There is a severe shortage of wood, and millions of rural people worldwide need help avoiding using fossil fuels as cooking fuels. An eco-friendly option would be converting manure into natural gas-like methane using a biogas digester. You can connect this to the kitchen’s plumbing system for cooking. A biogas digester’s byproducts are ideal for fertilizer use while reducing air pollution.
Here’s how to build a biogas digester in your backyard.
Materials Required:
- Container:
You will require a sizable, sealed container to store the organic waste and produce biogas. A big PVC pipe, a metal drum, a concrete or plastic tank, or any combination thereof can serve this purpose.
- Gas Outlet:
You can collect the produced biogas with a hose or pipe. You should place the gas on the digester’s top to allow it to build up.
- Outlet Pipe:
This is the discharge point for the digested material, often known as effluent. One more time, a PVC pipe will do the trick.
- Inlet Pipe:
We will add organic waste to the digester. Choose a PVC pipe whose inside diameter is just right for your container’s inlet.
- Storing the gas:
You can temporarily store biogas in a gas bag or other suitable container.
- Organic Waste:
You can use any organic waste, including animal manure, garden waste, or discarded food.
- Water Supply:
A water supply could be necessary to keep the digester at the ideal moisture level.
Steps to build a biogas digester:
- Choosing the container
Get a container appropriate for the amount of waste you will process and the area available in your backyard. Make sure that it is well-built and airtight.
- Install a gas outlet
The top of the container should have a gas outlet installed. Connect the biogas collector to the hose or pipe.
- Install inlet and outlet pipes
The container needs holes drilled into it for the inlet and outlet pipes. By sealing these pipes properly, you can prevent gas leaks.
- Preparing the organic waste
Make the organic waste into little pieces by chopping or shredding it. This improves digestion by increasing the surface area.
- Filling the digester
Introduce the organic material into the digester through the inlet pipe. Fill the container to approximately two-thirds or three-quarters of its capacity to allow gas accumulation.
- Add water (if necessary)
If you’re using materials high in carbon, such as paper or straw, or if the waste is dry, add water to prevent the mixture from being too dry. A moisture level of about 80% is considered optimum.
- Seal the container
When the container is full, seal it tightly so no oxygen can enter. Anaerobic digestion, which results in biogas, relies on this.
- Digestion time:
Give the microbes a chance to break down the organic matter. Depending on factors like waste type and temperature, this process may take several weeks to a few months.
- Biogas collection
Biogas, a byproduct of organic matter decomposition, will rise to the digester’s top. You can connect a gas storage tank to the gas outlet.
- Using biogas
Whatever your need, put the collected biogas in the kitchen or heating system.
- Waste removal:
At regular intervals, empty the digester’s contents into the drain pipe. You can apply this stuff as fertilizer in your garden.
Tips:
- Stirring:
By periodically stirring the biogas digester mixture to distribute nutrients and microbes evenly, you can increase gas output.
- Safety:
Because biogas might catch fire, it is important to keep the digester away from open fires and keep it in a well-ventilated area.
- Starting small:
Beginning with a small-scale biogas digester is the best way to start with biogas digestion if you are new to the process.
- Temperature:
Higher temperatures accelerate the digestive processes. To warm the biogas digester, place it somewhere sunny or cover it with insulation.
Constructing a biogas digester in your garden is an easy way to reduce your environmental impact and turn organic waste into usable energy.
How much does a biogas digester cost?
A biodigester can be very affordable or expensive, depending on additional features, materials, size, location, and technology. Smaller home-use models can cost from a few hundred to a few thousand. Bigger industrial digesters can cost anywhere from tens of thousands to millions.
A general breakdown of the costs is as follows:
- Small-Scale Home Digesters:
Usually, they are more basic setups made for small farms or single-family homes. Depending on the materials and size, its price might range from $250 to $5,500.
- Medium-Scale Community Digesters:
They aim to offer services to numerous families or communities. Prices might range from $5,500 to $55,000 or even more, depending on the resource’s capability and the technology used.
