Bioreactor landfill

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Landfills are the primary method of waste disposal in many parts of the world, including United States and Canada. Bioreactor landfills are expected to reduce the amount of and costs associated with management of leachate, to increase the rate of production of methane (natural gas) for commercial purposes and reduce the amount of land required for land-fills. [1] [2] Bioreactor landfills are monitored and manipulate oxygen and moisture levels to increase the rate of decomposition by microbial activity.

Contents

Traditional landfills and associated problems

Landfills are the oldest known method of waste disposal. [3] [4] Waste is buried in large dug out pits (unless naturally occurring locations are available) and covered. Bacteria and archaea decompose the waste over several decades producing several by-products of importance, including methane gas (natural gas), leachate, and volatile organic compounds (such as hydrogen sulfide (H2S), N2O2, etc.).

Methane gas, a strong greenhouse gas, can build up inside the landfill leading to an explosion unless released from the cell. [5] Leachate are fluid metabolic products from decomposition and contain various types of toxins and dissolved metallic ions. [6] If leachate escapes into the ground water it can cause health problems in both animals and plants. [7] [8] The volatile organic compounds (VOCs) are associated with causing smog and acid rain. [9] With the increasing amount of waste produced, appropriate places to safely store it have become difficult to find. [10]

Working of a bioreactor landfill

There are three types of bioreactor: aerobic, anaerobic and a hybrid (using both aerobic and anaerobic method). All three mechanisms involve the reintroduction of collected leachate supplemented with water to maintain moisture levels in the landfill. The micro-organisms responsible for decomposition are thus stimulated to decompose at an increased rate with an attempt to minimise harmful emissions. [11]

In aerobic bioreactors air is pumped into the landfill using either vertical or horizontal system of pipes. The aerobic environment decomposition is accelerated and amount of VOCs, toxicity of leachate and methane are minimised. [12] In anaerobic bioreactors with leachate being circulated the landfill produces methane at a rate much faster and earlier than traditional landfills. The high concentration and quantity of methane allows it to be used more efficiently for commercial purposes while reducing the time that the landfill needs to be monitored for methane production. Hybrid bioreactors subject the upper portions of the landfill through aerobic-anaerobic cycles to increase decomposition rate while methane is produced by the lower portions of the landfill. [11] Bioreactor landfills produce lower quantities of VOCs than traditional landfills, except H2S. Bioreactor landfills produce higher quantities of H2S. The exact biochemical pathway responsible for this increase is not well studied [1]

Advantages of bioreactor landfills

Bioreactor landfills accelerate the process of decomposition. [13] As decomposition progresses, the mass of biodegradable components in the landfill declines, creating more space for dumping garbage. Bioreactor landfills are expected to increase this rate of decomposition and save up to 30% of space needed for landfills. With increasing amounts of solid waste produced every year and scarcity of landfill spaces, bioreactor landfill can thus provide a significant way of maximising landfill space. This is not just cost effective, but since less land is needed for the landfills, this is also better for the environment. [1]

Furthermore, most landfills are monitored for at least 3 to 4 decades to ensure that no leachate or landfill gases escape into the community surrounding the landfill site. In contrast, bioreactor landfill are expected to decompose to level that does not require monitoring in less than a decade. Hence, the landfill land can be used for other purposes such as reforestation or parks, depending on the location at an earlier date. [14] In addition, re-using leachate to moisturise the landfill filters it. Thus, less time and energy is required to process the leachate, making the process more efficient. [11]

Disadvantages of bioreactor landfills

Bioreactor landfills are a relatively new technology. For the newly developed bioreactor landfills initial monitoring costs are higher to ensure that everything important is discovered and properly controlled. This includes gases, odours and seepage of leachate into the ground surface.

The increased moisture content of bioreactor landfill may reduce the structural stability of the landfill by increasing the pore water pressure within the waste mass. [15]

Since the target of bioreactor landfills is to maintain a high moisture content, gas collection systems can be affected by the increased moisture content of the waste.

Implementation of bioreactor landfills

Bioreactor landfills being a novel technology are still in the development phase and are being studied in the laboratory-scale. [16] Pilot projects for bioreactor landfills are showing promise and more are being experimented with in different parts of the world. Despite the potential benefits of bioreactor landfills there are no standardised and approved designs with guidelines and operational procedures. Following is a list of bioreactor landfill projects which are being used to collect data for forming these needed guidelines and procedures: [17]

United States

Canada

Australia

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 mixture of gases, primarily consisting of methane, carbon dioxide and hydrogen sulphide, produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste, wastewater, and food waste. It is a renewable energy source.

<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, economic mechanisms.

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

A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste materials. Landfill is the oldest and most common form of waste disposal, although the systematic burial of the waste with daily, intermediate and final covers only began in the 1940s. In the past, refuse was simply left in piles or thrown into pits; in archeology this is known as a midden.

<span class="mw-page-title-main">Composting toilet</span> Type of toilet that treats human excreta by a biological process called composting

A composting toilet is a type of dry toilet that treats human waste by a biological process called composting. This process leads to the decomposition of organic matter and turns human waste into compost-like material. Composting is carried out by microorganisms under controlled aerobic conditions. Most composting toilets use no water for flushing and are therefore called "dry toilets".

