Six Great Principles of Ecological Sanitation

The New Paradigms of Sanitary Engineering

The Key Idea behind a New Sanitary Engineering

First of all, you must assimilate the notion that management of water, plant biomass and animal/human biomass are intimately linked. These relationships are also linked to worldwide climate and energy problems.

Considerations for Nature's great natural cycles (water, carbon, nitrogen, phosphorus and other elements) must be integrated into any technical solution proposed. The many interdependencies involved make it totally unreasonable to take decisions on urban wastewater treatment without also considering the management of urban organic waste. A holistic vision necessarily requires a scope of knowledge that exceeds the field of most specialists. It also requires a work methodology for which these same specialists have not been formed.

A Specialist's Limited Scope of Vision

The limited knowledge that specialists have outside of their field can induce sometimes-grave mistakes. To illustrate this fact, here are three examples:

1. The design of a wastewater purification system or of an eco-toilet requires knowledge in the field of pedogenesis (process of soil formation). Consequently, you must also understand the processes that transform organic matter into humus during the various stages of composting, but also what happens to pollutants during composting. It is also indispensable to know how a region's climate interacts with that region's soil type and how these in turn interact with plant cover.

2. The importance that is given by «specialists» to the production of biomethane from sewage sludge and other organic matter is significant. During this anaerobic process, an organic molecule's carbon skeleton is destroyed and transformed into methane, carbon dioxide, and water. The compounds containing sulphur will produce hydrogen sulphur, making combustion of the biogas corrosive for installations. Un-denitrified organic nitrogen will supply important quantities of ammonium ions. The fertilizing value of biomethane digestate comes precisely from the presence of ammonium nitrate. Once introduced into soil, this ionic compound works like a chemical fertilizer: it speeds up humus' natural combustion. Such digestate, which is described as «organic agricultural soil amendment», in fact destroys the soil structure instead of improving it, and it also leads to pollution by nitrates.

3. The technical solutions for public water supply don't exclusively come under hydraulics, energy and public health considerations [1]. They must also become part of a wider vision that includes joint management of all available water resources relative to agricultural and forestry techniques. The 19th century hygienics approach to water consumption must also make way to a more pragmatic vision on the interrelations between water quality and public health.

[1]
To persist imposing chlorinated water for all domestic uses is an incoherent scientific stand that seriously threatens public health. By disinfecting water with chlorine to eliminate the threat of infectious bacterial disease (which is relatively under control by current medicine), we are exposing the population to many other viral and degenerative maladies (which are difficult to control by current medicine).

We could pursue the list of (sometimes grave) mistakes that have been committed in spite of the best intentions, mainly due to a narrow scope of vision. What is unfortunate is that on environmental issues, we only listen to «specialists». A technician's or scientist's prestige is measured by his number of publications, always within a restrained field of knowledge. Science «generalists» are not heeded, and are sometimes scorned by their peers.

Broadening the field of sanitation engineering

Let us insist that public water supply must also be considered as part of ecological sanitation considerations, because of the inherent interdependencies: there can be no sustainable sanitation without sustainable water supply management.

We must therefore rethink the fundamental concepts of ecological sanitation, in order that they truly become «ecological». This word is surely the most currently misused. It is high time to establish once and for all its primary principles and fundamental options.

Let us therefore state ECOSAN's six great principles (or the new paradigms of sanitary engineering), the first two of which concern water supply, the four others concerning wastewater treatment.

To resume, the six principles are:

• To adapt water quality to its end-use.
• To coordinate efforts to manage all available water resources.
• To avoid the discharge of treated wastewater into surface waters, while making maximum use of soil's and plants' remarkable purifying capability.
• To collect and treat grey water and black water separately.
• To prevent the discharge of human (and animal) dejecta into water, in any way, and resort to the BLT (biolitter principle) for their treatment, to generate humus for soil, after proper composting.
• To mobilize all nitrogen-based (animal) and carbon-based (plant) biomass towards their combined simultaneous treatment, to ultimately return them to the soil in the form of humus.

Water Supply

The first principle

The first principle of sustainable water management is to adapt water quality to its end-use.

