Process for biostabilization and humification of biological sludge in planted filtering beds

Abstract

A process for stabilization of biological sludge provides the step of laying in a containing volume, or basin (1), a draining material (2). In particular, the layer of draining material (2) can be a layer of gravel having granulometry set between 40 and 70 mm and a height (hi) about 25 cm. On the first layer (2) a second draining layer (3) can be laid comprising a material, for example gravel having granulometry less than the first layer (2), set between 4 and 6 mm. The second layer (3) has preferably a height (h2) about 15 cm. Once made the draining layers (2, 3) a planting step is made in the second layer (3) of a plurality of seedlings of an aquatic macrophyte, preferably Phragmites australis (10). The base granular filtering gravel layer has also the function of supporting the root ofthe seedlings. To ensure a high efficiency of the process a measured density of plants is chosen, corresponding to a relative distance between two seedlings of Phragmites australis set between 40 and60 cm. once achieved a measured vegetative growth, a first spilling in the containing volume (1) is carried out of an amount of biological sludge (12). The amount of sludge (12) fed in the containingvolume (1) corresponds to a predetermined height, set between 2 and 4 cm, of the layer of sludge (12) on the draining layer (3).

Description

technical field

[0001] The present invention relates to a method for stabilizing industrial or municipal sludge, in particular by means of "in situ" treatment. Background technique

[0002] It is well known that the treatment of biological sludge produced by purification plants is economically and operationally critical to the management of industrial and municipal wastewater treatment plants.

[0003] In fact, sludge represents the main waste of various purification plants, and the choice of whether to treat or recycle sludge is extremely important for the balance of plant operations as well as their environmental impact.

[0004] Depending on the nature of the sludges, they can be treated in many ways.

[0005] If the sludge comes from the purification of industrial wastewater, it can be disposed of in a special dump. However, before disposal, the sludge must be converted into a loose dewatered material by mechanical dewatering through a filter press and then mixed with ...

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