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Sun Apr 22, 2018, 05:52 PM

Recovery of Phosphate from Human Waste.

Many large areas of the planet have been sacrificed for so called "renewable energy," including places like Glen Canyon sacrificed by an "environmentalist" named David Brower from the Sierra club in a kind of cynical trade he had no moral right to make, something to somewhat dubious credit he regretted, not that the Canyon was ever restored, anymore than the Colorado River Delta's destroyed habitat was ever restored.

(The current Sierra Club is no better: Right now they are engaged in a completely destructive attempt to sacrifice huge swathes of the continental shelf off the coast of New Jersey for idiotic unsustainable wind turbines that will be leaky navigation hazards 20 years after they're built as well a huge environmental insult to the benthic ecosystem, not that these airheads give a shit about science. Apparently the illiterate adviser to the government here from the Sierra club hates nuclear energy and is willing to send thousands of ships to sea loaded with coal based steel and coal derived concrete, because, he says, of a few uranium Navajo miners he heard about from the 1950's. What an asshole...all the wind turbines in Denmark, more than 5000 of them, can't produce as much energy as one of the two Salem Creek nuclear power plants does in one single building.)

Among the most egregious destroyed ecosystems sacrificed on the altar of so called "renewable energy" - in this case owing to run off from the agricultural land in Iowa devoted to "renewable" ethanol for cars - is the delta of North America's largest river, the Mississippi.

Hypoxia in the northern Gulf of Mexico: Does the science support the Plan to Reduce, Mitigate, and Control Hypoxia?

However not all of the destruction of the Mississippi delta and similarly surface bodies, both fresh and saline, threatened by nitrate and phosphate driven hypoxia, "eutrophication," is tied to agricultural runoff either for putative "renewable automobile fuel" or for food. Some of it derives from run-off from cities and large towns and is tied to wastewater treatment.

Fecal matter is rich in phosphorous, and many wastewater treatment systems are not equipped to remove very much of it, and it ends up in rivers, lakes, creeks, ponds, bays and seas where it taxes the ecosystems.

Phosphorous remains an essential element for maintaining the "green revolution" of the 1950's - specifically the agricultural revolution that allows us to feed a large, if stressed, human population, now exceeding seven billion people.

It is thus with interest that I came across a paper in the scientific literature today written by scientists at Cal Tech that offers an interesting approach to addressing this problem, by electrolyzing waste water: Phosphate Recovery from Human Waste via the Formation of Hydroxyapatite during Electrochemical Wastewater Treatment (Hoffman et al, ACS Sustainable Chem. Eng., 2018, 6 (3), pp 3135–3142).

From the opening text:

Discharge of phosphorus-containing wastewater to surface waters can cause algal blooms, leading to growth of toxic cyanobacteria, hypoxia, and disruption of food webs.(1,2) At the same time, phosphorus is a limited resource with an average price that has nearly tripled between 2005 and 2015,(3) making the recovery of phosphorus from waste crucial.(4) Toilet and domestic wastewater are an important source of phosphorus, as up to 22% of the world’s consumption of phosphorus could be recovered from human urine and feces.(5,6) Recovery of phosphorus from toilet wastewater or septic systems could therefore reduce phosphorus pollution as well as reduce dependency on imported mineral phosphate in countries where access to affordable fertilizers is limited.(7)

Enhanced biological phosphorus removal (EBPR) may provide effective phosphorus recovery in centralized wastewater treatment processes,(8) but in rural communities, small onsite sanitation systems (e.g., septic tanks, latrines, or cesspools) make this technology challenging without engineered processes to maintain the correct microbial population.(9) Phosphorus recovery in rural communities can be accomplished via forced precipitation as struvite (NH4MgPO4·6H2O) or hydroxyapatite (Ca5(PO4)3OH), but these strategies typically require separation of urine and feces, addition of chemicals, or use of sacrificial electrodes that further complicates and increases the cost of existing wastewater treatment strategies.(10−12)

Electrochemical systems have previously been suggested for phosphorus removal from wastewater. Electrochemical coagulation of phosphate from synthetic wastewater has been achieved using sacrificial aluminum or iron anodes,(13,14) as well as magnesium anodes, which allowed for struvite recovery from ammonium-containing solutions.(15) However, this type of electrode is depleted by oxidation and needs to be replaced on a regular basis...

The authors have developed a new series of electrodes (albeit electrodes containing the rare elements tantalum (a conflict metal) and iridium, although the main material seems to be the wonder material titanium dioxide (rutile), one of the more common minerals on earth.

During a process utilizing these electrodes the authors report the precipitation of a phosphate mineral, hydroxyapatite, after describing their goals thusly:

The purpose of this study was to evaluate the potential for phosphate removal from human wastewater during electrochemical treatment using the same combined anode–cathode system previously shown to provide efficient wastewater treatment.(20,23,24) Phosphate-containing precipitates were identified and phosphate removal efficiencies were measured in authentic and synthetic toilet wastewater. Experiments in synthetic wastewater allowed quantification of the effects of ion composition, buffering capacity, current density, and electrode surface area to volume ratio on phosphate removal kinetics and equilibria.

