Biodegradable waste

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Biodegradable waste includes any organic matter in waste which can be broken down into carbon dioxide, water, methane, compost, humus, and simple organic molecules by micro-organisms and other living things by composting, aerobic digestion, anaerobic digestion or similar processes. It mainly includes kitchen waste (spoiled food, trimmings, inedible parts), ash, soil, dung and other plant matter. In waste management, it also includes some inorganic materials which can be decomposed by bacteria. Such materials include gypsum and its products such as plasterboard and other simple sulfates which can be decomposed by sulfate reducing bacteria to yield hydrogen sulfide in anaerobic land-fill conditions. [1] [2]

Contents

In domestic waste collection, the scope of biodegradable waste may be narrowed to include only those degradable wastes capable of being handled in the local waste handling facilities. [3] To address this, many local waste management districts are integrating programs related to sort the biodegradable waste for composting or other waste valorization strategies, where biodegradable waste gets reused for other products, such as using agricultural waste for fiber production or biochar.

Biodegradable waste when not handled properly can have an outsized impact on climate change, especially through methane emissions from anaerobic fermentation that produces landfill gas. Other approaches to reducing the impact include reducing the amount of waste produced, such as through reducing food waste.

Sources

Biodegradable waste can be found in municipal solid waste (sometimes called biodegradable municipal waste, or as green waste, food waste, paper waste and biodegradable plastics). Other biodegradable wastes include human waste, manure, sewage, sewage sludge and slaughterhouse waste. In the absence of oxygen, much of this waste will decay to methane by anaerobic digestion. [4]

In the UK, 7.4 million tonnes of biodegradable waste was sent to landfill in 2018 having reduced from 7.8 million tonnes in 2017. [5]

Collection and processing

In many parts of the developed world, biodegradable waste is separated from the rest of the waste stream, either by separate curb-side collection or by waste sorting after collection. At the point of collection such waste is often referred to as green waste. [6] Removing such waste from the rest of the waste stream substantially reduces waste volumes for disposal and also allows biodegradable waste to be composted.

Biodegradable waste can be used for composting or a resource for heat, electricity and fuel by means of incineration or anaerobic digestion. [7] Swiss Kompogas and the Danish AIKAN process are examples of anaerobic digestion of biodegradable waste. [8] [9] While incineration can recover the most energy, anaerobic digestion plants retain nutrients and make compost for soil amendment and still recover some of the contained energy in the form of biogas. Kompogas produced 27 million Kwh of electricity and biogas in 2009. The oldest of the company's lorries has achieved 1,000,000 kilometers driven with biogas from household waste in the last 15 years. [10]

Valorization

Crop residue

This section is an excerpt from Waste valorization § Crop residue.[ edit ]
Crop residue, such as corncob, and other residues from the food processing industry, such as residues from biorefineries, have high potential for use in further processes, such as producing biofuel, bioplastics, and other biomaterials for industrial processes. [11] [12]

Food waste

This section is an excerpt from Waste valorization § Food waste.[ edit ]

One of the more fruitful fields of work is food waste—when deposited in landfills, food waste produces the greenhouse gas methane and other toxic compounds that can be dangerous to humans and local ecosystems. [11] Landfill gas utilization and municipal composting can capture and use the organic nutrients. [11] Food waste collected from non-industrial sources is harder to use, because it often has much greater diversity than other sources of waste—different locations and different windows of time produce very different compositions of material, making it hard to use for industrial processes. [11] [12]

Transforming food waste to either food products, feed products, or converting it to or extracting food or feed ingredients is termed as food waste valorisation. Valorisation of food waste offers an economical and environmental opportunity, which can reduce the problems of its conventional disposal. Food wastes have been demonstrated to be valuable bioresources that can be utilised to obtain a number of useful products, including biofertilizers, bioplastics, biofuels, chemicals, and nutraceuticals. There is much potential to recycle food wastes by conversion to insect protein. [13]

