Organic Waste to Biogas in Rio de Janeiro’s Biomethanisation unit

The Rio de Janeiro collaboration initiative “Biomethanisation Unit – Treatment of the organic fraction of urban solid residues by anaerobic digestion for energy generation and organic compost production” aims at developing and implementing the first Brazilian and Latin American technology to treat the organic fraction of urban solid waste, regardless as to whether it was segregated at the source or not. The unit has the capacity to treat 35 tons per day, which is the equivalent to serving a population of 70,000 people per day. It can produce 10-20 tons of organic compound per day and can generate 3,150 Nm³ of biogas / day or up to 2,408 MWh / year of electricity. Through this pilot initiative, the city intends to identify and validate optimal operational parameters and to establish a new business model for the sector, contributing therefore to the fight against climate change.

What is the project? How does it work?

The biomethanisation technology developed has never been implemented in Brazil or Latin America before. This is a national expertise and technology developed through a partnership between the Methanum Company and the Federal University of Minas Gerais (UFMG) over the past 8 years. In order to do so, the technicians have visited more than 200 biomethanisation units worldwide and have found solutions for gaps identified in European technological lines. They were:  

• Difficulty to operate with mixed urban waste (not separated at the source) as it happens in Brazil;  
• High costs of implementation and maintenance of pumping systems for the introduction and extraction of waste;  
• Need to adapt the facilities’ inputs and outputs according to the Brazilian context, meaning the legal framework, market condition and demands, among others.

What are the CO2 reduction goals?

The Biomethanisation Unit has the capacity to process 35 tons of urban solid waste per day, equivalent to the waste generated by a population of 70,000 inhabitants on a daily basis. It will avoid the emission of approximately 3,150m³ of biogas per day, equivalent to 14 MtCO2e per year. Moreover, since the Biomethanisation Unit is located in one of the Waste Transfer Stations, part of the received waste will not have to be transported to the landfills. It means that there will be also a reduction of trucks trips between these places and of the emission of greenhouse gases.

One should highlight that among the general goals of the strategic initiative “Sustainable Solid Waste Management” (Result Area: “Rio – Green, Clean and Sound”), the City Hall expects to (1) Reduce the amount of waste disposed in landfills, encouraging the conscious participation of the population and sustainable alternatives of disposal; and (2) Promote the generation of energy from the adoption of solid waste treatment techniques, setting as a goal to reduce by 27% by 2020, the amount of solid waste disposed in landfills, as specified in the 2017-2020 Strategic Plan. The initiative aims to contribute locally to the achievement of Sustainable Development Goals (SDG) 6, 11 and 12.

Next steps

One of the main goals of the Rio de Janeiro City Hall Strategic Plan 2017-2020 is the reduction of the amount of waste disposed in landfills and increase in the amount of recovery of recyclables and organic fraction. In order to do so, the current pilot biomethanisation unit will have to be scaled. The current plant provides enough data that allows it to be replicated at different scales and with different levels of automation, with varying number of biomethanisation tunnels installed and their dimensions.

In order to achieve the Rio’s Plan strategic goals, other complementary initiatives such as pruning composting unit, civil construction waste treatment unit and a waste-energy unit will be developed, with the biomethanisation unit being part of a grater programme towards a better urban solid waste management.