Solid Waste and its Classification based on different Parameters

Waste

• Waste is defined as any unwanted or unusable substance that is discarded after primary use. Wastes are normally generated as a result of human and animal activities
• Waste management is intended to reduce adverse effects of waste on health, the environment or aesthetics.

Wastes are commonly classified based on the physical state as solid wastes, liquid wastes and gaseous wastes.

Solid wastes are any discarded or abandoned materials that can be solid, liquid, semi-solid or containerized gaseous material discarded by the human society. These include urban wastes, agricultural wastes, biomedical wastes and radioactive wastes. The term refuse is also used for solid wastes.

Examples of solid wastes include waste tires, septage, scrap metal, latex paints, furniture and toys, garbage, appliances and vehicles, oil and anti-freeze, empty aerosol cans, paint cans and compressed gas cylinders, construction and demolition debris, asbestos, plastics, styrofoam containers, bottles etc.

Liquid wastes: Liquid wastes can be defined as liquids/fluids that are generated from washing, flushing or manufacturing processes of the industries. They are also called as sewage. The most common practice of disposing liquid waste is to discharge it in ground or rivers and other water bodies without treatment.

Examples: domestic washings, chemicals, oils, waste water from ponds, Wastewater from manufacturing industries, manure, waste oil, fats, oils or grease (FOG), used oil, and hazardous household liquids

Gaseous wastes It is a waste product released in the form of gases from automobiles, factories, industries, burning of fossil fuels etc and get mixed in the atmosphere. These gases include carbon monoxide, carbon dioxide, sulphur dioxide, nitrogen dioxide, ozone and methane etc.

Solid Waste:

Municipal Solid Waste: Municipal solid waste commonly referred to as trash, garbage or refuse comprises of street wastes, dead animals, market wastes, abandoned vehicles, household garbage, rubbish, construction and demolition debris, sanitation residue, packaging materials, trade refuges etc.

Solid waste can be classified based on its source, which helps in understanding the nature of the waste and designing appropriate waste management strategies. The primary sources of solid waste are residential, commercial, industrial, agricultural and institutional.

Residential Solid Waste:

Household Waste: Generated from everyday activities in households. This includes kitchen waste, packaging materials, old furniture, clothing, and other items discarded by individuals and families.

Yard Waste: Comprising grass clippings, leaves, branches, and other organic materials from gardening and landscaping activities.

Commercial Solid Waste / Institutional Solid Waste:

Retail Waste: Generated by stores and businesses, including packaging materials, damaged goods, and obsolete inventory.

Office Waste: Includes paper, cardboard, electronic waste (e-waste), and other materials generated in office settings.

Restaurant Waste: Generated by the food service industry, including kitchen waste, packaging, and leftover food.

School and University Waste: Includes waste generated in educational institutions, such as paper, books, and laboratory waste.

Industrial Solid Waste

Manufacturing Waste: Generated during the production process, including scrap materials, defective products, and by-products.

Construction and Demolition Waste: Generated from construction sites and demolition activities, including debris, concrete, wood, and other materials.

Hazardous Waste: Generated by industries producing toxic, flammable, or otherwise hazardous materials. This category requires special handling and disposal methods.

Agricultural Wastes:

Agriculture wastes includes both natural (organic) and non-natural wastes generated through farming activities. These activities include but are not limited to dairy farming, horticulture, seed growing, livestock breeding, grazing land, market gardens, nursery plots, and even woodlands.

spoiled food grains, vegetables, animal and plant wastes, litter, pesticides, fertilizers etc.

Special Wastes:

Electronic Waste (e-waste): Includes obsolete electronic devices and components.

Bulky Waste: Large items such as furniture, appliances, and mattresses.

Household Hazardous Waste: Includes household products containing hazardous substances, such as cleaning agents, paints, and batteries.

Biomedical Wastes:

Wastes produced from hospitals, medical centres and nursing homes are called biomedical wastes. Hospital wastes are generated during diagnosis, treatment or immunisation of human beings/animals or in research activities in these fields or in the production/testing of biologicals. These wastes are highly infectious and may pose severe threat if not managed properly. Biomedical wastes may be solid or liquid.

Type Based Classification:

Garbage: Garbage encompasses animal and vegetable waste originating from kitchen activities, cooking, food serving, slaughterhouses, and market refuse. These wastes, rich in putrescible organic matter, emit strong odors and attract rats, vermin, flies, and other insects, necessitating immediate attention in handling and disposal.

Rubbish: Rubbish constitutes solid waste arising from households, commercial establishments, and institutions, excluding garbage and ashes. Categorized as combustible and non-combustible, combustible wastes include materials like leaves, plants, clothes, paper, leather, rubber, and grasses, while non-combustible wastes comprise glass, metals, plastic materials, stones, and auto parts.