Human excreta

This section is an excerpt from Reuse of human excreta.[ edit ]
Harvest of capsicum grown with compost made from human excreta at an experimental garden in Haiti Harvest of peppers at a SOIL experimental garden.jpg
Harvest of capsicum grown with compost made from human excreta at an experimental garden in Haiti

Reuse of human excreta is the safe, beneficial use of treated human excreta after applying suitable treatment steps and risk management approaches that are customized for the intended reuse application. Beneficial uses of the treated excreta may focus on using the plant-available nutrients (mainly nitrogen, phosphorus and potassium) that are contained in the treated excreta. They may also make use of the organic matter and energy contained in the excreta. To a lesser extent, reuse of the excreta's water content might also take place, although this is better known as water reclamation from municipal wastewater. The intended reuse applications for the nutrient content may include: soil conditioner or fertilizer in agriculture or horticultural activities. Other reuse applications, which focus more on the organic matter content of the excreta, include use as a fuel source or as an energy source in the form of biogas.

There is a large and growing number of treatment options to make excreta safe and manageable for the intended reuse option. [14] Options include urine diversion and dehydration of feces (urine-diverting dry toilets), composting (composting toilets or external composting processes), sewage sludge treatment technologies and a range of fecal sludge treatment processes. They all achieve various degrees of pathogen removal and reduction in water content for easier handling. Pathogens of concern are enteric bacteria, virus, protozoa, and helminth eggs in feces. [15] As the helminth eggs are the pathogens that are the most difficult to destroy with treatment processes, they are commonly used as an indicator organism in reuse schemes. Other health risks and environmental pollution aspects that need to be considered include spreading micropollutants, pharmaceutical residues and nitrate in the environment which could cause groundwater pollution and thus potentially affect drinking water quality.

Climate change impacts

Landfill gas

This section is an excerpt from Landfill gas.[ edit ]
A gas flare produced by a landfill in Lake County, Ohio Gas flare from a landfill in Ohio.jpg
A gas flare produced by a landfill in Lake County, Ohio

Landfill gas is a mix of different gases created by the action of microorganisms within a landfill as they decompose organic waste, including for example, food waste and paper waste. Landfill gas is approximately forty to sixty percent methane, with the remainder being mostly carbon dioxide. Trace amounts of other volatile organic compounds (VOCs) comprise the remainder (<1%). These trace gases include a large array of species, mainly simple hydrocarbons. [16]

Landfill gases have an influence on climate change. The major components are CO2 and methane, both of which are greenhouse gases. Methane in the atmosphere is a far more potent greenhouse gas, with each molecule having twenty-five times the effect of a molecule of carbon dioxide. Methane itself however accounts for less composition of the atmosphere than does carbon dioxide. Landfills are the third-largest source of methane in the US. [17]

Because of the significant negative effects of these gases, regulatory regimes have been set up to monitor landfill gas, reduce the amount of biodegradable content in municipal waste, and to create landfill gas utilization strategies, which include gas flaring or capture for electricity generation.

Food waste

This section is an excerpt from Food loss and waste.[ edit ]
Fruit and vegetables in a dumpster, discarded uneaten Trashed vegetables in Luxembourg.jpeg
Fruit and vegetables in a dumpster, discarded uneaten
Food recovered by food waste critic Robin Greenfield in Madison, Wisconsin, from two days of recovery from dumpsters Food Waste Fiasco (15819007150).jpg
Food recovered by food waste critic Robin Greenfield in Madison, Wisconsin, from two days of recovery from dumpsters

Food loss and waste is food that is not eaten. The causes of food waste or loss are numerous and occur throughout the food system, during production, processing, distribution, retail and food service sales, and consumption. Overall, about one-third of the world's food is thrown away. [19] [20] A similar amount is lost on top of that by feeding human-edible food to farm animals (the net effect wastes an estimated 1144 kcal/person/day). A 2021 meta-analysis, that did not include food lost during production, by the United Nations Environment Programme found that food waste was a challenge in all countries at all levels of economic development. [21] The analysis estimated that global food waste was 931 million tonnes of food waste (about 121 kg per capita) across three sectors: 61 percent from households, 26 percent from food service and 13 percent from retail. [21]

