Biogas is a one of a renewable energy and an alternative energy that now can be used in our daily life in exchange of electricity. Biogas came from a mixture of many types of gases, two main gases are methane and carbon dioxide. This biogas can be produced through any kinds of raw materials. To convert a variable mixture of gases into a pure biogas, we need a machine or an installation. That kind of installation divided into two, based on their place, it can be generated through sewage plant and can be generated also at landfill sites.
Landfill sites create a danger to our health and also bring danger to the environment. They produce much toxic gas that came from the decomposition of organic and inorganic waste, such as methane. Landfill gas also produces an explosive mixture when it combined with air in a specific proportion. There are many cases of explosion, one of the example is based on Atlanta Journal-Constitution (1999) an explosion occurs at Atlanta the victim is an 8-year-old girl that burned her arms and legs when playing in the playground, that area was reportedly used as an illegal dumping ground. To prevent this explosion and any other danger, it’s best to capture the gases and turn them into a biogas. To turn gases, especially methane, into biogas is to use an installation that called biogas plant. Based on Clarke Industry (2017), to make the biogas in landfill sites, the gases need to be extracted in a controlled situation inside perforated tubes that are drilled into deep down the sites and it’s interconnected by a pipework. The perforated tube can be placed horizontally or vertically depends on the landfill sites. At the perforated tube, the gases will be flared to remove the unwanted gas such as un-burnt hydrocarbons. And then, the gas is sucked in using a blower and after that, the gases will be treated to pure it using adsorption and absorption.
Landfill site biogas installation
Not only can be produced in landfill sites, biogas can also be produced by a sewage sludge. There are two types of producing biogas form sewage sludge based on its size, large scale plant and small scale plant. Based on Catarina Wellin (2011) explanation for a small producing biogas, interestingly biogas can be produced from a septic-tank gases, but not all types of septic-tank can be able to produce biogas, only the septic-tank that have a designated system, so don’t try to hooking up the septic-tank into the gas burner carelessly, it may cause an explosion. Septic-tank produce various gas, mostly is methane gas. The safe way to convert various gases into biogas through septic-tank, is that the septic-tank must be connected into a cesspool to filter the gas that produce from the septic-tank and the greywater connected to a two chamber for infiltration. After the filtration occurs in the septic-tank and then, it followed by an anaerobic digestion. That anaerobic digestion will turn septic gases into a biogas.
Small Scale Sewage Plant
In a large scale plant, there are two types of installation based on the digestion, there are wet digestion installation and dry digestion installation. At wet digestion plant the components are mixing tank to mix the materials, stirred tank is to maintain a temperature and to prevent the mixture to produce foam and sedimentation, and digestate storage to digestate it in anaerobic condition. At dry digestion plant, there are substrate tank which is a place to digestate and produce the gas and water tank which contain of water that will be sprayed into the substrate tank. The problem of using this digestion plant is that all materials will not be filtered that cause lessened production of the methane gases.
Dry Digestate Plant Wet Digestate Plant
In conclusion, biogas can be generated by any raw organic materials under an anaerobic process. The installation that convert raw organic materials into a biogas or a mixture of gases is called biogas plant. There are two types of biogas plant based on its place, sewage sludge plant and landfill site plant. Sewage sludge plant divided into two types of installation, such as large scale plant and small scale plant. The small scale plant is used at household utility and the large scale plant is used to larger utility. There are two types of large scale plant, such as dry digestate plant and wet digestate plant. The difference between both of the types of large scale plant is that the dry digestate produce less methane gas compared to wet digestate plant.