A lot of cities push rain barrels as a way to save water and reduce flooding. Our water comes from the Detroit and returns to it as sewage, so I’m not sure there is any water saving, but there is a small cash saving (very small) if you buy 30 to 55 gallon barrels from the city and connect them to the end of your drain spout. The rainwater you collect won’t be pure enough to drink, or safe for bathing, but you can use it to water your lawn and garden. This sounds OK, even patriotic, until you do the math, or the plumbing, or until you consider the wood-chip alternative.
The barrels are not cheap, even when subsidized they cost about $100 each. Add to this the cost and difficulty of setting up the collection system and the distribution hose. Water from your rain barrel will not flow through a normal nozzle as there is hardly any pressure. Expect watering to take a lot longer than you are used to.
40 gallon rain barrels. Two of these give about 70 usable gallons every heavy rain fall. That’s about 70¢ worth.
In Michigan you can not leave the water in your barrel over the winter, the water will freeze and the barrel will crack. You have to drain the tank completely every fall, an almost impossible task, and the tank is attached to a rainspout and the last bit of water is hard to get out. Still, you have to do it, or the barrel will crack. And the savings for all this is minimal. During a rainy month, you don’t need this water. During a dry month, there is no water to use. Even at the best, the The marginal cost of water in our town is less than 1¢ per gallon. For all the work and cost to set up, two complete 40 gallon tanks (like those shown) will give you at most about 70 usable gallons. That’s to say, almost 70¢ per full filling.
How much lawn can you water? Assume you like to water your lawn to the equivalent of 1″ of rain per week, your 70 gallons will water about 154 ft2 of lawn or garden, virtually nothing compared to the typical Michigan 2000 ft2 lawn. You’ll still have to get most of your water from the city’s main. All that work, for so little benefit.
Young trees with chip volcanos, 1 ft high x18″. Spread the chips to the diameter of the leaves.You don’t need more than 2″.
A far better option is wood chips. They don’t cover a lawn, but they’re great for shrubs, trees or a garden. Wood chips are easy to spread, and they stop weeds and hold water. The photo at left shows a wood chips around the shrubs, and a particularly poor use of wood chips around the trees. For shrubs, trees, or a garden, I suggest you put down 1 to 2 inches of wood chips. Surround a young tree at that depth to the diameter of the branches. Do not build a “chip volcano,” as this lazy landscaper has done.
Consider that, covering 500 ft2 of area to a depth of 1.5 inches will take about 60 cubic feet of wood chips. That will cost about $35 dollars at the local Home Depot. This is enough to hold about 1.25″ or rainwater, That’s about 100 ft3 or water or 800 gallons. The chips prevent excess evaporation while preventing weeds and slowly releasing the water to your garden. You do no work. The chips take almost no work to spread, and will keep on working for years, with no fear of frost-damage. A as the chips stop working, they biocompost slowly into fertilizer. That’s a win.
There is a worst option too, called a rain garden. This is often pushed by environmental-gooders. You dig a hole near your downspout, perhaps ten feet in diameter, by two feet deep, and plant native grasses (weeds). When it rains, the hole fills with water creating a mini wetland that will soon smell like the swamp that it is. If you are not lucky, the water will find a way to leak into your basement. If that’s your problem look here. If you are luckier, your mini-swamp will become the home of mosquitos, frogs, and snakes. The plants will grow, then die, and rot, and look awful. It is very hard to maintain native grasses. That’s why people drain swamps and grow trees or turf or vegetables. If you want to see a well-maintained rain garden, they have two on the campus of Lawrence Tech. A wetland isn’t bad, but you want drainage, Make a bioswale or muir.
Robert Buxbaum, May 31, 2023. I ran for water commissioner some years back.
The Dead Sea in Israel is a popular tourist attraction and health resort-area. It is also the lowest point on the planet, with a surface about 430m below sea level. Its water is saturated with an alkaline salt, and quite devoid of life, and it’s shrinking fast, loosing about 1 m in height every year. The Jordan river water that feeds the sea is increasingly drawn off for agriculture, and is now about 10% of what it was in the 1800s. The Dead Sea is disappearing fast, a story that is repeated with other inland seas: the Aral Sea, the Great Salt Lake, etc. In theory, one could reverse the loss using sea water. In theory, you could generate power dong this too: 430m is seven times the drop-height of Niagara Falls. The problem is the route and the price.
Five (or six) semi-attractive routes have been mapped out to bring water to the Dead Sea, as shown on the map at right. The shortest, and least expensive is route “A”. Here, water from the Mediterranean enters a 12 km channel near Haifa; it is pumped up 50m and travels in a pipe for about 52 km over the Galilean foothills, exiting to a power station as shown on the elevation map below. In the original plan the sea water feeds into the Jordan river, a drop of about 300m. The project had been estimated to cost $3 B. Unfortunately, it would make much of the Jordan river salty. It was thus deemed unacceptable. A variation of this would run the seawater along the Jordan in a pipe or an open channel. This would add to the cost, and would likely diminish the power that could be extracted, but you would not contaminate the Jordan.
A more expensive route, “B”, is shorter but it requires extensive tunneling under Jerusalem. Assuming 20 mies of tunnel at $500 MM/mile, this would cost $10B. It also requires the sea water to flow through the Palestinian West Bank on its way to the sea. This is politically sensitive and is unlikely to be acceptable to the West Bank Palestinians.
