Purify water with the local resources

Tools, traditional techniques and contemporary low-tech technologies

All ancient civilizations have developed a knowledge of plant and mineral substances that have the power to purify water, and techniques to limit the risks associated with the consumption of contaminated water. The inventory of this knowledge and traditional know-how and the review of contemporary research on their effectiveness and possible improvements, shows that all environments contain plant and mineral resources that can obtain good drinking water and that various soft technologies can be easily implemented everywhere.

Tools, traditional techniques and contemporary low-tech technologies

Purify water with the local resources

Living and farming in Nyamata, Rwanda, we are fortunate to be able to get our spring water from the Rwakibirizi fountain, just a few kilometers from our house. It’s a bit far, but this water, reputed for its virtues, is so pleasant to drink that we go every week to fill the cans that will be used for our consumption. But not everyone is so lucky to have such a pure water supply.

According to a 2017 WHO report, some 2.1 billion people, or 30% of the world’s population, lack access to safe drinking water and 60% lack safely managed sanitation.

Waterborne Diseases

Diseases and by extension health risks related to water quality and access to safe drinking water are among the most common in the world, and are the biggest killers (especially children).

There are different types of water-borne diseases:

1. Infectious diseases are induced by water containing microorganisms, mainly pathogenic bacteria, which cause diarrhoea and gastroenteritis, which are often exhausting and can lead to the death of vulnerable people. These diseases include cholera, typhoid, polio, meningitis, hepatitis A and E, and diarrhea.

2. Parasites can be acquired through activities that involve contact with water: swimming, fishing, hunting, working in wetlands, etc. These diseases are transmitted by organisms that spend part of their life in the water and another part as parasites. Without being necessarily mortal, these diseases strongly decrease the physical capacities. The best known is schistosomiasis, also called bilharzia.

3. Some pathologies are linked to the presence of toxic chemical compounds diffused by industrial and agricultural activities contaminating the soil and consequently the water of the water tables, rivers, and also the water distributed by the water networks treated within the purification plant.

If among the chemical compounds of agricultural, mining or industrial origin, some are considered without risk for health below a certain concentration, others are toxic even in the trace state. In addition to their concentration, the time and regularity of exposure to these substances is also a very important factor of toxicity. Some substances, like heavy metals, are not eliminated by the body. They accumulate in the body, and their prolonged ingestion can cause serious illness, even if the content in the water is low. Ingested in large quantities during an accidental pollution, these same substances are rapidly toxic.

4. Diseases are transmitted by vectors that are more numerous where there is a lot of water, such as mosquitoes and tsetse flies that infest certain aquatic areas. These diseases include yellow fever, dengue, sleeping sickness, filariasis, and malaria.

Water-borne diseases are often preventable diseases. We will focus here on ways to limit the risks associated with the consumption of contaminated water, containing vectors of infection and parasites, and on "techniques" that could be easily implemented in Rwanda and more broadly in tropical countries in areas without "safe" water supplies.

Traditional techniques for improving the quality of water for consumption

Throughout the world, rural communities have developed water treatment techniques that can be implemented within families or on a neighborhood scale. Traditional water treatment techniques range from simple filtration with a sieve or cloth to clarification and filtration with stone filters and locally available plant materials. Some traditional techniques only remove visible impurities such as leaves, twigs and suspended particles from the water. But there are also traditional techniques for not only obtaining clear water but also for removing pathogens and certain pollutants, which greatly improve the safety of water for drinking purposes.

In a future article, we will discuss how to create natural environments that provide uncontaminated groundwater and river water and sources of drinking water.

This article provides an inventory of traditional techniques for treating contaminated water. Our objective here is to identify the techniques that allow us to obtain easily and at a lower cost, the best possible drinking water according to the know-how and resources available locally.

Filtration techniques

Filtration using vans

When the water supply is soiled by wind-borne impurities such as dry leaves, stems and coarse particles, using a van as a filter screen removes the coarse impurities. This method, which is common in West Africa, cannot be used when the raw water is very cloudy or muddy, as the sieve cannot filter out the fine particles suspended in the water. It improves the appearance of drinking water but not its sanitary qualities.

Filtration with cloth

A common practice is to filter plant debris, insects, coarse dust particles or sludge through cloths, usually made of cotton. The filtration of fine particles suspended in water can only be achieved to a small extent with this method.

This type of filtration is therefore very suitable for the filtration of well water or rain water, but not for very turbid water.

In India, rainwater was once collected with a piece of white linen cloth. The cloth, which was hung outside, was shaped like a funnel with a stone placed in its center so that the collected water would flow into a clean container below.

Guinea Worm Cloth Filter

Filtration with clay vessels

Clay jars with appropriately sized pores are sometimes used to filter turbid water. Turbid water is collected in a large clay jar and left to settle. Water flowing through the porous bottom wall is collected in a second container placed at the bottom of the jar. This method of water treatment is common in Egypt. The porous clay ceramic has the property of removing some of the pathogens from the water.

Egyptian filtering jar
Engraving extracted from the Description of Egypt or Collection of observations and researches made in Egypt during the French expedition, published by the orders of His Majesty the Emperor Napoleon the Great, 1809

The addition of a piece of silver in the jar increases the purifying power of the device. This technique inspired a new design of filtering jar by adding colloidal silver to the clay of ceramics.

