to protect their employees, facilities and operations.

A Chemical and Biological Warfare Threat: USAF Water Systems At Risk Water and the systems that supply it are national critical infrastructures. Attack to deny or disrupt these systems could have catastrophic effects on the U.S. economy and military power. Water is particularly vulnerable to chemical or biological attack. Not limited to the “traditional” chemical weapons, an adversary has a plethora of cheap, ubiquitous and deadly chemicals on the worldwide market. Using an Internet search and $10,000, the adversary could build a biological fermentation capability, producing trillions of deadly bacteria that don't require missiles or bombs for delivery.

ILSI Risk Science Institute : Early Warning Monitoring to Detect Hazardous Events in Water Supplies The ILSI Risk Science Institute (RSI) convened a two-day specialty workshop in May 1999 that focused on three specific areas: threats to drinking water supplies from low probability/high public health impact events; early warning monitoring approaches; and interpretation, risk management, and public communication issues. The document is a PDF file which requires Adobe Acrobat. To obtain a free copy of Adobe Acrobat click here.

Chem/Bio Terrorism and Response from the Terrorism Research Center [This site contains coverage of terrorism in general and does not focus on attacks to drinking water systems - RJ] The terrorist threat to America is changing. During the 1970s and 80s, US policymakers prepared for bombings and hijackings overseas. Today, policymakers are preparing to defend against attacks against population and critical infrastructure targets in the US homeland. The worst of these threats confronting policymakers is the terrorist use of weapons of mass destruction (WMD), especially chemical or biological weapons.

Water Supplies - Make safeguards go with the flow

There are about 168,000 public water systems in the United States, some of which serve 8 million people. .... From the Newsweek, 11/5/01 issue, Special Report - Protecting America: The Top 10 Priorities

The Who, What, Why, and How of Counter Terrorism Issues

Gay Porter Denileon, Journal of the American Water Works, May 2001

The potential for terrorism against water utilities is not new, but with a growing number of terrorist groups that are increasingly extreme, the concern regarding an intentional attack on US infrastructure—including water systems—has heightened considerably since the end of the Cold War.

Emergency Family Preparedness Video

BOULDER, Colo., Oct. 23 /PRNewswire/ -- Recent events have raised people's concern about how to protect themselves and their families during an emergency. Arthur Levy says that being prepared for possible disasters, natural or man-made, can help lower stress and calm fears.  Levy has produced of a series of award-winning health and safety videos which show specific steps to take in order to be better prepared to cope with an emergency.  [not specifically about terrorist induced emergencies, just general preparedness, according to the report - RJ]

At the Institute for Homeland Security I found the following:

"The Journal of the American Medical Association (JAMA) has issued consensus reviews on five agents it considers the most likely candidates for a biological attack: anthrax, botulinum toxin, plague, smallpox, and tularemia. The reviews include the history of each agent, its epidemiology, diagnosis, vaccination, and therapy options, and links to additional research." (JAMA is one of the premiere medical journals in the world - RJ)

I read each report to determine if that agent was a threat that could be transmitted in drinking water, and copied the relevant information below. The links to the full articles are provided, but they are definitely NOT bedtime reading!

Of the 5 agents discussed by the JAMA articles, only two - Anthrax spores and Francisella tularensis - are capable of surviving in water. Anthrax spores can be filtered effectively by a good sub-micron filtration system. Francisella tularensis would be more difficult to filter with a standard home filter, unless it can effectively remove particles in the 0.1 - 0.2 micron size, but standard water treatment chlorination will effectively kill it.

Botulism

No instances of waterborne botulism have ever been reported. Although the potency of botulinum toxin has led to speculation that it might be used to contaminate a municipal water supply, this scenario is unlikely for at least 2 reasons. First, botulinum toxin is rapidly inactivated by standard potable water treatments (e.g., chlorination, aeration). Second, because of the slow turnover time of large-capacity reservoirs, a comparably large (and technically difficult to produce and deliver) inoculum of botulinum toxin would be needed. In contrast with treated water, botulinum toxin may be stable for several days in untreated water or beverages. Hence,such items should be investigated in a botulism outbreak if no other vehicle for toxin can be identified.

