Introduction: what is the waste recycling
Recycling of waste is the set of operations that allow the reuse of specific materials contained in urban or industrial waste. Together with the separate collection and reuse activities, the recycling of waste contributes decisively to energy saving and the reduction of polluting and climate-changing emissions.
Managing waste consciously is of fundamental importance because it can represent a resource that should not be underestimated in terms of energy needs and eco-sustainability.
Recycling of waste is part of the more complex waste management activity. The term indicates the set of policies, procedures or methodologies aimed at managing the entire process of waste, from its production to its final destination, thus involving the collection, transport, treatment (recovery or disposal) phase up to reuse / recycling waste materials, usually produced by human activity, in an attempt to reduce their effects on human health and the impact on the environment. The correct management of hazardous and non-hazardous waste, of urban or special origin, is part of the principles that the European Union has defined in specific Regulations and Directives.
The recycling process
All the waste that is produced, both at domestic and industrial level, is subject to the fundamental collection phase, after which it will then be destined for the various treatments based on the type of waste.
The main difference between separate and undifferentiated collection is linked to the environmental sustainability of recycling; the separate collection allows to achieve a partial recovery of the raw materials that make up the waste, an activity that can be done through the process of undifferentiated collection.
In 2005, the European Commission started the reform process of the waste regulation, which led to Directive 2008/98 / EC and in 2014 to Regulation 2014/955 / EU.
The European Union has contributed to defining a legal framework aimed at controlling the entire waste cycle, from production to disposal, paying particular attention to recovery and recycling activities.
Within this framework, a fundamental aspect is to determine the degree of priority to be assigned to waste disposal activities.
The priority level is determined on the basis of the environmental sustainability of the treatments which are as follows:
- preparation for reuse / reuse
- other types of recovery, for example energy recovery
According to this principle, prevention must be implemented by promoting the reduction of production and the danger of waste and facilitating its reuse, recycling and other recovery operations. Landfill disposal is located at the bottom of the staircase, conceived as a residual option to be reset over time.
Knowing the methods and types of materials that can be subject to recycling practices is of fundamental importance. Equally important, however, are the prevention practices to be adopted with regard to waste.
The term prevention refers to the need to make behavioral changes, both at the individual level and at the group level.
There are many gestures that can be performed daily at an individual level to prevent waste production such as:
- buy resistant and non-disposable items;
- prefer products with little packaging or in any case with easy-to-differentiate packaging;
- avoid disposable shopping bags by preferring reusable bags;
- prefer rechargeable products, such as draft detergents now available in many shops;
- drink tap water instead of bottled water;
- reuse organic waste by composting;
- do not use tissues or paper napkins.
The change necessary to adopt a series of behaviors devoted to waste prevention does not only concern individual users but also small, medium and large commercial companies.
For these subjects, the change in behavior must be based on the consideration of the entire life cycle of the products – from the extraction of the raw material to their manufacture, from transport to use, from transformation into waste to their management – and evaluating the environmental impact of the various possible options. Some strategies that can be implemented are:
- the promotion of the returnable vacuum for commercial users;
- the introduction of the Environmental Hygiene Tariff, which proposes to measure the amount of the tribute to the quantity of waste produced, instead of to the surface of the user, trying to favor mechanisms that encourage the consumer to reduce the waste produced ;
- circuit for the collection of foods that are no longer marketable, but perfectly edible, which are removed from the fate of waste and destined, by the non-profit organization, to enrich the diet of people in a state of discomfort;
- the ECOSAGRE, with environmentally friendly management and the adoption of green-marketing strategies, such as for example the reduction of the use of disposable tableware;
- reduction of the volume and weight of packaging;
- the reduction, in general, of corporate waste.
Recycling waste materials is an activity of fundamental importance since it allows you to create so-called secondary raw materials, which are made up of scraps from processing raw materials or materials derived from the recovery and recycling of waste. When we speak of a primary secondary source, therefore, we refer to a source of raw materials deriving from industrial waste of various kinds.
There are different types of waste treatment.
The heat treatment technologies are all attributable to the application of one of these three distinct processes:
These processes are distinguished from each other mainly by the different operating conditions in which they take place, determined by the temperature levels used and by the presence or absence of an oxidizing agent.
In particular, combustion consists of a rapid oxidation process of organic substances (fuels) by the action of an oxidizing agent, normally consisting of the oxygen present in the air. In the specific case of waste treatment, it is identified as “incineration“, as it refers to its primary function which is to convert substances that are in any case dangerous or putrescible (this is the case of municipal waste, RU) or which have characteristics of harmfulness (this is the case with some industrial waste) in gaseous compounds (carbon dioxide, water vapor) and in practically inert solid residues (ash).
From the recovery of the heat contained in the combustion fumes it is possible, through a conventional steam thermal cycle, to give rise to the production of thermal and / or electric energy.
Unsorted waste can also be recycled through the cold treatment of waste. This particular process, which takes the name of mechanical biological treatment (TBM), operates by separating the residual waste into two parts, a wet fraction and a dry fraction. The first is subjected to a biological process, based on the so-called anaerobic digestion. For the production of compost, however, aerobic treatment is used.