Modified Clay pot
Jar improved by adding colloidal silver in a hospital and domestic model

Porous stone filters

Pre-Columbian civilizations in Central and South America used porous rocks of volcanic origin as filters that retained impurities and produced fresh, safe drinking water.

For this purpose, they carved a hollow cone in the stone that was held in suspension by a wooden structure, called "tinajero". The water flowing out of the filtering rock was collected in a container placed underneath.

The stone cones were used to filter water from rain, river, estuary or reservoir. These stone cones had the advantage of keeping the water fresh and purifying it from many pathogens.

Pre-Columbian porous stone filtering cone
[Convent of Santa Catalina, Arequipa, Peru]

In some areas of the island of Bali and China where porous rocks are found, filtering tanks are cut into the rock and then placed in water collection basins fed by a running water source through an overflow system, or by a bamboo pipe.

The water collection basin is partially filled with coarse sand and gravel which serves as the first filter media. The water passes through this first filter before reaching the porous stone tank. This filter tank has an average height of 60 cm, a diameter of 50 cm and a wall thickness of 10 to 12 cm. The muddy water is filtered as it passes through the porous wall of the tank, which collects water that can be drawn off and drunk.

A tank with 13 cm thick walls filters an average of almost four liters per hour. This productivity can cover the drinking water needs of a family of five.

Techniques for reducing water turbidity

Natural organic substances have been used for more than 2000 years in India, Africa and China, and certainly elsewhere as well, to remove turbidity from drinking water and transform cloudy, muddy or eutrophic water into clear water. Mixing these substances has the effect of coagulating the cloudy particles in the water, which can then be easily removed by filtration, for example.

Among the many plant substances that can be used for this purpose are

- Tamil nut powder from the Clearing nut tree or Water purifying fruit (Strychnos potatorum)

- Okra of seed powder or mucilage (Abelmoschus sp.)

- Red bean seed flour (Phaseolus vulgaris)

- Moringa seed powder (Moringa oleifera)

- Chickpea flour (Cicer arietinum)

- Prosopis juliflora seed powder.

- Neem leaf extract (Azidiratcha indica)

- extract of prickly pear cactus (Opuntia ficus-indica) and other cacti such as Cactus latifera

- roasted corn flour (Zea corn)

- mustard seed powder (Brassica sp.)

- coriander seed powder (Coriandrum sativum)

- Tamarind fruit pulp (Tamarindus indica)

- Vetiver root powder (Vetivera zizanioides)

- wood ash from the Sal tree (Shora robura). (This process is used in some Indian villages, when the raw water is muddy and smelly: the ash is mixed with water before being filtered)

As this list, which is far from exhaustive, suggests, the plant substances used to clarify water intended for human or animal consumption are, because of their diversity, almost always locally accessible and cheap, if not free, in most tropical countries and beyond.

In Rwanda, where we live, we can for example easily dispose of groundnut, Moringa, vetiver, beans, corn, prickly pear

Many of these substances not only have the effect of reducing the turbidity of water but also eliminate, and sometimes in very large proportions, the pathogenic bacteria contained in the water. Oil extracted from neem leaves, for example, can control up to 99% of bacterial activity in water; Moringa seed powder reduces it by 96% and sometimes more. Peanut powder has the capacity to eliminate 61% of fecal coliforms; Neem leaf extract eliminates them at 81%.

While their use does not guarantee the eradication of all bacteria and various pollutants that can contaminate water, water treatment techniques using natural coagulants significantly improve the quality of drinking water and consequently the possibility of access to safe drinking water.

Compared to synthetic polymers, natural organic polymers that flocculate the colloids that cause water turbidity have the advantage of being non-toxic, fully biodegradable, and either free or much less expensive than the conventional chemicals used in conventional water treatment due to their availability in most rural areas.

Example of water purification with plants

Water purified by Moringa seeds

Moringa

Information from research by the NGO Echo , and the Moringa-News website https://miracletrees.org/larbremoringa.html

The purifying properties of Moringa have been known for centuries in China, India and the Middle East. The Arabic name of this tree, "shajarat al rauwaq", which means "purifying tree", refers to an ancient water treatment practice, which consisted of placing a few moringa leaves on brackish water to make it clear. All parts of the tree are endowed with this water clarifying potential but in different proportions. The seeds contained in the long pods concentrate this property in particular. When mixed with turbid water, the seeds coagulate the suspended particles responsible for turbidity and also remove most bacteria from the water. By eliminating up to 98 or 99% of colloidal matter, this very simple process produces water of a quality equivalent to that of city drinking water.

This property is due to the presence of a type of protein, particularly concentrated in the seeds. These proteins are active cationic polyelectrolytes that neutralize colloidal matter in muddy or dirty water, because most of this matter has a negative electrical charge. Moringa seed proteins act in the same way as some industrial coagulants, which they match in terms of results and surpass in terms of safety, low cost and ease of use.

The German International Development Cooperation Agency GTZ (Deutsche Gesellschaft für Internationale Zusammenarbeit) has conducted an evaluation of the purifying potential of moringa seeds.