Anthrax

There is little information available about the risks of direct contamination of food or water with anthrax spores. Although human infections have been reported, experimental efforts to infect primates by direct gastrointestinal instillation of anthrax spores have not been successful..... Vegetative bacteria (that is, the "hatched" spores) have poor survival outside of an animal or human host; colony counts decline to undetectable within hours following inoculation into water. This contrasts with the environmentally hardy properties of the B. anthracis spore, which can survive for decades. (the size of anthrax spores have been variously reported in different sources as about 1.0 micron and from 2-6 microns)

Plague - No mention of water-born transmission.

The epidemiology of plague following its use as a biological weapon would differ substantially from that of naturally occurring infection. Intentional dissemination of plague would most probably occur via an aerosol of Y. pestis, a mechanism that has been shown to produce disease in nonhuman primates.

Smallpox - Apparently only transmitted (in normal times) from human to human.

It was reasoned that if the virus were able to persist in nature and infect humans, there would be cases occurring for which no source could be identified. Cases of this type were not observed. Rather, when cases were found, there were antecedent human cases with whom they had direct contact.

Tularemia caused by the bacteria, Francisella tularensis

Tularemia's epidemic potential became apparent in the 1930s and 1940s, when large waterborne outbreaks occurred in Europe and the Soviet Union and epizootic-associated cases occurred in the United States.... Humans become infected with F. tularensis by various modes, including bites by infective arthropods, handling infectious animal tissues or fluids, direct contact with or ingestion of contaminated water, food, or soil, and inhalation of infective aerosols.... Standard levels of chlorine in municipal water sources should protect against waterborne infection. (The size of the F. tularensis bacterium is 0.2 X 0.3-0.7 micron)

Potential Threats to Drinking Water:

Most of the threats to drinking water I have read about might consist of:

A)    deliberate introduction of biological contaminants like viruses, cysts, E. Coli, anthrax spores, etc.  (again, I do not know what biological contaminant(s) would be the most likely threat, some of the articles above touch on the subject, however).  The size of the contaminant is important, because the pore size of the filter must be smaller than the size of the contaminant in order to be effective at removing it.  Bacteria are about 1 micron in size (some smaller, some larger).  Many viruses are about 100 - 200 times smaller than bacteria (I just read that if a bacteria were the size of a car, a virus would be the size of a cell phone).  Cryptosporidium and giardia cysts are several times larger than most bacteria.  My page, Relative size of some water contaminants, will give you a visual picture of how the size of some of these organisms compare with the pore size of different types of filters.  Biological contaminants dumped into the water source of a city would be highly diluted by the time they reached a treatment plant.  Also, water treatment methods now in place (including  flocculation, filtration, and disinfection), would effectively remove or kill most types of infectious agents before they entered the distribution system.

B)    deliberate introduction of some type of hazardous chemical compound.  I have not read much about specific chemicals that are thought to be possible threats to drinking water, but the consensus seems to be that they would be synthetic organic compounds or possible radioactive compounds rather than non-radioactive inorganic chemicals.  The concentration of many organic chemicals is effectively reduced by Activated Carbon filters, however.  Again, not knowing what specific chemicals might be used, it is impossible to know how effective an activated carbon filter would be against these potential threats.

C)    Physical attacks against water companies, waste treatment facilities (in an effort to contaminate water), or reservoir dams (in an effort to disrupt water supplies and cause damage from flooding).

Activated Carbon:

Activated carbon (AC) filters need some discussion here, because AC is an important component in many types of domestic water treatment filters, from whole house filters to point of use (POU) filtration systems.  AC works by attracting and holding certain chemicals (a process called adsorption) as water passes through it.  According to one article "AC is a highly porous material; therefore, it has an extremely high surface area for contaminant adsorption. The equivalent surface area of 1 pound of AC ranges from 60 to 150 acres (over 3 football fields)".  Another article states, "Under a scanning electron microscope the activated carbon looks like a porous bath sponge.  This high concentration of pores within a relatively small volume produces a material with a phenomenal surface area: one tea spoon of activated carbon would exhibit a surface area equivalent to that of a football field." (different estimates of surface area from different sources - RJ)