Vertical demand of the northern route
Two other routes, labeled “C” and “D” are likely even more expensive than route B. They require the water to be pumped over the Judaean hills near Bethlehem, south of Jerusalem. That’s perhaps 600m up. The seawater would flow from Ashkalon or Gaza and would enter the Dead Sea at Sodom, near Masada. Version C is the most politically acceptable, since it’s short and does not go through Palestinian land. Also, water enters the dead sea at its saltiest point so there is no disruption of the environment. Route D is similar to C, somewhat cheaper, but a lot more political. It goes through Gaza.
The longest route, “E” would go through Jordan taking water from the Red Sea. Its price tag is said to be $10 B. It’s a relatively flat route, but still arduous, rising 210m. As a result it’s not clear that any power would be generated. A version of this route could send the water entirely through Israel. It’s not clear that this would be better than Route C. Looking things over, it was decided that only routes that made sense are those that avoided Palestinian land. An agreement was struck with Jordan to go ahead with route D, with construction to begin in 2021. The project has been on hold though because of cost, COVID, and governmental inertia.
In order to make a $5-10B project worthwhile, you’ll have to generate $500MM to $1B/year. Some of this will come from tourism, but the rest must come from electrical power generation. As an estimate of power generation, let’s assume that that the flow is 65 m3/s, just enough to balance the evaporation rate. Assuming a 400 m power drop and an 80% efficient turbine, we should generate 80% of 255 MWe = about 204 MWe on average. Assuming a value of electricity of 10¢/kWh, that translates to $20,000/ hour, or $179 million per year. This is something, but not enough to justify the cost. We might increase the value of the power by including an inland pond for water storage. This would allow power production to be regulated to times of peak load, or it could be used for recreation, fish-farming, or cooling a thermal power station up to 1000 MWe. These options almost make sense, but with the tunnel prices quoted, the project is still too expensive to make sense. It is “on hold” for now.
It’s not like the sea will disappear if nothing is done. With 10% of the original in-flow of water to the Dead Sea, it will shrink to 10% its original size, and then stop shrinking. At that point evaporation will match in-flow. One could add more fresh water by increasing the flow from the sea of Galilee, but that water is needed. When more water is available, more is taken out for farming. This is what’s happened to the Arial Sea — it’s now about 10% the original size, and quite salty.
Elon Musk besides the prototype 12 foot diameter tunnel.
There’s a now a new tunnel option though and perhaps these routes deserve a second look: Elon Musk claims his “Boring company” can bore long tunnels of 12 foot diameter, for $10-20 MM/mile. This should be an OK size for this project. Assuming he’s right about the price, or close to right, the Dead Sea could be raised for $1B or so. At that price-point, it makes financial sense. It would even make sense if one built multiple seapools, perhaps one for swimming and one for energy storage, to be located before the energy-generating drop, and another for fish after. There might even be a pool that would serve as coolant for a thermal power plant. Water in the desert is welcome, even if it’s salt water.
Platinum catalysts can be very effective at removing hydrogen from air. Platinum promotes the irreversible reaction of hydrogen with oxygen to make water: H2 + 1/2 O2 –> H2O, a reaction that can take off, at great rates, even at temperatures well below freezing. In the 1800s, when platinum was cheap, platinum powder was used to light town-gas, gas street lamps. In those days, street lamps were not fueled by methane, ‘natural gas’, but by ‘town gas’, a mix of hydrogen and carbon monoxide and many impurities like H2S. It was made by reacting coal and steam in a gas plant, and it is a testament to the catalytic power of Pt that it could light this town gas. These impurities are catalytic poisons. When exposed to any catalyst, including platinum, the catalyst looses it’s power to. This is especially true at low temperatures where product water condenses, and this too poisons the catalytic surface.
Nowadays, platinum is expensive and platinum catalysts are no longer made of Pt powder, but rather by coating a thin layer of Pt metal on a high surface area substrate like alumina, ceria, or activated carbon. At higher temperatures, this distribution of Pt improves the reaction rate per gram Pt. Unfortunately, at low temperatures, the substrate seems to be part of the poisoning problem. I think I’ve found a partial way around it though.
My company, REB Research, sells Pt catalysts for hydrogen removal use down to about 0°C, 32°F. For those needing lower temperature hydrogen removal, we offer a palladium-hydrocarbon getter that continues to work down to -30°C and works both in air and in the absence of air. It’s pretty good, but poisons more readily than Pt does when exposed to H2S. For years, I had wanted to develop a version of the platinum catalyst that works well down to -30°C or so, and ideally that worked both in air and without air. I got to do some of this development work during the COVID downtime year.
My current approach is to add a small amount of teflon and other hydrophobic materials. My theory is that normal Pt catalysts form water so readily that the water coats the catalytic surface and substrate pores, choking the catalyst from contact with oxygen or hydrogen. My thought of why our Pd-organic works better than Pt is that it’s part because Pd is a slower water former, and in part because the organic compounds prevent water condensation. If so, teflon + Pt should be more active than uncoated Pt catalyst. And it is so.
where is molar volume. The substance-specific constants and can be understood as an attraction force between molecules and a molecular volume respectively. Alternately, they can be calculated from the critical temperature and pressure as
Now, I’m going to assume that the effect of a hydrophobic surface near the Pt is to reduce the effective value of a. This is to say that water molecules still attract as before, but there are fewer water molecules around. I’ll assume that b remains the same. Thus the ratio of Tc and Pc remains the same but the values drop by a factor of related to the decrease in water density. If we imagine the use of enough teflon to decrease he number of water molecules by 60%, that would be enough to reduce the critical temperature by 60%. That is, from 647 K (374 °C) to 359 K, or -14°C. This might be enough to allow Pt catalysts to be used for H2 removal from the gas within a nuclear wast casket. I’m into nuclear, both because of its clean power density and its space density. As for nuclear waste, you need these caskets.
