|In this Valentine's Day Occasional,
you'll hear about the Silt Density Index, the Cadiz Project, water hammer, the sphericity of anthracite, and the late Lake Jalanica. Also, there are scale, soap, and softeners, pH, THMs, and chloride.
You'll learn about the brine per inch capacity of a 20" diameter tank, Alaska's pitiful ranking in the waste water competition, and how squeaky clean may really be squeaky dirty. Read a lot about how lead got into Flint's water, the latest on the North Dakota Access fight, the almost, almost flooding of the towns below Oroville Dam, the use of orthophosphate, the water consumption of bowling alleys, the height of a 54" mineral tank, Pure Water Products' new line of big backwashing filters, and, as always, there is much, much more.
Pure Water Occasional for February 14, 2017
The full Occasional is no longer archived online, but most of the individual articles can be found on the Pure Water Gazette's website. Read the Gazette every day for the latest news from the world of water.
Turning Water Into Electricity
Pure Water Gazette's Famous Water Picture Series
What Used to Be Jalanica Lake in Bosnia
A large artificial lake in the Balkan state of Bosnia and Herzegovina, called Jalanica Lake, totally vanished this month and with it an estimated 2 million fish.
Water levels in the lake are usually regulated to keep enough water to generate hydroelectricity and to avoid floods in the city of Mostar, which lies downstream. So it came as a surprise to local people to see the lake completely drained and with it all its life gone.
Normally, the lake is 30 kilometres long and around a kilometre wide with a depth of about 70 metres. Water levels had dramatically dropped twice before, during droughts in 2005 and 2012, but never by this much.
The discharge was carried out largely last month by power firm Elektroprivreda BiH, which says it was needed to maintain electricity production during a dry and especially cold period when energy demand was above average.
Scientist agree that the ecosystem has been completely degraded. However, Elektroprivreda BiH said in a press release that the discharge didn’t cause an ecological disaster, and added that water is already returning, as it did in 2012, when low levels also didn’t hurt fish stocks.
How Lead Got Into Flint's Water
The following piece is excerpted from an excellent article by Michael Torrice in Chemical & Engineering News. It gives a concise and clear explanation of the procedures that city water departments use to keep contaminants like lead, copper, and iron in the pipes and not in the water, and it shows how fragile this system is and what happens when, through ignorance, greed, or lack of concern, water officials fail to follow the rules.--Hardly Waite
Lead contamination is the most troubling in a series of water problems that have plagued Flint since the summer of 2014. All of them were caused by corrosion in the lead and iron pipes that distribute water to city residents. When the city began using the Flint River as its water source in April 2014, it didn’t adequately control the water’s ability to corrode those pipes. This led to high lead levels, rust-colored tap water, and possibly the growth of pathogenic microbes.
The pipes in Flint's old distribution system had seen the same water for decades. Switching water supplies in 2014 changed the chemistry of the water flowing through those pipes. When a switch like this happens, the water system is going to move toward a new equilibrium, says Daniel Giammar, an environmental engineer at Washington University in St. Louis. “It could be catastrophic as it was in Flint, or it could be a small change.”
Before 2014, Flint was getting its water from the Detroit Water & Sewerage Department, which would draw water from Lake Huron and then treat it before sending it to Flint. Looking to lower the city’s water costs, Flint officials decided in 2013 to instead take water from the Karegnondi Water Authority, which was building its own pipeline from the lake. As an interim solution, while waiting for the new pipeline to be finished, Flint began taking water from the Flint River and treating it at the city’s own plant.
Problems with the city’s tap water started the summer after the switch. First, residents noticed foul-tasting, reddish water coming out of their taps. In August and September, the city issued alerts about Escherichia coli contamination and told people to boil the water before using it. A General Motors plant stopped using the water in October because it was corroding steel parts. In December, the Michigan Department of Environmental Quality notified Flint that its water was in violation of national drinking water standards because it contained high levels of trihalomethanes, toxic by-products of chlorine disinfection.