In a world where quality water is becoming rare, it's unreasonable to persist in using expensively produced potable water for all domestic usages. This aberration nevertheless prevails, in spite of the numerous problems it has created worldwide. The standard for «potable water access» has become the faucet, which dispenses potable water throughout each household. In the present environmental context, extending this vision to all of the planet's inhabitants involves financial investments that are beyond most countries' capabilities. To persist in this hygienics ideology excludes a good part of humanity from access to quality drinking water.

Even in regions where this approach is financially accessible, its environmental impact remains excessive (depletion of water tables) and it has a negative impact on health. As quality water becomes rare, producing legally compliant potable water becomes progressively more expensive. With water's increased price, private water supply corporations can obviously increase their profits while disregarding the principle of universal access to water. Social policies will be called upon to compensate this breach, simply by transferring the added costs (totally unnecessary as far as we are concerned) to society.

To avoid such a dead-end, the first step is to introduce the concept of « safe water »[2] alongside that of « potable » water. The accidental absorption of small amounts of safe water can in no way be harmful to someone's health, even without it being legally « potable ». For such water, you can downgrade standards in order to take into account non-food water needs. When considering our degrading water resources, production of safe water will be much less expensive than that of potable water. In some regions or cities where this situation is first likely to emerge [3], it's more rational to give up on potable water distribution and rather prioritize safe water distribution. Thenceforth for drinking water, the population will have the choice between commercially sold bottled water and decentralized domestically produced potable water. In the latter case, to produce one's drinking water, each will have the choice between purifying safe water or harvested rainwater, by filtration. Financial incentives can be implemented to aid those in need in acquiring the necessary equipment.

[2]
Based on the daily experience of hundreds of thousands of Belgian households harvesting rainwater, we can propose microbiological parameters for «safe hygienic water». Such water can contain up to 800 harmless bacteria per 100 ml at 25°C and less than 100 fecal contaminated bacteria per 100 ml for each type of bacteria.

[3]
For example, in some coastal regions where water tables have been overexploited, seawater has penetrated underground drinking water reserves. The solution proposed by water distribution companies is to treat water by nanofiltration, which eliminates part of the water's solutes. This solution is expensive.

Unfortunately, the concept of « safe water » comes up against the concept of hygienics, which imposes potable water not only for drinking (less than 3% of our consumption), but also for personal hygiene, laundry and dishwashing. The fact that more than 750 000 people in Belgium have been using «safe», non-potable rainwater for years illustrates how absurd those requirements are.

The second principle

The 2nd principle can be expressed as the coordinated effort to manage all water resources. In practice, this means creating a legal and regulatory framework that provides fair and equal treatment to all available water resources.

Presently, the notion of equity is not honoured. The sale and distribution of potable water is reserved almost exclusively to a few public and private corporations. In some instances, like in France, regulations even prohibit using harvested rainwater within the home [4].

[4]
In France, legislation prohibits the technical basis for properly harvested rainwater. The new law does not authorize cistern materials that react with water, thus preventing the use of concrete and masonry cisterns. Yet, it's precisely with these materials that you instil rainwater's primary treatment to neutralize its acidity. As a consequence, when using plastic or stainless steel cisterns as imposed by law, rainwater rapidly becomes putrid and unusable, not only from lack of neutralization, but also from the absence of dissolved minerals.

And yet, there can be no sustainable water management without total reuse of the precipitation that falls on building roofs. With this in mind, rather than regulate domestic rainwater use, it would be better to impose the installation of rainwater cisterns (backed with financial incentives). Those who realize new building constructions or major renovations should be prompted to install a cistern that is sized with respect to the home's roof area (i.e. water catchment capacity) [5]. For some odd reason, water technicians encourage the installation of cisterns that are too small. On rainy days, much of the water in such cisterns is lost through the overflow, water that would otherwise be needed during dry spells. Theoretically, 60 to 80% of household water needs could be provided by rainfall harvested from roofs (in Western Europe).

[5]
In temperate regions with an annual rainfall ranging between 500 and 1200 mm, you need to provide a minimum storage capacity of 15 m³ for each 100 m² of roof area. This (average) value in no way depends on the actual annual rainfall, nor does it depend on household water needs. In fact, it is determined by rainfall distribution throughout a year. In drier regions where rainfall is usually concentrated in one season, you need to increase the cistern's storage capacity. This may also apply to cold climate regions where an extensive winter period can be compared to a prolonged dry season. And it is also true for buildings that are only occupied part of the year.

