Sorting of waste

Types of waste sorting

The sorting of waste is a recycling process that separates different waste materials. Waste sorting is usually done at the source, where each household is encouraged to segregate its waste into different categories to make sorting easy and effective.

Materials are usually separated based on their economic value and market demand. Once sorted, the materials are taken to specialized recycling plants where they get processed into new raw materials and go back into the production cycle again.

Generally, there are 2 main types of waste sorting; manual sorting and mechanical sorting.

• Manual sorting: This refers to the process of removing waste materials from a waste stream by hand. It involves trained workers who use their hands to pick different waste materials in order to separate them according to specific categories. Usually, the types of materials that are manually sorted are paper, glass, plastic, metals, organics, hazardous materials and textiles. Hazardous materials are often handled separately by trained professionals because they can endanger human health. Manual sorting is commonly used in small scale recycling facilities. It is also used when processing particular materials like electronic waste.
• Mechanical sorting: This is a method used in large scale industrial recycling facilities. It involves using different kinds of machines to sort out various waste materials. The types of machines used for mechanical sorting include shredders, air classifiers, optical sorters, eddy current separators and magnets. Mechanical sorting is efficient and saves time. It can be used to sort thousands of waste materials at a go. However, one disadvantage of mechanical sorting is that it can be less accurate when separating certain materials that are mixed together.

Apart from the two main types of waste sorting mentioned above, there are other types of sorts that buyers should know about.

• Source separation: This is a type of waste sorting that focuses on separating materials at the very point they are created. Typically, businesses and households are provided with different kinds of bins so that they can collect different types of waste materials. This minimizes contamination and makes recycling easier.
• Centralized sorting: This refers to a system where different waste materials are collected together and transported to a centralized facility for sorting. Once collected, the waste materials are separated using a combination of manual and mechanical methods. In most large cities, a centralized sorting system is used because it is easier and more efficient.
• Clean MRFs: These are materials recovery facilities that only handle source separated recyclables. Once the materials are received at the clean MRF, they are sorted further by either using automated technology or manual labor before they are processed and sold to end markets.
• Dirty MRFs: Unlike the clean MRFs, dirty MRFs handle unsorted waste that has a lot of potential recyclable materials. Most dirty MRFs are located right at the municipal waste facility. They use automated and manual sorting techniques to separate out various potentially recyclable materials from the rest of the refuse. The residual waste is then sent to a landfill.

Specifications and maintenance of waste sorting

Specifications

Some general specifications for a typical municipal waste sorting system are as follows:

• Feed size: The system can deal with waste of different sizes. It can handle objects with a shape of 10cm-100cm and weights less than 5kg. It means small packages, containers, and lightweight items are all suitable.
• Throughput: The quantity or weight of waste that the system can process per hour. A normal sorting line may deal with 500-1000 kg/h. So, it is good for small to medium-sized cities. It can meet their daily waste treatment needs.
• Separation accuracy: The system can accurately identify and separate recyclable materials, organic matter, and non-recyclables. Its separation precision can reach 95% or above for common recyclable items like plastics, paper, metals, and glass.
• Power consumption: The sorting system's energy usage is linked to its capacity and the technologies utilized. The power used may fall between 50 and 200 kWh for each ton of waste processed.
• Operating environment: The waste sorting machine usually operates in a damp, hot, and dusty setting. Its components are made to withstand typical atmospheric corrosion, high temperatures up to 60°C, and humidity up to 90%.

Maintenance

• Regular inspection: Inspect the entire system at fixed intervals, including main frame, chains, pulleys, bearings, and drives. Check for signs of wear, damage, or leakage. Ensure all fasteners are tight and adjust the overall position as needed.
• Lubrication: Do lubrication work for bearings, chains, and other transmission parts. Apply proper lubricants to reduce friction, wear and thus extend the life of equipment over time. Change grease regularly to ensure effective operation.
• Tension adjustment of belts and chains: This adjusting motor belts and chains ensures the appropriate tension level. It avoids slacking or excessive tightness. Regularly check the tension and adjust them to maintain the efficient power transmission and smoothing movement.
• Cleaning: Keep the surface and parts inside the machine neat and free from dirt. Use the compressed air to blow away dust for hard-to-reach spaces. Remove blockages in air ducts. Cleaning reduces overheating and malfunction risks.
• Pay attention to safe operation: While maintaining the machine, operators should pay attention to safety. Before maintenance, check that equipment power is off. Ensure safe and reliable work conditions. Follow relevant operational safety specifications during the maintenance process.