Food loss and waste is a major part of the impact of agriculture on climate change (it amounts to 3.3 billion tons of CO2e emissions annually [22] [23] ) and other environmental issues, such as land use, water use and loss of biodiversity. Prevention of food waste is the highest priority, and when prevention is not possible, the food waste hierarchy ranks the food waste treatment options from preferred to least preferred based on their negative environmental impacts. [24] Reuse pathways of surplus food intended for human consumption, such as food donation, is the next best strategy after prevention, followed by animal feed, recycling of nutrients and energy followed by the least preferred option, landfill, which is a major source of the greenhouse gas methane. [25] Other considerations include unreclaimed phosphorus in food waste leading to further phosphate mining. Moreover, reducing food waste in all parts of the food system is an important part of reducing the environmental impact of agriculture, by reducing the total amount of water, land, and other resources used.

The UN's Sustainable Development Goal Target 12.3 seeks to "halve global per capita food waste at the retail and consumer levels and reduce food losses along production and supply chains, including post-harvest losses" by 2030. [26] Climate change mitigation strategies prominently feature reducing food waste. [27] In the 2022 United Nations Biodiversity Conference nations agree to reduce food waste by 50% by the year 2030. [28]

See also

Related Research Articles

<span class="mw-page-title-main">Compost</span> Mixture used to improve soil fertility

Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical, and biological properties. It is commonly prepared by decomposing plant and food waste, recycling organic materials, and manure. The resulting mixture is rich in plant nutrients and beneficial organisms, such as bacteria, protozoa, nematodes, and fungi. Compost improves soil fertility in gardens, landscaping, horticulture, urban agriculture, and organic farming, reducing dependency on commercial chemical fertilizers. The benefits of compost include providing nutrients to crops as fertilizer, acting as a soil conditioner, increasing the humus or humic acid contents of the soil, and introducing beneficial microbes that help to suppress pathogens in the soil and reduce soil-borne diseases.

<span class="mw-page-title-main">Biogas</span> Gases produced by decomposing organic matter

Biogas is a gaseous renewable energy source produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste, wastewater, and food waste. Biogas is produced by anaerobic digestion with anaerobic organisms or methanogens inside an anaerobic digester, biodigester or a bioreactor. The gas composition is primarily methane and carbon dioxide and may have small amounts of hydrogen sulfide, moisture and siloxanes. The methane can be combusted or oxidized with oxygen. This energy release allows biogas to be used as a fuel; it can be used in fuel cells and for heating purpose, such as in cooking. It can also be used in a gas engine to convert the energy in the gas into electricity and heat.

<span class="mw-page-title-main">Waste management</span> Activities and actions required to manage waste from its source to its final disposal

Waste management or waste disposal includes the processes and actions required to manage waste from its inception to its final disposal. This includes the collection, transport, treatment, and disposal of waste, together with monitoring and regulation of the waste management process and waste-related laws, technologies, and economic mechanisms.

<span class="mw-page-title-main">Landfill</span> Site for the disposal of waste materials

A landfill is a site for the disposal of waste materials. It is the oldest and most common form of waste disposal, although the systematic burial of waste with daily, intermediate and final covers only began in the 1940s. In the past, waste was simply left in piles or thrown into pits.

Alternative technology is a term used to refer to technologies that are more environmentally friendly than the functionally equivalent technologies dominant in current practice. The term was coined by Peter Harper, one of the founders of the Centre for Alternative Technology, North Wales, in Undercurrents (magazine) in the 1970s. Alternative Technologies are created to be safer, cleaner, and overall more efficient. The goals of alternative technology are to decrease demand for critical elements by ensuring a secure supply of technology that is environmentally friendly, increased efficiency with lower costs, and with more common materials to avoid potential future materials crises. Alternative technologies use renewable energy sources such as solar power and wind energy. Some alternative technologies have in the past or may in the future become widely adopted, after which they might no longer be considered "alternative." For example, the use of wind turbines to produce electricity.