Authorities should admit the principle by which everyone can become one's own drinking water producer (either from harvested rainwater or from a well, for example), without however imposing quality standards. This obviously doesn't preclude authorities from issuing recommendations and advice.

With such simple and really inexpensive measures, the strain on our water resources would be substantially reduced. This approach has a good chance of being less costly to society than centralized water distribution monopolies.

In addition, a more generalized use of properly harvested rainwater (naturally fresh, weakly calcareous) also has an impact on wastewater's pollution load and on the soil's moisture regime in urban areas. One can therefore understand the mutual dependence between water supply and wastewater treatment [6] .

[6]
There is a direct link between rainwater harvesting and a household's wastewater pollutant load. Thanks to rainwater's almost total lack of calcium carbonate content, homeowners who use such water for cleansing and household cleaning will use 30 to 60% less detergent than what is required by mains water supply, which is very often hard water. Much of these detergents transits through sanitation plants. Reducing detergent use at the source represents a substantial gain for watercourse quality levels.

Urban Wastewater Treatment

The third principle

The 3rd principle of ecological sanitation is tied to the prevalence of wastewater discharge, whereby we must avoid as best we can the discharge of treated wastewater into surface waters such as rivers or lakes, while making maximum use of soil's and plants' remarkable (and free) purifying capability.

This option can seem difficult to implement in an urban setting. Yet, when you consider the enormous costs involved in current wastewater collection, conveyance and treatment, the inception of policies that integrate this third principle could have brought about urban ecological sanitation at a cost comparable to, and even less expensive than the conventional approach [7]. Furthermore, as an added benefit, cities would effectively have ceased polluting surface and ground waters. And let's not forget corollary energy savings and ecosystem remediation.

[7]
And yet, since the 1990's, I have regularly explained the above proposals to the Belgian government's Walloon Region Water Advisory Committee. Ecological sanitation would have satisfied all of the European Community's requirements, while reducing costs and ensuring environmental protection far exceeding conventional techniques.

It's therefore imperative to define differential discharge standards, between surface water discharge and infiltration (dispersal) in the ground.

Another point that follows from the fourth principle consists in defining discharge standards for grey water only, without black water. The implementation of these standards would drastically reduce purification costs in rural and suburban areas [8].

[8]
As mentioned in the preceding chapter, this is particularly true of the unjustified prohibition of absorption pits (inexpensive set-ups) even when they are being considered for grey water infiltration only.

The fourth principle

The 4th principle consists in selectively treating grey water. Grey water and black water must be collected and treated separately. For black water treatment, one must resort to the BLT (biolitter toilet) principle.

From a scientific point of view, the « all to the sewer » system is just as absurd as our « throw-away » society of « all to the garbage » consumerism. Black water's and grey water's respective characteristics are so different that their selective treatment is self-evident. In addition, black water's pollutant load is not a waste that needs to be destroyed, but is a precious raw material for the biosphere's safeguard.

Unlike what some may think, applying the fourth principle in itself doesn't oblige dry toilet use in urban zones. It simply means that grey water must be collected and treated separately from sewage. As it contains no metabolic nitrogen or phosphorus, grey water's treatment becomes quite simple when compared to mixed wastewater. When done in respect of the third principle, grey water could simply be dispersed in soil [9], without the least harm to ground waters [10]. A generalized application of these measures would result in substantial savings on sanitation budgets [11].

[9]
To prevent a dispersal system's clogging, water must first transit through a grey water batch reactor where it will undergo spontaneous anaerobic fermentation (or digestion).

[10]
Except in flood plains, where the water table is too superficial, or in a soil with lots of fractured rock. In such cases, grey water must absolutely be treated by anaerobic fermentation, followed by particle filtration through a planted trench filter (0,5 m²/IH) and a wetland finish treatment (1 m²/IH). Crystal-clear water issuing from such a system often complies with potable water standards.

[11]
In neighbourhoods with individual on-site sewage facilities, there would be no need for activated sludge mini-sewage treatment plants as imposed in France and Belgium. These are expensive, energy-consuming and environmentally harmful. In neighbourhoods with home gardens (or «backyards»), the legally-imposed use of biolitter toilets would altogether eliminate sewage (black water), whereas grey water could simply be conveyed to drainage wells or dispersal drains. In infrequent cases (impossibility to infiltrate directly into the ground), grey water would require treatment in an anaerobic digester followed by clarification in a decorative wetland. With such techniques, luxury hotels could be implanted in sensitive nature zones (in remote mountainous areas for example), without the least pollution to water.

