Abstract
Waste disposal is one of the main environmental problems facing society today. Environmental impacts of solid waste landfilling include loss of land area, contamination of soil, leaching of hazardous substances to groundwater, as well as emissions of methane to the atmosphere. The world generates over 2 billion tonnes of municipal solid waste (MSW) each year, with at least 33% of that not managed in an environmentally safe manner. In many developed countries, municipal solid wastes (MSW) are dumped in sanitary landfills, while in many developing countries, they are dumped in an inappropriate way which poses a serious threat to the environment. The deficiency of land and the requirement for reuse of the landfill sites demand their rehabilitation. In recent years, phytoremediation has been used as an efficient, environmentally friendly, and cost-effective technology in the remediation and rehabilitation of contaminated sites, including municipal solid waste (MSW) landfills.
TopIntroduction
Municipal solid wastes (MSW), known as trash or garbage, are a heterogeneous mixture of residential, commercial, and industrial products (product packaging, grass clippings, furniture, clothing, bottles, food scraps, newspapers, appliances, paint, and batteries). While the composition of municipal solid wastes (MSW) could be highly variable, it is commonly accepted that organic fraction is the most abundant component (Vergara & Tchobanoglous, 2012).
Municipal solid waste (MSW) is an increasing concern due to rapid urbanization and industrialization. The most prevalent way of disposing of municipal solid waste (MSW) in developing countries is open dumping, which is the easiest and is considered to be the cheapest way of waste removal. In developed countries, landfills are engineered disposal sites that receive a wide range of materials (Kamaruddin et al., 2017). As previously mentioned, disposal of waste to landfill remains the most usual method of waste management. Despite the fact that landfilling provides a simple and beneficial means of waste disposal, if it is not appropriately managed can cause serious environmental risks relating to gaseous and particulate emissions, leaching, etc. (Vaverková, 2019).
The composition of landfill gas varies. The major constituents are methane and carbon dioxide. Carbon monoxide, hydrogen, oxygen, nitrogen and hydrogen sulphide are present in significant amounts. Landfill leachate forms as a result of waste decomposition and transportation of resulting products by water percolating through the soil profile (Licht & Isebrands, 2005; Qasim & Chiang, 1994). Leachate composition depends on the waste types and the phase of waste decomposition. Leachate contains high concentrations of dissolved and suspended organic matter and inorganic substances and poses a potential risk to the environment.
Establishing vegetation on the landfill has multiple significance: removal of contaminants, erosion prevention and control, as well as aesthetic effects. Phytoremediation is a promising technology for landfill remediation, as it can stabilize soil and, at the same time, remediate landfill leachate. Namely, phytoremediation, plant-based technologies, use green plants and their rhizospheric microorganisms to remediate contaminated sites (Sadowsky, 1999). Successful application of any phytoremediation system implies the selection and establishment of appropriate vegetation. Phytoremediation is evolving into a cost-effective means of managing wastes, especially excess petroleum hydrocarbons, polycyclic aromatic hydrocarbons, explosives, organic matter, nutrients and heavy metals (Nagendran, 2006). Phytoextraction, rhizofiltration, phytovolatilization, phytodegradation, rhizodegradation, hydraulic pumping, phytosorption and phytocapping are different types of phytoremediation based on the used mechanism (Nagendran, 2006).
Phytoextraction refers to the reduction of metal concentrations by cultivating plants with a high capacity for metal accumulation in shoots. Plants used for this purpose should ideally combine high metal accumulation in shoots and high biomass production (Pathak et al., 2012; Pathak et al., 2020).
Rhizofiltration is used for cleaning contaminated surface waters or wastewater by adsorption or precipitation of metals onto roots or absorption by roots or other submerged organs of metal-tolerant aquatic plants. For this purpose, plants must not only be metal-resistant but also have a high adsorption surface and must tolerate hypoxia (Pathak et al., 2012; Dushenkov et al., 1997; Horne, 2000; Poschenrieder & Coll, 2003).
Key Terms in this Chapter
Leachate: Liquid and suspended materials which it contains, which has percolated through or drained from a municipal solid waste disposal facility.
Sustainable Environmental Technology: Sustainable environmental technology is an umbrella term that describes innovation that considers natural resources and fosters economic and social development. The goal of these technologies is to drastically reduce environmental and ecological risks and to create a sustainable product.
Phytoremediation: The use of plants and the associated microorganisms, along with proper soil amendments and agronomic techniques to either contain, remove or render toxic environmental contaminants harmless.
Landfill (Sanitary Landfill): An engineered structure consisting of bottom liners, leachate collection and removal systems, and final covers. Landfills are designed both to store and to treat wastes.
Dumpsite (Open Dumpsite): Open dumpsites are those where solid waste is deposited without planning and consideration for environmental and health standards and are illegal to establish or operate.
Landfill Gas: Gas produced by the anaerobic decomposition of solid wastes, and includes primarily methane and carbon dioxide, with lesser amounts of other gasses such as hydrogen, hydrogen sulphide, and numerous volatile organic compounds.
Municipal Solid Waste: Municipal solid wastes (MSW), trash or garbage, are heterogeneous mixture of residential, commercial, and industrial products (product packaging, grass clippings, furniture, clothing, bottles, food scraps, newspapers, appliances, paint, and batteries).
Environmental Impacts: Changes in the natural or built environment, resulting directly from an activity, that can have adverse effects on the air, land, water, fish, and wildlife or the inhabitants of the ecosystem.