Digester Biogas from Cassava Mill Effluent

PT TEDCO AGRI MAKMUR

Bandar Lampung, Sumatra

March 2015 – 2016

PT Organics Bali completed the design, installation, and commissioning of a Closed Lagoon Bioreactor (CLBR) on the settling lagoon of the cassava mill owned by Tedco Agri Makmur.

The objective of the project was to treat the extremely high levels of Chemical Oxygen Demand (COD) found in the cassava mill effluent. The system ensures that the resulting methane gas—a powerful greenhouse gas—is captured rather than escaping to the atmosphere. The collected biogas is utilized as renewable energy, capable of powering the entire mill operation and providing an excess for potential export.

The Biogas Power Generation Project is designed to handle the high volume and high organic load of cassava effluent. The system utilizes a specialized CLBR covering the existing wastewater lagoon to stabilize the effluent and promote the conversion of organic matter into biogas.

The facility is capable of processing 3,600 m3/day of wastewater. The resulting biogas (which is equivalent to 2 MWe) is used to displace fossil fuels and reduce the environmental footprint of the agricultural processing facility.

• Waste Type: Cassava Mill Effluent

• Mill Process Capacity: 200 tonnes of cassava per day

• Wastewater Flowrate: 3,600 m3/day

• Lagoon Capacity: 50,000 m3 of wastewater

• Biogas Production Potential: Over 1,000 Nm3/hour (~24,000 Nm3/day)

• Electrical Potential: 2 MWe

• Biogas Application: Powering the entire operation, with excess for export

• Achieving an estimated 80% COD removal efficiency, the system removes approximately 288 tonnes of COD daily, significantly cleaning the effluent.

• Generates 2 MWe equivalent of bioenergy, providing enough power for the entire mill and ensuring energy independence.

• Captures methane, preventing its release into the atmosphere, with an estimated capture of ~13,200 Nm3 of methane per day.

• Carbon Equivalent Reduction: Converts methane capture into climate action, achieving an estimated emission reduction of ~265 tonnes of CO2e per day.

• Reduces odor, minimizes environmental pollution, and aligns the operation with strict environmental standards.

*Note (assumptions):

• COD Load: Initial Chemical Oxygen Demand (COD) load is estimated based on an industry standard Cassava effluent concentration (~100 kg/m3).
• Methane Fraction: Methane content in the biogas is assumed to be ~55%.
• GHG Reduction: Greenhouse Gas (GHG) reduction is calculated using the GWP100 for methane = 28 tCO2e per tonne of CH4.
• Carbon Credit Eligibility: Actual carbon credit issuance is dependent on project registration, verification methodology, monitoring data, and registry approval.

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