Every day, billions of people generate waste – from the food scraps left after breakfast to the plastic packaging discarded at grocery stores. At the same time, farms across the world produce millions of tonnes of crop residues, manure, and chemical containers that need to be dealt with responsibly. Understanding where waste comes from – and what it consists of – is the essential first step in managing it effectively. This post breaks down the major sources and types of solid waste, with a focus on municipal and agricultural waste streams.
Table of Contents
What is solid waste?
Solid waste is a broad term that covers any discarded material in solid or semi-solid form that is no longer useful to its producer. The Indiana Department of Environmental Management defines it as garbage, rubbish, refuse, sludge, and other discarded materials resulting from industrial, commercial, mining, agricultural, and community activities. In short, if it’s thrown away, it qualifies as solid waste.
Solid waste can be broadly classified into several categories based on its origin and nature:
- Municipal solid waste (MSW): Everyday waste from homes, businesses, schools, and institutions.
- Industrial waste: By-products from manufacturing and production processes, such as scrap metal, chemicals, and sludge.
- Agricultural waste: Residues and by-products from crop production and livestock farming.
- Biomedical/infectious waste: Waste from hospitals and healthcare facilities, including used syringes and contaminated materials.
- Hazardous waste: Materials that pose risks to public health or the environment, including radioactive, chemical, or toxic substances.
- Construction and demolition waste: Debris from building, renovation, and demolition projects.
Each category requires a distinct approach to collection, treatment, and disposal. The two most significant in terms of volume and everyday impact are municipal and agricultural waste – which we’ll explore in detail below.
Municipal solid waste: what cities throw away
Municipal solid waste (MSW) refers to everyday items discarded by the general public – things like food scraps, packaging, newspapers, furniture, and appliances. While the name implies it comes from municipalities themselves, it actually originates from a wide range of urban sources including homes, businesses, schools, and hospitals. According to the New Hampshire Department of Environmental Services, MSW is a catch-all term for a variety of solid wastes generated by households, businesses, and institutions.
The composition of MSW varies widely by region and changes over time, but the U.S. Environmental Protection Agency (EPA) reports that organic materials – food, yard trimmings, and paper – consistently make up the largest share. Paper and paperboard account for around 27%, while food and yard waste together account for another 28%. Plastics comprise about 13%, metals around 9%, and glass about 5%.
Residential waste
The residential sector is the largest single contributor to MSW. Research indicates that households contribute more than half of total waste generated in most urban areas. This includes food scraps and kitchen waste, packaging materials, plastics, textiles, yard debris, and household hazardous waste like batteries, cleaning products, and expired medicines. Waste generation can vary between single-family homes and apartment buildings depending on access to recycling services and household size.
Commercial waste
Commercial establishments – restaurants, grocery stores, retail shops, hotels, and offices – are major contributors to the urban waste stream. Commercial waste is primarily composed of food waste (especially from restaurants and food service outlets), packaging materials, paper, and discarded products. Because these businesses operate at scale, even small inefficiencies in waste handling can result in large volumes of waste reaching landfills.
Institutional waste
Schools, universities, hospitals, government offices, and other public institutions generate significant quantities of MSW through routine operations. A school cafeteria, for example, produces food waste daily, while a hospital generates a combination of general MSW and specialized infectious waste. The EPA notes that institutional facility waste includes materials from offices, cafeterias, and support operations, all of which feed into the broader municipal waste stream.
It’s important to note that most formal definitions of MSW specifically exclude industrial process waste, agricultural waste, medical waste, radioactive materials, and sewage sludge – even if these are sometimes managed by municipal systems.
Agricultural waste: what farms leave behind
Agricultural waste is defined as all material left over or discarded during and after agricultural production – from growing and harvesting crops to raising livestock and processing farm products. ScienceDirect classifies it into four broad types: crop waste, animal waste, processing waste, and hazardous waste from agrichemicals. The scale of this waste stream is massive – Wikipedia estimates the EU alone produces around 700 million tonnes of agricultural waste annually, while global estimates suggest up to 2 billion tonnes are generated each year.
Unlike municipal waste, agricultural waste is largely generated in rural areas, often far from formal waste management infrastructure, which makes its proper handling especially challenging.
