Anaerobic digestion in the context of "Incinerator"

Compressed natural gas (or simply shortened as CNG) is a fuel gas mainly composed of methane (CH₄), compressed to less than 1% of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of 20–25 megapascals (2,900–3,600 psi; 200–250 bar), usually in cylindrical or spherical shapes.

CNG is used in traditional petrol/internal combustion engine vehicles that have been modified, or in vehicles specifically manufactured for CNG use: either alone (dedicated), with a segregated liquid fuel system to extend range (dual fuel), or in conjunction with another fuel (bi-fuel). It can be used in place of petrol, diesel fuel, and liquefied petroleum gas (LPG). CNG combustion produces fewer undesirable gases than the aforementioned fuels. In comparison to other fuels, natural gas poses less of a threat in the event of a spill, because it is lighter than air and disperses quickly when released. Biomethane, biogas from anaerobic digestion or landfill, can be used.

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 (CH
₄) and carbon dioxide (CO
₂) and may have small amounts of hydrogen sulfide (H
₂S), 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 purposes, such as in cooking. It can also be used in a gas engine to convert the energy in the gas into electricity and heat.

Biogas can be upgraded to natural gas quality specifications by stripping carbon dioxide and other contaminants. Biogas that has been upgraded to interchangeability with natural gas is called Renewable Natural Gas (RNG). RNG can be used a drop-in fuel in the gas grid or to produce compressed natural gas as a vehicle fuel.

A septic tank is an underground chamber made of concrete, fiberglass, or plastic through which domestic wastewater (sewage) flows for basic sewage treatment. Settling and anaerobic digestion processes reduce solids and organics, but the treatment efficiency is only moderate (referred to as "primary treatment"). Septic tank systems are a type of simple onsite sewage facility. They can be used in areas that are not connected to a sewerage system, such as rural areas. The treated liquid effluent is commonly disposed in a septic drain field, which provides further treatment. Nonetheless, groundwater pollution may occur and is a problem.

The term "septic" refers to the anaerobic bacterial environment that develops in the tank that decomposes or mineralizes the waste discharged into the tank. Septic tanks can be coupled with other onsite wastewater treatment units such as biofilters or aerobic systems involving artificially forced aeration.

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.

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. 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.

Incineration is a waste treatment process that involves the combustion of substances contained in waste materials. Industrial plants for waste incineration are commonly referred to as waste-to-energy facilities. Incineration and other high-temperature waste treatment systems are described as "thermal treatment". Incineration of waste materials converts the waste into ash, flue gas and heat. The ash is mostly formed by the inorganic constituents of the waste and may take the form of solid lumps or particulates carried by the flue gas. The flue gases must be cleaned of gaseous and particulate pollutants before they are dispersed into the atmosphere. In some cases, the heat that is generated by incineration can be used to generate electric power.

Incineration with energy recovery is one of several waste-to-energy technologies such as gasification, pyrolysis and anaerobic digestion. While incineration and gasification technologies are similar in principle, the energy produced from incineration is high-temperature heat whereas combustible gas is often the main energy product from gasification. Incineration and gasification may also be implemented without energy and materials recovery.

Septic drain fields, also called leach fields or leach drains, are subsurface wastewater disposal facilities used to remove contaminants and impurities from the liquid that emerges after anaerobic digestion in a septic tank. Organic materials in the liquid are catabolized by a microbial ecosystem.

A septic drain field, a septic tank, and associated piping compose a septic system.

Renewable natural gas (RNG), also known as biomethane, is a renewable fuel made from biogas that has been upgraded to a quality similar to fossil natural gas and has a methane concentration of 90% or greater. By removing carbon dioxide and other impurities from biogas, the concentration of methane is high enough that it becomes possible to distribute RNG via existing gas pipeline infrastructure. RNG can be used in existing appliances, including vehicles with natural gas burning engines (natural gas vehicles).

The most common way of collecting biogas with which to produce biomethane is through the process of anaerobic digestion. Anaerobic digestion facilities are either purpose built such as facilities that digest manure, household organic waste, or wastewater treatment plants. Biogas is also byproduct of the decomposition of organic materials in landfills.