<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">Leachate</span> Any liquid that, in the course of passing through matter, extracts soluble or suspended solids

A leachate is any liquid that, in the course of passing through matter, extracts soluble or suspended solids, or any other component of the material through which it has passed.

<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.

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<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">Biodegradable waste</span> Organic matter that can be broken down

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, 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.

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The Hartland landfill is the waste disposal site for the city of Victoria, British Columbia and the Greater Victoria area. The landfill began operating in the early 1950's under private ownership and management. Phase 1 of the landfill reached capacity in 1996, Phase 2 filled in Heal Lake which was drained and was 2.5-hectares. The landfill was later purchased by the Capital Regional District in 1975 and has been directly operated by its Environmental Sustainability Department since 1985. The landfill, located in the District of Saanich on the southern slope of Mount Work, between Victoria and Sidney, at the end of Hartland Avenue is adjacent to Mount Work Regional Park to the west and the Department of National Defence rifle range is located across Willis Point Road to the northeast. To the east and southeast of the site are residential properties. Undeveloped CRD property lies to the west and south of the landfill site and is now being used by CRD Parks as a mountain bike recreation area under a land use agreement. Private residential properties exist to the east and southeast of the landfill.

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

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References

  1. 1 2 3 The Hinkley Center For Solid and Hazardous Waste Management, The Department of Environmental Engineering Sciences, University of Florida, The Civil and Environmental Engineering Department, University of Central Florida. (2008). Florida Bioreactor Landfill Demonstration Project: Executive Summary. Retrieved February 03, 2010, from
  2. ↑ Berge, Nicole D.; Reinhart, Debra R.; Batarseh, Eyad S. (2009-05-01). "An assessment of bioreactor landfill costs and benefits". Waste Management. First international conference on environmental management, engineering, planning and economics. 29 (5): 1558–1567. doi:10.1016/j.wasman.2008.12.010. PMID   19167875.
  3. ↑ "Landfills | Encyclopedia.com". www.encyclopedia.com. Retrieved 2022-06-17.
  4. ↑ Tammemagi, Hans (1999). The Waste Crisis : Landfills, Incinerators, and the Search for a Sustainable Future . Oxford: Oxford University Press. pp.  4. ISBN   9780195351682. OCLC   466431800.
  5. ↑ Christensen, T. H. (1999). Landfilling of waste: Biogas
  6. ↑ Washington State Department of Ecology. (n.d.). Solid Waste Landfill Design Manual. Retrieved February 3, 2010, from Archived 2009-10-17 at the Wayback Machine
  7. ↑ Abdel-Shafy, Hussein I.; Mansour, Mona S. M. (2018-12-01). "Solid waste issue: Sources, composition, disposal, recycling, and valorization". Egyptian Journal of Petroleum. 27 (4): 1275–1290. doi: 10.1016/j.ejpe.2018.07.003 . ISSN   1110-0621.
  8. ↑ Kjeldsen, P. M. (2002). Present and Long-Term Composition of MSW Landfill Leachate: A Review. Critical Reviews in Environmental Science and Technology , 297-336.
  9. ↑ Brosseau, J. H. (1994). Trace gas compound emissions from municipal landfill sanitary sites; Atmospheric-Environment. Atmospheric Environment, pp. 285-293.
  10. ↑ Abdel-Shafy, Hussein I.; Mansour, Mona S. M. (2018-12-01). "Solid waste issue: Sources, composition, disposal, recycling, and valorization". Egyptian Journal of Petroleum. 27 (4): 1275–1290. doi: 10.1016/j.ejpe.2018.07.003 . ISSN   1110-0621.
  11. 1 2 3 Hinkley Center For Solid and Hazardous Waste Management. (2006). Bioreactor.org - General Info. Retrieved February 3, 2010, from Bioreactor.org:
  12. ↑ Murphyb, S. R. (1992). A lysimeter study of the aerobic landfill concept . Waste Management & Research , 485-503.
  13. ↑ Reinhart, Debra R., and Timothy G. Townsend. Landfill Bioreactor Design and Operation. Boca Raton, Fla: Lewis, 1998. Print.
  14. ↑ Bard, S. (2002). Voices from the Past: Hong Kong. HK University Press , 1842-1918.
  15. ↑ Sustainable Practices for Landfill Design and Operation. Waste Management Principles and Practice. Springer. 2015. ISBN   9781493926619.
  16. ↑ Nair, V.V., Dhar, H., Kumar, S., Thalla, A.K., Mukherjee, S., Wong, J.W.C. (2016). Artificial neural network based modeling to evaluate methane yield from biogas in a laboratory-scale anaerobic bioreactor. Bioresource Technology 217, 90 – 99. doi: https://dx.doi.org/10.1016/j.biortech.2016.03.046
  17. ↑ Kjeldsen, P. M. (2002). Present and Long-Term Composition of MSW Landfill Leachate: A Review. Critical Reviews in Environmental Science and Technology , pp. 297-336
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