Recycling Processes and Environmental Impact
Glass Recycling
Glass is a silicate that melts at 1200 degrees Celsius. It consists primarily of silica (mainly from quartz), along with limestone and other materials that impart different colors.
Glass Recycling Process:
- Washing, screening, and selection
- Magnetic phase selection
- Manual separation of contaminants
- Screening
- Manual separation of pollutants or grinding
Polymer Recycling
A polymer is a high molecular mass compound consisting of many repeating units (monomers).
Polymer Recycling Process:
- Opening the bags
- Drum sieve
- Air separator
- Magnetic separation
- Visual separation of shredder operations
- Washing and crushing
- Shredding
- Removal of heavy fraction
Paper and Cardboard Recycling
Paper and cardboard represent the second-largest fraction of generated waste, with food waste being the largest. Approximately 70% of paper and cardboard waste is recyclable. Per capita consumption of paper has doubled in the past 15 years, growing faster than GDP.
Paper Recycling Process:
- Pulping waste
- De-inking
- Filtering and washing
- Pressing
- Drying
Iron Recycling
Iron recycling involves the separation of useful and hazardous materials, crushing, and reuse in production processes. 100% of scrap iron is used, achieved through simple separation with magnets.
Aluminum Recycling
Aluminum recycling uses magnetic separators or Foucault currents, followed by crushing, deslacamineto (removal of slag), casting, and rolling.
Biomethanation
Biomethanation: It is an anaerobic fermentation process of the organic fraction in waste, producing biogas. In addition, a slightly alkaline residue (pH = 7.5) can be used as fertilizer. Approximately 97% of the gas components generated are methane and CO2 in equal parts.
The process takes place in sealed conditions to avoid and control oxygen pressure, pH, and temperature throughout the process. These structures are known as digesters. There are no plagues or pathogens.
Resources and Sustainability
Resource: A resource is defined as a substance or energy obtained from the physical environment to meet our needs.
Types of Resources:
- Perpetual: Inexhaustible on a human scale (wind, sun, tides, etc.).
- Non-renewable: Exist in limited quantities and are considered depleted when 80% of the reserve is exhausted (e.g., fossil fuels, minerals, etc.).
- Potentially renewable: Replenished through natural processes but can be exhausted in the short term if used or contaminated at very high rates (exceeding the assimilative capacity) (e.g., forests, fisheries, soils, etc.).
The maximum exploitation rate is called the natural replenishment rate.
Sustainable Development: Meeting the needs of the present without compromising the ability of future generations to meet their own needs.
Pollution
Pollution: The presence in the environment of substances, elements, energy, or a combination of them, in concentrations and retention higher or lower, as appropriate, than those in force by law.
Types of Pollution:
- Point source pollution: Comes from a single identifiable source (chimneys, drains, etc.).
- Non-point source pollution: Comes from large, difficult-to-identify sources (runoff, etc.).
Contamination: The presence in a system of a substance or energy at a higher concentration than the system can assimilate without suffering degradation, involving harmful effects on organisms.
Productivity
Gross Primary Productivity: The rate at which producers capture and store a given amount of chemical energy for some time, expressed as the amount of energy produced in the form of plant material per unit area and unit time.
Net Primary Productivity: The basic food source for all consumers, expressed with the following formula:
PPneta = PPbruta – Respiration of plants
Anthropogenic Alterations to Phosphorus Cycle
Anthropogenic alterations to phosphorus include:
- Mining of massive amounts of phosphate rock to produce fertilizers and detergents.
- Adding excess phosphates to aquatic ecosystems due to agriculture (livestock, fertilizer, and erosion), deforestation (erosion), and discharges of untreated wastewater (sewage and detergents).
- Waste contributing to eutrophication.