AC is made of tiny clusters of carbon atoms stacked upon one another. The carbon source is a variety of materials, such as peanut shells, coconut husks, or coal. The raw carbon source is slowly heated in the absence of air to produce a high carbon material. The carbon is activated by passing oxidizing gases through the material at extremely high temperatures. The activation process produces the pores that result in such high adsorptive properties.  This article about Activated Carbon states that "Activated carbon is one of the best tools which can be used to reduce risks to human health and provide an aesthetically pleasing product at reasonable cost."  The article also describes how AC works and has some of the best scanning electron microscope pictures of actual AC granules I have seen.

The adsorption process depends on the following factors: 1) physical properties of the AC, such as pore size distribution and surface area; 2) the chemical nature of the carbon source, or the amount of oxygen and hydrogen associated with it; 3) chemical composition and concentration of the contaminant; 4) the temperature and Ph of the water; and 5) the flow rate or time exposure of water to AC.  An article, What is Activated Carbon, contains some interesting information.  For a fairly comprehensive and technical description of the characteristics of AC click here.

Some General Comments:

You will have to carefully examine the claims of contaminant reduction made by the manufacturer of any water purification device you are interested in purchasing  to make certain that it actually removes the contaminants you would like to have removed from your drinking water.  One of the best ways to make certain a purification device is effective is to make certain that it is certified by an independent, third party organization (the device should display the NSF International Certification Mark, or the WQA Gold Seal).  I have discussed third party certification in some depth on my Water Treatment page.  To the best of my knowledge, however, there is no independent certification for claims of bacterial or viral removal by any filtration system.  A pore size of 0.5 micron from a reputable company (backed up by laboratory tests) should remove most harmful bacteria that might be in the water, including E. Coli and anthrax.  A pore size of 0.1 - 0.2 micron should remove nearly all bacterial types.  Try to obtain laboratory test results that specify the percent removal of the contaminants.  Two filters could accurately state that lead, for instance, was reduced by their filter, but one might remove 60% of the lead and the other 98%.

 Although, in an emergency a good filter with an appropriately small pore size will remove biological contaminants larger than its pore size, most companies do NOT recommend that their products be used on water that is chronically biologically unsafe - in other words, a completely untreated water source that has continually high E. Coli counts, for example.  Any small defects in a sub-micron filter would normally not allow dangerous numbers of biological contaminants through if only a few organisms were to come into the filter periodically - an accidental exposure, for instance.  Nearly all of the contaminants would be filtered out by the non-defective parts of the filter.  On the other hand, if a constant flood of biological contaminants were to come into a filter with a small defect, enough infective organisms might get through the defect to cause sickness - even though the vast majority of organisms were stopped by the functional parts of the filter.

Treatment methods:

Details about how the various technologies work can be found on my Water Treatment page.

1) Whole house filters (both fiber and AC) usually have a fairly large pore size (typically larger than 10 - 15 microns) and will NOT effectively trap harmful biological contaminants.  Fiber filters will not remove any organic contaminants, and the water typically moves through a whole house granular activated carbon (GAC) filter too fast to have all of the organic chemicals removed.  

2) The popular GAC pitcher filters would be completely useless in removing most kinds of seriously harmful contaminants.  The pore size is too large to trap harmful particulates, like the biological contaminants discussed above, and there is too little activated carbon to remove all organic contaminants that might be in the water.  In addition, channeling (described below) would reduce the effectiveness of the filters even further.

3) Larger GAC filters, used in counter-top and under-counter filtration systems, also have extremely large pores that will not remove small, harmful particulates.  Although activated carbon is good at removing a wide spectrum of organic chemicals, all GAC filters can suffer from a phenomenon called channeling where the water pressure forces channels to open up in the loose carbon granules.  Some of the water, following the route of least resistance, will flow through the channel and not come into contact with the carbon filtration medium.  Consequently, some of the water flowing through a GAC filter may not have been filtered at all, and there is no way of knowing if the water still contains some harmful contaminants.

