Environmental technology (envirotech) or green technology (greentech), also known as clean technology (cleantech), is the application of one or more of environmental science, green chemistry, environmental monitoring and electronic devices to monitor, model and conserve the natural environment and resources, and to curb the negative impacts of human involvement. The term is also used to describe sustainable energy generation technologies such as photovoltaics, wind turbines, etc. Sustainable development is the core of environmental technologies. The term environmental technologies is also used to describe a class of electronic devices that can promote sustainable management of resources. Purification and waste management Examples Biofiltration Bioreactor Bioremediation Desalination Thermal depolymerization Composting toilet Pyrolysis Water purification Water purification: The whole idea/concept of having dirt/germ/pollution free water flowing throughout the environment. Many other phenomena lead from this concept of purification of water. Water pollution is the main enemy of this concept, and various campaigns and activists have been organized around the world to help purify water. Air purification Air purification: Basic and common green plants can be grown indoors to keep the air fresh because all plants remove CO2 and convert it into oxygen. The best examples are: Dypsis lutescens, Sansevieria trifasciata, and Epipremnum aureum. Besides using the plants themselves, some species of bacteria can also be added to the leaves of these plants to help remove toxic gases, such as toluene. Sewage treatment Sewage treatment is conceptually similar to water purification. Sewage treatments are very important as they purify water per levels of pollution. The most polluted water is not used for anything, and the least polluted water is supplied to places where water is used affluently. It may lead to various other concepts of environmental protection, sustainability, etc. Environmental remediation Environmental remediation is the removal of pollutants or contaminants for the general protection of the environment. This is accomplished by various chemical, biological, and bulk methods. Solid waste management Solid waste management is the purification, consumption, reuse, disposal and treatment of solid waste that is undertaken by the government or the ruling bodies of a city/town. Sustainable energy Concerns over pollution and greenhouse gases have spurred the search for sustainable alternatives to our current fuel use. The global reduction of greenhouse gases requires the adoption of energy conservation as well as sustainable generation. That environmental harm reduction involves global changes such as: reducing air pollution and methane from biomass virtually eliminating fossil fuels for