Scenarios

• Municipal Waste Sorting: Municipalities implement waste sorting to enhance recycling and minimize landfill dependency. Citizens sort their waste into distinct bins. Recyclables like paper, plastics, and glass go in one; organic waste goes in another, and non-recyclables in a final bin. Waste sorters ensure only designated materials head to the plants. Sorting boosts local recycling rates and diminishes environmental footprints.
• Industrial Waste Sorting: Manufacturing firms adopt waste sorting to curb operational costs and foster sustainability. Factories set up waste segregation areas where employees classify waste as per material streams. Recyclables, metals, and hazardous wastes receive separate treatments. Waste sorters enhance recycling and cut disposal expenses.
• Electronic Waste Sorting: Electronics waste sorting is imperative as gadgets reach their end of life. E-waste like phones, computers, and TVs often house recyclable metals and harmful substances. Waste sorters carefully segregate electronic junk into subcategories like screens, circuit boards, and batteries. Proper sorting averts environmental pollution and allows valuable resources to be recovered.
• Construction Waste Sorting: The construction sector generates vast amounts of waste. Huge construction waste sorting systems are set up to recover recyclable materials like metals, wood, concrete, and bricks from the job site indirector to landfill. Waste sorters improve resource efficiency and lower environmental impacts of the building industry.
• Hazardous Waste Sorting: Hazardous waste requires meticulous sorting as it poses threats to health and the environment. Hazardous waste like chemicals, batteries, medical waste, and radioactive materials needs separate handling, treatment, and disposal. Waste sorters use specialized containers to classify toxic waste accurately. They minimize risks linked with improper disposal and enable safe treatments.

How to choose sorting of waste

Various manufacturers of waste sorting machines have different selling points for their machines to sort waste. Here are some primary features one is likely to come across when deciding which waste sorter to go for.

• Sortline configurations

  Choose a machine that can handle the types of materials one is likely to have in one's waste stream. Different waste sorting machines are built to identify and separate various material kinds, so select one with a sortline capacity tailored to one's particular waste composition.

• Throughput capacity

  This is the volume of waste a machine can process in a given period, usually an hour. It is vital to select a sorter with a capacity that matches the user's waste volume to sort efficiently and at a time that meets the user's operational needs.

• Sorting technologies

  Various sorters have been equipped with different technological features. When choosing what kind of waste sorter to settle on, it is essential to go for a machine with the right combination of separation technologies to achieve the desired purity levels and maximize material recovery.

Beyond the features of the waste sorter itself, it is also imperative to consider other factors of great importance, such as the waste management system in place, including how the sorted materials will be processed further. Also, consider the amount of waste that will need to be sorted on a daily basis. Finally, a budget is always a reasonable factor to consider as one seeks to invest in a waste sorting machine.

Q&A

Q: Why is sorting of waste important?

A: The sorting of waste is crucial because it enables the recycling of materials that would have otherwise ended up in landfills. Furthermore, it enhances resource recovery, reduces environmental pollution, decreases landfill usage, and conserves natural resources.

Q: What are the challenges in sorting waste?

A: The challenges in waste sorting include contamination, lack of public awareness, insufficient infrastructure, economic factors, and safety hazards for workers.

Q: What technologies are used in waste sorting?

A: Several technologies are employed in waste sorting, including automated conveyor belt systems, AI-driven optical recognition, electromagnetic fields, air classifiers, and robotics.

Q: How does waste sorting impact recycling?

A: Waste sorting is paramount to successful recycling. It guarantees that the appropriate materials are processed, improves the quality of recycled products, and facilitates more efficient recycling operations.

Q: What are some benefits of proper waste sorting?

A: Proper waste sorting has several benefits, including reducing landfill space, conserving resources, protecting the environment, creating job opportunities in the recycling sector, and educating the public about sustainability.