4) Solid block, activated carbon (SBAC) filters:

SBAC filters are composed of extremely small particles of activated carbon that are highly compressed and bonded into a solid, block with uniform size pores. A good SBAC filter will have a pore size of 0.5 micron.  This pore size removes asbestos fibers and biological contaminants like protozoan cysts (cryptosporidium and giardia) and many strains of bacteria (including E. Coli and anthrax) effectively (but not viruses or smaller bacteria). Many kinds of organic contaminants are also removed by SBAC filters.  Examples include,

insecticides, herbicides, solvents, MTBE, chlorine disinfection byproducts, etc. SBAC filters will remove chlorine, and some are specially formulated to remove lead and mercury as well. 

Since the carbon particles are not loose, channeling can not occur - all water entering the filter will come in contact with the filter medium.  This results in far more effective contaminant removal than can occur in GAC filters.  The larger the SBAC filter, the better the contaminant removal - water has a longer contact time with the AC than in smaller filters.  Large, counter-top or under-counter filters, for example, can contain about 10 times the weight and volume of AC than the small SBAC filters that attach directly to the faucet - they last 10 times longer, and are more effective at removing contaminants at the same flow rates. There are hundreds of different SBAC filters on the market with a wide range of performance characteristics.  To be assured that the filter you purchase performs as advertised, make certain that it is certified by an independent, third party organization to remove the contaminants you are interested in.

Benefits:

A good SBAC filtration system is very effective at removing a wide spectrum of biological and organic and inorganic contaminants.  The range of contaminants that are removed by different SBAC filters varies widely, however.  You will have to check carefully with each manufacturer to determine if a particular model removes the contaminants you are interested in, and then verify that their filters are independently certified to actually remove those contaminants.  A high-end SBAC filter will effectively remove the contaminants normally found in municipal drinking water. SBAC filters are very simple and inexpensive to maintain - High end systems typically require a single filter to be changed about once a year.  Replacement filters are around $50.

SBAC filters are an excellent choice to purify water in emergency situations where the electricity might be out and/or the normal water distribution system might be disrupted.  They require no electricity to filter the water and minimal water pressure (a hand pump can be used to push water through the filter, and water can even be siphoned through the filter by placing the source about 3 feet or more above the filter - slow, but it works).  With water that is known (or suspected) to be biologically unsafe, you can add chlorine or iodine to disinfect the water and then use the SBAC filter to remove the disinfectant and other contaminants that might be in the water.

A significant advantage of a good SBAC filter is that in an emergency situation, water from many sources can be pumped or siphoned through the filter and purified (with or without prior disinfection depending on the source).  For example, water from the toilet holding tank, and from ponds, streams, or lakes can be all be used safely with a good filtration system.  Other treatment methods that require electricity (distillation, UV, etc.) or high water pressure (RO) might not work in an emergency. Filtered water is always available for use.  Water is filtered as you need it.  You do not have to wait for water to be processed through a RO membrane into a holding tank, and you do not have to wait for a distillation unit to boil and condense the water.

Beneficial minerals, calcium and magnesium are not removed - that's good for health, and the water also tastes better to many people than water that has everything removed.

Down- Side:

SBAC filters will not remove as complete a spectrum of water contaminants as reverse osmosis or distillation.  Specifically, they will not remove arsenic, nitrates, heavy metals (other than those the filter has been specifically designed to remove, like lead and sometimes mercury), small bacteria, or viruses.

 Read the warning in the General Comments section above about the use of any type of filter on water that is chronically biologically unsafe. Not really a down-side, but a warning - Any water treatment device must be properly maintained, or they may not operate properly - resulting in contaminated water exiting the device.  In the case of SBAC filters, the filter cartridge must be changed on a regular basis - typically specified by the manufacturer.  Most home filtration systems are designed to be used on water from a municipal water supplier, in other words, fairly clean water.  If the source water is really "ugly", the filter may lose effectiveness and need to be replaced more quickly than specified.  

 5) Reverse Osmosis (RO):

Reverse osmosis filters work by forcing water through pores in the RO membrane that are so small that ideally, only pure water molecules can get through.