I’ve begun to test of my theory by making hydrogen removal catalyst that use both platinum and palladium along with unsaturated hydrocarbons. I find it works far better than the palladium-hydrocarbon getter, at least at room temperature. I find it works well even when the catalyst is completely soaked in water, but the real experiments are yet to come — how does this work in the cold. Originally I planned to use a freezer for these tests, but I now have a better method: wait for winter and use God’s giant freezer.
It is a fundamental of science that that the properties of every pure one-phase material is totally fixed properties at any given temperature and pressure. Thus for example, water at 0°C is accepted to always have a density of 0.998 gm/cc, a vapor pressure of 17.5 Torr, a viscosity of 1.002 centipoise (milliPascal seconds) and a speed of sound of 1481 m/s. Set the temperature and pressure of any other material and every other quality is set. But things go screwy near surfaces, and this is particularly true for water where the hydrogen bond — a quantum bond — predominates.
its vapor pressure rises and it becomes less inclined to condense or freeze. I use this odd aspect of thermodynamics to keep my platinum-based hydrogen getter catalysis active at low temperatures where they would normally clog. Normal platinum catalysts are not suitable for hydrogen removal at normal temperatures, eg room temperature, because the water that forms from hydrogen oxidation chokes off the catalytic surface. Hydrophobic additions prevent this, and I’d like to show you why this works, and why other odd things happen, based on an approximation called the Van der Waals equation of state:
(1)
This equation described the molar volume of a pure material, , of any pure material based not the pressure, the absolute temperature (Kelvin) and two, substance-specific constants, and . These constants can be understood as an attraction force term, and a molecular volume respectively. It is common to calculate a and b from the critical temperature and pressure as follows, where Tc is absolute temperature:
, (2 a,b)
For water Tc = 647 K (374°C) and 220.5 bar. Plugging in these numbers, the Van der Waals gives reasonable values for the density of water both as a liquid and a gas, and thus gives a reasonable value for the boiling point.
Now consider the effect that an inert surface would have on the effective values of a and b near that surface. The volume of the molecules will not change, and thus b will not change, but the value of a will change, likely by about half. This is because, the number of molecules surrounding any other molecule is reduced by about half while the inert surface adds nothing to the attraction. Near a surface, surrounding molecules still attract each other the same as before, but there are about half as many molecules at any temperature and pressure.
To get a physical sense of what the surface does, consider using the new values of a and b to determine a new value for Tc and Pc, for materials near the surface. Since b does not change, we see that the presence of a surface does not affect the ratio of Tc and Pc, but it decreases the effective value of Tc — by about half. For water, that is a change from 647 K to 323.5K, 50.5°C, very close to room temperature. Pc changes to 110 bar, about 1600 psi. Since the new value of Tc is close to room temperature, the the density of water will be much lower near the surface, and the viscosity can be expected to drop. The net result is that water flows more readily through a teflon pipe than through an ordinary pipe, a difference that is particularly apparent at small diameters.
This decrease in effective Tc is useful for fire hoses, and for making sailing ships go faster (use teflon paint) and for making my hydrogen removal catalysts more active at low temperatures. Condensed water can block the pores to the catalyst; teflon can forestall this condensation. It’s a general trick of thermodynamics, reasonably useful. Now you know it, and now you know why it works.
We just got a new toilet. Commonly called a commode, and it’s got a cool feature that I’d seen often in Europe but rarely in the US: two levels of flush strength. There is a “small flush” option that delivers, about 3 liters, intended for yellow waste, and a “big flush” option that delivers 6 liters. It’s intended for brown waste, or poop.
The main advantage of two mode flushing, in my opinion, is that the small flush is quieter than the normal. The quality of the flush is quite acceptable, even for brown waste because the elongated shape of the bowl seems better suited to pushing waste to the back, and down the drain. The flush valve is simple too, and I suspect the valve will last longer than the “flapper valve” of my older, one mode commodes. The secondary advantage is from some cost savings on water. That was about 1¢ per small flush in our area of Michigan, but the water department changed how they charge for water in our area and the cost savings have largely disappeared. Even under the old system, the savings in water cost amounted to only about $15 per year. At that rate it would take 15 years or more to pay for the new commode.
There is no real need for water savings in Michigan, and particularly not in our area, metro-Detroit. In other states there often is, but our drinking water comes from the Detroit river, and the cleaned up waste goes back to the river. It’s a cycle with no water lost no matter how much you flush, and no matter how big shower heads. I’d written in favor of allowing big flush toilets and big shower heads in our state, but the Obama administration ruled otherwise. Trump had promised to change that, but was impeached before he could. Even Trump had changed this, Biden has reversed virtually every Trump order related to resource use including those prohibiting China from providing critical technology to our water and power systems. Bottom line, you have to have a low-flush toilet, and you might as well get a two-mode.
Our commode has an elongated front, and I’d recommend that too. It can minimize floor dribbles, and that’s a good thing. The elongated shape also seems to provide a smoother flush path with less splatter. I would not recommend a “power flush” though for several reasons, among them that you get extra splatter and a louder flush noise. We’d bought a power flush some years ago, and in my opinion, it flushed no better than the ordinary toilet. It was very loud, and had a tendency to splatter. There was some slight water savings, but not worth it, IMHO.
Robert Buxbaum, February 8, 2021. I ran for water commissioner with several goals, among them to improve the fairness of billing, to decrease flooding, and to protect our water system from cyber attack.