Then, in early 2015, reports of high lead levels started making news. In January, it was Flint’s University of Michigan campus; in February, it was a private home.
By early September 2015, a Virginia Tech team had sampled water from 252 homes and reported on their website, flintwaterstudy.org, that the city’s 90th percentile lead level was 25 ppb. EPA’s action limit is based on a 90th percentile calculation, meaning that if 10% of homes exceed the agency’s 15-ppb threshold, then action is required.
That same month a team led by Mona Hanna-Attisha, a pediatrician at Hurley Children’s Hospital, in Flint, released data showing that the number of Flint children with elevated levels of lead in their blood had increased since the water change. In areas with the highest lead concentrations in the water, about 10% of the children had elevated blood levels of the element. Lead is neurotoxic and can disrupt children’s development, leading to behavioral problems and decreased intelligence.
With evidence of lead contamination mounting, Flint switched back to the Detroit water in October.
Why did the switch to Flint’s river water cause this catastrophe?
To understand the problem, consider that as water travels through the miles of pipes in a city’s distribution system, molecules in the water react with the pipes themselves. “The distribution system acts like a geochemical reactor,” says Haizhou Liu, an environmental engineer at the University of California, Riverside. “There are miles and miles of pipes—some iron, copper, and lead—that get corroded.” This corrosion occurs when oxidants, such as dissolved oxygen or chlorine disinfectant, react with elemental iron, lead, or copper in the pipes.
Cities no longer install lead pipes. But older cities such as Flint still rely on them, usually as service lines that connect water mains in the street to a home’s water meter. A 1990 report from the American Water Works Association estimates there are millions of lead service lines in the U.S. To limit how much lead leaches into the water from these pipes and some homes’ plumbing, EPA’s Lead & Copper Rule requires water utilities serving more than 50,000 people to establish a plan to monitor and control corrosion.
The Passivation Layer: As Important as the Pipe Itself
As part of these plans, utilities treat their water to maintain a mineral crust on the inside surfaces of their pipes. This so-called passivation layer protects the pipes’ metal from oxidants in the water. The coatings consist, in part, of insoluble oxidized metal compounds produced as the pipe slowly corrodes.
If the water’s chemistry isn’t optimized, then the passivation layer may start to dissolve, or mineral particles may begin to flake off of the pipe’s crust. This exposes bare metal, allowing the iron, lead, or copper to oxidize and leach into the water.
In Flint, the water chemistry was not optimized to control corrosion.
Most important, the treated Flint River water lacked one chemical that the treated Detroit water had: phosphate. Cities such as Detroit add orthophosphate to their water as part of their corrosion control plans because the compound encourages the formation of lead phosphates, which are largely insoluble and can add to the pipes’ passivation layer.
The entire Flint water crisis could have been avoided, experts believe, if the city had just added orthophosphate. In experiments using the city's water, simply adding a phosphate corrosion inhibitor sharply reduced the amount of lead leached from pipes.
Still, orthophosphate isn’t the only corrosion solution. Some water utilities treat water so it has a high pH and high alkalinity. Such conditions decrease the solubility of lead carbonates, which also contribute to the pipe’s protective mineral layer.
The treated Flint River water had a relatively low pH that decreased over time. According to monthly operating reports from the Flint treatment plant, the city’s water had a pH of about 8 in December 2014, but then it slowly dropped to 7.3 by August 2015. Environmental engineers say that if water pH drifts too low in the absence of orthophosphate, the water can start to leach high levels of lead from pipes.
The pH drop over time seems to indicate that plant operators in Flint didn’t even have a target pH as part of a corrosion plan. Water utilities usually find a pH that’s optimal for preventing corrosion in their system. For example, in Boston, another city with old lead pipes, average water pH held steady around 9.6 in 2015.
Another chemical factor that contributed to the treated river water’s corrosiveness was its chloride concentration. The treated Detroit water’s average chloride level was 11.4 parts per million in 2014. The treated Flint water had 85-ppm chloride in August 2015. The plant may have contributed to these high levels when it tried to address high levels of toxic trihalomethanes.