For Samia Jahn, a German researcher who has worked for many years for this agency:

"At high turbidity, moringa’s action is almost as fast as alum’s, but at medium or low turbidity, its action is slower. The concentrations of seed powder required do not exceed 250 mg/l. The removal of the suspended solids from the water by coagulation removes much of the bacteria at the same time. At the GTZ sampling site, the total coliform count was 1600-18,000 per 100 ml. After one hour of treatment with moringa seed powder, the number of coliforms had decreased to 1 to 200 per 100 ml. Good results are obtained by swirling a small cloth bag filled with moringa seed powder in turbid water. [...]

The dried seeds are first removed from their wings and then ground to a powder which is mixed with water. The mixture is shaken for five minutes, then left to stand for an hour before being filtered through a cloth to obtain pure water. Another method is to suspend a cloth bag containing the seed powder in water, usually overnight, to coagulate the impurities. The bag of powder is then removed, and the purified water is decanted to leave the coagulated particles at the bottom of the container."

Internationally recognized moringa usage expert and consultant Lowell Fuglie suggests the following general rule of thumb for determining the amount of powder required: "one moringa seed powder per 2 liters of water when the water is slightly cloudy and the same amount per liter of water when the water is very cloudy. But the review of published studies on this purifying property of moringa shows the existence of divergent recommendations as to the quantity of seeds necessary to obtain drinkable water. According to the sources, the quantity indicated is 3 seeds, 50 seeds, or 30 to 200 mg of seeds per liter of water. Recommendations for the length of time the seeds should be immersed also vary from 30 minutes to a few hours.

It appears that the clarification/flocculation capacity of M. oleifera seeds varies with the season. The purification potential of the seeds is higher in the dry season. During the rainy season, the level of polyelectrolytes present in the seeds is considerably lower. Seeds and powder can be stored, so harvesting of seeds for use in water purification should only be done in the dry season.

Vetiver water

Vetiver roots (Vetivera zizanioides) which have a great capacity to absorb a variety of chemical compounds are used to sanitize soil and storm water.

Used to purify drinking water, these roots also have the remarkable property of giving drinking water a freshness, aroma and a very pleasant flavor.

Vetiver roots in a jug

Soaking some roots in drinking water is a common practice in South India. Traditionally, the roots are put in a clay pot in which is poured water previously boiled.

Another practice is to add a few grams of vetiver root powder to the drinking water. After 2 to 3 hours this water is filtered and ready to be drunk. It should be used within 10 to 12 hours. Every day, the water and the vetiver must be renewed.

In southern Kerala and Tamil Nadu, vetiver roots (Veriveria zizanoides) are placed in a clay jar with tiny holes in the bottom. The water poured into the jar flows slowly through the bottom. Filtered in this way, the water is very clear, has a pleasant smell and a very pleasant fresh taste.

The combined properties of the clay in the filter vessel and the vetiver produce a very healthy and drinkable water.

Flower water

The Ayurvedic medical treatise "Sushruta Samhita", whose successive versions written between 1000 and the 2nd century compile the medical knowledge of Ayurveda, indicates that water can be purified by immersing certain flowers.

- Utpala", the flower of the sacred lotus - (Nelumbo nucifera)

- Naga", the flower of the Ironwood tree (Mesua ferrea)

- Champaka", the flower of the magnolia tree (Magnolia champaca) and

- Patala", the flower of the Rose Flower Fragrant (Stereospermum suaveolens)

Treatment method using several purifying materials

Vetiver, Coriander and Moringa Clay Jar

Some Indian families combine several natural substances and techniques to ensure that the drinking water they consume is purified.

The filter they use is made from available materials.

- an earthen pot with a downward opening (matka / matki),

- three sieves of the same size,

- cotton bolls or a few cotton rags to fill the first sieve on top,

- Vetiver roots to fill the second layer / sieve and some Moringa and coriander seeds.

1. The cotton fibers act as a primary filter

2. The second layer of vetiver roots (Chrysopogon zizanoides) keeps the water fresh, purifies the water from some of the pathogens and also eliminates any bad smell.

3. Moringa oleifera seed coat, eliminates 95% of pathogenic microbes and sediments, thanks to the positively charged Moringa proteins that help destroy harmful microbes.

Coriander seeds help eliminate heavy metal contaminants such as lead and nickel.

In addition to their purifying properties, the seeds and root also have medicinal properties.

The ceramic itself has purifying properties.

The purification process takes a long time, but it is an inexpensive and very effective method.

Purification by heat

Purification by boiling

Boiling provides safe water when there is no alternative. It has the advantage of being a simple decontamination method to implement. It eliminates all germs and bacteria present in the water and its decontaminating efficiency remains the same whether the water is cloudy or clear, pure or contaminated by organic matter.

It is advisable to let the water cool down in the container where it was boiled to avoid the risk of recontamination when moving from one container to another.

This method has two major drawbacks:

- it requires abundant fuel and therefore cannot be promoted in areas where wood is scarce and no other heating options are available at an affordable cost to families

- boiling changes the taste of the water and makes it bland by changing its composition and structure.

Purification by exposure to solar radiation

Exposure of water to the sun has been used as a technique for "purifying" water for four thousand years. Ayurvedic medical texts mention it and add the prescription to expose the water to lunar radiation as well.

