The process involved in the treatment of special waste within Herambiente is highly intricate. Specifically, it depends on the nature of the special waste to be treated.
The rules on waste management were first established by Presidential Decree 915 of 10 September 1982 on the disposal of waste. As well as introducing a number of principles for defining systems to limit waste production, this subdivided waste into four types: municipal, special, toxic and harmful. In February 1997, this decree was superseded by Legislative Decree 22 (the "Ronchi Decree"), which focuses on preventing and reducing the quantity and hazardousness of waste.
In April 2006, Legislative Decree 152 (the "Consolidated Environmental Act") came into force. This profoundly changed the legislative framework by introducing a wide range of innovations into the rules on environmental impact assessments and strategic environmental assessments, soil protection, water pollution prevention and water resources management, waste treatment and management, reclamation of contaminated sites, and pollution. The Consolidated Environmental Act makes a distinction between hazardous and non-hazardous special waste. Each of these two types may include solid, liquid or sludge waste. Special waste is subject to disposal limits defined, on a plant-by-plant basis, by the provincial authorities via the Integrated Environmental Authorisations (IEAs). However, the legislation does not specify any predefined geographical catchment area for its disposal, unlike in the case of municipal waste, for which a provincial and regional scope is specified.
The law treats special waste as a free market commodity, for which the waste producers can select the management and disposal plant of their choice, either inside or outside of their province. Most special waste derives from industry, wastewater purification, construction works, the commercial and services sector, healthcare activities and reclamation works.
Herambiente and its subsidiaries have 29 plants devoted exclusively to the disposal of special waste, with approximately 2.5 million tonnes handled in 2011.
Below is a brief description of the main types of plants.
Ecological platforms: The ecological platforms receive hazardous and non-hazardous special solid waste (for example, from various industrial processes, demolition works and healthcare activities), which follows a process very similar to that of municipal waste. Here, after initial checking for acceptance and weighing, the waste is separated and grouped by material in the various sectors that comprise the platform, into groups with compatible physical and chemical characteristics so as to maximise the recoverable portion. The waste thus grouped is then temporarily stored in suitable areas, ready to be transferred to treatment plants.
The residual portion, if suitable, is subjected to sorting operations aimed at extracting the recoverable fractions, such as iron and wood. The rest completes the cycle in waste-to-energy plants or in landfills, where they still contribute towards increasing the overall energy recovery.
Physical-chemical and biological plants: The types of waste sent to these treatment plants may include, depending on their characteristics, hazardous and non-hazardous liquid and sludge waste (e.g. leachates from landfills, liquids and sludges from industrial processes, foodstuffs, fabrics, left-over earth from reclamation projects, sludges from extraction activities). After being checked for acceptability, the waste is stored in various reinforced-concrete tanks and steel containers of different sizes, according to the specific composition of the waste. All structures are equipped with the required safety equipment, such as containment tanks, high-level detection filling pumps, etc. For both liquid waste and sludges, the aim is to achieve maximum separation of the liquid and solid portions and, in the case of liquid waste, to reduce the levels of polluting substances, thanks to the use of reagents and special technological equipment. After physical-chemical treatment, if it meets the necessary requirements, the liquid residue can be reintroduced into the environment, i.e. emptied into bodies of water. If it does not meet these requirements, it must be made suitable for biological treatment at the appropriate plant and brought into conformity with legislation for subsequent discharge.
Sludge - whether primary or produced by the various liquid waste treatment processes - must be given a suitable physical consistency for the chosen form of final disposal, which may mean that it is sent to a controlled landfill or a waste-to-energy plant, or used as a landfill covering material after stabilisation or neutralisation treatment.
Neutralisation plants: Certain types of waste with an inorganic matrix and high concentrations of heavy metals (such as lime from fume abatement systems in the ceramics industry, or sludges and particulates from similar systems in the iron and steel industry), require a neutralisation treatment, which makes it possible to render the waste harmless by binding the pollutants into a cement matrix. The product thus obtained has excellent heavy metal retention qualities, allowing it to be disposed of in landfills.
All of these plants are equipped with a rainwater collection system for road run-off and a system of holding tanks for collecting the process water.
In terms of controlling emissions and environmental impacts, certified laboratories are commissioned to carry out regular checks on wastewater, waste, soil and subsoil at the frequency defined in the Integrated Energy Authorisation.