When smoke rises from the chimneys of palm oil mills, and its wastewater flows into holding ponds, few ask where all that matter ends up. Palm Oil Mill Effluent, or POME, has long been considered ordinary waste—an inevitable byproduct of an industry that sustains Indonesia’s economy. But who would have thought that from this waste, energy could emerge—and beyond that, it could be reborn into clean water, fertilizer, even better air to breathe.

 

This is a story from the heart of a damp laboratory filled with the scent of fermentation—a story captured in research authored by an Indonesian team in the Case Studies in Chemical and Environmental Engineering journal (2025). The team—comprising Bambang Trisakti, Rivaldi Sidabutara, Irvana, Gloria Clarita Sinamo, Renata Ambarita, Vikram Alexander, Michael Michael, Juan Akmal Nasution, Yasmin Nabilah, Hiroyuki Daimon, and Mohd Sobri Takriff—proposed a simple yet revolutionary idea: eliminating toxic hydrogen sulfide gas (H₂S) from biogas and recycling wastewater using a life-based approach. Not high-tech machines or harsh chemicals. The solution? Soil bacteria and aquatic plants.

 

Lead researcher Bambang Trisakti welcomed me via a virtual interview from his workspace surrounded by glass columns filled with active microbes. “We believe industrial waste solutions don’t have to be expensive or complicated. Often, the answers are right around us: microorganisms and aquatic plants we’ve long overlooked,” he said enthusiastically.

 

The problem they addressed is no small matter. Biogas from palm oil waste processing is rich in energy but often contaminated with H₂S—a foul-smelling gas that corrodes equipment and poses health risks. Typically, the industry uses chemical treatments to address this, but these come with high operational costs and generate secondary waste. This is where the team broke new ground: using water as an H₂S absorption medium in a vertical packed column, then regenerating that water with two natural biological agents—Thiobacillus sp. bacteria and Azolla microphylla, a type of aquatic plant.

 

With this system, biogas that was once “dirty” becomes clean and ready for use, while wastewater is not discarded but purified and reused. All of this is done without producing additional waste. “We didn’t want to solve one problem only to create another. This system was designed to be a closed cycle—a zero-waste model,” Bambang Trisakti emphasized.

 

The trials were carried out with high precision. Water absorbs H₂S from biogas inside a column filled with Raschig rings—small cylindrical structures that maximize contact surface between gas and water. Then, the H₂S-laden water is channeled into a culture pond of Thiobacillus sp., a microbe that naturally oxidizes H₂S into sulfate. Within nine hours, H₂S concentrations dropped drastically from 3000 ppm to 900 ppm—an efficiency of up to 70%.

 

But the real wonder occurred when that water was combined with a pond of Azolla microphylla, a small aquatic plant often found growing wild in rice fields. With its phytoremediation abilities, Azolla reduced H₂S concentrations from 10,000 ppm to just 1700 ppm in four days—an impressive 83% efficiency. This plant not only cleans the water but also grows prolifically and is ready to harvest as a high-nutrient biofertilizer.

 

“Azolla is not just a pollutant absorber. It’s also an oxygen producer, pH stabilizer, and a natural fertilizer source. In one small pond, you get the function of three technologies at once,” Bambang Trisakti explained.

 

Further tests showed the system not only reduces H₂S but also lowers BOD (biochemical oxygen demand), COD (chemical oxygen demand), and dissolved solids—key indicators in wastewater treatment. Even the water’s pH, previously acidic due to H₂S, returned to near-neutral. The end result: water that can be reused as technical water in the factory or as a base for organic liquid fertilizer.

 

One of the strengths of this research lies in its outstanding cost-efficiency. The system’s production cost is only around IDR 54.8 per liter, while its economic value reaches IDR 709 per liter—mainly from the sale of Azolla biofertilizer and the sulfur resulting from oxidation. This is a concrete example of how sustainability and profit can go hand in hand.

 

“We wanted to prove that environmentally friendly technology doesn’t have to be expensive or exclusive. With this bio-based approach, even small palm oil mills can adopt it,” said Bambang Trisakti.

The impact of this system is not limited to the micro-environment within factories. On a broader scale, this system can address the major challenges in the palm oil sector: disposing of waste without pollution, producing clean energy, and recovering water for reuse. It touches on all three pillars of sustainability—economic, social, and ecological.

 

This story is a tangible example of how scientific research can solve real national problems. Not just an ivory tower, but a bridge to cleaner, more economical, and more just industry. A small column absorbing toxic gas, a row of bacteria under a microscope, and tiny aquatic plants floating in a pond—all working together in a system that transforms waste into blessing.

 

And perhaps, one day, when palm oil mills in Indonesia no longer emit foul odors or release wastewater into rivers, we’ll look back and say it all began in a humble laboratory—with a glimmer of courage to challenge the tide of waste, and a firm belief that not even a single drop of water should go to waste.