An important part of the department is the management and maintenance of the waste water system. The system basically includes a grease trap, a system of horizontal and vertical filters filled with gravel and a pond. These filters and the pond support the planting of Reed, Comfrey, Nettles and Mint, they will contribute to the treatment and reuse of the waste water.
One of the tasks of the department is the care of these plants, in order to guarantee their purifying function and therefore being able to use the waste water as a resource. In the pond, as the last phase after the filters, we proceeded to plant new plants of Comfrey (Symphytum officinale L.). This plant is commonly known as knitbone, a medicinal plant with healing properties and is grown as a green manure.
Here you can see the development of the pond after the plantation of Comfrey . First picture represents the pond before planting, the second picture after and last picture one month later.
The maintenance of the pond includes the harvest of Comfrey leaves. The gained leaves will fulfill a further function by being used as fertilizer.
The leaves were cut into small pieces and stuffed into a plastic bottle. A simple filter consisting of a small sieve was situated between the opened lid and the Comfrey. The content was compressed as much as possible. Afterwards, the plastic bottle was put upside down on another jar. All the liquid from the Comfrey leaves slowly dripped into the bottom jar. After two weeks, the content of the plastic bottle had been reduced to a fifth of the original filling. There was only the dry texture of the plants left in the upper plastic bottle whilst there was about a litre of fertilizer accumulated in the bottom jar. As this fertilizer is generated without adding water, it is durable for about a year.
Very similar methodology is been used with Nettles from the bed next to the vertical filters. After harvesting the leaves, they were used following the same technique to obtain liquid fertilizer. After two weeks the result is a liquid fertilizer very rich in nitrogen.
In the picture the darker jar on the left is Nettle fertilizer, and the one on the right is Comfrey.
This pond, at the end of the waste water system, is also a habitat for animals such as frogs. Due to the humidity and the presence of many insects, this place looks like a perfect place for them. It is nice to see that the management of waste water it can also improve the biodiversity of the area.