You may know that engineers recently succeed in decreasing the tilt of the “leaning” tower of Pizza by about 1.5°, changing it from about 5.5° to about to precisely 3.98° today –high precision given that the angle varies with the season. But you may not know how that there were at least eight other engineering attempts, and most of these did nothing or made things worse. Neither is it 100% clear that current solution didn’t make things worse. What follows is my effort to learn from the failures and successes, and to speculate on the future. The original-tilted tower is something of an engineering marvel, a highly tilted, stone on stone building that has outlasted earthquakes and weathering that toppled many younger buildings that were built straight vertical, most recently the 1989 collapse of the tower of Pavia. Part of any analysis, must also speak to why this tower survived so long when others failed.
First some basics. The tower of Pisa is an 8 story bell tower for the cathedral next door. It was likely designed by engineer Bonanno Pisano who started construction in 1173. We think it’s Pisano, because he put his name on an inscription on the base, “I, who without doubt have erected this marvelous work that is above all others, am the citizen of Pisa by the name of Bonanno.” Not so humble then, more humble when the tower started to lean, I suspect. The outer diameter at the base is 15.5 m and the weight of the finished tower is 14.7 million kg, 144 million Nt. The pressure exerted on the soil is 0.76 MPa (110 psi). By basic civil engineering, it should stand straight like the walls of the cathedral.
Bonanno’s marvelous work started to sink into the soil of Pisa almost immediately, though. Then it began to tilt. The name Pisa, in Greek, means swamp, and construction, it seems, was not quite on soil, but mud. When construction began the base was likely some 2.5 m (8 feet) above sea level. While a foundation of clay, sand and sea-shells could likely have withstood the weight of the tower, the mud below could not. Pisano added length to the south columns to keep the floors somewhat level, but after three floors were complete, and the tilt continued, he stopped construction. What to do now? What would you do?
If it were me, I’d consider widening the base to distribute the force better, and perhaps add weight to the north side. Instead, Pisano gave up. He completed the third level and went to do other things. The tower stood this way for 99 years, a three-floor, non-functional stub.
About 1272, another engineer, Giovanni di Simone, was charged with fixing the situation. His was the first fix, and it sort-of worked. He strengthened the stonework of the three original floors, widened the base so it wold distribute pressure better, and buried the base too. He then added three more floors. The tower still leaned, but not as fast. De Simone made the south-side columns slightly taller than the north to hide the tilt and allow the floors to be sort-of level. A final two stories were added about 1372, and then the first of the bells. The tower looked as it does today when Gallileo did his famous experiments, dropping balls of different size from the south of the 7th floor between 1589 and 1592.
Fortunately for the construction, the world was getting colder and the water table was dropping. While dry soil is stronger than wet, wet soil is more plastic. I suspect it was the wet soil that helped the tower survive earthquakes that toppled other, straight towers. It seems that the tilt not only slowed during this period but briefly reversed, perhaps because of the shift in center of mass, or because of changes in the sea level. Shown below is 1800 years of gauge-based sea-level measurements. Other measures give different sea-level histories, but it seems clear that man-made climate change is not the primary cause. Sea levels would continue to fall till about 1750. By 1820 the tilt had resumed and had reached 4.5°.
The 2nd attempt was begun in 1838. Architect, Alessandro Della Gherardesca got permission to dig around the base at the north to show off the carvings and help right the tower. Unfortunately, the tower base had sunk below the water table. Further, it seems the dirt at the base was helping keep the tower from falling. As Della Gherardesca‘s crew dug, water came spurting out of the ground and the tower tilted another few inches south. The dig was stopped and filled in, but he dig uncovered the Pisano inscription, mentioned above. What would you do now? I might go away, and that’s what was done.
The next attempt to fix the tower (fix 3) was by that self-proclaimed engineering genius, Benito Mussolini. In 1934. Mussolini had his engineers pump some 200 tons of concrete into the south of the tower base hoping to push the tower vertical and stabilize it. The result was that the tower lurched another few inches south. The project was stopped. An engineering lesson: liquids don’t make for good foundations, even when it’s liquid concrete. An unfortunate part of the lesson is that years later engineers would try to fix the tower by pumping water beneath the north end. But that’s getting ahead of myself. Perhaps Mussolini should have made tests on a model before working on the historic tower. Ditto for the more recent version.
On March 18, 1989 the Civic Tower of Pavia started shedding bricks for no obvious reason. This was a vertical tower of the same age and approximate height as the Pisa tower. It collapsed killing four people and injuring 15. No official cause has been reported. I’m going to speculate that the cause was mechanical fatigue and crumbling of the sort that I’ve noticed on the chimney of my own house. Small vibrations of the chimney cause bits of brick to be ejected. If I don’t fix it soon, my chimney will collapse. The wet soils of Pisa may have reduced the vibration damage, or perhaps the stones of Pisa were more elastic. I’ve noticed brick and stone flaking on many prominent buildings, particularly at joins in the chimney.
John Burland’s team cam up with many of the fixes here. They are all science-based, but most of the fixes made things worse.
