North Goa, India

Renewable energy from food scraps

The Calangute/Saligao Village plant in North Goa District was completed in December 2021. The plant is located on the site of an existing landfill. The entire landfill has a site area of 1,217,248 sq ft. Every day, 275,577,828 tn. sh. of waste arrive at the facility. Recyclables are recovered from the dry waste and sold to local recycling companies for further recovery. Biogas is extracted from the wet waste at the facility, which is used to generate electricity. The residual materials are further composted.
The two tanks at the biogas plant are 65.6 ft in diameter and 24.6 ft high. 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 a solids content of 10 - 12 %. The organic waste produced is separated from the solid municipal waste in a first step. The substrate places certain demands on the agitator technology used. The shredded organic substrate then has a fiber length of between 0.2 and 0.8 in.
In order to achieve the necessary circulation capacity, three OPTIMIX 2G 150-275 submersible motor agitators 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 correct arrangement 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 feedthrough. It is installed on the annular ceiling of the vessels and allows easy positioning of the agitator in the vessel. The submersible mixer is lowered to the desired position on the mast. The GDD can be swiveled horizontally up to 360°, depending on the positioning in the vessel. In addition to the built-in sight glass, a height indicator is included for exact determination of the agitator height in the vessel.

The innovative gas-tight rope bushing prevents gas leakage at the bushing. The GDD is made entirely of corrosion-resistant stainless steel in the area in contact with the gas.