Law 748 of 19 October 1984, "New rules for the regulation of fertilisers", identified four types of soil improvers: simple un-composted soil improver of vegetable origin, composted green soil improver, composted mixed soil improver and composted peat-based soil improver.
At national level, Legislative Decree 22/97 (the "Ronchi Decree") unified the previous legislation and defined the results to be achieved in terms of recovery of the organic fraction from municipal solid waste and from recycling. It also attributed full jurisdiction to Law 748/84 with regard to the use of compost as a fertiliser.
In April 2006, Legislative Decree 152 (the "Consolidated Environmental Act") came into force.
This concerned various aspects of the soil improver and compost sector. In 2008, it was amended by Legislative Decree 4 of 16 January 2008, which established further corrective and supplementary provisions; in particular, Article 183 defines the notion of "high-quality compost" as "a product obtained from the composting of separately collected organic waste, which conforms to the requirements and characteristics established by Annex 2 of Legislative Decree 217 of 2006, as amended".
Resolution 1996/2006 of the Emilia-Romagna Regional Council defines the conditions for the use, as an engineering material, of "biostabilised" non-hazardous special waste (EWC 19 May 2003), obtained by aerobic biostabilisation of the mainly wet fraction of mechanically separated undifferentiated municipal waste, as well as of the wet fraction of waste deriving from separated collection.
With Legislative Decree 205 of 3 December 2010, the legislator transposed into Italian law the indications of the European Union concerning the policies to be adopted with regard to the disposal of waste, and defined the priorities for waste management on the basis of what represents the best environmental option in planning policy.
The organic waste obtained from the separate collection or from the mechanical separation of unseparated waste is taken to the composting and biostabilisation plants.
The first of these two types of waste undergoes a composting treatment to transform it into compost for use as an agricultural soil improver, while the second, since it derives from unseparated waste and may, therefore, still contain traces of other waste, does not have the required "purity" characteristics for use in agriculture and is therefore biostabilised and used for other purposes, such as covering landfills, thus replacing raw materials.
Composting: Even organic refuse from kitchens and gardens can become valuable resources. This is biological waste with a high water content and is therefore also referred to as the wet fraction of municipal waste, to distinguish it from the dry fraction (glass, plastic, metals, etc.). Recovery of the wet fraction can have a significant impact on the reduction of residual municipal waste.
Composting uses the natural process of the decomposition of organic matter. This is a biological process that transforms organic matter into compost, a soil-improving fertiliser used in agriculture. The process takes place under controlled humidity and temperature conditions, through the activity of naturally-occurring microorganisms (bacteria, fungi, worms, mites, etc.), resulting in the production of heat and the formation of carbon dioxide and water.
Herambiente produces high-quality compost from approximately 150,000 tonnes per year of organic waste derived from separated collection.
The experience acquired in this sector has led Herambiente to make greater use of organic waste in order to obtain, in addition to soil improvers, electricity, by means of an anaerobic digestion process using "dry" technology. The good results obtained in the two years of operation of the first plant, through the subsidiary Romagna Compost, have led to this activity being extended to five other sites, four of which were already equipped with composting plants.
Biostabilisation: In the plants dedicated to the treatment (biostabilisation) of the organic fractions obtained from the mechanical separation of unseparated municipal waste, the fermentation of the organic waste is accelerated, with the recovery, among other things, of biogas that can be used as a fuel. The end result is a material (biostabilised material or non-conforming compost) capable of being used as a covering for landfills, as an alternative to earth or other natural quarry materials. Other possible uses include the creation of embankments and escarpments, the environmental recovery of exhausted quarries and the restoration of disused landfills or polluted sites.