The livestock industry is not solely profit-oriented; it also bears a responsibility to manage and utilize waste in ways that benefit society and the environment. As part of this commitment, researchers from Universitas Gadjah Mada (UGM) have successfully demonstrated that liquid waste from biogas production, known as anaerobic digested manure wastewater or bio-slurry, can be optimally used as a cultivation medium for Euglena sp. IDN 22 microalgae, which have potential as raw material for various industrial sectors.
The research team was led by Professor Ambar Pertiwiningrum and included Professor Nanung Agus Fitriyanto from the UGM Faculty of Animal Science (Animal Science UGM); Dhomas Indiwara Prana Jhouhanggir, a doctoral student at the same faculty; and Dr. Eko Agus Suyono, a lecturer and researcher at the UGM Faculty of Biology (Biology UGM).
Professor Pertiwiningrum expressed her gratitude for the team’s research, which was published in the Journal of Ecological Engineering (2025).
According to her, integrating the utilization of bio-slurry with microalgae cultivation offers both economic and environmental benefits.
Economically, bio-slurry contains essential nutrients, such as nitrogen (N), phosphorus (P), and potassium (K), which are required for the growth of microalgae.
“This allows farmers to reduce or even eliminate the need for synthetic fertilizers, thus lowering operational costs for microalgae cultivation,” she said on Wednesday (Jul. 16).
From an environmental perspective, Professor Pertiwiningrum explained that bio-slurry utilization can reduce livestock waste pollution.
The liquid by-product of biogas production contains nutrients such as nitrogen and phosphate, which can cause eutrophication if discharged directly into water bodies without treatment.
By processing it as a microalgae cultivation medium, waste residue is significantly reduced, greenhouse gas emissions such as methane (CH₄) and nitrous oxide (N₂O) are minimized, and the approach supports circular economy principles and environmental sustainability.
She emphasized that this waste management method is more environmentally friendly as it does not require synthetic chemical additives during processing. Bio-slurry is used in its natural form as a medium for microalgae cultivation.
“This approach avoids the risk of secondary pollution typically caused by chemical waste treatment and helps maintain the integrity of surrounding ecosystems,” she said.
The integration of microalgae in this system, she noted, also contributes to the absorption of carbon dioxide (CO₂) and the removal of excess nutrients, such as nitrogen and phosphate, which could otherwise cause eutrophication if released into water bodies.
However, she acknowledged that large-scale microalgae biomass production is still uncommon among farmers or farmer groups in Indonesia. While some initiatives have been launched, especially by academics, biotechnology startups, and community empowerment projects, their scale remains limited.
According to Professor Pertiwiningrum, the main challenges are the lack of technical knowledge among farmer groups about microalgae cultivation and the limited market access for its sale. As a follow-up, the team is currently conducting further research.
“We are working to determine the optimal bio-slurry composition based on its nutrient content, particularly the carbon-to-nitrogen ratio, which directly affects microalgae growth and productivity,” she added.
Reporter: Animal Science UGM/Satria
Author: Agung Nugroho
Post-editor: Anisa Nurliana