Human-generated waste comes from a number of different sources. Classifying the various types of waste is therefore an important step in ensuring that all waste is directed to the right treatment facility so that it can be handled appropriately.
Different municipalities, regions, countries, and institutions will often have their own particular classification systems. The European Union, for example, has implemented a classification based on a number of criteria including the type of waste, origin, and collection method. One common classification method is for different types of waste, also known as “waste streams,” to be sorted into broad categories based on the source of the waste. They include:
This category encompasses all waste generated from residential dwellings, ranging from single-family homes to high-density apartment towers. Many different kinds of waste fall into this category, including food waste, packaging waste, paper, plastic, leaves and yard waste, consumer electronics, and household hazardous waste.
Waste generated from any commercial enterprise, such as restaurants, hotels, or service stations, falls into the category of commercial waste. Many of the same types of waste found in a residential setting are also found in a commercial setting, including food waste, glass, and paper, although the commercial sector tends to include a higher proportion of special waste and hazardous waste (such as the solvent perchloroethylene, which is waste produced in the dry cleaning process).
Institutional waste is produced by hospitals, universities, schools, prisons, and government centers. It is similar to commercial waste, but since hospitals are included in this category, it also includes specialized types of waste such as regulated medical waste (waste that contains or could release blood or other potentially infectious materials), pharmaceutical waste (a subset of hazardous waste that includes things like bulk chemotherapeutic waste), and controlled substances (addictive pharmaceuticals or narcotics).
Industrial (non-process) waste
This category essentially includes all the commercial waste produced by industries such as construction, light and heavy manufacturing, chemical plants, power plants, and refineries. It does not include process wastes, which are classified in a separate category.
Municipal solid waste
Municipal solid waste, which is commonly known within the waste management industry as MSW, includes waste from all the aforementioned sources. The general category is what most of us think of when we mention “garbage.” It can also be referred to as mixed ordinary waste, black bag, or simply “trash.”
Construction and demolition (C&D) waste
The construction and demolition sector is a huge generator of specialized materials waste. New construction and renovation, building demolition, and road and pavement repair produce waste in the form of steel, concrete, wood, gypsum board, asphalt paving and asphalt roofing, and rocks and soil. Bulky materials such as ceiling tile, carpeting, and plumbing fixtures are also considered to be construction and demolition (C&D) waste.
Since C&D is such a major generator of waste, recycling efforts are becoming increasingly common in new construction and renovation projects. Many municipalities have bylaws or other requirements in place that specify a percentage of C&D waste that must be recycled or otherwise diverted from the landfill. It is also interesting to note that—given its large volume and significant weight, as well as its non-recurring nature—C&D waste quantities are often exempt from the calculations of total waste generated by a particular facility.
Industrial (process) waste
A type of special or hazardous waste, industrial process waste describes any solid, semisolid, liquid, or gaseous waste that is generated as a result of an industrial process, such as product manufacturing. Solvents used to clean parts, metallic dust sweepings, cutting oils, paint sludges, equipment cleanings, and any wholesale or retail products that are contaminated, off-specification, or that have been recalled are included in this category. The category does not include non-process waste such as uncontaminated packing materials or machinery components, municipal solid waste, or construction and demolition debris.
Agricultural waste encompasses a number of different types of organic and inorganic waste generated by agricultural operations such as farms, orchards, vineyards, and dairies. These types of waste include spoiled food or harvest waste; salt and silt drained from fields; manure and other livestock waste; fertilizer run-off from fields; and pesticides in the soil, air, or water.
Once waste has been categorized by source, additional classifications are needed to further specify the type of waste, and consequently, its destination for treatment. Again, different classifying bodies will approach this identification process in their own ways. Under the European Union system, waste from these varied sources is further sorted into the subgroups of hazardous waste, which the EU defines as organic, mineral, or gaseous waste that contains toxic elements that could negatively affect human and environmental health; non-hazardous waste, which includes recyclable, compostable, and biodegradable waste; and inert waste, a non-biodegradable type of waste, principally generated by C&D and extractive industries, which does not react physically or chemically with the environment.