Ecological Sanitation

Introduction

Conventional forms of centralized sanitation are coming under increasing criticism. Especially because of the enormous investment involved, the huge operating and maintenance costs, high water consumption and other drawbacks, they are not suitable as a blanket solution for developing countries, particularly in arid zones. Even conventional individual disposal systems, such as latrines and cesspits, make poor alternatives – especially in view of increasing population densities and the substantial groundwater pollution they can cause. Moreover, all conventional types of wastewater and sewage disposal systems usually deprive agriculture, and consequently food production, of the valuable nutrients contained in human excrement.

A more holistic approach towards ecologically and economically sound sanitation is offered by the concepts referred to as “ecological sanitation”. Ecological sanitation technologies take the principle of environmental sanitation a step further: Environmental sanitation means keeping our surroundings (the environment) clean and safe and preventing pollution. It includes wastewater treatment and disposal, vector control and other disease-prevention activities. Ecological sanitation, on the other hand, is premised on recycling principles. The key objective of this approach is not to promote a certain technology, but rather a new philosophy of dealing with what has been regarded as waste in the past. The systems of this approach are based on the implementation of a material-flow-oriented recycling process as a holistic alternative to conventional solutions. Ideally, ecological sanitation systems enable the complete recovery of all nutrients from faeces, urine and greywater to the benefit of agriculture, and the minimisation of water pollution, while at the same time ensuring that water is used economically and is reused to the greatest possible extent, particularly for irrigation purposes.

Linear Flow Systems

Most families in the North make use of ‘flush and discharge’ systems – the regular waterborne sewerage toilet. These are designed on the premise that human excreta are a waste, suitable only for disposal. This approach also assumes that the environment has an infinite capacity to absorb and assimilate these wastes.

On average, 15,000 litres of treated, safe, drinking water is used to flush 35 kilograms of faeces and 500 litres of urine per person every year. This conversion of cleanwater into ‘blackwater’ is a massive waste of water for arid regions. In developing countries 90 percent of this sewage is flushed into surface waters, polluting rivers, lakes and coastal areas. This can contribute to the spread of disease, as well as lowering the oxygen content of the water bodies, leading to increased algae growth and eutrophication.

In developing countries the most common sanitation system is the pit latrine, based on the ‘drop and store’ principle. Although this uses much less water than flush systems it also has its drawbacks. Due to the large volume of the underground pit needed it is not suitable for densely populated urban areas. If the groundwater table is high, or the ground is very hard it is not possible to construct these toilets.

In areas where they are used there is the risk that the surrounding groundwater will be contaminated from seepage or from water flowing in during floods. This has implications for health as pathogens can contaminate drinking water supplies. Due to the high humidity levels in the pits disease vectors breed rapidly, producing diseases such as filariasis, yellow fever and cholera.

As mentioned above, all linear systems have the other major disadvantage that nutrients and organic matter are wasted. Nutrients, such as nitrogen, phosphorous and potassium are plentiful in urine and faeces provide carbon and condition the soil.

Advantages

  • Removal of pathogens from the domestic environment.
  • Elimination of foul odors – if properly constructed.
  • Convenient & easy to use.

Disadvantages

  • Nutrients are wasted.
  • Downstream areas potentially receive pollution.
  • Lots of water wasted.
  • Hormones & antibiotics enter the drinking water system.
  • Very costly to construct and maintain effective sewerage network.
  • The energy contained in the organic carbon from faeces is lost.
  • Pit latrines can’t be used in high density areas.
  • Pit latrines can’t be constructed in areas with hard ground or high water tables.

Circular Flow Systems

Ecological sanitation is a safe method of recovering nutrients from human excreta, then recycling them back into the environment and productive systems.

A human being produces exactly the amount of nutrients that is needed for growing his or her food (measured in crops) – 7.5 kg of nitrate, phosphorus and potassium for 250 kg of crops. Urine hardly contributes at all to the spread of diseases (e.g. bilharziasis) and contains approximately 88% of the nitrogen, 67% of the phosphorus and 71% of the potassium carried in domestic wastewater. Faeces contain 12% of the nitrogen, 33% of the phosphorus, 29% of the potassium and also 46% of the organic carbon, as well as most of the pathogens.

If separated, urine can easily serve as a fertilizer after it has been diluted with water. After feces have been desiccated (dried-out), they are free from pathogens, diseases and odor. They can then serve as a soil conditioner for agriculture, returning a significant part of the nutrients and trace elements to the soil.

The remaining treated Greywater may be used for irrigation and also for recharging the local aquifer. This closes local cycle, helping to improve food security and to conserve soil fertility. At the same time, human health is improved due to the removal of disease sources from the domestic environment.