Treatment for THMs
Disinfection by-products such as trihalomethanes can form through reactions between organic matter in water and chlorine disinfectant added at treatment plants. The Flint plant had increased the amount of chlorine it used in the summer of 2014 to combat the E. coli contamination problem. To reduce levels of trihalomethanes that formed, the plant removed organic matter from the water by adding ferric chloride, which coagulates organic matter, making it easier to filter out. Even though the treatment took care of the trihalomethanes problem, it increased the water’s chloride levels.
Environmental engineers worry about high chloride levels because studies have shown that lead corrosion is more likely when the ratio of chloride to sulfate concentrations is greater than 0.58. Researchers at Virginia Tech calculated the ratio for treated Detroit water as 0.45 and for treated Flint River water as 1.6.
Iron Pipes and Lead Pipes
Corrosion of lead pipes caused Flint’s most serious water issue, but corrosion of the city’s iron pipes also created problems. The chemistry that controls iron pipe corrosion is a little more complicated than the chemistry surrounding lead pipe corrosion, but some of the same factors play a role.
Iron Corrosion in Flint Pipes
Problems with Flint’s iron pipes started early: The rust color and bad taste of the water coming out of residents’ taps in the summer of 2014 was a sign that the passivation layer on iron pipes was dissolving into the water.
But the issue that worries environmental engineers most about iron corrosion is that it could encourage the growth of pathogens in the distribution system. As the mineral layer in iron pipes falls off, it exposes bare iron that can reduce free chlorine added to the water as a pathogen-killing disinfectant. Some homes had no detectable chlorine levels when monitored.
Another issue could have worsened both the corrosion and disinfection problems. Much of the distribution system was built when the city’s population was about 200,000 and Flint was a major manufacturing center. But the city now has less than half the population, and much of the industry, which used a lot of Flint’s water, has left town. As a result, water usage has dropped significantly, while the system’s capacity has remained the same.
This means that water sits in the distribution system for long periods. In some places, the water sits in pipes for more than six days before use, providing more time for reactions that corrode pipes and break down chlorine.
Now that Flint has switched back to the Detroit water, environmental engineers believe that it may take months to a year for pipes to regain their passivation layers, for corrosion to slow to normal levels, and for lead concentrations to drop back into an acceptable range. The lesson, according to one authority, is that "when we collect data, we need to use those data. Utility officials had all the data they needed about pH, alkalinity, and chloride levels to determine that the water was corrosive. They just failed to act on that information. She points out that the water utility officials were already collecting all the data they needed—pH, alkalinity, chloride levels—to determine if the water was too corrosive. The lesson is that there is an undeniable connection between water chemistry and infrastructure.
The Army will allow the $3.8 billion Dakota Access oil pipeline to cross under a Missouri River reservoir in North Dakota, clearing the way for completion of the disputed four-state project. The Army intends to cancel further environmental study and allow the Lake Oahe crossing, according to court documents the Justice Department filed. The Standing Rock Sioux tribe, which has led opposition, said it would fight the latest development in court.
More than 100,000 people in communities downstream of Lake Oroville were told to evacuate after authorities grew concerned that dangerous flood waters would start surging out of the huge reservoir. The flood threat emerged suddenly when a hole developed in the auxiliary spillway that was being used for an emergency spill to lower the level of the full-to-the brim reservoir, the second-largest in California. The hole developed although overflow was much below the gpm rating for the spillway. The Sierra Club and two other environmental organizations warned about potential problems with the emergency spillway 12 years ago, but federal and state officials rejected concerns and said the spillway met guidelines.
A new study shows that decades after a uranium mine is shuttered, the radioactive element can still persist in groundwater at the site, despite cleanup efforts. It is very difficult to remove.
The American Society of Civil Engineers recently rated the nation's waste water systems. Alaska ranked worst in the nation. Some areas in rural Alaska were ranked the same as many third world countries.The report pointed out that conditions vary widely between urban and rural areas of the state.
