Innovation

Innovation

1.1.2 - Treating wastewater as a resource

Normally wastewater is seen as a substance to get rid off as soon as possible. This thinking influenced the treatment technology developed until now led to expensive and energy guzzling treatment plants with negligible reuse of nutrients and water. At the same time wastewater was increasingly considered a convenient means of disposal of all types of even hazardous wastes. The recycling of treated sewage sludge to agriculture is decreasing due to reduced acceptance by farmers and consumers. A reason for this development is the total mixing of all wastewater types occurring in a municipality: e.g. hygienically hazardous waters from households, storm water loaded with heavy metals, wastewater containing drugs from hospitals, industrial runoffs et cetera. In order to reuse compounds of the wastewater effectively it will be necessary to segregate the different parts at their source.
Zer0-M focuses mainly on domestic sewage. Within this context an important step will be to distinguish black from grey water. Black water is the outlet from flushing toilets; grey water is the term for all the other used water from a household, mainly from washing and cleaning. If they are collected separately, new and interesting solutions for treatment but also for reuse of the compounds are accessible. Grey water makes up for most of the wastewater flow of a household but has low concentrations of nitrogen and phosphorus and a low concentration of pathogens. After treatment ? e.g. in a vertical flow reed bed - the water will have a hygienic quality better than bathing water and can be used for different purposes like irrigation or toilet flushing.

Grey water treatment AquaCycle® by Pontos

The concentrated black water opens up new possibilities as well. It can be composted or treated like ordinary wastewater. After further segregation of urine from faeces the urine can be used as a fertiliser. A wide variety of new processes and technologies become possible, which are already tested one by one but rarely implemented and working as an integrated system and not yet introduced to the MEDA countries. Constructed wetlands, as an efficient method for treating wastewater has also to be adapted to these new challenges. Another key issue will be to establish contacts and co-operations between wastewater producers and re-users.

Constructed wetland among olive trees, Baggiolino, Italy