Joel Immermann, a retired freelance photographer, takes self-sufficient living to the next level. His house in the Karoo is fitted with solar panels, a gas stove and a BiogasPro 6 digester from Agama Biogas that supply enough energy for him to do his daily chores.
Six months ago Immermann installed a bio-digester. He decided to try it out, as the bio-digester enables him to recycle his household waste rather than feeding it into the environment. “My aim is to become totally self-sufficient by living off the grid,” he says. He wants to minimise his carbon footprint. Immermann says it was easy to install the bio-digester. All he needed to do, was to connect his sewerage pipe to the device and then feed it with biomass to produce gas.
Each day he feeds his bio-digester with cow dung, vegetable offcuts and sewage producing enough gas for 50 minutes of cooking time on his stove. The cow dung is sourced from a local farmer, while the vegetable offcuts and sewage are come from his household.
Caryl Richmond, a medical doctor from Cape Town, also installed a bio-digester at her house. Richmond and her family divide their time between their home on a smallholding in Cape Town and a house in Johannesburg.
About half a bucket of clean, fresh horse manure is added to the digester weekly, as well as sewage from two labourers who are working on weekdays. This is sufficient to ensure a constant supply of biogas. If the family is away for a period, gas production may drop as the digester is receiving less food waste and sewage but the amount will build up within days of their return. Even when Richmond is in the house alone, there is still sufficient gas for cooking and to boil the kettle despite the reduced feeding of the digester.
When asked whether caring for the digester has been inconvenient, Richmond replies: “No, it’s no hassle. It takes one to three minutes to feed kitchen scraps to the digester when I’m there and twice a week I give it a good stir. It has never blocked or required any maintenance.”
Richmond’s digester has been operating for six years now with no need for the accumulated sludge to be pumped out. The constant flow of water through the digester gradually removes the solids as they break down over time, releasing the nutrient-rich water which can be used for irrigation and as a fertiliser.
A living machine
The Agama BiogasPro is a one-stop shop that enables everyone to extend their sustainable living activities and integrate their current waste management systems to produce renewable energy on-site. Marisa Naude, sales and marketing manager of Agama Biogas, says that you achieve this by investing in a BiogasPro digester, a living machine that has a range of bacteria as its engine. “When bio-waste is fed to the digester, bacteria degrade the material yielding gas.”
She says the BiogasPro produces a biogas which consists primarily of methane, which is stored in the top of the bio-digester and piped directly to a gas appliance like a cooker or a water heater. “Biogas produced by the digester can also be used to generate electricity, but this is an inefficient use of the gas and is usually only financially worth doing in large applications.” Naude lists the benefits of installing the BiogasPro. She says it is a convenient, integrated waste management system and is a source of renewable energy. Using a bio-digester avoids dumping waste into landfill and the effluent produced by the digester can be used as a liquid fertiliser if no sewage is involved, or further purified and used for irrigation if sewage is involved. “You can also lower your carbon footprint by recycling waste and using biogas on site instead of LP gas or grid electricity.”
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