U.S. Sen. Dianne Feinstein of California wrote the Desert Protection Act of 1994 and has long been the Mojave’s guardian. She has the ear of ranchers and conservationists who fear that a massive pumping scheme called the Cadiz project could damage the desert’s range lands and ecosystems.
Under the Trump presidency, prospects are looking much brighter for Cadiz, a California company that sees Mojave Desert groundwater as liquid gold.It is expected that federal permits that have previously been denied will soon be forthcoming.
Water Fact: It takes around three years’ worth of drinking water to make a cotton T-shirt using conventional manufacturing practices. That’s roughly 713 gallons.
The Issues with "Softened Water"
You'll sing better with softened water (once you realize that the slimy feeling is really good for you)
As pure water falls to earth, it picks up contaminants, absorbing gases like carbon dioxide and dissolving metals and minerals it comes in contact with. Rain water is naturally "soft," low in Total Dissolved Solids (TDS), but it is "aggressive," looking for minerals to dissolve. As it picks up minerals like calcium and magnesium, it become "hard."
Even small amounts of hardness minerals, calcium and magnesium, cause the water to exhibit typical hard-water characteristics. The higher the hardness level, the more evident the problems will be. Residential and commercial water users typically identify two significant problems when dealing with hard water:
Scale: Hardness scale causes water heaters to waste energy and eventually fail, and unattractive mineral deposits accumulate on fixtures. Faucets and appliances fail. Metal pipes pick up interior scale deposits and inhibit the free flow of water.
Soap interactions: Laundering results aren’t satisfactory; dishes, glasses and silverware are not clean enough and larger amounts of cleaning materials are required.
For over a century, salt-based ion exchange softening has been the gold standard in addressing these issues. Water softener technology is relatively easy to install in homes and businesses and relatively cost-efficient to own and operate. Salt-based softeners are now very user friendly, with such efficiency enhancements as metered vs. timer controls, twin-tank systems, improved resins, and upflow regeneration. Advances in technology save water and salt. Even with these technological improvements, however, many people can’t or won’t use a salt-based system and actively seek alternatives. While many alternatives exist in the marketplace today, it is important to understand that ion exchange softeners alone deal with the soap issue and that most alternatives address only the problem of scale formation.
Probably the three most common objections to softened water are that it might be corrosive, that it is not healthful to drink, and that it leaves a slimy feel on the skin.
Corrosion in the form of damaged hot water heaters or heater anodes does not occur because water has been softened, but it is true that it can occur in spite of softening if pH is outside the acceptable range (7.0 to 8.5), if TDS exceeds 500, or if the softener itself is not rinsing itself thoroughly during regeneration. Water actually retains its alkaline nature after softening and softened water is usually only slightly higher in total dissolved solids than the pre-treated water, since softening normally gives back more or less what it takes out in terms of TDS. For the calcium and magnesium it removes, it exchanges a nearly equal amount of sodium.
As for the healthfulness of softened water, Greg Reyneke writes:
Softened water does not contain sodium chloride or potassium chloride salt. During the ion exchange process, sodium or potassium ions are added to water in direct proportion to the amount of other ions being removed from the raw water. The result of this sodium addition is the formation of sodium carbonate and bicarbonate compounds in the water, which do indeed contribute to taste. At hardness levels < 15 gpg (grains per gallon), many people describe the additional sodium as making the water taste sweet or well-rounded. At higher hardness levels, some drinkers begin to identify an alkaline or soda flavor in the water. If the water from a softener tastes salty, this is not normal, and [you] shouldn’t drink it.
Hypertensive persons, or those on sodium-restricted diets, are concerned about the total amount of sodium that they consume in a day. The process of softening water generally adds 1.86 mg/L for every grain of hardness removed, so when you soften 15-gpg water, you’re adding almost 28 mg/L of sodium to whatever is already naturally there. To put that into perspective, one teaspoon of salt contains approximately 2,000 mg of sodium and cow’s milk contains approximately 125 mg of sodium per cup. . . .