- Large-Scale Industrial Digesters:
Large-scale enterprises, such as wastewater treatment plants, farms, and other business establishments, frequently use these. Depending on the customization, technology, and capacity chosen, industrial biogas digesters can cost tens of thousands to millions of dollars.
Operating costs, maintenance, and possible revenue or savings from biogas production need careful consideration alongside the initial investment. Depending on where you live and what you want to do with the biogas digester, you might be eligible for financial aid in the form of subsidies or incentives from the government.
What is not put in a biodigester?
Anaerobic digestion occurs when a biogas digester converts organic waste into biogas and fertilizer. While biodigesters can process a diverse range of organic waste, it is advisable to separate certain materials due to potential damage or interference.
Things you shouldn’t put in a biogas digester include:
- Synthetic or inorganic chemicals
Do not introduce ammonia, bleach, and other synthetic chemicals to a biogas digester. These can harm the environment and disturb the natural bacterial community.
- Hazardous materials
The beneficial microbes that aid in digestion are at risk of compromising their health. This can occur if pesticides, solvents, chemicals, and other harmful compounds contaminate the biogas and fertilizer that result from the process.
- Dairy products:
When added in excess, dairy products can emit unpleasant scents and disturb the biodigester’s delicate balance of microbes.
- Too much grease, oils, and fats
Although a little grease, oil, or fat is usually fine, too much might prevent microbes from doing their jobs or clog pipes.
- Hard materials and large bones
A biogas digester may need help breaking down large bones or other tough materials, such as woody branches or shells, which take a long time to break down.
- Contaminated or diseased organic waste
It is important to avoid adding contaminated food or other materials to a biogas digester to keep the biogas and fertilizer free of pathogens and diseased animals’ waste.
- Non-biodegradable materials
Never put anything that isn’t organic in a biogas digester. They can’t break down glass, metals, plastic, or non-biodegradable materials.
Maintaining a biogas digester
Maintenance is key if you want your biogas digester to last and work well. A few must-do maintenance tasks include these:
Removing slurry
Periodically draining the surplus slurry is necessary to keep the digester at the correct volume and avoid solid buildup.
Training
All individuals responsible for operating and maintaining the biogas digester must have sufficient training in the required preventive measures and maintenance procedures.
Inspecting regularly
Make sure to visually inspect the biodigester on a regular basis for cracks, leaks, or other indications of damage.
Routine maintenance:
Establish a regular maintenance schedule for things like lubricating moving parts, part replacement, and filter cleaning.
Mixing
Maintaining a well-mixed digester is crucial to prevent solid or scum accumulation and ensure the uniform distribution of nutrients and microbes.
Monitor the pH.
Regular measurements of the pH level within the biogas digester are necessary. The ideal pH levels for biogas production are usually between 6.5 and 7.5.
Addition of substrate
Maintain microbial activity in the biogas digester by continuously adding new substrate, which is organic waste.
Collection and storage of gas:
Keep an eye out for gas leaks and obstructions in the collection system. Gas storage containers must be airtight and well-sealed.
Safety measures:
Always wear protective gear when dealing with biogas systems. Handle biogas with caution as it poses a significant fire risk.
Record keeping:
Consistently document all aspects of gas production, including repairs and maintenance, temperature, feedstock input, and pH levels. This information will be useful for fixing problems and making the system better in the long run.
Controlling the temperature
The temperature within the digester needs monitoring and regulation. Thermophilic digestion works best at temperatures between 50 and 60 degrees Celsius, while mesophilic digestion is most effective at temperatures between 25 and 40 degrees Celsius.
Feedstock management
Make sure to distribute the organic materials evenly before feeding them into the biogas digester. This will prevent materials with a high fat or nitrogen content from overwhelming the digester.
Following these maintenance instructions will ensure that your biogas digester system runs smoothly and safely. Regular maintenance maximizes biogas production and extends the equipment’s lifespan.
Conclusion
If you want to know what materials work best with your biogas digester, you should refer to the manufacturer’s instructions. The biogas digester needs frequent monitoring and maintenance, including checking the input materials, to work at its best and keep everyone safe.