The solar radiation destroys most of the pathogenic germs and notably leads to the inactivation of the organisms causing diarrhea. This is due in part to the ability of ultraviolet light to "break down" many organic compounds in the water and destroy pathogens.

- UV-A interferes with the metabolism and destroys the cell structure of the bacteria.

- UV-A radiation with a wavelength of 320-400 nm reacts with oxygen dissolved in water and produces a highly reactive form of oxygen - the free oxygen radical - and hydrogen peroxides that destroy pathogens.

- Infrared radiation heats the water.

Purification by exposure to sunlight is a simple method of water treatment: plastic or glass water bottles are exposed to the sun.

In tropical regions, a period of exposure of about 6 hours in the middle of the day is sufficient to purify the water.

When the water is cloudy, the time of exposure of the bottle to the sun must be doubled. It then takes two days instead of one. The exposure time should also be increased on cloudy days during the rainy season.

The use of plastic or clear glass bottles increases the temperature of the water by exposing it to direct sunlight. For more efficiency, the bottles can be exposed on a corrugated iron roof. The use of glass bottles is preferable, but in the absence of bottles the method can be implemented with clean, transparent plastic bags.

Solar disinfection eliminates most pathogens if the exposure to the sun is long enough. However, it does not remove non-biological substances such as toxic chemicals and heavy metals.

Because improper or prolonged storage can lead to re-contamination, water treated with this method should be used within days of its radiation treatment.

In 2012, researchers showed that adding lemon juice to water exposed to the sun, shortened the process to purified water in 30 minutes instead of several hours.

Purification using activated charcoal

In Japan, since the Edo period (17th century), white charcoal, known as Binchotan, has been used to purify water and provide it with minerals, and also deodorize it if necessary.

The charcoal is obtained after carbonizing the wood over a low fire (400°c) for several days. Then comes the activation phase: the door of the oven is opened and with the air intake, the wood, which has become charcoal, enters in combustion (1200°C).

The intense heat causes the volatilization of the tars created in the pores of the coal during the carbonization phase and it is these empty pores that will give the Binchotan its adsorption capacities.

Binchotan coal is riddled with small holes and pores. These cavities, once in the water, absorb contaminants by attracting their ions as well as toxins such as chlorine or certain heavy metals (mercury, lead, cadmium, copper).

In addition, while absorbing these impurities, charcoal releases minerals essential to our good health and shape (calcium, magnesium or iron).

To purify water with activated charcoal, simply dip a piece of activated charcoal in a bottle or pitcher and leave it at the bottom for 6 to 8 hours. The carbon is effective for three months. After this time, it must be boiled for ten minutes before being left to dry in the sun. After this treatment it can be used again for three months. After six months the charcoal must be changed.

The piece that has been used so far can be recycled as fertilizer for crops or as deodorizer for garbage, litter or shoes.

Purification and improvement of water by silver or copper

The ancient Indian texts of Ayurveda indicate that the quality and virtues of water are improved when water is kept in copper (tamba) or silver (chaandi) containers. Water poured into such containers would have the ability to balance the three doshas of the body by positively charging the water. [In Ayurvedic medicine, the doshas are three vital energies or "humors" combining one or more of the "five elements" (water, air, fire, earth, akasha or ether) and responsible for physiological and psychological processes. Their imbalance is considered the cause of disease].

The qualities of liquid enhancement through silver were known to the Phoenicians, Greeks and Romans who used large silver vessels called "craters" to preserve water, wine and vinegar.

This knowledge has persisted until very recently in Europe, where a silver coin was placed at the bottom of milk jugs and other food containers to preserve freshness. In sufficiently wealthy circles, it was customary to give a silver kettle and a silver spoon to newborns at their baptism. It was also common to have silver cutlery. Expensive, fragile, tarnishing quickly, and requiring regular maintenance, the use of this metal can only be explained by its virtue of protecting against certain infections.

Amphore romaine en argent, fin IVe début Ve siècle

Historians have speculated that the British tradition of serving tea in silver teapots may have helped officers in the colonial army of the British crown resist miasma both in Africa, India, Hong Kong, and everywhere else.

Silver prevents bacteria from forming chemical bonds essential to their survival. This is why bandages charged with silver ions are used to promote wound healing, especially in the case of burns. Silver ion has a broad spectrum of antimicrobial action, against Gram-negative and Gram-positive bacteria, some molds and yeasts. The manufacturer of Urgo dressings offers dressings impregnated with silver salts.

Before the discovery of antibiotics, colloidal silver was used in conventional medicine. It was not removed from medical textbooks until 1975.

According to Dr. Akhilesh, copper has many antioxidant and antibacterial properties that help strengthen the body’s immune system. It also has anti-cancer properties.

Clay treatment

The treatment of water taken from the Nile for drinking is a traditional practice in. Sudan.

Clay can be used to decontaminate water or to prevent the risk of infection from drinking unsafe water.

To show the potential use of clay in the prevention of risks related to the consumption of water potentially carrying infection, we rely on the research of Jade Allègre who wrote a thesis on this subject: Les silicates d’alumine (argiles) en thérapeutique. Une pratique coutumière ancienne relayée dans la médecine moderne, Thèse de Doctorat en Médecine, 2012.

