North Goa, India

Renewable energy from food waste

The plant in Calangute/Saligao Village in the North Goa District was finalised in December 2021. The Plant was constructed on an existing dump site. Approximately 70,000 MT of legacy waste was remediated and disposed-off to construct the plant. The entire landfill has a land area of 113,086 square metres.
Every day, 250 megatonnes of waste arrive at the plant. From dry waste, recyclables are recovered and sold to local recycling vendors for further recycling. Biogas is produced from the wet waste in the plant, which is used to generate electricity. The residues are subsequently composted.
The two tanks of the biogas plant have a diameter of 20 metres and a height of 7.5 metres. The plant supplies 1,372 megawatts. The electricity is fed into the power grid. The waste heat generated by the process is in turn used to heat the two tanks.

The substrate is food waste from private households and commercial enterprises with dry matter from 10 - 12 %. First the organic waste is separated from the municipal solid waste. The substrate demands certain requirements of the agitator technology used. The shredded organic substrate has a fibre length of between 5 and 20 mm.
In order to achieve the appropriate agitation performance, three OPTIMIX 2G 150-275 submersible mixers were installed in each of the two tanks. The agitator has an output of 15 kW and a thrust of 4.1 kN. The high efficiency of the motor ensures energy-efficient operation. The proper placement of the submersible mixers plays a decisive role. After several simulations by Suma, the right setting for the installation was found.
The submersible mixers form a unit with a gas-tight ceiling lead- through. The gas-tight ceiling lead-through GDD is a product developed by SUMA and optimised in terms of serviceability for biogas tanks.
It is installed on the ring top of the tanks and enables easy positioning of the agitator in the tank. The submersible agitator is lowered to the desired position on the mast. The GDD can be swivelled horizontally up to 360°, depending on the positioning in the container. In addition to the built-in inspection glass, a height indicator is included to determine the exact height of the agitator in the tank.