ECO-SAN solution to water pollution

By Dr Roshan Raj Shrestha

How much water do we need? And how much so we have? This is a frequently asked question all around the world. We have become conscious about providing safe drinking water to all the people living in the world, but the water is far away from being sufficient to the world population. On the other hand, the disposition of human excreta has been a major problem everywhere, be it in developing or developed countries. Flushing out the waste from toilet is so easy but we don’t think how much water we need for that and how huge problems it can create in the water body. We must do something to address both of the problems - now.

It is estimated that more than three billion people lack safe sewage disposal, according to a report of World Health Organization prepared in 1997. That means approximately half of the world population lack even basic sanitation. And only less than ten percent of wastewater in developing countries is treated. Similarly, within 20 years, it is expected that additional two billion people, living mainly in cities in developing countries will naturally be demanding sanitation. Every year, two to three billion people die because of inadequate sanitation, insufficient hygiene and contaminated food and water. Therefore new approach in sanitation is current global demand.

Reusing human excreta is not a new phenomenon. Human excreta has traditionally been used for crop fertilization in many countries. Human excreta has been composted in China for thousands of years. In Japan, recycling of urine and faeces was introduced in the12th century. In Swedish cities, organised collection and transportation of latrine products to farms started in the 18th century. Similarly, in the 19th century, urine was used as detergent for wasting clothes in Denmark. Urine was used even to smear wounds and dry skin and to some extent to drink as a therapy too. Coming back to home country, in Nepal use of faeces was common practice for fertilizer.

During the mid nineteenth century, Water Closets (WC) was introduced in Europe. In Sweden, the first "official" WC was installed in 1883 but people accepted it quite later as they refused to use water for flushing. Actually, there was an intense debate for the introduction of WC. While the health authorities urged the people to use WCs, the farmers were against it since it would end the recycling and utilization of plant nutrients from urine and faeces in agriculture. That time latrine contents were considered as "a mine of wealth".

Medical science was advancing in full swing to discover more and more about the foes of human health. The role of hygienic practices was more widely realized in Europe. Bacteria and viruses were recognized as cause to diseases so the use of latrine products in agriculture was questioned. Furthermore, mineral fertilizers were developed at the turn of the century. All these developments threatened the thousand- years old tradition. Finally WC was considered to be the ideal solution to improve sanitary condition and Flush and discharge of all kind of liquid waste through sewer line becoming a common practice in the world.

Flush and Discharge system considers human excreta as a waste and only suitable for disposal. To dispose such waste it needs huge investment like lying of sewer system, construction of centralized treatment plants, sophisticated operation and maintenance system. Believe it or not, the US estimated that installation of sewer system in the country will need 325 billon US dollors for next 20 years and more than 200 billion dolors will be needed to treat sanitary sewer overflows alone.

In addition, a person excretes 35 to 50 kg of faeces and 500 liters of urine per year. It means he is flushing away 15000 liters of treated drinking water. This way of disposal is contaminating huge amount drinking water resources and at the same time it is also polluting rivers, lakes and ponds since most of the developing nations don’t have any sewer treatment facilities. To sum up, it can be said that this model has failed to solve the sanitation needs for developing countries.

Apart from that, in many developing countries, drop and store model is another practice for sanitation. The model requires pit latrines where people do not let the faeces flush in the river but store in an underground. But there is again high risk for groundwater contamination with pathogens and it may also increase nitrate level that is carcinogenic to drink.

Both system, flush and discharge and drop and store model have now been realized unsustainable in this world. Western world is also thinking for new approach for excreta disposal since they are now spending huge amount of fund for treatment of wastewater. Now the professionals are rethinking of early use of human excreta and its potential to solve current global problem. Ecological Sanitation (ECOSAN) is the concept that incorporates early use of human excreta with scientific approach.

ECOSAN is an ecosystem approach to excreta disposal that can be defined as a system, which prevents diseases, protects the environment, conserves waste and recovers and recycles nutrients and organic matter. ECOSAN defines human excreta as a resource, not a waste. According to this new system, very little water is required, thus it is appropriate to solve water shortage problem.

Though the modern science has taught us that human excreta is "untouchable", it is in fact our resource and use of it also can save billions and billions liters of water we need to drink. The faeces and urine contain nitrogen, phosphorus, potassium, which are basic plant nutrients. These nutrients, provided by the soil to the plants are some essential parts of the food we consume. The nutrients are removed from the fields when we harvest. Instead of replacing the original nutrients, we are applying mineral fertilizers of fossil origin.

Those fossil minerals have limited source. Reserves of those fossil minerals are decreasing in the world. Phosphorus will be there only for less than 200 years. And Potassium is assumed to last for 300 years. Production of Nitrogen fertilizers requires energy as does the reduction of nitrogen in sewage treatment plants. Oil and gas, the most important energy resources for production of nitrogen fertilizers, have been calculated to last for 40 and 60 years respectively. On the other hand, many chemical fertilizers on the international market may contain higher levels of heavy metals like Cadmium (a toxic element that can damage the kidney once it accumulates in the human body).

An adult produces about 400 litres of urine per year. That is equivalent to 4 kg of Nitrogen (N), 0.4 kg of Phosphorus (P) and 0.9 kg of Potassium (K). Experiments have proved that plant nutrients excreted in urine is easily accessible for plants and the nutrients are as efficient as chemical fertilizer and heavy metal contains are much lower than in the chemical fertilizers. Though not sterile, the pathogenic content of fresh urine is generally low. So it can be applied on the open soil without dilution but better if diluted 1:2 to 5 ratio.

Similarly, a person releases about 50 kg of faeces in a year that is rich with 0.55 kg of Nitrogn (N), 0.18 kg of Phosphorus (P) and 0.37 kg of Potassium (K). It also contains millions of pathogens or parasites’ eggs but most of the pathogens eventually die or lose capacity to infect people.

However, some organisms like Salmonella remain alive and capable of causing diseases. Eggs from most worms do not increase in number but they can survive longer. So we can increase the temperature; decrease moisture, nutrients and microorganisms or keep in sunlight to destroy pathogens. In the same way, we can also increase content of pH by adding lime or ash that will help to kill pathogens.

Such sanitized or composted faeces act as a soil conditioner, which increases water holding capacity, reduces pests and diseases, improves soil structure, breaks up organic matter into the basic useful elements, releases nutrients at the rate plants need them and neutralize soil toxins and heavy metals.

In an experiment in Zimbabwe, use of urine and composted faeces increased maize yield more than two times. It was also found valuable in onions and tomatoes. The best thing is to give back the nutrients we get through the food to the filed by following ECOSAN methodology. This will keep the "back to earth" tradition alive.

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