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On Bill Gates and Sewage Treatment
Here’s some good news, via Wired and the Bill and Melinda Gates Foundation: a Washington State company has developed a small, prototype sewage treatment plant that produces potable drinking water and an excess of electrical power. How good is the water? Let Bill show you:
Stipulating that sources on this are only one-step removed from press releases, the reports are intriguing and, importantly, there’s a working prototype. Bill Gates actually drank the water and the plant is — again, according to the manufacturer — operating up to both Washington state and federal standards.
If it sounds a little too good to be true, that’s not a bad instinct, though the Wired piece quotes one engineer not affiliated with the project who maintains that, yes, this is plausible (I’m curious to hear from members with similar backgrounds). The one thing my non-expert eye noticed was that Janicki’s website describes the OmniProcessor as producing “150 kW. When producing maximum power.” Unfortunately, this is neither very much — the average American household uses about 2kW — and not very helpful. Kilowatts are a measure of electrical power, whereas kilowatt-hours are a measure of electrical energy. Roughly analogized, printing only the number of kilowatts that can be produced is like a car company advertising its latest model’s maximum speed, but neglecting any mention of how long it can maintain it and, therefore, how far it can go.**
On the other hand, an inexpensive, largely* self-powered sewage plant good enough to produce potable water is no small achievement. Sewage treatment is one if those un-sexy but massively important issues that we tend to take for granted — and its hugely important in the developing world. Again, from the Wired piece:
Forty percent of the global population—or 2.5 billion urban residents—practice open defecation or otherwise lack adequate sanitation, and an additional 2.1 billion urban residents use facilities that do not safely dispose of human waste. About 1.5 million children die every year from contaminated food and water, and in developing countries, half of all patients in hospitals are there because of problems with water and sanitation. What’s more, all this puts an economic strain on such countries. In India, bad sanitation practices costs the country nearly $54 billion a year, or 6.4 percent of its GDP.
But best of all, the Gates Foundation isn’t treating this as purely humanitarian mission; the goal is to sell the plants to people in the developing world and run them as businesses. To adapt the old adage: “Treat a man’s sewage and he’ll be healthy for a week. Teach a man to treat his own sewage — and those of his neighbors, while generating potable water and a trickle of excess energy — and he’ll be healthy and rich for life.”
* It’s unclear— to me, at least — from the reports whether the is entirely self-sufficient, or whether it needs energy from an external source to get running.
** Member Mark Wilson emails me to point out that — while I was correct to question the output only being listed in kilowatts — I was off to ask for kilowatt-hours as a remedy. The better question would be to ask for its duty cycle, or its average power output.
Published in General
One aspect of this that may be a complication, is getting the poo, to the poo treatment facility, particularly in a reliable way such that the treatment plant can run efficiently. It’s one thing to have a sludge treatment process that can turn the sludge into useful components, but in the US we have both sewage lines installed all over communities and septic tanks available to be pumped all over rural areas.
If the countries or areas that could benefit from this treatment equipment do not have the ability to safely and reliably collect the sludge and ensure that it is of a relatively useful nature (the sludge must be of a known composition or you don’t get the burnable products) then additional steps will be necessary.
Additionally, while this equipment may be able to return some power to a local grid system, perhaps up to 150 kW, some sort of start-up and operating power supply will be necessary to accommodate the operation of the machinery.
In all it’s a neat development, but it’s one that would need to be incorporated along with other changes to see its relative use. In some ways, it may be beneficial for the facility operator to pay people or communities to collect their own waste for use so that the operator isn’t also responsible for setting up waste repositories and collection trucking.
A working prototype is the first step. Proof of concept. Good for Gates to push it this far.
This is almost certainly more expensive than installing solar panels, so the power angle of this is probably overblown, but the sanitation angle is intriguing and there is another side to this. The disposal of sewage sludge is a really big issue. (Listen to the RadioLab episode Poop Train and you will learn that NY creates enough sewage sludge to fill the Rose Bowl each day) Offering another method for cities to dispose of their sludge could be very popular.
I’m guessing they are assuming the “inputs” will be collected by the owner of this plant, somehow.
But I can’t see the how, either. This is supposed to be a post-sewage treatment process, since you already have the sludge.
But then to go through all that trouble just to get a little bit of water and a little bit of electricity?
The Old Republic (that is, The New Republic before the purge) ran an article criticizing the Bill Gates approach to foreign aid. The author, Michael Hobbes, started with a nice idea, the play pump:
Hobbes doesn’t completely discount foreign aid. In some places, the best thing to do for children is pay for text books. In others, the kids won’t read but could really use vaccines or deworming medicine.
A few places will hugely benefit from sewage treatment. But maintaining the plants will be hard work and beyond the capacity of the locals.
Microsoft Office scales up amazingly well: lawyers, nonprofits, doctors, Ricochet authors, and high school students can all get something out of it. Making something scale up is where Bill Gates is a genius. But foreign aid isn’t a single problem, but is rather a complicated tangle of problems. It seems that we can best help the poor with many small initiatives, which is precisely where Bill Gates’s genius for scaling up probably won’t solve problems, but might lead to a gigantic waste of money.
It appears if you read the article it doesn’t require sludge. You actually put raw sewage in.
Assuming one of these things actually get placed in various foreign sites I’d be awfully interested to see what sorts of operating experience they get from the input poo of different communities. It seems to me that the byproducts of the local diets could drastically affect power efficiency and thus profitability.
I haven’t delved into it deeply but the unit must run on digester gas which is a low quality source of methane from the breakdown of solids in a tank. The electricity is generated using the methane as fuel for a engine driven generator unit, and I guess the 150 kw is what is left over after powering the electric motors that pump water from one chamber to another. There are issues with using this sort of a fuel in terms of engine maintenance because the fuel is about 40% carbon dioxide which can be corrosive, but nothing insurmountable.
This sort of batch water treatment is not uncommon either, a number of US manufacturers sell this type of equipment for locations with no sewer and/or for whatever reason a septic tank is not an option. A septic tank is much simpler if you have room for leach lines. My recollection is that large chlorine tablets were used in the discharge end to purify the effluent but I never had the urge to test that.
One last thing is that just looking at the unit in the picture, it looks pretty complex (for example compared to a septic tank) and I suspect would require someone checking on it pretty regularly.
I doubt it. Looks more like burning “dry dung”.
Which makes me wonder what’s coming out of those exhaust pipes.