"Mass tourism is developing throughout the world: we travel more and more. Who doesn’t jump at the chance to spend a few days in the sun at the other end of the world? But these opportunities bring us into contact with germs to which we have no personal immunity, and the trip will all too often be ruined or even interrupted by repatriation.

For twenty years I have been living in the most unhealthy places on the planet: with local populations in direct contact (immersion), I eat rotten corn, I drink polluted water. And yet, no health problem... unless I forget to ingest clay powder several times a day.

Clay offers a double benefit: first, it makes the local water drinkable. Second, its billions of particles are included in the intestinal mucus, where they trap the dangerous contaminants present in the food I eat. No way to get sick. On the other hand, when I travel with a group of tourists, however over-equipped with antiseptics and antibiotics, I am regularly solicited by my companions, prey to turista or worse...

Possible protocol in this case:

In case of declared turista, 300 milligrams of "green" clay powder per kilo of the patient’s weight (see anthropometric measurement), sprinkled on the surface of a glass of water: let the powder fall to the bottom, without stirring, and wait 10 minutes. After this time, mix with a food plastic or natural wood instrument (no metal, nor painted, treated, and/or varnished wood), and drink the whole. This dosage should be repeated if the diarrhea resumes. If no measuring instrument is available, see anthropometric measurement.

With specialties: Smecta 3 sachets 3 times a day. Suspend as soon as the symptom is resolved.

4. In a health emergency with risk of epidemic: collective accidents
In the event of a disaster, the supply of drinking water is an urgent and crucial problem for the populations, whether it is a question of conflict situations, climatic accidents, epidemics, or even nuclear contamination.

The distribution of bottles and the provision of tanks and trucks are often difficult to set up, especially as roads may have been damaged.

It is now essential that each country plan to be able to meet the emergency needs of its population for safe water, and clays can massively meet these needs.

a. Water

In the case of population displacement and risk of epidemic: systematic treatment of available water, first at the individual level (protocol below), then relayed by small mobile units that would need to be studied: the engineering of such systems should be researched in view of adapted solutions that can be implemented in emergency. Stockpiles of "three-layer" clays should be built up by government authorities.

Individuals:

For emergency situations, obtain a water bottle with a glass-ceramic interior (contact of alumina silicates with metal should be avoided). Fill with available water, filtering through several layers of cloth if there are particles in suspension or if parasites (eggs) are suspected, then add a block of green clay ("pebble" or "crushed" clay) the size of the neck. Let it rest for 10 minutes before the first ingestion, and then stir it systematically before drinking. Take this gourd with you during the day, in order to regularly "re-seed" the digestive tract with the preparation. Make a new preparation once every 24 hours.
If you don’t have a gourd, take a plastic bottle, and put a clay stone the size of the neck for 1 liter of local water, or 4 tablespoons of "three layer" clay. (smectites, illites).

I. Epidemics

Prevention of cholera, and other intestinal infestations and intoxications. For an adult, 1 teaspoon of "green clay" powder (or a bag of smectite-based specialties) four times a day, suspended for 10 minutes, then ingested after mixing. For a child ½ teaspoon.

If only "white clay" or kaolinite is available: multiply the doses by four.

In Mopti, Mali, this preventive protocol was disseminated by my nursing correspondents during periods of cholera epidemics, and none of the people treated in this way were affected by the disease. [...]

II. Food shortage

As we have seen:

- the ingestion of clays does not nourish, but it allows an increased assimilation of nutrients, in particular of their lipidic components (see veterinary studies) ;
- alumina silicates ingested in large quantities slow down the transit, which also favors assimilation;

- if we are led to consume food to which our intestinal flora is not accustomed, or food of poor quality, containing germs, toxins, mycobacteria, or toxic secondary compounds, the thousands of particles of alumina silicates can contribute to the decontamination of the ration.

III. Decontamination

In the case of nuclear risk, radioactive decontamination by chelation of radionuclides - already widely practiced in livestock - must be made available to civilian populations. Clays easily capture radioactive caesium, and can also help with radioactive strontium, the efficiency with respect to radioactive iodine (electronegative) being less.

Three notable experiments on the latter subject:

- rats given cesium-134 by injection and orally (10% of the ration) were able to double the elimination of the contaminant by the feces thanks to clays [147].

- Cows, sheep, and reindeer fed 500 mg of bentonite per kilogram of feed weight showed a 50% reduction in cesium in their milk and meat. The addition of 2 grams per kilo of weight resulted in an 80% reduction [78].

- Ewes fed soil artificially contaminated with radioactive cesium, to reproduce the conditions of a nuclear accident, showed that the cesium consumed remained bound to the clays naturally present in the soil, and then came out unhindered in the feces [76].

The application to humans must be studied in view of potential - and unfortunately increasingly probable - emergency situations and contaminating accidents (cf. Japan). This is a field that it seems imperative and urgent to develop.

As we have just seen, clays can provide an effective and reproducible response in these areas, where the stakes are vital. In these contexts, they present an additional advantage: they have no expiration date, and remain active for many years, provided they have been stored in dry form, protected from humidity.

