Turning Water Into Electricity

Posted February 12th, 2017
Energy, Famous Water Pictures

Turning Water Into Electricity

Pure Water Gazette’s Famous Water Picture Series

Jablanicalake

Jalanica Lake, 2017

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, 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.

Reference: New Scientist.

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How Flint’s Water Got Lead In It

Posted February 12th, 2017
Corrosion, Lead, Water Treatment, Advanced

How Lead Got Into Flint’s Water

The following 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.

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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.

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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.

Phosphate

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.

pH

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.

Chloride

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.

ironcorrosion

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.

Decreased Usage

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.

Reference: How Lead Ended Up in Flint’s Tap Water, by Michael Torrice.

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All About “Soft” Water

Posted February 10th, 2017
Introductory Reading, Sodium, Water Softener, Water Treatment 101


The Issues with “Softened Water”

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 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.

Water Softeners

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.

Reference: Grey Reyneke, “Hard to Lather, Easy to Fix” from Water Treatment and Purification magazine.

Reusing Stormwater

Posted February 5th, 2017
Environmental, Shortage, Wastewater

How We Can Better Plan Our Cities to Utilize Stormwater

We are finally learning that stormwater can be an asset to communities but now we need to make some urban planning and engineering changes to take advantage of it

by Rinaldo Veseliza

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Our urban areas have lost their ability to naturally recycle stormwater due to the impervious nature of infrastructure engineering over the past 100 years. We have been building roadways and streets to capture the runoff and send it somewhere else, usually to the river or ocean. For decades in California, controlling stormwater was the main goal but today, with more water scarcity, we are beginning to see this same water more as an asset and less as a liability.

One way of better using stormwater is by refilling underground aquifers that have been depleted by overpumping. Recycling of all captured waters would then reduce pollution of our creeks, rivers, bays and oceans. Therefore we need to revisit current policies and practices and change the popular mindset to manage water effectively and redirect water into the proper channels, starting with a simple solution to retrofit our streets with permeable surfaces to change the dynamics of water management.

Our cities and counties need to reengineer our water collection systems to release as much water as possible into the ground locally before it gets into the storm drains so the earth beneath us can recycle most of the water, reducing the amount of mercury and PCBs released into waterways. The remaining water should be captured and processed in the way sewage is, before reuse or release into the environment. Both simple and complex solutions are available and several have been incorporated in new projects.

In the 1950s, the U.S. Army Corps of Engineers (USACE) built large stormwater pipelines and basins/aqueducts, like the Los Angeles River basin, to move the water quickly away from the newly built communities and directly to bays and oceans. After years of learning about the value of this precious commodity, water, and the damage this solution causes the environment, plus subsequent legal issues and public pressure, USACE has redesigned the L.A. River and restored sections to more natural conditions so water can percolate naturally into the groundwater basin. This allows the sandy soil to filter the chemicals while helping to replenish the underground aquifers.

The 18–24 inch strip at the curb could be replaced with pavers or pervious concrete that could significantly reduce stormwater drainage problems by allowing polluted water to be filtered by natural soils and help refill the underground aquifers.

Many large coastal cities have serious pollution problems after each rainfall, where stormwater carries more dangerous pollutants than raw sewage due to the presence of oils, trash, feces and chemicals on streets and sidewalks. The pollution is washed directly into the bay and ocean without any filtration. To make matters worse, broken sewers and faulty septic systems can add significant numbers of pollutants, resulting in added stress on our rivers and waterways.

If we could reengineer our streets to absorb the stormwater locally so it could percolate and purify locally, we would reduce the amount of water polluting our waterways, beaches, lakes and streams. Removing impervious surfaces and replacing with pervious surfaces would be ideal but is costly and disruptive to urban life and traffic. Removing some portions of roadway would be less expensive and can be better managed.

 

More specific solutions include:

Bioswales: Most new projects require landscape (“green street”) designs that take advantage of natural drainage into bioswales, which allow water to be treated slowly and absorbed into the soil, filtering pollutants along the way. Large pools, reservoirs and lakes can be used for stormwater storage. However, they must be tested or separated from public access to prevent illness and disease. It’s imperative they be planted with trees and vegetation, which filter out pollutants through the process of phytoremediation.

biowsale

 

Pervious concrete or pavers: Many new roadway and driveway surfaces can be designed with pervious concrete and a variety of pavers, which allow water to penetrate below the pavement. One simple solution is to replace the 18–24 inch concrete slabs against the curb with a permeable concrete or pervious concrete tiles. The work can be implemented immediately on urban roadways without major interruption to traffic and can be given to smaller contractors, providing thousands of construction jobs.

Stormwater treatment: The Santa Monica Urban Runoff Recycling Facility (SMURRF) was built in 2001, the first stormwater treatment plant in the country. It processes 500,000 gallons (1.9 million liters) per day using modular systems and recycles the water throughout the community, including schools, office buildings and municipal facilities. The plant is fully automated and requires minimal maintenance and management. Similar modular plants can be located wherever larger volumes of polluted water flow into main streams. All the water processed can be recycled locally.

Rinaldo Veseliza is an architect and director of sustainability for Alisto Engineering Group in Walnut Creek and L.A. He works on urban redevelopment, with a passion for sustainable communities, renewable energy and cleaning up water pollution. He has been directly involved in preventing water pollution since 1998 when he managed construction for the Water Garden, a self-contained office complex that recycles 80 percent of its wastewater through onsite treatment plants.

Adapted from Water Deeply.

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