The government of Rwanda is considering scaling up eco-friendly technology to generate biogas from wastewater treatment and be used as cooking fuel across different schools in the country.
The announcement was made by Water and Sanitation Corporation (WASAC) Limited, following the installation of a wastewater treatment facility at Groupe Scolaire Rilima in Bugesera District in the Eastern Province, which uses the technology known as biological anaerobic baffled reactor (ABR).
Anaerobic baffled reactor (ABR) is a type of sanitation technology that has been in existence for so many years and it is designed to treat wastewater and fecal sludge, thereby producing energy.
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The technology is part of Rwanda’s Nationally Determined Contributions (NDCs) which are climate action plans aimed at reducing greenhouse gas emissions to help meet the global goal of limiting temperature rise to 1.5 degrees Celsius and adapt to the impacts of climate change.
The Paris Agreement, negotiated in 2015, requires that NDCs are updated every five years with increasingly higher ambition, taking into consideration each country’s capacity.
Countries have to update their NDCs by February, 2024, under the terms of the Paris Agreement – and some may announce their targets at the ongoing COP29 in Azerbaijan.
In its NDC, Rwanda has identified potential within energy utilisation measures such as landfill gas recovery and direct waste-to-energy initiatives.
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The country seeks to invest $8 million in the waste management process chain to increase access to electricity and reduce dependency on traditional biomass energy.
It also seeks to invest $1.5 million in wastewater treatment and reuse technology to cut down methane emissions from wastewater and provide a nutrient-rich digestate that can be used as fertiliser.
There are over 3.8 million pupils and students in Rwanda in 9,645 schools including nursery, primary and secondary schools.
According to Methode Rutagungira, the head of hygiene sanitation at WASAC Utility Ltd, cooking meals for this large number of students requires cutting many trees for wood fuel.
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The treatment of wastewater in schools will generate the biogas used as cooking fuel in the kitchen, while treated water is used for the toilet cleaning and sludge used as fertilizer for soil amendment
"The technology to produce cooking gas from wastewater treatment can be scaled up in schools, correctional facilities, hospitals, real estates, hotels, refugee camps and grouped settlements,” he said.
The technology
The Forum of Private Operators for Water and Sanitation Systems (FEPEAR) is the organisation behind the initiative to introduce biological anaerobic baffled reactors across schools.
According to Fidele Nteziyaremye, Project Manager at FEPEAR, the newly installed wastewater treatment facility, costing $100,000, can use solar energy to power its equipment.
"The wastewater treatment in one school of GS Rilima with 500 students can supply 10 cubic nanometres or five kilogrammes of cooking biogas per day,” he explained.
He also indicated that the new technology is sustainable given that the previous technology to generate biogas in Rwanda was not successful. It will contribute to the circular economy.
Ildephonse Dushimiyimana, Head Teacher at GS Rilima in Bugesera District which is using the technology in generating gas for cooking, said they were spending Rwf60,000 on buying firewood.
"The amount of firewood we were using will decrease and thus reduce pressure on forests. We hope to get six kilogrammes of biogas per day and save at least Rwf20,000 per day,” he said.
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How the technology works
The wastewater treatment system consists of three operating units, which are wastewater collection and biological treatment, degassing, biogas collection and storage, wastewater reuse.
The system has a control panel to monitor physically or remotely the treatment.
As the plant is installed in a standard shipping container above the ground, a pumping station is installed that will pump the wastewater to the container.
A pump with a grinder is used, which helps larger solids grind to smaller pieces to avoid blocking in further treatment stages.
Wastewater is pumped from the pumping station to a container that is designed to biologically remove excess organic pollution from the water in oxygen free conditions.
Also, a vacuum operated degassing unit is installed on the ABR effluent line to minimize the methane loss via effluent.
During this process solubilized methane will be separated from the water and will be directed to the biogas storage to be then channeled to the kitchen.