Other researches on water purification with clay

Mogens Madsen and Joergen Schlundt, "Low technologiy water purification by bentonite clay flocculation as performed in Sudanese villages. Vrological examinations", Water Research Volume 23, Issue 7, 1989, pp. 873-882

The effects of a water purification method traditionally used in Sudan to treat turbid waters were studied with respect to removal of faecal indicator bacteria as well as selected enteric bacterial pathogens. Water treatment was performed with natural bentonite clays (rauwaq) from the banks of the Nile, and the technique employed corresponded closely to that used to clarify Nile water in Sudanese villages. Employing various types of waters a primary bacterial reduction of 1-3 log units (90-99.9%) was obtained within the first 1-2 h of flocculation. During the 24 h observation period bacterial multiplication in the water phase occurred consistently for Vibrio cholerae and test organisms belonging to the Enterobacteriaceae group, but not for Streptococcus faecalis and Ctostridium perfringens.

H.R. Cripps, N.P. Isaias A. Jowett, "The use of clays as an aid to water purification", Hydrometallurgy, Volume 1, Issue 4, April 1976, Pages 373-387

"The conditions under which cationic species will adsorb intensely onto silicate surfaces have been investigated with a view to specifying basic requirements for successful operation of a water purification process based on silicate/cation interactions. Zeta-potential measurements have been related to effectiveness of cation precipitation. It is shown that clay additions enhance ferric iron removal, optimum pH range being pH 9 to 10. Coal measures shale addition increases the rate of settling of precipitates several-fold. Electro-kinetic measurements show that clay additions also remove uncharged particles efficiently. The precipitation/clay adsorption process is reversible with respect to pH."

Conclusion

The inventory of the knowledge of natural substances and processes allowing the treatment of raw water to transform it into water suitable for drinking shows the diversity of plant and mineral materials, and of the techniques that can be used.

Because of this diversity, each environment has the resources to implement relatively simple and inexpensive or free techniques to obtain quality drinking water.

The dissemination of the world heritage of knowledge and know-how concerning water treatment could allow the right to have "drinkable" water to become effective rather than merely theoretical.

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- K. A. Yongabi, "Biocoagulants for Water and Waste Water Purification: a Review", International Review of Chemical Engineering (I.RE.CH.E.), Vol. 2, N. 3 May 2010

- Anu Matilainen, Mikko Vepsäläinen, Mika Sillanpää, " Natural organic matter removal by coagulation during drinking water treatment : A review ", page d’accueil de la revue Advances in Colloid and Interface Science.

- Hayelom Dargo Beyene, Tessema Derbe Hailegebrial, et Worku Batu Dirersa, " Investigation de l’activité de coagulation de la poudre de cactus dans le traitement de l’eau ", Journal of Applied Chemistry Volume 2016.

- Hussein Janna, " Efficacité de l’utilisation des matériaux naturels comme coagulant pour la réduction de la turbidité de l’eau dans le traitement de l’eau ", World Journal of Engineering and Technology, 2016, 4, 505-516.

- Kenneth Yongabi, " Studies on the potential use of Medicinal Plants and Macrofungi (Lower plants) in water and waste water purification ", Phytobiotechnology Research Foundation Institute, Catholic University of Cameroon, Bamenda, Cameroon.

- Jahn, Samia Al- Azharia.Effectiveness of traditional floculant as primary coagulant and coagulant aids for the treatment of tropical raw water with more than a thousand-fold flutuation in turbidity.Documento presentado en la 15 ème conf. Int. de l’international de distribution del Agua, Monastic,Tunez, publicado en water supply, oct 1984, 2 (3/4).

- Odile G. NACOULMA, Jean PIRO et Ali BAYANE, " Étude de l’activité floculante d’un complexe protéine-mucilage végétale dans la clarification des eaux brutes ", J. Soc. Ouest Afr. Chim (2000) 009. 43-57.

- Mme Renuka A. Binayke, Prof. M.V. Jadhav, " Application of Natural Coagulants in Water Purification ".

- Md. Asrafuzzaman, A. N. M. Fakhruddin, et Md. Alamgir Hossain, " Reduction of Turbidity of Water Using Locally Available Natural Coagulants ", International Scholarly Research Network.

- Vicky Kumar, Norzila Othman, et Syazwani Asharuddin, " Applications of Natural Coagulants to Treat Wastewater - A Review ".

- Ida Bodlund, " Coagulant Protein from plant materials : Agent potentiel de traitement des eaux ". 2013, École de biotechnologie, Institut royal de technologie (KTH), Stockholm, Suède.

- Hubele C ; Bernazeau F., " Automatic control of the coagulant dose in drinking water treatment. Procedings of the 1st Macau workshop on water treatment ", nov,1989, 199-214.

- Nacoulma Odile G. , Piro Jean et Bayane, " Etude de l’activité floculante d’un complexe protéine-mucilage végétale dans la clarification des eaux brutes ", J. Soc. Ouest-Afr. Chim. (2000) 0093 ; 43-57

Water Treatment with Okra

- Shristee Mishra, Sneha Singh, Ruchira Srivastava, " Okra Seeds : An Efficient Coagulant ", " International Journal for Research in Applied Science & Engineering Technology (IJRASET) "

- Kumari Anjali Jatav, Sandhya Gawas, Shalu Yadav, Akshita Parmar, Puja Kadam, « Coagulation Efficiency of Okra Seed Extract for Surface Water Treatment », International Journal of Science and Research: 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2014): 5.611 `Volume 5 Issue 3.

