Tuesday, November 29, 2016

About Shit

In the late sixties, when I worked briefly at Vancouver's mountain-top Simon Fraser University, I encountered a Communist agitator who made much of the fact that "even the Queen shits." I never discussed this proposition with him, but I suppose the idea was to associate with Canada's monarch, Queen Elizabeth II, one's deeply ingrained aversion to the sight, smell, or thought of shit. In particular, it must have been supposed that once identified as a shitter, Her Majesty would, together with the entire Canadian political establishment, lose all credibility and thus be thrust aside by a disgusted proletariat to make way for the revolution. The same approach was adopted with a view to discrediting the Pope and thus the Catholic faith.

Happily, despite exposure to such treasonous and heretical propaganda, I remain a loyal subject of Her Majesty the Queen and no enemy to the Catholic church. Still, the line of attack did make some sense, and reveals why shit remains one of the world's outstanding problems, for shit is something people just don't like to think about. But with seven billion, going on ten billion, humans on the face of the planet, we do need to confront the reality of around ten million tons of shit a day. That's about 350 kilograms per hectare per year, worldwide. So mind where you step: especially in poorer parts of the World, where people mostly just shit behind a bush and leave disposal to natural processes, or people walking away with it adhering to the soles of their shoes — if they have shoes.

Ground disposal of shit, is more or less ecologically sound but aesthetically repugnant to those not used to the pervasive smell of shit in crowded areas. It is also a huge hazard to public health since shit is the carrier of a multitude of human parasites and pathogens.

Another solution is the latrine, or pit toilet, comprising a hole in the ground with a toilet seat mounted above. For the user and close neighbors, the flies and stench make this an unappealing arrangement. But on the plus side, it eliminates the risk of parasite or disease transmission provided that the excrement is left in place.

But in Asia, where rice is cultivated, latrines are usually emptied with a bucket, the contents distributed in the paddy fields to nourish the crop. This is a solution that is both ecologically sound, and a public health disaster, although the farming people who work barefoot in the paddy fields likely have some inherited resistance to the hazard of sewage exposure, the more susceptible members of previous generations in their community having died young without posterity.

In the more prosperous West, the desire for a convenient, hygienic and aesthetically more acceptable method of shit removal led the nineteenth Century British plumber, Thomas Crapper, to invent the siphonic flush toilet, or water closet as it is still known in Britain. (Surprisingly, the term "crap" long antedates the inventive Mr. Crapper.)

But while the water closet may have seemed the ultimate solution to the problem of shit disposal, it in fact created a whole set of new problems. For every flush is required many litres of what is usually expensively purified and transported drinking water. Moreover, the shit, though now out of sight and out of mind, has certainly not been disposed of. It has simply been diluted, thereby transforming several pounds of warm fertilizer into several gallons of hugely polluted water.

In the early days of the WC, the thing was to flush the water down a drain to the nearest river, where it would, so it was hoped, be carried safely to the ocean, there to be rendered harmless by near infinite dilution. Unfortunately, drains were often located upstream of drinking water intakes, with the result that Crapper's W.C. was the proximal cause of many epidemics of typhoid and other diseases.

The primary solution to the problem of the contamination of inland surface waters by sewage  has been water purification by filtration and sterilization with chlorine, ozone or ultra-violet irradiation. In addition, measures are usually taken to decontaminate sewage before it is released. This entails treating not merely the effluent from toilets, but the vast quantity of water with which the effluent of toilets has been mixed by the time it reaches the point of treatment and disposal. Sewage treatment plants are thus large industrial-scale operations costing in most cases billions to build and entailing considerable expense to operate. Moreover, only the most extravagantly expensive sewage treatment plants produce water suitable for human consumption, and therefore, there remains in most cases, a huge volume of somewhat contaminated water to dispose of, with often severe negative consequences for lake, river or ocean receiving waters.

The convenient, hygienic, aesthetically less distressing Western way of disposing of shit is, therefore, not only expensive, but an ever-present danger to public health, and often hugely damaging to aquatic ecosystems. Moreover, it results in a colossal waste of plant mineral nutrients, which in a more natural ecosystem would be recycled.

Thus the world remains without a satisfactory and widely tried method of disposing of shit. Here, then, in the absence of any great university faculties of shit disposal, we offer our ideas about a solution to the great ecological and human disaster of inappropriate shit disposal.

required. Waste material is sealed in plastic for stor-
age prior to disposal. 
The essential features of a suitable method for the disposal of shit are as follows:

1. Little or no dilution, which only increases the quantity of material for disposal, and hence the cost.

2. Reformulation of shit as a sterile, odorless, dry fertilizer for farm and forest application.

3. Zero contamination with other waste materials that would contaminate soils and enter the human food chain via crops raised on treated soils.

4. Zero sight, sound or smell to upset even the most shy and delicate persons.
All of these objectives can be achieved in a number of ways. The best method would have to be determined on the basis of engineering studies, economic analyses, and local conditions. It's not my intention to review the options or define the optimum solution. But here to demonstrate the undoubted feasibility of attaining the above objectives is one possible solution:

Build a sanitary sewer to carry nothing but toilet effluent. Then deliver effluent as a concentrated slurry to a fermentation plant where it is incubated at high temperature with thermophilic methanogenic micro-organisms to kill pathogens and parasites while generating natural gas. Deliver the processed slurry to a drying unit powered by natural gas from the fermentation process. Pelletize the dried slurry for use as fertilizer.

The capital cost of such a system would be high, but it would provide a long-term, environmentally sound system of recycling vast quantities of costly plant nutrients from the soil, via crops and humans, back to the soil.

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