In 1990, a committee of science and engineering experts was formed to decide upon a fix for the tower of Pisa. It was headed by Professor John Burland, CBE, DSc(Eng), FREng, FRS, NAE, FIC, FCGI. He was, at the time, chair of soil mechanics at the Imperial College, London, and had worked with Ove, Arup, and Partners. He had written many, well regarded articles, and had headed the geological aspects of the design of the Queen Elizabeth II conference center. He was, in a word, an expert, but this tower was different, in part because it was an, already standing, stone-on stone tower that the city wished should remain tilted. The tower was closed to visitors along with all businesses to the south. The bells were removed as well. This was a safety measure, and I don’t count it as a fix. It bought time to decide on a solution. This took two years of deliberation and meetings
In 1992, the committee agreed to fix no 4. The tower was braced with plastic-covered, steel cables that were attached around the second and third floors, with the cables running about 5° from the horizontal to anchor points several hundred meters to the north. The fix was horribly ugly, and messed with traffic. Perhaps the tilt was slowed, it was not stopped.
In 1993, fix number 5. This was the most exciting engineering solution to date: 600 tons of lead ingots were stacked around the base, and water was pumped beneath the north side. This was the reverse of the Mussolini’s failed solution, and the hope was that the tower would tilt north into the now-soggy soil. Unfortunately, the tower tilted further south. One of the columns cracked too, and this attempt was stopped. They were science experts, and it’s not clear why the solution didn’t work. My guess is that they pumped in the water too fast. This is likely the solution I would have proposed, though I hope I would have tested it with a scale model and would have pumped slower. Whatever. Another solution was proposed, this one even more exotic than the last.
For fix number 6, 1995, the team of experts, still overseen by Burland, decided to move the cables and add additional tension. The cables would run straight down from anchors in the base of the north side of the tower to ten underground steel anchors that were to be installed 40 meters below ground level. This would have been an invisible solution, but the anchor depth was well into the water table. So, to anchor the ground anchors, Burland’s team had liquid nitrogen injected into the ground beneath the tower, on the north side where the ground anchors were to go. What Burland did not seem to have realized is that water expands when it freezes, and if you freeze 40 meters of water the length change is significant. On the night of September 7, 1995, the tower lurched southwards by more than it had done in the entire previous year. The team was summoned for an emergency meeting and the liquid nitrogen anchor plan was abandoned.
Tower with the two sets of lead ingots, 900 tons total, about the north side of the base. The weight of the tower is 14,700 tons.
Fix number 7: Another 300 tons of lead ingots were added to the north side as a temporary, simple fix. The fix seems to have worked stabilizing things while another approach was developed.
Fix number 8: In order to allow the removal of the ugly lead bricks another set of engineers were brought on, Roberto Cela and Michele Jamiolkowski. Using helical drills, they had holes drilled at an angle beneath the north side of the tower. Using hoses, they removed a gallon or two of dirt per day for eleven years. The effect of the lead and the dirt removal was to reduce the angle of the tower to 4.5°, the angle that had been measured in 1820. At this point the lead could be removed and tourists were allowed to re-enter. Even after the lead was removed, the angle continued to subside north. It’s now claimed to be 3.98°, and stable. This is remarkable precision for a curved tower whose tilt changes with the seasons. (An engineering joke: How may engineers does it take to change a lightbulb? 1.02).
The bells were replaced and all seemed good, but there was still the worry that the tower would start tilting again. Since water was clearly part of the problem, the British soils expert, Burland came up with fix number 9. He had a series of drainage tunnels built to keep the water from coming back. My worry is that this water removal will leave the tower vulnerable to earthquake and shedding damage, like with the Pavia tower and my chimney. We’ll have to wait for the next earthquake or windstorm to tell for sure. So far, this fix has done no harm.
Robert Buxbaum, October 9, 2020. It’s nice to learn from other folks mistakes, and embarrassments, as well as from their successes. It’s also nice to see how science really works, not with great experts providing the brilliant solution, but slowly, like stumbling in the dark. I see this with COVID-19.
When I was eight or nine year old, I went to the 1963-64 World’s Fair in New York. Among the attractions, in “the kitchen of the future”, I saw the first version of an amazing fry-pan that was coated with plastic. You could cook an egg on that plastic without any oil, and the egg didn’t stick. The plastic was called teflon, a DuPont innovation, whose molecule is shown below.
The molecular structure of Teflon. There is an interior carbon backbone that is completely enclosed with tightly bound fluorine atoms. The net result is a compound that does not bind readily to anything else.
Years later, I came to understand that Teflon’s high-temperature stability and non-stick properties derive from the carbon-fluorine bonds. These bonds are much stronger than the carbon-hydrogen bonds found in food, and most solid, organic things. Because of the strength of the carbon-fluorine bond, Teflon is resistant to oxidation, and to chemical interaction with other molecules, e.g. in food. It does not even interact with water, making it hydrophobic and non-wetting on metals. The carbon-carbon bonds in the middle remained high temperature stable, in part because they were completely shielded by the fluorine atoms.
This is a PFAS. The left side is just like teflon, and very hydrophobic. The right side is hydrophilic and highly bonding to pans, and many other things like water or cotton.
But as remarkable as teflon’s non-stick properties are, perhaps the most amazing thing was that it somehow sticks to the pan. For the first generation pans I saw, it didn’t stick very well. Still, the DuPont engineers had found a way to stick non-stick Teflon to a metal for long enough to cook many meals. If they had not found this trick, teflon would not have the majority of its value, but how did they do it? It turns out they used a thin coating of a di-functional compound called PFAS, a a polyfluoro sulphonyl (or polyfluoroalkyl) substance. The molecular structure of a common PFAS, is shown above.
Each molecule of PFAS has one end that’s teflon-like and another end that’s different. The non-Teflon end, in this case a sulfonyl group, is chosen to be both high temperature stable and sticky to metal oxides. The sulphonyl group above is highly polar, and acidic. Acidic will bind to bases, like metal oxides. The surface of the metal pan is prepared by applying a thin layer of oxide or amidine, making it a polar base. The PFAS is then applied, then Teflon. The Teflon-end of the PFAS is bound to teflon by the hydrophobicity of everything else rejecting it.