While there are many arguments for and against consuming the inorganic minerals found in hard water, my personal decision is simple: since the inorganic minerals in water are so difficult for the human body to assimilate compared to the abundant and easily assimilated organic mineral compounds found in common fruits and vegetables, I choose to derive nutrition from food and hydration from water, while making sure that the water I drink is as pure as possible.
We can add that if the salt content of water is objectionable, addition of an undercounter reverse osmosis unit will remove the sodium and leave only pure, excellent tasting water. There are now even post filters for reverse osmosis units that add a small amount of mineral hardness back into the treated water to polish the taste and satisfy those who object to drinking low-mineral water.
Squeaky Clean Is Really More Like Squeaky Dirty
The slimy feel that people often complain of in regard to softened water is harder to pin down. This is also experienced as the feeling that soap won't wash off of the skin. According to Reyneke, the feel of any water on the skin is affected mainly by pH. Water low in pH feels rough and water with higher pH feels smooth or slick. This is true even if soap isn't used.
In hard water, soap loses its ability to clean and forms into a sticky, waxy precipitate called soap scum or soap curd. This scum clings to skin and hair, producing the "squeaky clean" feel that we are accustomed to with hard water. "The problem is," according to Reyneke, "that squeaky clean, is really more like squeaky dirty, since soap precipitate and soil deposits are left behind on the skin."
So, you can just tell yourself that the slick feel and the illusion that soap won't wash off are really advantageous, or you can try some tricks that might make the softened water more to your liking. Reyneke suggests switching to a potassium-base soap or changing the regenerant of the softener from sodium to potassium. Note also that various soaps have different pH levels, so it may be your soap raising the pH so much that the water feels slick. You may be blaming your softener for something that's actually your fault for using the wrong soap.
Or, you certainly might consider that being "squeaky dirty" isn't really a disadvantage. There are those who believe that most of us bathe too much anyway and that it isn't healthful to wash away the natural oils from our skin. From this point of view, a little hardness in the water might keep us from scrubbing away the natural skin oils that form a natural protection from the sun.
Watch for Pure Water Products' new selection of large-sized backwashing filters. We will soon be offering a tough line of Fleck control filters using 2750, 2850, and 3150 controls, Structural mineral tanks (starting with 14" X 65" and going up to 36" X 72"), and most of the popular media used in our smaller backwashing filters. These will include filters for sediment, chlorine reduction, chemical reduction, iron and manganese removal, treatment of odors, and more.
Also coming, a full line of filters and softeners with Fleck's 5810 control, plus the new Pentair ultra-convenient 3000 Series undersink filters.
The Ceiling is Up and the Floor is Down
by Gene Franks
A Rare Pure Water Occasional Book Review
As a foreign language student in college, long, long ago, I was impressed by the really important information you could get from foreign language textbooks. There were practice sentences that provided useful information like "The Rodriguez family is Mexican. They live in a Mexican house." My all-time favorite was, "The ceiling is up and the floor is down." That's a bit of wisdom I have taken through life. It has served me well.
Now that I mainly study water filtration, there are two books, both written in English, that help me a lot. I use them frequently. They are the Entingh Corporation's Engineering Handbook and Alamo Water's Water Improvement Engineering Guide.
The last mentioned was published by Alamo Water Refiners of San Antonio (the copyright date of my copy is 1991, but I have a feeling it goes back further). Alamo Water is now part of Watts Water Quality and Conditioning Products, but the AlamoEngineering Guide lives on. It is a 47-page fine print treasury of very useful information.
Here are some universal truths from the Alamo guide, so helpful they're worthy of inclusion in foreign language textbooks:
If you want to avoid water hammer (and who doesn't?), the size of your pressure tank should be limited to the maximum GPM (gallons per minute) divided by 60 seconds times 2 seconds times 10.
For bowling alleys, you should plan for 175 gallons daily usage per lane!
If you want to install electrical equipment in a manhole, quarry or mine, submerged in water, you must conform to Nema 6 Electrical Enclosure Standards.
