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Ecological sanitation or ECOSAN
Ecological Sanitation and EAUTARCIE

Failings of Sanitary Engineering

Six Principles of Ecological Sanitation

Components of Ecological Sanitation

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The EAUTARCIE concept is one of the possible forms of ecological sanitation, with a distinct feature: instead of doing an inventory of the problems, it rather goes to the source of these problems and proposes efficient, simple and inexpensive solutions. Its other main feature is its holistic approach, which takes into account various environmental impact issues.

The text within this page was first published in French on : in March 2008

The original text has since been adapted and first published in English on this page at : 2009-06-15

Last update : 2014-03-06


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.

Furthermore, there are close interdependencies between wastewater management and global food production. One can easily show that a starting point of worldwide water problems is the « all-to-the-sewer » system. We must first abandon this system before truly adopting sustainable sanitation and sustainable food production. There is no other way.

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. You must possess the requisite knowledge to understand the harmful nature of source-separating (urine diverting) dry toilets and those that involve alternating receptacles.

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. Biomethanation efficiency is very low, when calculations are based on the amount of energy produced per kg of organic matter destroyed. Thermogenic composting of human dejecta to heat homes is much more efficient.

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.

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 present the six great principles of EAUTARCIE’s version of ECOSAN (or the new paradigms of sanitary engineering), the first five of which concern wastewater treatment, whereas the sixth addresses water supply.

To resume, the six principles are:

These six principles set out the specific criteria that apply to truly sustainable management techniques as opposed to those that claim to be sustainable and can qualify as « greenwashing ». The inclusion of those criteria into legislation would greatly simplify matters: for wastewater treatment, any technique that meets the five first principles would be automatically authorized. This would form the basis of New Sanitary Engineering.

Let us analyse these principles.

Urban Wastewater Treatment

Domestic wastewater management as advocated by EAUTARCIE’s ECOSAN (SAINECO) is highlighted in a 14 minute video that can be found at: .

The first principle

The 1st principle – collecting and treating greywater and black water separately – sets the stage for the further implementation of truly sustainable water management and sustainable agriculture. It puts an end to the « all-to-the-sewer » system. Grey (soapy) water and sewage (or « black water », containing faeces) must be collected separately to undergo a specific selective treatment tailored to each one’s composition, in order that sewage and greywater be exploited as resources. They become waste only when combined.

When you read closely about EAUTARCIE’s version of ECOSAN (SAINECO), you discover how the respective characteristics of greywater and black water facilitate their individual selective treatment.

The « all-to-the-sewer » system is as scientifically absurd as consumer society’s « all-to-the-garbage » system. Black water and greywater have such distinct chemical and biological characteristics that their selective treatment becomes self-evident. Black water’s environmentally harmful nature can also become a precious resource for the biosphere instead of a waste.

In cities, the selective collection of both types of wastewater would require doubling the sewerage networks (separate sanitary and greywater sewers). Doubling the sewers is already recommended in cities, but for different reasons. Since many (if not most) cities are serviced by a combined sewerage network (sanitary and stormwater), recommendations to split them (separate sanitary and stormwater sewers) aims to address the drawbacks associated with combined systems that tend to overflow directly into rivers during storms, bringing the full black water pollutant load into rivers with the overflow. In EAUTARCIE’s ECOSAN, the second sewer would be reserved for greywater and roadway stormwater runoff. Unlike what happens when stormwater is combined with sanitary water, stormwater has a beneficial effect when combined with greywater, in that rainwater dilutes the greywater and makes its treatment and reuse much easier.

The greywater could then be conveyed through a natural slow-flowing wetland where natural light, air and plants would constitute the vectors of greywater purification. Ecological sanitation could already have been achieved in cities, at comparable or even lesser cost than conventional sanitation, if policies had been put in place incorporating this principle [2]. By means of EAUTARCIE’s ECOSAN techniques, cities would have ceased to pollute water, contributed to ecosystem regeneration, and saved energy in the process.

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.

The second principle

The 2nd principle – never releasing black water into the environment – defines the key element to safeguarding the biosphere: do not process wastewater containing human or animal dejecta in any way that is environmentally harmful, such as purifying it in a wastewater treatment plant, spreading it on farmland or infiltrating it into the soil. Rather, it must be treated with cellulosic carbon-rich plant biomass.

Specialists are struggling to understand and accept the idea of banning wastewater purification. This misunderstanding lies in the fifth paradigm of conventional sanitation, which asserts that you simply need to introduce nutrients (e.g. N-P-K) into the soil in order to sustain agricultural production. When agriculture is reduced to such a simplistic logic, one cannot recognize the difference between nitrogen contained in sewage sludge, biogas digestate and liquid pig manure with that contained in optimally-produced compost. Yet soil life and its biodiversity constitute the only true guarantors of sustainable agriculture, as per the 3rd principle.

Under EAUTARCIE’s ECOSAN, the black water collected in cities from separate sanitary sewer systems (without stormwater) would be conveyed to impregnation and composting centres. These would become the hubs of centralized biomass management and would constitute the main source of organic nitrogen and phosphate for soil amendment in agriculture.

The overall supply of animal-based/nitrogen-based biomass comes from concentrated black water discharged from urban flush toilets, but also from the fermentable part of household waste, and from liquid livestock manure [3].