There are many other uses for PFAS. For example, PFAS is applied to clothing to make it wrinkle free and stain resistant. It can also be used as a super soap, making uncommonly stable foams and bubbles. It is also used in fire-fighting and plane de-icing. Finally, PFAS is the main component of Nafion, the most common membrane for PEM fuel cells. (I can think of yet other applications..) There is just one small problem with PFAS, though. Like teflon, this molecule is uncommonly stable. It doesn’t readily decompose in nature. That would be a small problem if we were sure that PFAS was safe. As it happens it seems safe, but we’re not totally sure.
The safety of PFAS was studied extensively before PFAS-teflon pans was put on the market, but the methodology has been questioned. Large doses of PFAS were fed to test animals, and their health observed. Since the test animals showed no real signs of ill-health though some showed a slight liver enlargement, PFAS was accepted as safe for humans at a lower exposure dose. PFAS was approved for use on pans and allowed to be dumped under conditions where humans would be exposed to 1/1000 of that used on the animals. The assumption was that there would be little or no health hazard at these low exposure levels.
But low risk is not no risk, and today one can sue for even the hint of an effect though use of a class action suit. That is, lawyers sue on behalf of all the people who might have been damaged. My city was sued successfully this way for complicity in sewage over-flows. Of course, since the citizens being paid by the suit are the same ones who have to pay for the damage, only the lawyers benefit. Still, the law is the law, and at least for some judges, putting anyone at risk is enough evidence of willful disregard to hand down a stinging judgement against the evil doer. Judges have begun awarding large claims for PFAS too. While no individual can get the claim more than a tiny amount of money, the lawyers can do very well.
There is no new evidence that PFAS is dangerous, but none is needed if you can get yourself the right judge. In this regard, an industry of judicial tourism has sprung up, where class-action lawyers travel to districts where the judges are favorable. For Teflon suits, the bust hunting grounds are in New York, New Hampshire, and California, and the worst are blood-red states like Wyoming and Utah. Just as different judges promote different precedents, different states allow vastly different PFAS concentrations in the water. A common standard, one used by Michigan, is 70 ppt, 1 billion times stricter than the amounts tested on animals. This is roughly 500 times stricter than the acceptable concentratios for lead, a known poison. The standard in New York is 7 times stricter than Michigan, 10 ppt. The standard in North Carolina is 140,000 ppt, in in several states there is no legal limit to PFAS dumping. There is no scientific logic to all of this, and skeptical view is that the states that rule more strictly for PFAS than lead do so make money for lawyers. Lead is everyone in the natural environment, so you can’t sue as easily for lead. PFAS is a man-made intruder, though, and a strict standard helps lawyers sue. You can find a summary of state by state regulations here.
Any guideline stricter than about 1000 ppt, presents a challenge to the water commissioner who must measure it and enforce the law. There are tricks, though. You can use the surfactant quality of PFAS to concentrate it by a factor of 100 or more. To do this, you take a sample of river water and create bubbles. Any bubbles that form will be highly concentrated in PFAS. Once PFAS can be identified this way, and the concentrators estimated, the polluters can be held liable. Whether we benefit from the strict rulings is another story. If I were making the law for Michigan, I’d probably choose a limit about 1 ppb, but I’m not making the law. The law, as written, may be an idiot, as Bumble said, but the Law is the Law.
In terms of Michigan fishing, while some rivers have PFAS concentrators above the MI-legal limit, they are generally not far over the line. I would trust the fish in the Huron River, even west of Wixom road but I’d suggest you avoid any foam you find floating there. The PFAS content of foam will be much higher than that of the water in general.
Robert E. Buxbaum, June 30, 2020, edited July 8, 2020. There are seven compounds known as PFAS’s: perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), perfluoroheptanoic acid (PFHpA), and perfluorobutanesulfonic acid (PFBS).
Our county, like many in the US and Canada, is served by thousands of miles of lead pipes. Some of these are the property of the government, others sit beneath our homes and are the property of the home-owner. These pipes are usually safe, but sometimes poison us. There is also problem of lead-tin solder. It was used universally to connect iron and copper pipes until it was outlawed in 1986. After years of sitting quietly, this lead caused a poisoning crisis in DC in 2004, and in Flint in 2015-16. Last month my town, Oak Park, registered dangerous lead levels in the drinking water. In an attempt to help, please find the following summary of the relevant lead chemistry. Maybe people in my town, or in other towns, will find some clue here to what’s going on, and what they can do to fix it.
lead pipes showing the three oxides: brown, yellow, and red, PbO2, PbO, and Pb2O3.
Left to itself, lead and solder pipe could be safe; lead is not soluble in clean water. But, if the water becomes corrosive, as happens every now and again, the lead becomes oxidized to one of several compounds that are soluble. These oxides are the main route of poisoning; they can present serious health issues including slow development, joint and muscle pain, memory issues, vomiting, and death. The legal limit for lead content in US drinking water is 15 ppb, a level that is far below that associated with any of the above. The solubility of PbO, lead II oxide, is more than 1000 times this limit 0.017 g/L, or 17,000 ppb. At this concentration serious health issues will show up.
PbO is the yellow lead oxide shown in the center of the figure above, right; the other pipes show other oxides, that are less-soluble, and thus less dangerous. Yellow lead oxide and red lead oxides on the right were used as paint colors until well into the 20th century. Red lead oxide is fairly neutral, but yellow PbO is a base; its solubility is strongly dependent on the PH of the water. In neutral water, its solution can be described by the following reaction.
