If the process of waste digestion is merely a crude mimicking of animals’ digestion, and if the ingredients of waste digestion are discarded, partly-eaten food, animal carcasses, or animal & human excrement, and all of the chemicals and substances attached to any of them, then there remains an even more astounding truth: what comes out of a digester.

Just as with animals’ excretions of feces, urine, and of flatulence, waste digesters produce solids, liquids, and gases. The surprising truth is that the production of foul-smelling methane for sale entails dumping the digester’s resulting solids onto the ground, pouring its water into the environment, and often breaching its gases into the air by burning.

However odd and absurd it seems, the results of  composting discarded and masticated food, the rotting carcasses of rendered animals, and animal & human excrement are returned to the environment.  They are returned as solids, liquids, and gases, with added risk of the chemicals & diseases to which the digester’s original contents may have come into contact.

Sludge (‘BioWaste’ or “BioMass’).

A digester, like a stomach, does not digest food into neat canisters for ready transportation or storage.  The composting process doesn’t produce tiny cans of cooking fuel.  It produces, principally, a solid mixture of the dark and foul contents of the digester, itself: sludge.  Truck after truck dumps load after load into the digester, and those contents do not stay there forever.  Out they must come, in time, as cheeseburgers come out of people: as a mostly solid but wholly unpleasant substance.      

To make room for more, these solids have to be dumped somewhere, somehow.  They’re often spread on the ground.  Although that seems like an ordinary process of fertilization, it’s hardly so: this is not, and will never be, the compost from one’s garden.  Containment of disease causing agents, pathogens, is a constant concern of waste digestion.

So much so, that it’s a national focus of the USDA’s National Agricultural Biosecurity Center’s Consortium.  See, Carcass Disposal: A Comprehensive Review.  National Agricultural Biosecurity Center’s Consortium (August 2004).

From Chapter 7 on Anaerobic Digestion, Section 4.2, on Risk of Contamination:

If the end products of anaerobic digestion (biosolids) are applied to land without pathogens being sufficiently reduced, the pathogens may pose a risk of contamination. Human beings and animals can be contaminated after being exposed to variable quantities of pathogens, as shown in Table 7. The infective dose depends on the type of pathogen and health of the host. Indeed children, older people, and people with compromised immune system are at greatest risk.

(Emphasis added.)

Generally, sludge accumulates in the bottom of the digester. Consequently, all pathogen agents capable of surviving in the digester could still be found in the end product several months after the introduction of pathogens in contaminated carcasses.

Careful research has established how long these pathogens might survive in the environment. Again, from the Consortium report, page 14:

Days, months, years.  

One will not want to walk over those fields anytime soon.  

Liquids: ‘Water, water every where,  Nor any drop to drink’

Not merely solids, but liquids, too, will come from a digester. Proponents of these devices will look carefully for a way to dispose of the liquids from them.  Perhaps they’ll seek to burden an existing municipal water facility with the additional, vast flow of water from the digester.  They may likewise seek the entitlement to use an existing municipal permit from the state to allow final discharge into a nearby stream or creek.

This is especially troublesome  in those areas (like much of Wisconsin) with karst areas, areas with bedrock that is easily dissolved by water, after which there are numerous cracks, sinkholes, and ways for water to seep down into the ground, and into people’s wells.  Limestone is like this.

This is true for both liquids and solids in karst areas – they can contaminate the environment more easily than in areas with less porous bedrock.

Gases.

What, then, of the methane gases these digesters produce?   They are produced, but not alone: other gases come from a digester, too.  Even methane, while produced, isn’t always used – it’s sometimes burned off, when demand is low (as when competing natural gas is cheap) or when necessary despite demand.

Here, from Lusk, P. (1998). Methane Recovery from Animal Manures: A Current Opportunities Casebook. (3rd Edition. NREL/SR-25145. Golden, CO: National Renewable Energy Laboratory. Work performed by Resource Development Associates, Washington, DC., is a table from page 3-12 showing the gases a digester produces:

 Methane, carbon dioxide, hydrogen sulfide, sulfur dioxide, nitrogen oxides, carbon monoxide.

There you are – not in some faraway place, but in your own city or town.

Tomorrow: The Economics of Waste Digesters.

Waste digesters take organic waste (and any substances, chemicals, or concoctions attached to that waste) and process it through composting (‘digestion’). Although a few describe these ingredients as ‘clean and green,’ that’s false: they’re mostly brown and entirely foul. Nor are these ingredients assured to be natural: they will inevitably include the unnatural, concocted chemicals and pollutants with which the natural ingredients will have come into contact.

Organic Ingredients.

Of the organic ingredients, digesters take in discarded and masticated food, the rotting carcasses of rendered animals, animal excrement, or even human excrement. Take it in they do, in large amounts: a commercial operation will require dozens of full truckloads of waste – perhaps fifty or more – each day. As the digester operates both day and night, these trucks will travel great distances at all hours to deposit their contents. The filth and dead animals of other places, far from the host city, will be carted to the digester at a continuous, relentless pace.