Simplifying, the wet fraction is dried and then used as a biofuel or to cover landfills. The result of the wet fraction treated in the TMB plants shows a fermentability reduced by up to 90%, guaranteeing the absence of methane production, which is highly polluting.
The dry fraction, on the other hand, becomes waste-derived fuel (RDF), to be used in cement factories, coal-fired power plants and waste-to-energy plants.
The recycling plants
There are different types of recycling plants, which can be classified on the basis of the material to be disposed of. Each plant consists of several machines capable of contributing to the waste disposal process.
The available implant models are:
- CDR / CSS plant:it is designed for the transformation of industrial, domestic and commercial waste with the aim of obtaining alternative fuels: CDR (waste fuel) and CSS (secondary solid fuel).
- separation and shredding plant r.s.u .: for the treatment of municipal solid waste, from the discharge of the collected waste, up to the production of Secondary Solid Fuel. It is mainly composed of five machines / equipment.
- plant for the treatment of ELTs (end-of-life tires): it allows to obtain secondary raw material of different grain sizes, while separating other components, such as steel and textile fiber.
- WEEE waste treatment plant (Waste Electrical and Electronic Equipment) for the recovery of valuable material with semi-automatic processes. WEEE is a real resource whose volumes are comparable to the world of mining for the wealth of valuable materials. (Gold, Silver, Copper etc ..)
- car bumpers and tanks treatment plant: it is expressly designed for the transformation of rigid plastics with hollow body into granules to be used as MPS (second raw material).
- systems dedicated to the disposal of toners: they are designed to separate the plastic materials that make up the wrappers.
- plant for the treatment of plastic: it is a natural evolution of the plant for tanks and bumpers.
- paper treatment plants: These are machines dedicated to the recycling of paper and cardboard. Particular shredding processes are dedicated to confidential documents that can be pre-treated to protect the content and then start the shredded material in the recycling process.
- systems for the treatment of hospital waste: they are highly customized and the most modern technologies are applied in the field of grinding.
- plants for the treatment and grinding and treatment of electric cables: plants used in a very profitable sector because it allows to obtain raw materials, including copper, whose demand is constantly increasing.
- plants for wood recycling: new materials used for industrial purposes and also for the production of renewable energy can be obtained.
- plants dedicated to cardboard: these are extensions of the paper treatment plants.
The stages of waste treatment
Within the plants, waste treatment takes place through several stages:
it consists of picking, sorting and grouping for transport. The volume of waste is reduced through shredding and compacting operations carried out on board the same vehicles that collect it
is carried out with means suitable for the various types of waste
consists of the set of reuse or recycling operations that allow to recover material or energy
they are operations that allow to neutralize the danger of certain wastes in order to make them suitable for transport and their final destination.
the resulting products of the various recovery operations or the materials from which there is nothing to recover are sent for final disposal which can take place in controlled landfills, in the open air or underground, or for incineration.
According to the legislative decree D.Lgs. 152/06, annex B it is possible to classify the treatment – waste disposal activities according to the following division:
- D1: Deposit on or in the soil (e.g. landfill)
- D2: Treatment in terrestrial environment (e.g. biodegradation of liquid waste or sludge in soils)
- D3: Injections in depth (for example injections of pumpable waste in wells. In salt domes or natural geological faults)
- D4: Lagooning (e.g. discharge of liquid waste or sludge into wells, ponds or lagoons, etc.)
- D5: Landfill specially set up (for example systematization in separate alveoli, covered or isolated from each other and from the environment)
- D6: Discharge of solid waste into the water environment except immersion
- D7: Diving, including burial in the marine subsoil
- D8: Biological treatment that gives rise to compounds or mixtures which are eliminated according to one of the procedures listed in points D1 to D12
- D9: Physico-chemical treatment that gives rise to compounds or mixtures eliminated according to one of the procedures listed in points D1 to D12 (e.g. evaporation, drying, calcination, etc.)
- D10: Incineration on the ground
- D11: Incineration at sea
- D12: Permanent storage (e.g. placing containers in a mine, etc.)
- D13: Preliminary grouping before one of the operations referred to in points D1 to D12
- D14: Preliminary reconditioning before one of the operations referred to in points D1 to D13
- D15: Preliminary deposit before one of the operations referred to in points D1 to D14 (excluding temporary storage, before collection, in the place where they are produced)
The importance of human intervention
The presence of ecological operators within the recycling plants is fundamental alongside the equipment of technologically advanced machinery suitable for the specific waste treatment that will be carried out in that plant. Generally it is the task of the ecological operators to carry out the following activities:
- transporting waste to disposal places;
- load and unload waste;
- check the condition of the bins and report the need for maintenance;
- drive the waste collection truck and operate the waste collection controls;
- collect separate waste;
- provide for the collection of waste at industries, public places or buildings;
- carry out ordinary or extraordinary maintenance on equipment, plants or machinery;
- manage and prepare the necessary material for cleaning;
- divide the material to be recycled;
- provide for the collection of bulky waste;
- carry out administrative activities;
- empty and clean the bins or waste bins and change the bags of the bins;
- to operate cleaning machinery;
- collect special waste;
- clean the streets, sidewalks or gardens.
In a delicate process such as waste treatment, the adoption of excellent technologies and human intervention prove to be decisive for its optimal success.