In the near future, industrial pig farming, for example, will need to adapt to the needs of sustainable agriculture. Pending the application of sustainable agriculture principles, one of the possible channels is the widespread adoption of deep-litter housing systems that in fact apply the second principle of EAUTARCIE’s ECOSAN.

The overall supply of plant-based/carbon-based biomass comes from, organic plant waste from city park and tree maintenance (pruning, cutting and shredding), seasonal leaf and garden waste collection, etc. – but also from the cellulosic part of household waste (soiled paper, cardboard and any paper that is difficult to recycle). You can also include sawmill and millwork residues such as wood bark, wood shavings, sawdust, etc.

The third principle

The 3rd principle – restoring the humus content and biodiversity of soils – aims to restore and safeguard the health of the biosphere instead of combating anthropocentric « faecal hazards » at all cost. The health of man is the corollary of a healthy biosphere.

At this level, the nutrients (N-P-K, etc.) added to the soil have less importance than their embedding within the molecular structures that lead to the formation of humus for the soil. Restoring the symbiotic relationships between plants and soil life triggers a succession of reinforcing effects that will eventually eliminate food and water problems, health issues, and will even have a decisive and favourable effect on climate change.

The fourth principle

The 4th principle – reusing greywater for irrigation and groundwater recharge – considers grey water as a precious resource for the irrigation of living soils, and most certainly for replenishing diminishing groundwater levels.

It is worth remembering that greywater becomes a nuisance only when it is mixed with black water, and when the combined mixture is treated or purified, as in a sanitation plant. From the moment greywater is collected separately, it becomes a valuable resource, most especially in dry regions. Its infiltration into the ground has zero impact on groundwater quality, provided certain rules are respected. Also remember that living soil, oxygenation and natural light are biological reactors that eliminate greywater’s pollution load.

The fifth principle

The 5th principle - avoid the discharge of treated or untreated wastewater in surface waters – establishes the effective protection of aquatic ecosystems. Current sanitation techniques have not resolved the problems brought upon these particularly sensitive ecosystems. Many harmful residues are not filtered out from wastewater at the sanitation plant, and ultimately outfall into water courses, where detergents, micro-pollutants and drug and medicinal residues are harmful to aquatic life. Residual nitrates and phosphates contribute to the eutrophication of water courses at varying degrees, and even provoke algae growth on maritime beaches. Drug and medicinal residues that adversely affect mains water supply cannot even be filtered out with ultrafiltration systems.

The simplest solution is obviously to not discharge wastewater, either treated or untreated, into surface waters. From the moment black water is combined with plant cellulose and dispatched for adequate treatment (composting), while greywater is treated separately to irrigate crops or recharge groundwaters through ground infiltration, then no domestic pollution reaches water courses.

Thus all the wastewater is recovered, becoming a resource instead of a waste.

Human Water Supply

The sixth principle

The 6th principle – adapting water quality to its end uses – ensures a sustainable supply of high quality drinking water for the population without involving important capital costs. It is also necessary to provide an identical legal status for all water sources, including rainwater. We must also recognize the principle by which water used for domestic purposes other than drinking and food preparation need not be potable, only safe or « inoffensive ».

Indeed, adapting water quality to its end-uses helps reduce the cost of providing water for households. An important part of the world population suffers from a lack of good quality water, while the hygienics ideology imposes legally compliant « potable » water for all domestic uses.

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. Persisting in this hygienics ideology [1] prevents a good part of humanity from having 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 to society (totally unnecessary as far as we are concerned).

To avoid such an impasse, an essential step is to introduce the concept of « safe water » [4] 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 [5], it's more rational to abandon the distribution of potable water and rather prioritize the distribution of « safe water ». Thenceforth for drinking water, the population will have the choice between commercially sold bottled water (expensive) and decentralized domestically produced potable water (less expensive and more efficient). In the latter case, to produce one's drinking water, each will have the choice between purifying mains « safe water » or harvested rainwater, by means of domestic filtration systems. Financial incentives can be implemented to aid those in need in acquiring the necessary equipment.

Based on the daily experience of hundreds of thousands of Belgian households that harvest rainwater, one can propose microbiological parameters for « safe hygienic water ».
For example, in some coastal regions where water tables have been overexploited, seawater has penetrated into subterranean 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 sixth principle also touches on legal issues. It stipulates that you must « provide an identical legal status for all water sources, including rainwater ». Its application would represent a breakthrough for the population as it would help alleviate the stranglehold of monopolies and private corporations (sometimes disguised as « public corporations ») on water resources and drinking water supply.

Presently, the concept of equity does not apply. The sale and distribution of potable water is reserved almost exclusively for a few public and private corporations. In some instances, like in France, regulations even prohibit using harvested rainwater within the home [6].

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) [7]. 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).

In temperate regions with an annual rainfall ranging between 500 and 1200 mm, you need to provide a minimum storage capacity of 16 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 recognize the principle by which everyone can become one's own drinking water producer (either from harvested rainwater or from a well, for example), by recommending rather than imposing quality standards. In addition, people should not be obliged to hook up to mains water. Water supply is a billable service that all citizens should have the choice of refusing. Imposing the use of water that may not be suitable to some people is a violation of one’s privacy and free choice.

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

In addition, a more generalized use of properly harvested rainwater (naturally soft, 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 purification [8].

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.

To continue your reading, go to Components of ecological sanitation


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