Water treatment with Neem leaves

- Jigar Joshi, Omprakash Sahu, « Azadirachta Indica Leaves as Antibacterial Treatment on Drinking Water »

Water treatment with tamarind fruit pulp

- Sa’id, S., Mohammed, K., Adie, D. B. and Okuofu, C. A., Turbidity Removal From Surface Water Using Tamarindus indica Crude Pulp Extract

Traitement de l’eau avec des racines de Vétiver

- Kanokporn Boonsong and Monchai Chansiri, « Domestic Wastewater Treatment using Vetiver Grass Cultivated with Floating Platform Technique », AU J.T. 12(2): 73-80 (Oct. 2008)

- Barbara Hart, Ron Cody, and Paul Truong, « Hydroponic vetiver treatment of post septic tank effluent », CodyHart Environmental, Gold Coast, Queensland, Australia & 2Veticon Consulting, Brisbane, Queensland, Australia, 2003.

- Narong Chomchalow, « The Role of Vetiver in Controlling Water Quantity and Treating Water Quality: An Overview with Special Reference to Thailand »,AU J.T. 6(3): 145-161 (Jan. 2003) Office of the President, Assumption University, Bangkok, Thailand.

- D. Balasankar, K. Vanilarasu, P. Selva Preetha, S. Rajeswari M. Umadevi, Debjit Bhowmik, « Traditional and Medicinal Uses of Vetiver », Journal of Medicinal Plants Studies, 2013, Volume: 1, Issue: 3, pp. 191-200

- Weerachai Nanakorn 1/ & Narong Chomchalow, « Uses and Utilization of Vetiver », Queen Sirikit Botanic Garden, Ministry of Natural Resources and Environment, Chiang Mai THAILAND & Office of the President, Assumption University Bangkok 10240: THAILAND

- Paul Truong, « Vetiver System for Water Quality Improvement. Clean Water Shortage, an Imminent Global Crisis. How Vetiver System can Reduce Its Impact », The Vetiver Network East Asia and South Pacific Representative Veticon Consulting, Brisbane, Australia

- Paul Truong, « Vetiver System For Wastewater Treatment », Pacific Rim Vetiver Network Technical Bulletin No. 2001/2, The Vetiver Network and Queensland Department of Natural Resources and Mines

- K.N. Njau and H. Mlay, « Wastewater Treatment and other Research Initiatives with Vetiver Grass », University of Dar es Salaam, Prospective College of Engineering and Technology, Department of Chemical and Process Engineering, Dar Es Salaam

Water treatment with Moringa seeds (Moringa oleifera)

- Faby J. Antoine, « Utilisation de la graine de Moringa: essai de floculation en laboratoire et en vraie grandeur » C.I.E.H 1993, 1-99.

- Folklard, G., Sutherland J. et Al-Khalili R. S., La clarification de l’eau par coagulation en utilisant les graines du Moringa oleifera. In : L. Fuglie, 2002. L’arbre de la vie, les multiples usages du Moringa. CWS/CTA, Dakar, Sénégal, 2002, pp 79-82.

- Kawo A.H. and Daneji, I.A., « Bacteriological and physcio-chemical evaluation of water treated with moringa Oleifera Lam », Bayero Journal of Pure and Applied Sciences, 4(2): 208 – 212, Received: January, 2010. Accepted: December, 2011

- Jahn, Samia Al-Azharia. Using moringa seeds as coagulant in developing countries. Journal AWWA, June 1988, pp.43-50.

- Tadis D. Hocquemeiller R., « Etude du pouvoir floculant des graines de Moringagcées ». Centre d’étude pharmaceutique de ChatenayMalabry. (Université de Pari-Sud) 1988. PP 1-65.

Water treatment with Cacti mucilage

- Abderrezzaq Benalia, Kerroum Derbal, « Application de cactus traité par l’eau distillée sur la réduction de la turbidité et de la matière organique », 3 ème Colloque International sur la Géologie du Sahara Thème III Eau & Environnement.

Water treatment with activated carbon

- Beatriz Jurado-Sánchez, Sirilak Sattayasamitsathit, Wei Gao , Luis Santos, Yuri Fedorak , Virendra V. Singh , Jahir Orozco, Michael Galarnyk, and Joseph Wang, « Self-Propelled Activated Carbon Janus Micromotors for Efficient Water Purification », www.MaterialsViews.com

- Contaminants Ijaola, O.O; Ogedengbe, K; Sangodoyin, A.Y. « On The Efficacy of Activated Carbon Derived From Bamboo in the Adsorption of Water », International Journal of Engineering Inventions e-ISSN 278-7461, p-ISBN: 2319-6491 Volume 2, Issue 4 (February 2013) PP: 29-34 www.ijeijournal.com

- Amit Bhatnagar, William Hogland, Marcia Marques, Mika Sillanpää, « An overview of the modification methods of activated carbon for its water treatment applications », Chemical Engineering Journal, 2012.