<span class="mw-page-title-main">Anaerobic digestion</span> Processes by which microorganisms break down biodegradable material in the absence of oxygen

Anaerobic digestion is a sequence of processes by which microorganisms break down biodegradable material in the absence of oxygen. The process is used for industrial or domestic purposes to manage waste or to produce fuels. Much of the fermentation used industrially to produce food and drink products, as well as home fermentation, uses anaerobic digestion.

<span class="mw-page-title-main">Landfill gas</span> Gaseous fossil fuel

Landfill gas is a mix of different gases created by the action of microorganisms within a landfill as they decompose organic waste, including for example, food waste and paper waste. Landfill gas is approximately forty to sixty percent methane, with the remainder being mostly carbon dioxide. Trace amounts of other volatile organic compounds (VOCs) comprise the remainder (<1%). These trace gases include a large array of species, mainly simple hydrocarbons.

Articles related to waste management include:

<span class="mw-page-title-main">Waste-to-energy</span> Process of generating energy from the primary treatment of waste

Waste-to-energy (WtE) or energy-from-waste (EfW) refers to a series of processes designed to convert waste materials into usable forms of energy, typically electricity or heat. As a form of energy recovery, WtE plays a crucial role in both waste management and sustainable energy production by reducing the volume of waste in landfills and providing an alternative energy source.

A mechanical biological treatment (MBT) system is a type of waste processing facility that combines a sorting facility with a form of biological treatment such as composting or anaerobic digestion. MBT plants are designed to process mixed household waste as well as commercial and industrial wastes.

<span class="mw-page-title-main">Sewage sludge treatment</span> Processes to manage and dispose of sludge during sewage treatment

Sewage sludge treatment describes the processes used to manage and dispose of sewage sludge produced during sewage treatment. Sludge treatment is focused on reducing sludge weight and volume to reduce transportation and disposal costs, and on reducing potential health risks of disposal options. Water removal is the primary means of weight and volume reduction, while pathogen destruction is frequently accomplished through heating during thermophilic digestion, composting, or incineration. The choice of a sludge treatment method depends on the volume of sludge generated, and comparison of treatment costs required for available disposal options. Air-drying and composting may be attractive to rural communities, while limited land availability may make aerobic digestion and mechanical dewatering preferable for cities, and economies of scale may encourage energy recovery alternatives in metropolitan areas.

<span class="mw-page-title-main">Green waste</span> Biodegradable waste

Green waste, also known as "biological waste", is any organic waste that can be composted. It is most usually composed of refuse from gardens such as grass clippings or leaves, and domestic or industrial kitchen wastes. Green waste does not include things such as dried leaves, pine straw, or hay. Such materials are rich in carbon and considered "brown wastes," while green wastes contain high concentrations of nitrogen. Green waste can be used to increase the efficiency of many composting operations and can be added to soil to sustain local nutrient cycling.

<span class="mw-page-title-main">Biodegradable plastic</span> Plastics that can be decomposed by the action of living organisms

Biodegradable plastics are plastics that can be decomposed by the action of living organisms, usually microbes, into water, carbon dioxide, and biomass. Biodegradable plastics are commonly produced with renewable raw materials, micro-organisms, petrochemicals, or combinations of all three.

<span class="mw-page-title-main">Digestate</span> Material remaining after the anaerobic digestion of a biodegradable feedstock

Digestate is the material remaining after the anaerobic digestion of a biodegradable feedstock. Anaerobic digestion produces two main products: digestate and biogas. Digestate is produced both by acidogenesis and methanogenesis and each has different characteristics. These characteristics stem from the original feedstock source as well as the processes themselves.

<span class="mw-page-title-main">Green bin</span> Container for biodegradable waste or compostable materials

A green bin is a large, movable, rigid plastic or metal container that contains biodegradable waste or compostable materials as a means to divert waste from landfills. In some local authorities, green bins are also used to contain unsorted municipal solid waste.

