Landfill Rescue: How Bacteria Can Help Us Solve Waste Problems
"Discover how a novel, strongly resistant Bacillus salmalaya strain is revolutionizing landfill leachate treatment, reducing chemical oxygen demand and ammonia nitrogen."
The growing amount of waste we produce is a significant threat to our environment. Finding sustainable ways to deal with this waste is more critical than ever to protect our planet and our health. Bioengineering, using biological systems to solve environmental problems, is becoming a key area of focus.
Landfill leachate, a highly toxic liquid that forms when rainwater filters through waste, poses a serious challenge. It's loaded with ammonia nitrogen and has a high chemical oxygen demand (COD), making it difficult and expensive to treat. Traditional methods often fall short, highlighting the need for new approaches.
Now, a promising solution has emerged from an unexpected source: a resilient bacterium called Bacillus salmalaya strain 139SI. This article dives into the groundbreaking research demonstrating how this novel microbe can significantly reduce ammonia nitrogen and COD levels in landfill leachate, offering a sustainable and efficient way to manage this environmental hazard.
Leachate: A Complex Treatment Challenge
A 2024 study analyzed leachate data from 318 landfill sites used primarily for municipal solid waste disposal, examining chemical and microbiological characteristics. Landfill leachate can contain high concentrations of organic matter, ammonia and nitrogen, as well as high salinity and toxicity. The EPA report says most landfills in non-arid areas send leachate to municipal wastewater treatment plants, but that option may be insufficient for many sites, particularly in the eastern United States.
Treatment Uses Biological and Physical Processes
For non-hazardous landfills, the EPA identifies equalization, activated sludge biological treatment and multimedia filtration as the technologies underlying its effluent limitations. For hazardous waste landfills, the listed treatment basis also includes chemical precipitation. A 2025 review warns that untreated leachate can jeopardize aquatic environments and human health because of its high organic matter concentrations and toxicity, while a 2024 review calls for continued improvement in treatment technologies and more sustainable practices.
A Shift Toward Combined Treatment
A 2021 overview reports that combined treatment techniques have been used to address landfill leachate's high chemical oxygen demand, ammonia concentrations and low biodegradability. A 2026 review highlights the need for integrated treatment technologies to protect environmental and public health. It also links leachate remediation research with environmental policy and the Sustainable Development Goals.
The Power of Bacillus salmalaya: A Natural Solution
Researchers investigated Bacillus salmalaya strain 139SI, a newly identified bacterium, for its ability to remove ammonia nitrogen from landfill leachate. What makes this strain special is its ability to survive in environments with high concentrations of ammonia nitrogen, a common challenge in landfill leachate treatment. The study explored how different conditions, such as temperature, inoculum dosage (the amount of bacteria used), and pH levels, affected the bacterium's performance.
- Optimal Conditions: The best results were achieved within 11 days under specific conditions: a 10% v/v inoculant (volume of bacteria relative to the volume of leachate), a pH of 6, and a temperature of 35°C.
- Ammonia Removal: Under these optimal conditions, Bacillus salmalaya removed 78% of the ammonia nitrogen.
- COD and BOD Reduction: The bacterium also significantly reduced the chemical oxygen demand (by 88%) and biological oxygen demand (by 91.4%).
- Visual Evidence: Scanning electron microscopy revealed that ammonia ions were effectively captured on the surface of the Bacillus salmalaya cells.
Microbial Materials and Nitrogen Removal
A 2023 study of biochar-based aerobic denitrifying bacteria functional microbial materials reported maximum removal rates of 14.39% for chemical oxygen demand, 98.38% for nitrate nitrogen, 75.87% for nitrite nitrogen and 79.31% for ammonium nitrogen, at pH values of 11, 7, 1 and 9, respectively. A systematic review also lists a 2017 Malaysia case involving landfill soil and NH(3)-N. Separately, a review of Bacillus sp. L2 notes that recent work on heterotrophic nitrification–aerobic denitrification has included waste leachate and high-salt wastewater.
Field Performance Still Needs Testing
In a study of landfill leachate, Bacillus salmalaya strain 139SI removed chemical oxygen demand more effectively than ammonia nitrogen. The researchers investigated sterilized degradation to assess the strain's bioaugmentation ability while excluding the effects of native bacteria. They said a simple field trial would be proposed in future work, so the reported results do not establish performance in a field trial.
Recirculation Reduced Leachate Production
Three-year experimental results reported for Harbin indicated that leachate recirculation reduced leachate production by 87.6%. The source says this reduction meant less or no facility for leachate treatment was required. These results describe leachate production under recirculation, rather than a comparison of bacterial treatment performance.
A Cleaner Future with Bacterial Allies
Bacillus salmalaya strain 139SI presents a promising avenue for significantly reducing the levels of harmful pollutants in landfill leachate. Its ability to thrive in harsh conditions and efficiently remove ammonia nitrogen and COD makes it a strong candidate for real-world applications.
Complexity Drives New Treatment Goals
Landfill leachate management is described as a significant environmental challenge requiring a comprehensive and dynamic treatment approach. Although leachate is a small volumetric fraction compared with municipal wastewater, its complexity remains a concern for researchers and practitioners. The field has shifted over the past decade from removing contaminants toward simultaneous resource recovery, while emerging treatment technologies are being investigated to address continuing challenges.
Bacillus salmalaya Shows Promise in Leachate Treatment
A 2017 study concluded that Bacillus salmalaya strain 139SI significantly reduced chemical oxygen demand and NH3–N in landfill leachate, reporting treatment within 11 days. The article describes the bacterium as a potential eco-friendly way to clean toxic landfill leachate. The study's conclusion supports its promise in treatment, while the findings provided here do not establish broader real-world outcomes.
This research underscores the potential of bioaugmentation as a sustainable and cost-effective solution for waste management. By harnessing the power of microorganisms, we can develop innovative strategies to protect our environment and build a cleaner future.
Further research and field trials will be essential to optimize the use of Bacillus salmalaya in large-scale leachate treatment. However, these initial findings offer a beacon of hope for more effective and environmentally responsible waste management practices.