Wasser in der Landwirtschaft - agriwaterpedia.info

esources. To account for the health aspect in resource-recycling, the WHO published in 2006 the
”Guidelines for the safe use of wastewater, excreta and greywater” in agriculture and aquaculture. This is
just another reason why reuse-oriented practices should be considered in commercial agriculture as well as
in subsistence farming as they improve agricultural productivity by delivering nutrients, organic matter and
water needed for plant growth.
Sustainable sanitation systems comprise decentralized
and locally adapted as well as large scale
centralized solutions that favour no specific
technology and range from low cost basic sanitation
(e.g. urine (e.g. vacuum systems, membrane
technology, etc.). Reuse-oriented sanitation practises
not only have the potential to decrease global food
insecurity but also improve public health and aim at
using the limited global resources more effectively.
The idea that human residues including excreta are
wastes with no useful purpose can be seen as a
modern misconception. Ecological sanitation applies the natural principle of closing the loop by using safe
sanitation and reuse technologies, thereby continuing the tradition of recycling human waste once applied
in most farming societies. Indeed the aspect of growing food and achieving food security is historically
strongly linked with the idea of reusing liquid and solid waste from households in agriculture. Through the
years human and animal excreta played a crucial role in maintaining soil fertility and providing essential
plant nutrients for food production.
The fertilizer needs could partly or fully be met by using the nutrients excreted by humans and animals.
Each year, one person excretes about 4.5 kg Nitrogen and 0.5 kg of Phosphorous (depending on the diet).
It is important to know that a) the amount of nutrients taken up in the diet equals those excreted (to
almost 100 per cent); and b) the amount of nutrients excreted equal the requirements for growing plants
to feed that one person.
Excreta and greywater reuse in agriculture could lead to three benefits for the farmers:
• Nutrients (N, P, K)
• Compost (organic matter – beneficial for soil structure)
• Water for irrigation
Two types of reuse in agriculture are well known:
• Treated wastewater
• Sewage sludge
However, there are more – lesser known – options, which form part of the set of technologies which are
promoted by the ecosan approach.
Several regions of the world already value the reuse of human excreta and wastewater among them is
Jordan where people were encouraged to use treated wastewater (reclaimed water) for irrigation as
substitute for freshwater since water resources are limited. In China for instance the use of ‘night-soil’ has
been practiced for several millennia with well-developed inner-urban collection and composting systems
and transportation to the fields. Also in Central Europe some 150 years ago human excreta together with
animal manure were commonly used in agriculture.
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