PbO + H2O(l) –> Pb2+(aq) + 2 OH–(aq).
In high pH water (basic water), there are many OH–(aq) ions, and the solubility is lower. In low pH, acidic water the solubility is even higher. For every 1 point of lower pH the lowubility increases by a factor of 10, for every 1 point of higher pH, it decreases by a factor of ten. In most of our county, the water is slightly basic, about pH 8. It also helps that our water contains carbonate. Yellow lead forms basic lead carbonate, 2PbCO3·Pb(OH)2, the white lead that was used in paint and cosmetics. Its solubliity is lower than that of PbO, 110 ppb, in pure water, or within legal limit in water of pH 8. If you eat white lead, though, it reacts with stomach acid, pH 2, and becomes quite soluble and deadly. Remember, each number here is a factor of ten.
A main reason lead levels a very low today are essentially zero, even in homes with lead solder or pipe, involves involves the interaction with hypochlorite. Most water systems add hypochlorite to kill bacteria (germs) in the water. A side benefit is significant removal of lead ion, Pb2+(aq).
Pb2+(aq) + 2 ClO–(aq) –> Pb(ClO)2(s).
Any dissolved lead reacts with some hypochlorite ion reacts to form insoluble lead hypochlorite. Lead hypochlorite can slowly convert to Lead IV oxide — the brown pyrophilic form of lead shown on the left pipe in the figure above. This oxide is insoluble. Alkaline waters favor this reaction, decreasing solubility, but unlike with PbO, highly alkaline waters provide no significant advantage.
Lead IV oxide, PbO2 was used in old-fashioned matches; it reacts violently with phosphorus or sulfur. People were sometimes poisoned by sucking on these matches. In the stomach, or the presence of acidic drinking water, PbO2 is decomposed forming soluble PbO:
PbO2(s) +2 H+(aq) + 2 e– –> PbO(s) + H2O(l).
You may wonder at the presence of the two electrons in the reaction above. A common source in water systems is the oxidation of sulphite:
SO3-2(aq)–> SO4-2(aq) + 2 e–.
The presence of sulphite in the water means that hypochlorite is removed.
ClO–(aq) + 2 H+(aq) + 2 e– —> Cl–(aq) + H2O(l).
Removal of hypochlorite can present a serious danger, in part because the PbO2(s) slowly reverts to PbO and becomes soluble, but mostly because bacteria start multiplying. In the Flint crisis of 2016, and in a previous crisis in Washington DC, the main problem, in my opinion was a lack of hypochlorite addition. The lead crisis was preceded by an uptick in legionnaires disease; It killed 12 people in Flint in 2014 and 2015, and 87 were sickened, all before the lead crisis. Eventually, it was the rise of legionaries disease that alerted water officials in Virginia that there was something seriously wrong in Flint. Most folks were unaware because Flint water inspectors seem to have been fudging the lead numbers to make things look better.
Most US systems add phosphate to remove lead from the water. Flint water folks could have stopped the lead crisis, but not the legionnaires, by adding more phosphate. Lead phosphate solubility is 14 ppb at 20°C, and my suspicion is that this is the reason that the legal limit in the US is 15 ppb. Regulators chose 15 ppb, I suspect, not for health reasons, but because the target could be met easily through the addition of phosphate. Some water systems in the US and Canada disinfect with chloramine, not hypochlorite, and these systems rely entirely on phosphate to keep lead levels down. Excess phosphate is used in Canada to lower lead levels below 10 ppb. It works better on systems with hypochlorite.
Chloramine is formed by reacting hypochlorite with ammonia. It may be safer than hypochlorite in terms of chlorite reaction products, a real problem when the water source is polluted. But chloramine is not safe. It sickened 72 soldiers, 36 male and 36 female in 1998. They’d used ammonia and bleach for a “cleaning party” on successive days. Here’s a report and first aid instructions for the poisoning. That switching to chloramine can expose people to lead is called “the chloramine catch”.
Unlike PbO, PbO2is a weak acid. PbO2 and PbO can react to form red lead, PbO•PbO2(s), the red stuff on the pipe at right in the picture above. Red lead can react with rust to form iron plumbable, an insoluble corrosion resister. A simple version is:
PbO•PbO2(s) + Fe2O3(s) —> 2FePbO3(s).
This reaction is the basis of red-lead, anti-rust compounds. Iron plumbable is considered to be completely insoluble in water, but like PbO it is soluble in acid. Bottom line, slightly basic water is good, as are hypochlorite in moderation, and phosphate.
Robert Buxbaum, November 18, 2019. I ran for water commissioner, and might run again. Even without being water commissioner, I’ll be happy to lend my expertise, for free, to any Michigan town or county that is not too far from my home.
Most towns have at least one water tower. Oakland county, Michigan has four. When they are sized right, they serve several valuable purposes. They provide water in case of a power failure; they provide increased pressure in the morning when people use a lot of water showering etc.; and they allow a town to use smaller pumps and to pump with cheaper electricity, e.g. at night. If a town has no tower, all these benefits are gone, but a town can still have water. It’s also possible to have a situation that’s worse than nothing. My plan is to show, at the end of this essay, one of the ways that can happen. It involves thermodynamic properties of state i a situation where there is no expansion headspace or excess drain (most towers have both).
A typical water tower — spheroidal design. A tower of the dimensions shown would contain about 1/2 million gallons of water.