Before being discharged in the nearest watercourse, grey water from large cities would be conveyed to landscaped wetlands specially established in peri-urban zones (urban-rural fringes). Sole grey water behaves quite unlike conventional urban wastewater. Daylight and atmospheric oxygen obliging, such wetlands will eliminate the entire pollutant load (remember: there's no nitrogen) by process of coagulation, followed by flocculation and sedimentation. Bacteria will go the same route to end up at the wetland bottom as sludge while many will simply be eliminated by the sun's UV. Based on experiments carried out at Université de Mons in Belgium, water that issues from such wetlands contains less nitrogen than what can be found in mains supply water. Thus, by creating wetland reserves specifically for grey water purification, you get the additional benefits of creating natural reserves and stopover sites for aquatic migratory birds. The portion of the wetland situated just before discharge into a watercourse could become a recreational park area.

The fifth principle

The fifth principle is that of the BLT. Human (and animal) dejecta must absolutely not be discharged in any way into water. They must be treated, in the form of a concentrate, concomitantly combined with plant-based cellulose to generate humus for soil, after proper composting.

To treat our dejecta while abiding to the BLT principle, the biolitter toilet is the pre-eminent way. In rural and suburban areas, the use of dry toilets is technically possible, providing as much convenience (although in a different way) as a conventional flush toilet. In such areas, composting in gardens or yards (i.e. « back yard » composting in Canada and the USA) should ultimately become the rule, once mentalities will have evolved. In the meantime, one could implement a program in selected neighbourhoods for the pick-up of fermentable garbage, including garden trimmings, kitchen scraps, and dry toilet effluent. Nevertheless, this is an expensive and somewhat unreasonable solution. The decision to inhabit such neighbourhoods should ultimately be tied to an obligation to compost one's own fermentable waste. This is much simpler and less constraining than what some people may think.

In urban areas or high-density housing, the biolitter toilet would be replaced by a new type of toilet that I have coined the turbo-toilet, or TT. It would resemble those toilets found on trains or airplanes, with a high-pressure flush that would deliver very little water with each flush. This is necessary to avoid diluting the dejecta, in the interest of ulterior treatment based on the BLT principle. TT's would also come equipped with grinders to liquefy the effluent and facilitate its evacuation. The liquefied TT effluent would then be conveyed in a separate collection network towards a litter impregnation and composting facility.

Remark : The TT does not yet exist, but its operational principle is known and well experimented. Its elaboration is simply a question of adapting the WC to tried and tested techniques, as described above.

The sixth principle

The 6th principle sets the conditions for combined treatment of waste. It is also tied to our energy problems, and as a consequence, to climate change. All nitrogen-based (animal) and carbon-based (plant) biomass contained in our waste must be mobilized towards their combined simultaneous treatment, to ultimately return them to the soil in the form of humus.

Ecological sanitation extends far beyond the field of sanitation engineering. Or rather, tomorrow's sanitation engineering should integrate remediation of the world's degraded ecosystems in its goals.

Litter-impregnation facilities for black water treatment will become hubs for urban biomass management. In effect, they will constitute the main source of nitrogen- and phosphorous- based organic soil amendment for agriculture.

To supply our nitrogenous animal-based biomass, we will dispose of concentrated black water from urban turbo-toilets, liquid pig manure from industrial pig-farming facilities [12] and the fermentable part of urban waste.

[12]
In a foreseeable future, industrial livestock raising will have to adapt to sustainable agriculture imperatives. In the meantime, one possible venue is the generalized application of deep-litter livestock housing systems, which in effect is the transposition of the fifth principle to livestock raising.

For our carbonaceous plant-based biomass, we will dispose of the cellulose component of household waste (soiled paper, cardboard packaging, and all paper waste that is inappropriate for recycling as paper), shredded plant waste from city park and tree maintenance, seasonal leaf and garden waste collection, shredded wood pallets, boxes, cardboard, etc. In need, you can also include waste from wood mills (bark and sawdust) and carpentry shops (wood shavings).

To continue your reading, go to Components of ecological sanitation

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