Benefits:

RO is one of the finest (as in smallest pore size) form of filtration presently known.  Reverse osmosis membranes typically only permit pure water through the membrane.  The actual size of the pores in these polymeric type membranes is measured in terms of Angstroms, which is one 10 billionth of a meter (a micron, by comparison, is 1 millionth of a meter).  Reverse osmosis membranes have pore sizes from about 2 - 10 Angstroms (0.00025 to 0.001 micron).  These pore sizes are about 10 times smaller than virus particles.  To put this size in perspective: consider if one square foot of membrane were enlarged to the size of the entire Pacific Ocean, a reverse osmosis pore would be roughly the size of a dime (and a virus would be about the size of a salad plate - about 7.5 inches in diameter).  The Filtration Spectrum diagram shows the size range of particles, and what types of filtration are used for each range.

According to the article, Microbial Control and Sanitation of Membrane-Based Pure Water Treatment Systems, "many applications for reverse osmosis (RO) systems include, as their treatment objective, the reduction of microbes. The term "microbes" includes algae, mold and yeast (fungi), protozoa (Giardia and Cryptosporidium are now well known), and the most popular target, bacteria. Related waterborne particles are virus (DNA particle) and endotoxins, which do not exactly fit the definition, but are often of concern and may need to be removed. Various media and levels of filtration can accomplish removal of these organisms. The finest filtration, RO, will remove them all [and produce sterile water]." (When functioning properly - RJ) According to Reverse Osmosis Treatment of Drinking Water from the Cornell Cooperative Extension, "Reverse osmosis treatment decreases the dissolved impurities in water.  It successfully treats water with high salt content, cloudiness, dissolved minerals such as sulfate, calcium, magnesium, sodium, potassium, manganese, aluminum, silica, bicarbonate, chloride, nitrate, fluoride, boron, and orthophosphate.  RO also is effective with some detergents, some taste, color and odor-producing chemicals, certain organic contaminants, and specific pesticides."

RO filters are very effective at removing inorganic chemicals and somewhat weaker at removing organic compounds.  SBAC filters on the other hand, are very effective at removing organic compounds and not as good at removing inorganic compounds.  High quality RO filtration systems will frequently use a SBAC filter as a post-filter.  This combination of filtration technologies is capable of producing very pure water.  There is also the advantage of having a high quality SBAC filter to use in the event water pressure falls below what is required to force water through the RO membranes.

Down Side:

Although the RO membrane is capable of rejecting virtually all microorganisms, it can develop pinholes or tears that allow viruses, bacteria or other microorganisms to pass into the treated water. Therefore, RO, like other filter technologies, is recommended for bacteriologically safe water only. The RO water treatment unit is often more costly than simpler treatment methods. RO is not effective for removing dissolved gases and light weight organic chemicals, including some pesticides and solvents. RO systems are more complex and require more maintenance than a SBAC filtration system.  They usually consist of a pre-filter, the RO membranes, a holding tank, and a post-filter that must be changed and cleaned periodically.

Point of Use RO units make only a few gallons of treated water a day for drinking or cooking.

RO systems typically cost more than a good SBAC filtration system, both in initial and in ongoing costs.

RO systems waste water. Two to four gallons of "waste" water are flushed down the drain for each gallon of filtered water produced.

RO filtration systems require fairly high water pressure to operate effectively.  Normal the home water pressure is sufficient for Point of Use RO systems, although sometimes an electric pump is used to boost water pressure.   In the event of an emergency that disrupts the water pressure, however, a reverse osmosis system will not work without another method (like an electric pump) to pressurize the water.

An elementary prerequisite for users of the RO process in industrial water-treatment applications is to understand the RO membrane’s tendency to become fouled by the contaminants it is removing from the feed water.

By Stan Lueck

A prior article entitled “RO-system architecture” covered the basic configuration of reverse-osmosis membrane devices used in industrial water-treatment applications. By way of review, a brief description of spiral-wound membrane water treatment elements follows.

Fouling Happens

The elements of an RO system are placed end-to-end in a cylindrical pressure vessel (PV) (See Figure 1.) The permeate tubes of each element are connected to form a channel, which allows the permeate from the collective elements to exit one end of the PV.