Manure and animal waste
Livestock operations – cattle ranches, pig farms, poultry units – generate enormous quantities of animal excreta daily. Manure constitutes a significant share of organic farm waste, and when produced in large volumes at intensive farming operations, it can cause serious environmental problems. Improperly managed manure can contaminate water sources through runoff, release methane (a potent greenhouse gas) during decomposition, and create persistent odor issues. Used animal bedding, slurry, and carcasses from livestock operations also fall within this category.
That said, manure is not purely a problem – when properly managed, it is a valuable soil amendment and fertilizer, rich in nitrogen, phosphorous, and potassium. The challenge lies in balancing its usefulness against the risks of mishandling at scale.
Crop residues
Crop residues are the plant materials left after the main harvest – stalks, leaves, husks, straw, shells, and roots. The four crops generating the largest share of residues globally are sugarcane, maize, cereals, and rice. On average, about 80% of the plant biomass from such crops ends up as residue not destined for human or animal consumption. Rice production alone generates over 700 million tonnes of straw annually worldwide.
Crop residues can be reused beneficially – as animal feed, as compost, as raw material for biofuel production, or left on soil to prevent erosion. However, in many parts of the world, farmers resort to field burning, which releases particulate matter, carbon dioxide, and other pollutants. The World Health Organization has identified smog from burning agricultural waste as one of the largest contributors to ambient air pollution in affected regions.
Packaging and agrichemical waste
Modern farming operations rely heavily on fertilizers, pesticides, herbicides, and seeds – all of which come in containers and packaging that must be disposed of after use. These include plastic bags, cardboard boxes, fertilizer sacks, pesticide containers, and irrigation tubing. Because agrochemical containers often retain trace amounts of their original contents, they cannot simply be discarded in regular waste streams – they require specialist disposal to prevent soil and water contamination.
Plastic waste from agrichemical containers and packaging is a growing environmental concern. Globally, agriculture contributes substantially to plastic pollution, with plastics used for crop coverings, mulch films, greenhouse sheeting, and storage materials – all of which eventually need to be managed as waste. Farm machinery also contributes inorganic waste in the form of used oils, brake fluids, and worn machinery parts, classified as hazardous farm waste.
Why understanding waste sources matters
Identifying where waste originates is not just an academic exercise – it directly informs how waste should be collected, treated, and managed. The University of Michigan’s Center for Sustainable Systems emphasizes that different waste streams require different management strategies: what works for diverting food waste from restaurant kitchens won’t apply to handling crop residues from large-scale farm operations. Similarly, plastic packaging from agricultural supply chains eventually moves into urban municipal waste streams, showing how the two systems are deeply interconnected.
Globally, managing solid waste is the largest budget item for many municipalities, consuming up to 50% of their budgets in some cities, according to World Bank data. At the same time, agricultural waste – particularly from chemical containers and improper manure management – poses serious risks to soil, water, and air quality in rural and peri-urban regions. Recognizing the diversity of waste sources and their specific characteristics is the starting point for building more effective and sustainable waste management systems.
What do you think? Given that agricultural packaging waste from farms eventually ends up in urban waste streams, how should responsibility for managing it be shared between farmers, manufacturers, and local governments? And with organic materials making up such a large share of municipal waste, what practical steps could households and businesses take to reduce what they send to landfill?
References
- https://www.in.gov/idem/waste/solid-waste/municipal-and-non-municipal-solid-waste/
- https://en.wikipedia.org/wiki/Municipal_solid_waste
- https://www.des.nh.gov/news-and-media/blog/trash-municipal-solid-waste
- https://archive.epa.gov/epawaste/nonhaz/municipal/web/html/
- https://burcellteam.com/articles/where-does-most-municipal-solid-waste-come-from-a-breakdown-by-sector/
- https://cfpub.epa.gov/roe/indicator_pdf.cfm?i=53
- https://www.sciencedirect.com/topics/earth-and-planetary-sciences/agricultural-waste
- https://en.wikipedia.org/wiki/Agricultural_waste
- https://shapiroe.com/blog/agricultural-waste-disposal-guide/
- https://www.ebsco.com/research-starters/agriculture-and-agribusiness/agricultural-wastes
- https://www.businesswaste.co.uk/waste-facts/agricultural-waste-facts/
- https://www.homebiogas.com/blog/agricultural-waste-management/
- https://www.wastemanaged.co.uk/our-news/agriculture/agricultural-waste-guide/
- https://css.umich.edu/publications/factsheets/material-resources/municipal-solid-waste-factsheet
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