<span class="mw-page-title-main">Source-separated organics</span>

Source-separated organics (SSO) is the system by which waste generators segregate compostable materials from other waste streams at the source for separate collection.

Resource recovery is using wastes as an input material to create valuable products as new outputs. The aim is to reduce the amount of waste generated, thereby reducing the need for landfill space, and optimising the values created from waste. Resource recovery delays the need to use raw materials in the manufacturing process. Materials found in municipal solid waste, construction and demolition waste, commercial waste and industrial wastes can be used to recover resources for the manufacturing of new materials and products. Plastic, paper, aluminium, glass and metal are examples of where value can be found in waste.

<span class="mw-page-title-main">Harvest Power</span> American organics management company

Harvest Power, Inc. was a privately held organics management company headquartered in Waltham, Massachusetts, United States that specializes in converting food waste and yard waste into biofuel, compost, mulch and fertilizer. In 2014 Fast Company named it one of the most innovative companies in the world. In August of 2020 Harvest Power Orlando ceased operations for unknown reasons and all assets were put up for sale; the company was dissolved in April 2021.

<span class="mw-page-title-main">Reuse of human excreta</span> Safe, beneficial use of human excreta mainly in agriculture (after treatment)

Reuse of human excreta is the safe, beneficial use of treated human excreta after applying suitable treatment steps and risk management approaches that are customized for the intended reuse application. Beneficial uses of the treated excreta may focus on using the plant-available nutrients that are contained in the treated excreta. They may also make use of the organic matter and energy contained in the excreta. To a lesser extent, reuse of the excreta's water content might also take place, although this is better known as water reclamation from municipal wastewater. The intended reuse applications for the nutrient content may include: soil conditioner or fertilizer in agriculture or horticultural activities. Other reuse applications, which focus more on the organic matter content of the excreta, include use as a fuel source or as an energy source in the form of biogas.

Waste valorization, beneficial reuse, beneficial use, value recovery or waste reclamation is the process of waste products or residues from an economic process being valorized, by reuse or recycling in order to create economically useful materials. The term comes from practices in sustainable manufacturing and economics, industrial ecology and waste management. The term is usually applied in industrial processes where residue from creating or processing one good is used as a raw material or energy feedstock for another industrial process. Industrial wastes in particular are good candidates for valorization because they tend to be more consistent and predictable than other waste, such as household waste.