Advantages

  • Removal of pathogens from the domestic environment.
  • Elimination of foul odors – if properly constructed.
  • Diseases are destroyed, not just contained.
  • No potential to contaminate other water sources.
  • Use very little, or no water.
  • Nutrients and organic matter is recovered.
  • Very cheap to build and operate, with very few components which can malfunction.

Disadvantages

  • Users do need to be taught how to use them properly.
  • Feces need to be treated in the correct manner, otherwise they pose a health risk.
  • High density urban areas don’t always have the capacity to use the byproducts produced.

Frequently Asked Questions About Ecological Sanitation

Ecological Sanitation, often abbreviated as EcoSan, is a revolutionary approach to sanitation that flips the script on human waste. Instead of treating it as a waste product to be disposed of, EcoSan sees it as a valuable resource. This approach focuses on safely collecting, treating, and reusing human excreta (feces and urine) to benefit agriculture and minimize environmental impact. EcoSan offers a range of technologies, from simple dry toilets to more complex systems, all aiming to “close the loop” by returning nutrients to the soil while protecting water resources.

Traditional sanitation systems often rely heavily on water for flushing and treatment, leading to high water consumption and potential contamination of water sources. EcoSan offers several advantages:

  • Resource Recovery: EcoSan treats human waste as a resource, recycling valuable nutrients like nitrogen and phosphorus back into the soil, promoting healthy plant growth and reducing reliance on chemical fertilizers.
  • Water Conservation: EcoSan systems often use less water compared to conventional methods, which is crucial in water-scarce regions.
  • Environmental Protection: EcoSan minimizes water pollution by reducing the amount of untreated wastewater released into the environment.
  • Economic Benefits: EcoSan systems can be more affordable to implement and maintain in some regions, particularly for communities without access to centralized sewage systems.

There are various EcoSan technologies available, but a key principle is separating urine and feces at the source. This allows for targeted treatment:

  • Urine: Urine is relatively sterile and rich in nitrogen. It can be diluted and used directly as fertilizer or further treated for reuse.
  • Feces: Feces require more extensive treatment to kill pathogens. Composting toilets or special containers can be used, with the treated product becoming a safe and valuable soil amendment.

EcoSan offers a range of technologies suitable for different contexts. Here are a few examples:

  • Urine-Diverting Dry Toilets (UDDTs): These toilets separate urine and feces, allowing for safe and hygienic waste collection.
  • Composting Toilets: These toilets use a bulking agent like sawdust or wood chips to break down feces aerobically, creating a safe and fertile compost.
  • Wet Systems: Some EcoSan systems use small amounts of water to transport waste to treatment facilities where it undergoes further processing for safe reuse.

When properly designed, implemented, and maintained, EcoSan systems can be safe and hygienic. The key lies in proper treatment of waste to ensure pathogen destruction before reuse. EcoSan promotes good hygiene practices like hand washing after toilet use, further contributing to public health.

EcoSan offers a variety of adaptable technologies, making it suitable for a wide range of regions. However, certain factors influence its effectiveness:

  • Climate: Dry climates favor composting toilets where evaporation plays a role in decomposition. In wetter areas, additional treatment steps might be needed for feces.
  • Water Availability: While EcoSan conserves water, some systems require minimal water for flushing or processing. Understanding local water resources is crucial.
  • Social Acceptance: Adapting to new sanitation practices might require community education and cultural sensitivity.

Costs for EcoSan systems vary depending on the chosen technology, materials, and construction complexity. Generally, simpler dry toilets can be more affordable compared to traditional water-based systems. However, long-term maintenance and user training might be necessary with some EcoSan approaches.

EcoSan offers advantages for various communities:

  • Rural Areas: For regions lacking centralized sewage systems or facing water scarcity, EcoSan provides a sustainable and affordable solution.
  • Urban Slums: Densely populated areas with limited sanitation infrastructure can benefit from EcoSan’s water-saving features and resource recovery potential.
  • Disaster Relief: EcoSan systems can be easier and quicker to implement in emergency situations due to their lower water dependence.

Despite its benefits, EcoSan faces some challenges:

  • Initial Investment: Initial setup costs for certain EcoSan technologies might be higher than traditional systems in some situations.
  • Operation and Maintenance: Some EcoSan systems require user training and ongoing maintenance to ensure proper functioning and hygiene.
  • Public Perception: Shifting attitudes towards human waste as a resource might require community outreach and education.

There are numerous resources available to learn more about EcoSan:

These organizations provide valuable information on EcoSan technologies, case studies, and best practices.