Generating energy through waste

Harnessing alternative energy for domestic and industrial purposes is a challenge in the backdrop of a rapidly increasing demand for power sources. Biotech, an agency implementing biogas and solar energy programmes of the Ministry of Non-Conventional Energy, has introduced several techniques for generating energy through effective treatment of waste. Two of the popular technologies are being implemented in the State by the agency. One is the anaerobic treatment (Biomethanation), suitable for treating fast decomposing bio-waste and the other is Biocinerator for the treatment of slow decomposing materials.

Biocinerator is a biomass burning unit. Waste materials like dry leaves, coconut husk, other types of dry plant waste, paper, etc. can be burned under controlled conditions in a chamber. This process does not require any external fuel. The excess gas generated in anaerobic treatment plants can be utilised as a fuel for operation of biocinerator.

It is a process based on micro-organism. A waste treatment plant, consisting of a gas collector and a digester/reactor, is installed for treating bio-degradable organic matter to produce methane gas. The organic waste and wastewater from domestic, industrial or agricultural process can be used for the purpose.

Renewable source

Methane gas is a renewable source of energy, which is used for cooking, lighting, running engines and for generation of electricity. The cost involved is low when compared to other fuels, according to Saji Das, Managing Director of Biotech.

Initially, the digesters are filled with `Biotech culture' consisting of water and cow dung to start the digestion phase. Once the microbes are cultured in the plant, it will grow and remain inside the treatment plant.

The bio-waste generated in markets, hotels and other places are collected in separate bins, which are transported to the treatment plant site after final sorting and fed into a pre-conditioner for minimizing the size of the waste materials.

The organic waste thus fed into the plant decomposes within days through anaerobic process and methane gas is generated which is collected in the gasholder of the plant. After filtration, it is channelised to the duel fuel generator for electricity generation. Electricity thus generated from the plant is utilised for street-lighting and other power applications. Through proper planning, every home can clear the domestic waste, says Mr.Das. Bio-waste materials from kitchen are collected in a bucket along with wastewater. It is fed into the inlet tank of the plant. The biogas generated is stored in the fibreglass gasholder.

The flow of gas from gasholder to the stove is made possible by opening the control valve on the gasholder. Digested waste (slurry) comes out of the plant automatically through the outlet pipe. The slurry can be utilised as manure for plants. Gas output from a domestic plant using the waste generated by a family of five members is sufficient to operate a single burner stove for two hours everyday.

R. Ramabhadran Pillai

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