References

  1. ↑ "Why can't I put my leftover gyproc/drywall in the garbage?". Recycling Council of British Columbia. 19 September 2008.
  2. ↑ "Fact Sheet: Methane and Hydrogen Sulfide Gases at C&DD Landfills" (PDF). Environmental Protection Agency. State of Ohio, U.S.
  3. ↑ "Organics -Green Bin". Christchurch City Council. Retrieved 19 March 2016.
  4. ↑ CSL London Olympics Waste Review. cslondon.org
  5. ↑ "UK Statistics on Waste" (PDF). March 2019. Retrieved 7 November 2019.
  6. ↑ "Organics - Green Bin". Christchurch City Council. Retrieved 12 March 2016.
  7. ↑ National Non-Food Crops Centre. NNFCC report on Evaluation of Opportunities for Converting Indigenous UK Wastes to Fuels and Energy Archived 20 July 2011 at the Wayback Machine . nnfcc.co.uk
  8. ↑ Recycling chain Archived 2012-03-23 at the Wayback Machine . kompogas-utzenstorf.ch
  9. ↑ AIKAN website. aikantechnology.com
  10. ↑ "Gesundheit, Kraft und Energie für 2002". zuonline.ch. 3 January 2002. Archived from the original on 2 September 2002.
  11. 1 2 3 4 Arancon, Rick Arneil D.; Lin, Carol Sze Ki; Chan, King Ming; Kwan, Tsz Him; Luque, Rafael (2013). "Advances on waste valorization: new horizons for a more sustainable society". Energy Science & Engineering. 1 (2): 53–71. Bibcode:2013EneSE...1...53A. doi: 10.1002/ese3.9 . ISSN   2050-0505.
  12. 1 2 Nayak, A.; Bhushan, Brij (2019-03-01). "An overview of the recent trends on the waste valorization techniques for food wastes". Journal of Environmental Management. 233: 352–370. doi:10.1016/j.jenvman.2018.12.041. ISSN   0301-4797. PMID   30590265. S2CID   58620752.
  13. ↑ Jagtap, Sandeep; Garcia-Garcia, Guillermo; Duong, Linh; Swainson, Mark; Martindale, Wayne (August 2021). "Codesign of Food System and Circular Economy Approaches for the Development of Livestock Feeds from Insect Larvae". Foods. 10 (8): 1701. doi: 10.3390/foods10081701 . PMC   8391919 . PMID   34441479.
  14. ↑ Tilley, Elizabeth; Ulrich, Lukas; Lüthi, Christoph; Reymond, Philippe; Zurbrügg, Chris (2014). "Septic tanks". Compendium of Sanitation Systems and Technologies (2nd ed.). Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag). ISBN   978-3-906484-57-0.
  15. ↑ Harder, Robin; Wielemaker, Rosanne; Larsen, Tove A.; Zeeman, Grietje; Öberg, Gunilla (2019-04-18). "Recycling nutrients contained in human excreta to agriculture: Pathways, processes, and products". Critical Reviews in Environmental Science and Technology. 49 (8): 695–743. Bibcode:2019CREST..49..695H. doi: 10.1080/10643389.2018.1558889 . ISSN   1064-3389.
  16. ↑ Hans-Jürgen Ehrig, Hans-Joachim Schneider and Volkmar Gossow "Waste, 7. Deposition" in Ullmann's Encyclopedia of Industrial Chemistry, 2011, Wiley-VCH, Weinheim. doi:10.1002/14356007.o28_o07
  17. ↑ "Methane Emissions". Environmental Protection Agency. 23 December 2015. Retrieved 13 June 2016.
  18. ↑ Greenfield, Robin (2014-10-06). "The Food Waste Fiasco: You Have to See it to Believe it!". www.robingreenfield.org.
  19. ↑ Jenny Gustavsson. Global food losses and food waste : extent, causes and prevention : study conducted for the International Congress "Save Food!" at Interpack 2011 Düsseldorf, Germany. OCLC   1126211917.
  20. ↑ "UN Calls for Action to End Food Waste Culture". Daily News Brief. 2021-10-04. Archived from the original on 2021-10-04. Retrieved 2021-10-04.
  21. 1 2 UNEP Food Waste Index Report 2021 (Report). United Nations Environment Programme. 2021-03-04. ISBN   9789280738513. Archived from the original on 2022-02-01. Retrieved 2022-02-01.
  22. ↑ "FAO - News Article: Food wastage: Key facts and figures". www.fao.org. Archived from the original on 2021-06-07. Retrieved 2021-06-07.
  23. ↑ "A third of food is wasted, making it third-biggest carbon emitter, U.N. says". Reuters. 2013-09-11. Archived from the original on 2021-06-07. Retrieved 2021-06-07.
  24. ↑ "Brief on food waste in the European Union". European Commission. 2020-08-25. Archived from the original on 2022-11-15. Retrieved 2022-11-15.
  25. ↑ "Food Recovery Hierarchy". www.epa.gov. 2015-08-12. Archived from the original on 2019-05-23. Retrieved 2022-05-15.
  26. ↑ United Nations (2017) Resolution adopted by the General Assembly on 6 July 2017, Work of the Statistical Commission pertaining to the 2030 Agenda for Sustainable Development (A/RES/71/313 Archived 2020-10-23 at the Wayback Machine )
  27. ↑ "Reduced Food Waste". Project Drawdown. 2020-02-12. Archived from the original on 2020-09-24. Retrieved 2020-09-19.
  28. ↑ "COP15: Nations Adopt Four Goals, 23 Targets for 2030 in Landmark UN Biodiversity Agreement". Convention on Biological Diversity. United Nations. Archived from the original on 2022-12-20. Retrieved 9 January 2023.
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