Biogas station is technological facility which uses process of anaerobic digestion for processing and utilization of; bio waste and biologically decomposable material. The main product of anaerobic digestion is biogas, which can be used as alternative energy source.
Anaerobic digestion
Anaerobic digestion (or fermentation) is a process, when microorganisms decompose organic material in hermetic space. It can work spontaneously or it can be driven in biogas stations. The whole process has 4 phases:
- Hydrolysis: A chemical reaction where particulates are solubilized and large polymers converted into simpler monomers
- Acidogenesis: A biological reaction where simple monomers are converted into volatile fatty acids.
- Acetogenesis: A biological reaction where volatile fatty acids are converted into acetic acid, carbon dioxide, and hydrogen
- Methanogenesis: A biological reaction where acetates are converted into methane and carbon dioxide, while hydrogen is consumed.
Substrates
Biogas station can process manure, cattle excrements and other waste from animal production, phytomass, plant production waste, food waste, biologically decomposable communal waste. Moist materials are especially suitable. All possible materials are mixed altogether in the right ratio to reach the right mixture with right conditions (humidity). The better is the mixture the more biogas is produced.
The conditions of the process
There are several necessary conditions which are necessary for fluent anaerobic digestion process:
- Strictly anaerobic space
- Optimal pH
- Constant temperature
- The right mixture of substrate
Anaerobic digestion products
Biogas
Biogas consists of methane and CO2. The amount of methane in biogas is between 50 and 75%. Biogas is mostly burnt in burner and produced heat is used for house heating or water heating. Another option is combined production of heat and electricity in cogeneration unit
Digestate
The solid waste after fermentation with lowered contain of biologically decomposable substance sis called digestate. Digestate can be used as a high quality fertilizer or compost addition.
Fugate
Fugate is a putrid liquid product which has a character of waste. It is highly muddy. Fugate is supposed to be removed to sewage disposal plant.