To use Birm to remove iron from water, the water's Dissolved Oxygen (DO) content must be equal to at least 15% of the iron (or iron and manganese) content.
The Sphericity of Anthracite is 0.61 in loose pack format and 0.60 in tight pack.
When sizing a treatment system for a motel with 50 units, you should allow for 145 gallon per minute flow during peak demand if your toilets have flush valves. With flush tank toilets, 75 gallons per minute is enough.
For bowling alleys, you should plan for 175 gallons daily usage per lane.
If sizing a water system for an oil refinery, allow 80,000 gallons of water per day per 100 barrels of crude processed.
For taverns, plan on 20 gallons per day per seat.
A 2" pipe will support a normal water flow of 65 gallons per minute but you can push up to 120 gallons per minute through it if you have to.
Barber shops need 55 gallons of water per day per chair.
Water boils at 212 degrees F. at 0 PSI pressure, but at 52 PSI it boils at 300 degrees F.
In dealing with boilers, you can convert pounds of steam per hour to horsepower by dividing it by 34.5.
Moderately hard water is defined as water with 3.5 to 7.0 grains per gallon hardness.
A 10" X 54" mineral tank (a common size) holds 1.5 cubic feet of filter medium or softener resin. It has a square foot media surface of 0.54 square feet, holds 0.45 cubic feet per inch of height, is 50" tall to the sideshell, has a media bed depth of 34" and a freeboard (empty space on top) of 16". It supports a softener flow rate of 5.0 gallons per minute and a filter flow rate of 2.7. As a softener tank, it has as 45,000 grain capacity if salted at 22 lbs. per regeneration and 30,000 grains if salted at 9.
A 30" X 72" mineral tank requires a gravel underbed of 200 lbs. of 1/4" X 1/8" gravel to support carbon filter media.
A circular brine tank, 20" in diameter, holds 1.33 gallons of brine per inch of height.
The Sphericity of Anthracite is 0.61 in loose pack format and 0.60 in tight pack?
The maximum operating temperature for Filter Ag is 140 degrees F.
Filox is effective between pH 5.0 and 9.0.
Weak acid cation resin is best at reducing alkalinity.
Vaseline or common grease should not be used on softener control valves.
The diameter of a human hair is about 75 microns.
The smallest bacteria measure about 0.2 microns.
It is advisable to feed a dealkalizer with softened water.
A cylindrical tank 3' 2" in diameter holds 58.92 gallons of water per foot of depth.
Manways on top of steel tanks can be either elliptical, flanged, davited, or hinged.
One of the popular manway styles is called a thief hatch.
Ductile iron has the strength properties of steel using casting techniques similar those of gray iron.
EPDM is made from ethylene-propylene diene monomer. It has exceptionally good weather aging and ozone resistance and is fairly good with ketones and alcohols.
A check valve installed near a pump in the discharge line will keep the line full and help prevent excessive water hammer during pump startup.
PVC has an excellent chemical resistance when used with fatty acids, but poly tubing is not recommended.
One gallon of muratic acid is equal in treatment capacity to 3.2 lbs. of hydrochloric acid.
One pound of polyphosphate typically treats 40,000 gallons of water at a 2 ppm concentration, but it is a good idea to slug the system initially at 10 ppm for 30 days to clean out the lines at a faster rate.
It takes 2 to 3 ppm chlorine with 30 minutes residence time to oxidize one ppm H2S.
One oz of calcium hypochlorite equals two level tablespoons.
To calculate the percentage rejection rate of a reverse osmosis unit subtract the product TDS from from the feedwater TDS, multiply by 100, then divide by the feedwater TDS.
SDI stands for Silt Density Index and it is a measurement of suspended solids in RO feedwater.
Watts divided by amps equals volts.
A gallon of water weighs 8.337 pounds.
To figure the gallon capacity of a reservoir, multiply the length by the width by the depth in feet. This gives the cubic foot total. To convert to gallons, multiply the cubic feet by 7.4805.
I could go on and on and on and on. The Alamo Water Improvement Engineering Guide has a million of them.