The typical tower stands at the highest point in the town, with the water level about 170 feet above street level. It’s usable volume should be about as much water as the town uses in a typical day. The reason for the height has to do with the operating pressure of most city-level water pipes. It’s about 75 psi and each foot of water “head” gives you about 0.43 psi. You want pressures about 75 psi for fire fighting, and to provide for folks in apartment buildings. If you have significantly higher pressures, you pay a cost in electricity, and you start losing a lot of water to leaks. These leaks should be avoided. They can undermine the roads and swallow houses. Bob Dadow estimates that, for our water system the leakage rate is between 15 and 25%.
Oakland county has four water towers with considerably less volume than the 130 million gallons per day that the county uses. I estimate that the South-east Oakland county tower, located near my home, contains, perhaps 2 million gallons. The other three towers are similar in size. Because our county’s towers are so undersized, we pay a lot for water, and our water pressure is typically quite low in the mornings. We also have regular pressure excursions and that leads to regular water-boil emergencies. In some parts of Oakland county this happens fairly often.
There are other reasons why a system like ours should have water towers with something more like one days’ water. Having a large water reserve means you can benefit from the fact that electric prices are the lowest at night. With a days’ volume, you can avoid running the pumps during high priced, day times. Oakland county loses this advantage. The other advantage to having a large volume is that it gives you more time to correct problems, e.g. in case of an electric outage or a cyber attack. Perhaps Oakland thinks that only one pump can be attacked at one time or that the entire electric grid will not go out at one time, but these are clearly false assumptions. A big system also means you can have pumps powered by solar cells or other renewable power. Renewable power is a good thing for reliability and air pollution avoidance. Given the benefits, you’d expect Oakland county would reward towns that add water towers, but they don’t, as best I can tell.
Here’s one way that a water column can cause problems. You really need those pressure reliefs.
Now for an example of the sort of things that can go wrong in a water tower with no expansion relief. Every stand-pipe is a small water tower, and since water itself is incompressible, it’s easy to see that a small expansion in the system could produce a large pressure rise. The law requires that every apartment hose water system has to have expansion relief to limit these increases; The water tower above had two forms of reliefs, a roof vent, and an overflow pipe, both high up so that pressure could be maintained. But you can easily imagine a plumber making a mistake and installing a stand pipe without an expansion relief. I show a system like that at left, a 1000 foot tall water pipe, within a skyscraper, with a pump at the bottom, and pipes leading off at the sides to various faucets.
Lets assume that the pressure at the top is 20 psi, the pressure at the bottom will be about 450 psi. The difference in pressure (430 psi) equals the weight of the water divided by the area of the pipe. Now let’s imagine that a bubble of air at the bottom of the pipe detaches and rises to the top of the pipe when all of the faucets are closed. Since air is compressible, while water is not, the pressure at the bubble will remain the same as the bubble rises. By the time the bubble reaches the top of the pipe, the pressure there will rise to 450 psi. Since water has weight, 430 psi worth, the pressure at the bottom will rise to 880 psi = 450 + 430. This is enough to damage pump and may blow the pipes as well. A scenario like this likely destroyed the New Horizon oil platform to deadly consequences. You really want those pressure reliefs, and you want a competent plumber / designer for any water system, even a small one.
Robert Buxbaum, September 28- October 6, 2019. I ran for water commissioner is 2016.
Water costs vary greatly about Oakland county, and around the US, and I have struggled in vain to find out why. In part the problem is that each city gets to add as much maintenance and management costs as the city government thinks appropriate. High management and infrastructure fees can increase to the cost of water, but I also not that different cities about Oakland County Michigan get their water at different rates from the multi-county organization that oversees water in South East Michigan: GLWA, The Great Lakes Water Authority.
$112 water bill for zero usage. The base charge is so large that prices are essentially independent of useage.
I’ve attended meetings, both local and multi county and have tried to find out why one town gets its water at a far lower rate than another, near by. Towns get lower rates if they have a water tower, but it is not at all clear what the formula is. It also helps to separate the storm sewage from the sanitary sewage — something that I have proposed for all of Oakland county, but if there is fixed formula of how that affects rates, I’ve not seen it. And I wonder how well communities monitor the amount of storm sewage they generate.
The water itself is free. For the most part, in this county, we pump it from the Detroit river. Some of the rest of the water is pumped from wells. None of this costs anything. There is a pump cost, but it is manicure. Pumping 1 gallon of water up 75 feet, costs about 0.002¢ in pumping cost. The rest of the cost is infrastructure: the cost of the pumps, the pipes, the treatment, the billing and sewage. Among the sewage fees is a pollution penalty, and Oakland county pays plenty of pollution penalties. When it rains, we generate more sewage than the system will handle, and we dump the rest into the rivers and lakes. This results in closed beaches and poisoned fish, and fines too. The county pays the EPA when we do this, and the county passes the cost to the cities. I don’t know what the formula for fee distribution is, and don’t even know what it should be. What I do know is that we do this vastly too often.
Another oddity is that we bill on a per gallon basis. For my home, the bill is about 2¢/ gallon — 100 times the pumping cost. Though the city can claim that we are paying for infrastructure, both clean water infrastructure and sewage infrastructure, it seems odd to bill on a per-gallon used basis, and 1000 times the true per-gallon price. Since most of the price of water is the infrastructure and management cost, it seems like a regressive tax to charge people on the basis of per-gallon used. I also find it odd that cities do a propaganda campaign to tell folks to use less water. Why? I’d much prefer to charge a far lower base charge, and then bill significantly per-gallon. As with much that is socialist, the current system is inefficient, but pleasant for the management.
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