In this way, a waste digester reverses the tried-and-true method of waste disposal: instead of taking rotting food, flesh, and excrement to places far away from people’s homes, they bring that waste from faraway places near the very homes in communities with digesters.

A digester reverses all experience, and even the habits of animals: it’s natural to stay away from rotting substances and excrement. There’s never been, in all the history of the world, a successful culture that brought these substances closer to their homes. Not one.

In all history, there’s never been a culture that wished to be nearer to waste, or have their children closer to it. Not one.

The Organic Ingredients’ Other Ingredients.

Perhaps the strong of stomach and confused of mind are unconcerned about the excrement and rotting things that go into a digester. Perhaps. That’s not all that goes through a community’s streets, day and night, into a digester: it’s not only those rotting things, but each and every thing of which those rotting things may be contaminated.

If discarded food, then it’s also what went into it: pesticides, plant diseases, fertilizers, additives, dyes, with whatever unnatural genetic modifications that food underwent.

If partly-eaten, masticated food, then it’s also all those substances that went into the food during eating: whatever those consuming it took with the food, including any infections or viruses they may have had, or medicines they may have been given. Few would happily hold the half-chewed remains a burger found on the street, or comfortably carry the masticated patties in their pockets.

If excrement, that organic matter includes everything those animals ate or touched and then excreted: their medicines, their diseases whether bacterial or viral, and their meals of whatever unhealthy and chemically-enhanced kind.

Some of these other ingredients are themselves organic, but dangerous; others are inorganic and dangerous.

Not Simply Plants.

Though one will hear that digesters process food waste (with an emphasis on vegetables), that’s only part of what they consume. (There’s a way in which talking about food waste is a feint, a distraction from the full ingredients’ list in waste digestion. Even if food, the food itself is only part of the contents: it’s every unnatural thing in the food, of course.)

Despite rosy claims, the contractual agreements for waste digesters won’t specify the exclusive use of ‘really-clean vegetables’ or ‘perfectly fine but uneaten food.’ Of course not – the full truckloads are crammed with whatever can go into the digester, whether plants or animals or excrement.

In it all goes.

With so many truckloads, day and night, how would one verify their contents, anyway? Even if one could verify that only the certain things went in, one would have no way to know the contents’ contents, so to speak (of contaminants, etc.).

If these things are trucked into a town, and then into a digester, where do they go thereafter?

Tomorrow: What Comes Out of a Digester.

Waste digesters take organic refuse (e.g., rotting food, dead animal carcasses, human or animal excrement) and process that waste by composting it into sludge, liquids, carbon dioxide, and methane. The methane (‘biogas’) is sometimes used for fuel, and the sludge and moisture extracted from the composting is spread on the ground or released into the air.

Waste digestion may involve oxygen (aerobic digestion) or may operate without oxygen (anaerobic digestion).

Proponents describe this as a new, green, and clean process. It’s really an old, brown, and filthy one. There’s nothing pristine in this: it’s waste in, waste out.

You may have heard it works like this:

It’s really more like this:

I once heard it described as analogous to human digestion, of those of poor nutrition: filth and junk goes in, and excrement, fluids, and gases come out. That’s a solid analogy.

This principle isn’t new or innovative. Even less-developed peoples, centuries ago, tried anaerobic digestion:

Anaerobic digestion has been used for centuries. During the 10th century BC, bath water was heated by biogas in Assyria. In the 17th century, Jan Baptista Van Helmont learned that flammable gases could evolve from decaying organic matter, and in 1808 Sir Humphrey Davy determined that the anaerobic digestion of cattle manure produced methane. In 1859, a digestion plant was built at a leper colony in Bombay, India.

These peoples hit upon the idea of anaerobic digestion because it was like human and animal digestion: the result mimics defecation, expectoration, urination, and flatulence.

It’s says all one needs to know that experimenters placed their anaerobic digester near a leper colony.

Tomorrow: What Goes into a Digester.

You may have heard that Whitewater has before her a ‘monumental’ opportunity for the construction of a vast waste digester in the city, and that this prospect is an example of green technology. There have been two local newspaper stories to this effect, but little substance to either (and significant errors in one).

I have a post category dedicated to the proposal, but over the next few days I will write about waste digesters generally. I’ll describe how they work, what goes into them, what comes out of them, and the economics of digesters.

There are other questions, particular to Whitewater, that I will consider in detail another time.

One should be clear about what digesters are truly like, beyond vague claims and airy speculation. An American community should be a place of sound reasoning, open discussion, and good policy. We are an honest, reasonable, technologically-advanced people. No one deserves less than a plain and accurate description.

Tomorrow: How Digesters Work.