Feed water enters one end of the vessel and concentrate exits from the other. A typical industrial element is of 8 in diameter by 40 in. long. PVs may hold one to eight elements, with six being average, and are arranged as shown in the figure. Entire membrane systems may contain from one to hundreds of PVs.

Fouling Promoter: Configuration of Membrane Units

Feed spacers mounted inside the element can cause problems. They limit the velocity of the feed water flowing through the element and reduce the cleaning ability of the cross flow. These spacers also provide locations where colloidal particles can be retained and bacteria can grow, increasing the tendency of a typical spiral-wound element to foul.

As the feed channels become fouled, the feed water flow through the element becomes uneven. The feed water seeks the path of least resistance, resulting in lower cross-flow velocities downstream of the fouling. This can produce even more fouling, especially if microbiological growth is present. At some point the system shut down and cleaning become necessary.

Three Kinds of Fouling that Reduce Membrane Performance

A membrane treatment system can be fouled by virtually anything present in the water being fed to the unit. However, in common treatment systems such as reverse osmosis, the fouling materials generally may be categorized as inorganic, organic, and biological.

Inorganic compounds that cause fouling of membrane modules include inorganic salts with low solubility. They can enter the treatment system in particle form, or they may precipitate inside the system as a result of concentration changes occurring in the feed water as permeate is recovered through the membrane. The highest concentration of dissolved solids occurs immediately adjacent to the surface of the membrane in the treatment module.

If the feed water contains salts of low solubility, it is likely that these salts will precipitate on the surface of the membrane to form scale. Salts such as calcium carbonate (CaCO3) and calcium sulfate (CaSO4) are common in most feed waters. Other salts such as barium sulfate (BaSO4), strontium sulfate (SrSO4), and calcium fluoride (CaF2) also may be in solution.

In many feed-water sources these salts are present at or near their solubility limits and will precipitate as the concentration of the feed water in the system increases. Although this precipitation can be controlled with proper pretreatment, fouling from these salts frequently occurs because of operator error or unknown changes in feed-water quality.

Metal hydroxides are other inorganic compounds that cause fouling. The most common culprits are iron hydroxide, [Fe(OH3)] and aluminum hydroxide, [Al(OH3)]. As in the case of inorganic salts, these hydroxides may enter the system as suspended particles or they may form inside the system. Unlike the inorganic salts however, metal hydroxides do not deposit a hard crystalline scale; rather it is a soft, gelatinous layer.

Clay, silt and other silica-based materials can cause fouling if the particles are not removed by upstream pretreatment equipment. In some feed-water sources, clay occurs as very finely divided (1 to 5 microns) particles.

These small colloidal particles can be very difficult to remove with conventional equipment. Silica also may enter the membrane system in the dissolved or reactive form. This low molecular form of silica will polymerize as the feed-water concentration increases at the surface of the membrane. The resulting solid silica deposit on the membrane can be extremely difficult, if not impossible, to remove.

Organic compounds make up the second category of fouling materials. Surface-water sources like rivers and lakes may contain such naturally occurring organics as humic acids. Clarified water may contain residual polymers, and wastewater influents may contain any number of organic compounds.

The mechanism of organic fouling depends upon the size and chemical nature of the specific substance causing the fouling. High molecular-weight compounds may act more as particles and mechanically plug the feed spacer in the membrane element. This plugging may be worsened if inorganic particles, such as clays and metal hydroxides, also are present.

Low molecular-weight organics may foul the surface of the membrane through chemical interaction. For example, chlorinated phenols will adhere to the surface of an RO membrane by means of hydrogen bonding. In such a situation, a small concentration of the chlorinated phenol in the feed water can cause a large loss of flux in the treatment system.

Biological organisms tend to foul membrane surfaces. Although they are technically organic, biological organisms demand special consideration. Concern is primarily because of single-cell organisms, including bacteria, algae, and fungi. Of them, bacteria cause the majority of problems in membrane water-treatment systems—for a variety of reasons.

First, many types of bacteria can adapt to the environment inside the membrane modules. Unfortunately, a great number of these species are found in typical feed waters, particularly water from a surface source, such as a river or lake.

