Biogas Production

Biogas Production

Biogas Generator

This is a system of motors used to convert biogas into electricity. Biogas is a mixture of flammable gases, mostly methane. It also contains carbon dioxide that forms anywhere there is an anaerobic decomposition of organic matter. This could be in the water, in a landfill, or in the guts of animals, including you. Household biowaste can also be used for biogas production that’s used  for cooking, lighting, and heating

A well-maintained generator will fairly digest the material in a month in a temperature of 70 – 105 degrees. The generator needs conditions almost similar to those in an animal’s gut. Biological activity inside the generator will produce heat. When there is a hot climate, provide some shade to prevent the temperature inside the generator from rising above 105 degrees.

During the cold climate, you must provide additional warmth since biogas production takes place in warm environments. You can wrap the barrel with insulated tubes then pump hot water through them. A larger generator might produce enough gas for some of it to keep heating water, which can circulate in closed piping acting as a heat exchanger.

You must weigh the cost of producing gas against that of heating.

 How to Make a Biodigester                                               

First, you need an airtight space.

Second, make sure you have put enough water in the bio-waste.

Third, ensure that you have a warm surrounding.

Fourth, find the right ph. 5 at the beginning and 7 when the process ends.

In the first 48 hours; it releases only carbon dioxide. Light a match to it, and it will be blown out. You will hear a hissing sound then see black smoke. When the biogas is released, these will disappear and you will smell a scent like rotten eggs. This is the signal to start capturing your gas.

 Biogas Digester Construction

A bio-digester is comprised of a sealed tank that holds biowaste and a means to collect produced gases. For these parts to work you need a way to mix the bio-matter. You also need to pipe off the gas and dry off the effluent.

Always consider how much organic waste you can collect a day for putting in the tank. Also, consider the model of digester you want as they are built differently. You also require things like adhesives and tools. Finally, make sure you know what you’re doing.

How the Biogas is Produced

The bio-matter is crushed into very small pieces for an even consistency. Water with nutrients from a further stage in the process is added to make the mixture easier to process. The mixture is sanitized and heated above 70 °C for an hour then put in a biogas digester.

The microbes begin decomposing this mixture to release methane. This gas can be used without further processing. It can also be purified to become biogas which is almost equivalent to natural gas. The process also gives out organic nutrients which can be used for agricultural purposes.

How Long Does it Take to Produce Biogas?

How quickly your organic waste is broken down and converted into biogas depends on the type of waste you use the temperature available.

The bio-digester will begin to produce biogas 1 – 3 weeks after it’s started using little manure. The bacteria inside the bio-matter will then start the decomposition process 24/7 to start releasing gas. Our stomachs usually do the same when it is warm enough.

In theory, a 1000 litre home digester should make 1m3 of biogas in a day or so after being filled with organic waste.

What Are the Inputs for Biogas Production

Bio-digesters accept any organic waste  material which may include;

  • Biodegradable waste from industries and treatment plants.
  • Rotten food from shops and homes.
  • Biowaste that is given by consumers
  • Sludge given from wastewater treatment plants
  • Manure and biomass from agriculture

In some cases, lignocellulosic stuff (woody material) is used. With these, you might get more biogas after an animal has digested it than before.

Sewage and other different types of manure are the most common. However, they give less gas than non-woody organic waste such as grass and plants whose energy has not been taken out already.

Biogas Production from Biomass

First, biomass is collected and prepared for processing. The biomass can be kitchen refuse, decaying plants and even bio-degradable waste from industries and treatment plants.

The biomass is usually put in a bio-digester and mixed with water. It is then put under warm conditions to allow for decomposition. Microbes then begin breaking down this material in anaerobic digestion to release methane gas. The methane gas is captured and reprocessed to be purified so it can release biogas.

Organic bio-matter gives more biogas because it has a higher concentration of anaerobic bacteria which carry out decomposition.

Biogas production

biomass in the form of nappier grass.

How to Make Biogas from Cow Dung.

Cow dung is also called manure. In manure, the major chemical element in manure is carbon. Anaerobic bacteria digest this carbon to release biogas. However, these bacteria also need Nitrogen in order to derive their energy from carbon.

The ration of Carbon to Nitrogen in the bio-matter is crucial. If it is high then that means the Nitrogen will be exhausted before the Carbon is digested. However, Nitrogen is more than Carbon, it becomes toxic for the bacteria. This is especially in high ammonium concentrations.

The mixture also undergoes anaerobic digestion to release bio-gas.

Biogas Production from Human Waste

 

biogas production

Sewage with liquid human waste

A human waste bio-reactor is used. The biogas produced from human waste is limited compared to livestock manure and other feedstocks. Human waste contains disease-causing pathogens and must be properly treated to protect handlers from infections.

 

Human waste has no methanogens hence low biogas production. However, it has the same bacteria in the human body which causes farts. Farts contain methane. To begin only use human waste at the sewerage plant as it is in liquid form. Put it in a tank for anaerobic digestion and connect it to a device for collecting the gas.

 

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