Bulk Waste: Bulky household waste consists of items such as furniture, appliances, mattresses, rugs, TV sets, and lawn mowers. Commercial bulky waste includes packaging materials like cardboard, wood boxes, fiber, plastic, and steel drums, as well as bundled paper and textiles. Industrial bulky waste comprises crates, cartons, drums, bales, rolls of paper, plastics, textiles, and miscellaneous metal items.

Ashes: Ashes refer to fine powdery residues, cinders, and clinkers resulting from burning wood, coal, charcoal, coke, and other combustible materials during cooking and heating. These residues are generated in houses, institutions, and other industrial establishments.

Street Wastes: Street wastes consist of leaves, dirt, dust litter, paper, plastics, and other vegetable matter collected from streets, walkways, alleys, parks, beaches, and vacant lots.

Dead Animals: Dead animal wastes include animals that die naturally or accidentally, categorized as small animals like cats, dogs, rats, rabbits, and poultry, as well as large animals such as horses, cows, goats, and sheep. Carcasses and parts from slaughterhouses are excluded and considered industrial wastes, posing health risks and requiring prompt collection and disposal.

Construction and Demolition Wastes: Construction and demolition wastes are materials generated during the construction, refurbishment, repair, and demolition of structures. They include earth, stones, concrete, bricks, lumber, steel, roofing materials, plumbing materials, heating systems, and electrical wires.

Sewage Wastes/Sludge: Sewage wastes consist of settled solid components, residual or semi-solid materials discharged from sewage treatment plants and septic tanks. They contain organic matter, including pathogens, necessitating prompt disposal.

Plastics: Plastics, due to their versatile properties, are generated as wastes in various sectors, including agriculture, construction, consumer goods, healthcare, hotels, catering, packaging, telecommunications, air travel, etc. Common plastic wastes include carry bags, bottles, plates, spoons, glasses, gloves, boxes, syringes, catheter tubes, and surgical items. The non-biodegradable nature of plastics poses serious threats to the environment and health.

Mining Wastes: Mining wastes arise from extractive operations of mineral resources, including topsoil, overburden, waste rock, slags, mine water, mine tailings, water treatment sludge, and gaseous wastes. Careful characterization is necessary to prevent and minimize air, water, and soil contamination, particularly in non-ferrous metal mining, where dangerous substances such as heavy metals may be present.

Radioactive Wastes: Radioactive wastes are hazardous by-products of nuclear reactions, posing threats to human life and the environment. Their decay period varies, and proper isolation and confinement at appropriate disposal facilities are crucial. Sources of radioactive wastes include mining of radioactive substances, atomic explosions, nuclear fuel cycles, nuclear weapons reprocessing, and medical and industrial activities.

Classification Based on Properties

Solid wastes can be categorized according to their biological and chemical properties.

Biodegradable/Organic Wastes:

Biodegradable wastes can undergo decomposition through natural processes such as composting or aerobic/anaerobic digestion, transforming into elemental forms like carbon dioxide, methane, water, or simple organic molecules. Examples of biodegradable wastes include municipal solid wastes (green waste, food waste, paper waste, biodegradable plastics, human and animal wastes, sewage, sludge, slaughterhouse wastes, etc.).

Non-Biodegradable/Inorganic Wastes:

Non-biodegradable wastes cannot decompose naturally and persist indefinitely in the environment. These materials pose challenges in landfills, emphasizing the need for recycling as the ideal management option. Examples of non-biodegradable wastes include plastics, nuclear wastes, glass, rubber tires, styrofoam, fiberglass, and metals.

Hazardous Wastes:

Hazardous waste refers to chemical materials that are no longer usable for their intended purpose and are known to be harmful to plants, animals, human health, or the environment. These wastes may exist in the form of solids, liquids, sludges, or gases and are generated primarily by chemical production, manufacturing, and industrial activities. Hazardous waste materials may exhibit toxicity, reactivity, ignitability, explosiveness, corrosiveness, infectiousness, or radioactivity. Proper management practices involve separate collection, storage, transportation, and disposal to mitigate potential harm. Examples of hazardous wastes include lead, mercury, cadmium, chromium, drugs, leather, pesticides, dyes, rubber, solvents, paints, and industrial effluents.

Non-Hazardous Wastes:

Non-hazardous wastes are substances deemed safe for commercial, industrial, agricultural, or economic use. Examples of non-hazardous wastes are generated from food processing plants, cotton mills, paper mills, textile mills, sugarcane industries, as well as materials like paint, oil, antifreeze, buffers, and salts. These materials do not pose significant risks to human health or the environment when handled properly.