Second, since the membrane rejects the bacteria, they end up on its surface. Although their presence of itself is of appreciable concern, their food, consisting of organic matter, also is being concentrated at the membrane surface. And the reality is that when bacteria are in a livable environment with sufficient food, they multiply rapidly. Thus even more bacteria end up on the membrane surface.

Finally, bacteria have a number of defense mechanisms that add to their fouling ability. Several have small hair-like appendages, called fimbriae, that protrude from all sides of the cell. These allow the bacteria to attach themselves, and remain attached, to the surface of the membrane or to the feed spacers. In addition, bacteria secrete a mucous capsule, or slime, which coats the cell and protects them from any harsh elements entering their environment.

Contact: RODI Systems at 936 Highway 550, Aztec, NM 87410; Tel. 505-334-5865; Fax. 505-334-5867.

6) Distillation:

To remove impurities from water by distillation, the water is boiled causing the pure (or mostly pure) steam to vaporize leaving the non volatile contaminants behind. The steam is then cooled until it condenses, and the resulting distillate drips into a container. Salts, sediment, metals - anything that won't boil or evaporate - remain in the distiller and must be cleaned out.  Volatile Organic Chemicals (VOCs) are a good example of contaminants that boil off with the water vapor. A carbon filter (or other VOC trap) must be used with a distiller to ensure the complete removal of all contaminants.

Benefits:

 A good distillation unit produces very pure water (with the proper VOC traps almost all contaminants will be removed). This (in addition to RO) is one of the few simple ways to remove nitrates, chloride, and other salts that carbon filtration can not remove.

 Distillation also effectively kills all biological contaminants in the water.

Down side:

 Distillation uses electricity all the time the unit is operating.

 Distillation takes time to purify the water.  It can take about five hours to make a gallon of distilled water and can use $.25 to $.35 of electrical energy per gallon of distilled water produced - that's about twice the cost of water from a RO system and about 4 times the cost of water from a SBAC filter. The cost of ownership is high because you not only have the initial cost of the distillation unit to consider, but you also must pay for the electrical energy for each gallon of water produced.

 In an emergency situation where the electricity is disrupted, a distillation unit will not work, although solar distillation units are available for emergency water purification. If the sun is shining, they will produce distilled water by solar evaporation and condensation.

7) Bottled Water:

I provide an extensive discussion about bottled water on my Water Treatment page.  If you are planning to stockpile a quantity of bottled water, try to use glass bottles as your first choice for storage container, or the hard, rigid plastic bottles as a second choice.  Glass bottles will provide the best tasting water and there is no danger of some of the plastic components leaching out into the water over time.  Make certain you choose water from a company that is certified by NSF International or is a member of the International Bottled Water Association - otherwise you might be drinking filtered tap water.  Also, check to see if the water is suitable for long-term storage.  Some natural spring water, for example, is not filtered and will start to teem with life after a few weeks of storage, particularly in a sunny location.

Benefits:

 If you have the foresight to stockpile a sufficient quantity of quality bottled water, in the event of an emergency (of any type) that compromises the quality or safety of your home water, you will have a supply of safe water to drink and cook with.

FEMA's recommendation -

     Store one gallon of water per person per day (two quarts for drinking, two quarts for food preparation and sanitation)

     Keep at least a three-day supply of water for each person in your household.

Washington State Department of Health's brochure, Safe Drinking water in Emergencies,  recommends storing a 2 week supply of water for emergencies. Your supply of safe drinking water does not depend on the availability of electricity or home water pressure.

Down side:

 Expensive - bottled water can be from 4 to more than 20 times as expensive as water filtered through a SBAC filtration system.

 If you happen to run out of your supply of bottled water before the emergency is over, it may be very difficult to obtain a new source of safe water - stores may be sold out of bottled water or any bottled water that was available may be even more expensive.

Water Disinfection:

Disinfection refers only to killing or removing biological contaminants from water - most other contaminants that may be present in the water will not be removed.

According to "Treating Water in Emergencies" from the Washington State Department of Health's brochure, Safe Drinking water in Emergencies:

 If a safe supply of water is not available, or if your usual supply becomes unsafe for drinking, you must treat the water before it can be used for drinking, cooking, or brushing teeth.  There are two ways of treating water: boiling or adding bleach.  If the supply has been made unsafe because of untreated surface water (from floods, streams or lakes), boiling is the better treatment. 