Water treatment with clay (aluminum-silicate)

- Annette Olsen, « Low technology water purification by bentonite clay and moringa seeds in Sudan », 1985, Water Research, No 5, pp. 517-522, 1987.

- Ebba Lund & Birte Nissen, « Low Technology Water Purification by Bentonite Clay Flocculation as performed in Sudanese Villages, Virological Examinations », Water Research, 20, No 1, pp 37-43, 1986

- Ismail M.A., Eltayeb M.A.Z. and Abdel Maged S.A. « Elimination of Heavy Metals from Aqueous Solutions using Zeolite LTA, Synthesized from Sudanese Clay », Research Journal of Chemical Sciences, Vol. 3(5), 93-98, May (2013) Res. J. Chem. Sci., International Science Congress Association, Department of Chemistry, Faculty of Science and Technology, Al Neelain University, Khartoum, SUDAN

- B.Y. Gao, H.H. Hahn, E. Hoffmann, « Evaluation of aluminum-silicate polymer composite as a coagulant for water treatment », Water Research 36 (2002) 3573–3581, Department of Environmental Engineering, Shandong University, Jinan, People’s Republic of China, Institute of Aquatic Environmental Engineering, University Karlsruhe, Forschungszentrum Umwelt, Adenauerring, Karlsruhe, Germany

- Samia Al Azharia Jahn, « Traditional methods of water purification in the riverain sudan in relation to geographic and socio-economic conditions »

Water treatment by filtration with ceramic jars

Tshishonga M, Gumbo JR, « The Use of Ceramic Water Filters in improving the Microbial Quality of Drinking Water », Conference Paper, November 2017, 9th International Conference on Advances in Science, Engineering, Technology and Waste Management (ASETWM-17)., At Parys, South Africa
Robert W. Dies « development Of A Ceramic Water Filter For Nepal » Bachelor of Applied Science University of British Columbia, Canada, 2001 Submitted to the Department of Civil and Environmental Engineering In Partial Fulfillment of the Requirements for the Degree of Master Of Engineering In Civil And Environmental Engineering at the Massachusetts Institute Of Technology June 2003.

Judy Hagan, Nick Harley, David Pointing, Mickey Sampson, and Vanna SOAM. « Resource Development International - Cambodia Ceramic Water Filter Handbook » Draft Document for Engineers without Borders

Sophie M. Johnson, « Health and Water Quality Monitoring of Pure Home Water’s Ceramic Filter Dissemination in the Northern Region of Ghana », Document Submitted to the Department of Civil and Environmental Engineering on May 18, 2006 in Partial Fulfillment of the Requirements for the Degree of Master of Engineering in Civil and Environmental Engineering

Martella du Preez, Ronán M. Conroy, James A. Wright, Sibonginkosi Moyo, Natasha Potgieter, and Stephen W. Gundry, « Short Report: Use of Ceramic Water Filtration in the Prevention of Diarrheal Disease: A Randomized Controlled Trial in Rural South Africa and Zimbabwe », The American Society of Tropical Medicine and Hygiene., 79(5), 2008, pp. 696–701, 2008

AJ Varkey and MD Dlamini, « Point-of-use water purification using clay pot water filters and copper mesh », African Journal online (AJOL) Journal Home, Vol 38, No 5 (2012),

Joe Brown, « Evaluation of point-of-use microfiltration for drinking water treatment in rural Bolivia », Dissertation submitted in partial fulfilment of requirements for the degree of Master of Philosophy in Environment and Development Department of Geography, University of Cambridge, August 2003

- Sandeep Gupta, Raj Kumar Satankar, Amrita Kaurwar, Muhammad Sharif, Usha Aravind & Anand Plappally, « Household Production of Ceramic Water Filters in Western Rajasthan, India », International Journal for Service Learning in Engineering, Humanitarian Engineering and Social Entrepreneurship Vol. 13, No. 1, pp. 53-66, Spring 2018

- Doris van Halen, « Ceramic Silver impregnated Pot filters for low-cost point-of-use drinking water treatment », Master of Science Thesis in Civil Engineering, 2006, Delft University of Technology Section Sanitary Engineering

- OMS, « Use of Ceramic Water Filters in Cambodia »

- Potters for Peace (PFP), « Summaries of Reports and Studies of the Ceramic Water Purifier (CWP): A Colloidal Silver (CS) Impregnated Ceramic Water Filter »

Évaluation de différentes méthodes de traitement de l’eau

- Okwadha G.D.O. & Ahmed A. A., « Determination of Effectiveness of Traditional Drinking Water Treatment Methods », International Journal of Advanced Engineering Research and Applications, Volume – 2, Issue – 10, February – 2017

- Piyush Gupta, Surendra Roy, Amit B. Mahindrakar, « Treatment of Water Using Water Hyacinth, Water Lettuce and Vetiver Grass - A Review », Resources and Environment 2012, 2(5): 202-215, National Institute of Rock Mechanics, Kolar Gold Fields, India 2Vellore Institute of Technology, Vellore, India

Published online by La vie re-belle
 26/12/2018
 https://lavierebelle.org/purifier-l-eau-avec-les-ressources

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