In accordance with GOST 30772-2001, garbage disposal – activities for the use of garbage at the stages of its technological cycle, or its processing and reuse. Recycling is a type of waste processing associated with the reuse of raw materials for their intended purpose. It implies the return of processed raw materials to the production cycle. Recycling is a narrower term in relation to recycling.

Waste types suitable for recycling

Waste recycling is more often applied to solid waste and construction waste – that is, to products created by humans and not subject to rapid natural decomposition. It can be processed into secondary raw materials:

metal cans;
metal cord from tires;
wood shavings;
glass containers;
pulp and paper industry products;
plastics
scrap of ferrous and non-ferrous metals.

Possible amount of garbage recycling

Primary recycling is applied to materials of the same type that are not contaminated with paint, impurities, etc. An example is the processing of domestic waste in enterprises in connection with the launch of a new line. Garbage is mixed with the feedstock to ensure product quality.
In secondary recycling, additional mechanical processing is needed: sorting, cleaning from contamination and grinding. The process is applied to polyethylene films, as they are very dirty due to the large surface area. Recycling is more energy intensive and expensive.
Tertiary recycling is understood to mean chemical re-processing of raw materials. It heats up and turns into low molecular weight substances that can be used to make new products.
Quaternary waste recycling is the burning of waste in incinerators or pyrolysis plants. Old tires, dirty plastic helmets, medical waste, etc. go through this process. This is the most effective way to utilize raw materials, as the volume of waste is minimized, and the fractions formed in the process – gas, pyrolysis liquid – can be used as fuel.

Waste Recycling Classes

Recycling and recycling are not universal processes, that is, for each type of garbage you need to choose the right option. 4 processing methods are applied, which are used individually or in a complex.

Mechanical method

Machining involves grinding. Cut materials can be recycled, reused, used as fillers. The higher the quality of the recyclable materials, the more complex products can be created.

The advantage of the method is simplicity and reliability. In the workshops, raw materials are crushed on automatic production lines, which allows for the establishment of low-cost production.

The disadvantages of the method include:

poor quality of secondary products compared to new products;
limited use of recyclables due to inferior quality;
increased risk of spontaneous combustion of materials during the grinding process (due to the presence in the polymers of catalysts that can ignite upon contact with air).

Waste incineration

Incinerator waste burning for thermal energy is the most primitive processing technology. Its advantages:

cheap elimination of the most toxic and dangerous substances;
waste reduction;
during combustion, a lot of thermal energy is generated;
ash can be used for the production of concrete aggregates.
A serious minus of this method is the ingress of toxic substances into the atmosphere, including carcinogenic gases. The problem is partially solved by installing smoke detectors and trap filters, but this is an expensive upgrade.

Waste pyrolysis

Pyrolysis is a combustion method in which oxygen is not involved. As a result of heat treatment, the waste decomposes into simple substances, gas and liquid are simultaneously released, which serve as fuel. There are three types of pyrolysis: low temperature, medium temperature and high temperature.

Pyrolysis is a more environmentally friendly recycling method, especially when equipped with filters and emission detectors that measure the concentration of volatile sulfur and phosphorus compounds.

Pyrolysis releases more energy than burning fuel oil. Recycled materials (for example, metal cord from tires) can be used in the manufacture of new products. The pyrolysis liquid is refined and processed into artificial oil. Gas from the plants is used for afterburning or is used at thermal power plants.

The semi-coke remaining after pyrolysis can be buried in a standard solid waste landfill, since it does not pose a significant threat to ecosystems.

Chemical method

Waste of one type is sorted and exposed to them with chemical reagents (example: depolymerization, gasification). As a result, the structure of the material changes. The chemical method is suitable for the processing of construction waste and plastic.

As chemical reagents are used:

alcohols;
alkali solutions;
acids.
Chemical recycling products are used in the paint and varnish industry and in the manufacture of films and powders.

The disadvantage of this method is the high science intensity and high cost. In this regard, chemical waste recycling is not sufficiently developed in the CIS.

Recycling Technologies

The choice of recycling technology depends on the type of waste. The volume and condition of the garbage, i.e. the presence of structural damage, rust, dirt, etc., are also taken into account.

At the first stage, the garbage is sorted and cleaned. Some products (used glass containers) do not have to be recycled; thorough washing is sufficient. Purification of ferrous scrap from debris is carried out using powerful magnets.

Sorted garbage is distributed across different production lines:

Tires, large solid waste are cut with industrial scissors, then burned in pyrolysis furnaces.
Pieces of wood are crushed for conversion into chipboard or burned in incinerators.
Metal debris (cans, wires, pipe cuts) is melted into new products.
Plastic waste chemically turns into a ready-to-use raw material.

Depending on the processing method, the final product is stored for further processing (example: metal cord from tires), buried at landfills (semi-coke) or reused for its intended purpose (washed glass containers, recycled waste paper).

The processing of multicomponent products (computers, cell phones, etc.) is significantly complicated by the need to dismantle and disassemble the devices.
For the effective implementation of recycling, it is necessary to introduce a separate collection of garbage, because in enterprises, for technical reasons, it is impossible to ideally sort the raw materials.

Types of Recycled Materials

By origin, recyclables are divided into biological (wood, food waste, waste paper) and technological (everything else).

The main types of recycled materials are scrap metal, glass, waste paper and plastic.
Scrap metal is allowed to manufacture new products that do not require high quality material: cans, rods, pipes, etc.

If the glass product is not damaged, quality cleaning is sufficient. In the case of complete processing, new glass containers are blown out of it. From crushed glass, sand is made for construction.

Waste paper from old books and newspapers is used to produce new printed materials.

Plastic is chemically processed (taking into account its grade) and used in the assembly of plastic products.

The thermal energy obtained during pyrolysis can be used for space heating. Combustible fractions (gas and liquid) released in the process are used as fuel.

The economic benefits of recycling

Properly organized recycling reduces the cash costs of producing goods. To create many products from scratch requires more energy, labor and time than processing. It is necessary to obtain raw materials, deliver them to a processing plant, then deliver the processed raw materials to the plant and make goods from them.

The economic feasibility of processing depends on the difference in cost between primary and secondary raw materials required for fuel processing and the technical complexity of the process. If recycling is recognized as unprofitable, garbage is disposed of at the landfill.