 If the water looks cloudy, it should be filtered before you treat it. You can use coffee filters, towels (paper or cotton), cheese cloth, a cotton plug in a funnel, etc. Use several layers of material for best results. You can also use filters designed for use when camping and backpacking. 

8) Boiling:

 Boiling is a very effective way to disinfect water that is unsafe because of presence of bacteria [or other biological contaminants - RJ].  Place the water in a clean container and bring it to a full boil and continue boiling for at least 3 minutes.  If you are more than 5,000 feet above sea level, you must increase the boiling time to at least 5 minutes (plus about a minute for every additional 1,000 feet).  Boiled water should be kept covered while cooling.  Boiling will also remove some volatile organic chemicals.

9) Disinfection by Adding Liquid Bleach:

 If boiling is not possible and the water contains bacteria or viruses, the water can be made safe for drinking by treating with liquid household chlorine bleach (such as Clorox, Purex, etc.).  Avoid using scented and “color-safe” bleaches.  Household bleach has a strength of about 5% chlorine (most labels show it as 5.25%). Place the water (filtered if necessary) in a clean container, add the amount of bleach according to Table 1 or 2 on the Washington State Department of Health site.  It is important to mix thoroughly and allow to stand for at least 30 minutes before using the water. If the water is cloudy, or very cold, increase the standing time to 60 minutes. For treating small amounts of water, you may find it easier to use a 1% bleach solution.  See instructions on the same page on how to make a 1% solution. You can also use water purifying tablets or chemicals designed for use when camping or backpacking.  Always follow the directions on the package.

Note:  Chlorine and other common disinfectant chemicals will not kill cysts of the parasite Cryptosporidium (“Crypto”), which may be present in water supplies affected by untreated surface water.  Cryptosporidium is an organism that can cause severe illness and even death in persons who have been weakened because of health problems.  Boiling is the best water treatment in these situations in the absence of a good SBAC filter, RO unit, or distillation system. Boiling and adding liquid bleach to disinfect water work only in situations where the water is unsafe because of the presence of biological contaminants. If you suspect the water is unsafe because of chemicals oils, poisonous substances, sewage, etc., do not use the water for drinking, or use other purification methods that are effective on the contaminants that are present in the water. Boiling can actually concentrate any chemical contaminant that does not vaporize.

10) Other Methods of Water Treatment:

There are several other water treatment methods that I have discussed on my Water Treatment page.  I will discuss them very briefly, because they will not provide complete protection against a wide range of contaminants.  They are usually not sold as stand-alone water treatment devices, but they are commonly used in combination with other treatment methods.

They include:

Ion exchange (water softeners, for example) - Each of the many types of ion exchange resins available only remove a limited number of contaminants (mostly inorganic chemicals are removed).  The resins must be recharged periodically. Most organic and biological contaminants are not removed by ion exchange.

KDF filters - usually granular particles that remove mostly inorganic chemicals and few organic chemicals.  Must be backwashed periodically. The loose granules will make most of these filters unsuitable for removing biological contaminants because of large pore size and channeling. UV light - An effective disinfection process that will kill most biological contaminants with the proper dose of UV radiation. Three primary disadvantages of UV disinfection are 1) that the method requires electricity,  2) only biological contaminants are destroyed, not organic or inorganic chemicals, 3) The water entering the UV chamber must be extremely free of particulate materials in order for the UV light to reach and kill all organisms. Ozone - primarily a disinfectant that effectively kills biological contaminants. Ozone also oxidizes and precipitates iron, sulfur, and manganese so they can be filtered out of solution.  Ozone will oxidize and break down many organic chemicals as well, but ozone treatment creates its own set of undesirable byproducts that can be harmful to health if they are not controlled (e.g., formaldehyde and bromate).

Summary

CES has solved all said technology problems at less than one cent per gallon. Every treatment method has some advantages and some disadvantages that must be carefully considered. CES uses six stages of different types of treatment in modular sets which includes three forms of disinfection which can kill all known bacteria, virus and pathogens.