They use synthetic and real toilet water in their experiments, and recover calcium, phosphate and the eutrophic participant ammonium as well. A graphic from one set of experiments:

The caption:

Figure 1. Mg2+, Ca2+, PO43–T, and ammonia (NH4+ + NH3) percent removal during electrochemical treatment (3.3 V; 50 A) of toilet wastewater ([Cl–] = 80 mM) in pilot-scale reactor. Initial ion concentrations are indicated in the legend.

They do considerable analysis of their phosphate material, x-ray crystallography, all that good stuff, and then produce more results relevant here with real toilet water:

The caption:

Figure 3. Percent PO43–T, Ca2+, and Mg2+ remaining during potentiostatic electrochemical treatment (3.6 V; ∼18 mA cm–2) of genuine toilet wastewater (filled markers) and synthetic wastewater (empty markers) with similar ionic compositions. [PO43–]T,0 ≈ 0.5 mM; [Ca2+]0 ≈ 1.3 mM; [Mg2+]0 ≈ 1.3 mM. Error bars represent ± one standard deviation of three replicates.

The authors find a limitation, the concentration of calcium needs to be relatively high to obtain nearly complete precipitation of the phosphate, although they note that urine usually contains significant calcium.

Here is a theory vs. experimentt graph of recovery of phosphate:

The caption:

Figure 4. Measured vs predicted percent total phosphate removal following galvanostatic electrolysis (4 h; 10 mA cm–2). Error bars represent ± standard deviation of three replicates. Experiments are referenced by letter and are described in Table S1.

They write:

Based on eqs 1 and 3, high phosphate removal is predicted at high initial calcium concentrations and high initial ratios of calcium to phosphate concentrations (Figure 5). Reliance on high calcium concentrations for efficient phosphate removal is a limitation of this technology. However, urine in toilet wastewater typically contains sufficient calcium to achieve greater than 50% phosphate removal (i.e., ∼1 mM following ∼10× dilution by flushing).(44)

Equations 1 and 3 are ordinary equilibrium equations one might find in an introductory chemistry course:

They have a nice 3D theoretical prediction graph on the relationship between calcium concentration and phosphate removal:

The caption:

Figure 5. Predicted percent total phosphate removal. Predictions are based on solving the simultaneous eqs 1 and 3 at varying initial total phosphate and calcium concentrations and a cathodic pH of 9.4.

Discussion of toilet water might be inclined to induce giggles, but it is a very serious matter.

As it happens the number of people who [Idie from a lack of toilets or even more primitive waste treatment facilities numbers about 361,000 human beings a year, children under the age of 5.

This amounts to roughly 1000 children a day.

Toilets and the water in them are serious issues, very serious issues.

But in this country, we're not at all into seriousness.

It's a little off topic as I consider the proposed destruction of the coastal benthic zone of New Jersey for a literally quixotic adventure in providing rotting steel at sea for future generations to clean up, but...but...

By contrast to the thousand children people who die each day because of trivializing selective attention, it can be shown by appeal to the scientific literature that over a period of a half a century, the number of excess deaths attributed to uranium mining by Navajos owing to cancer was less than 100.

Still, according to the asshole at the New Jersey Sierra Club, a fetish over the miners justifies destroying the benthic zone of the New Jersey coastal shelf.

The asshole notwithstanding, if we're going to bring electricity to the third world to provide toilets that are safe for the environment, that electricity needs to be nuclear electricity.

If you want to be a real environmentalist, as opposed to an ersatz environmentalist spewing 50 year old slogans about uranium miners, you need to read and think about what you read.

Have a nice Sunday evening.

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Reply Recovery of Phosphate from Human Waste. (Original post)
NNadir Apr 2018 OP
msongs Apr 2018 #1
NNadir Apr 2018 #2
Ferrets are Cool Apr 2018 #3
hunter Apr 2018 #4
NNadir Apr 2018 #5

Response to NNadir (Original post)

Sun Apr 22, 2018, 06:39 PM

1. time saver: OP is promoting nuclear energy industry nt

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Response to msongs (Reply #1)

Sun Apr 22, 2018, 06:44 PM

2. Absolutely. It is the ONLY clean form of energy there is.

I'm a scientist, not a wishful thinker.

One of the fun thing about people who have a reflexive hatred of nuclear energy - which saves human lives - is that they never take the time to open a scientific paper.

A lazy set, they. They want to save time since from my perspective, they'd rather wax romantic about their bourgeois Tesla cars than actually think.

Basically, they don't give a rat's ass about the environment.

I do.

It's why I spend so much time going through scientific papers in detail, to support a serious interest.

Have a nice evening.

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Response to msongs (Reply #1)

Sun Apr 22, 2018, 07:28 PM

3. +1

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Response to msongs (Reply #1)

Mon Apr 23, 2018, 12:11 AM

4. Or flush toilets and advanced sewage treatment...

I have a flush toilet that's connected to a very advanced sewage treatment plant.

It's not something I'd deny other human beings.

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Response to msongs (Reply #1)

Tue Apr 24, 2018, 06:44 AM

5. And let's not overlook the other point. The OP is also pointing out the huge destruction...

...of the environment by so called "renewable energy," which hasn't worked, isn't working and won't work to address serious environmental issues, the worst of which is climate change.

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