Surreal illustration of a food waste digester being optimized with trace elements.

Food Waste's Secret Weapon: How Trace Elements Can Save Anaerobic Digestion

Jordan Keane in Climate & Environment August 2025 • 4 min read.

"Unlock the power of trace elements to stabilize anaerobic digestion, maximize methane production, and create a sustainable solution for food waste."

In a world grappling with escalating waste and a pressing need for sustainable energy, food waste presents a unique challenge and opportunity. Mountains of discarded food not only contribute to environmental strain but also represent a significant untapped resource. Anaerobic digestion (AD), a process where microorganisms break down organic matter in the absence of oxygen, has emerged as a promising solution for converting food waste into valuable biogas, a renewable energy source.

However, the AD process isn't always smooth sailing. Long-term operation often faces instability, leading to reduced efficiency and even complete failure. One major culprit behind this instability is an imbalance in volatile fatty acids (VFAs), particularly propionate, which can inhibit the microorganisms responsible for methane production.

But what if there was a secret weapon to combat VFA imbalance and stabilize AD? Recent research points to the crucial role of trace elements – micronutrients essential for the health and activity of those very microorganisms. By understanding how trace elements influence the AD process, we can unlock new strategies for maximizing biogas production and creating a truly sustainable system for food waste management.

Why are Trace Elements the Key to Unlocking Stable Anaerobic Digestion?

Surreal illustration of a food waste digester being optimized with trace elements.

The study highlights that the deficiency of essential trace elements (TEs) in food waste is a primary reason for process imbalance. Anaerobic digestion (AD) of food waste gets strongly inhibited by volatile fatty acids (VFA, mainly propionate). Regular substrate feeding and digestate discharge gradually decrease TEs contents in the digester, which greatly limits the growth and metabolism of hydrogenotrophic methanogens and Methanosarcina.

To investigate the role of trace elements, researchers set up two anaerobic digesters: one with food waste alone (R1) and another with food waste supplemented with trace elements (R2). Here’s what they discovered:

R1 (No Trace Elements): Initially stable, R1 eventually crashed. VFA levels soared, methane production plummeted, and the microbial community shifted to less efficient organisms.
R2 (With Trace Elements): R2 thrived, maintaining stable VFA levels, high methane production, and a balanced, diverse microbial community.

In simpler terms, the digester without trace elements (R1) experienced a breakdown in its microbial ecosystem, leading to process failure. Supplementing with trace elements (R2) acted like a multivitamin for the microorganisms, keeping them healthy and productive.

The Future of Food Waste Digestion is Micronutrient-Rich

This research offers a compelling case for the importance of trace element management in anaerobic digestion. By ensuring that digesters have the right balance of these essential micronutrients, we can stabilize the AD process, maximize biogas production, and unlock the full potential of food waste as a renewable energy resource. As we move towards a more sustainable future, optimizing the microbial ecosystems within our digesters will be key to turning waste into a valuable asset.

About this Article -

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Everything You Need To Know

What is Anaerobic Digestion (AD) and why is it important for food waste?

Anaerobic Digestion (AD) is a biological process where microorganisms break down organic matter, like food waste, in the absence of oxygen. This process converts the waste into biogas, a renewable energy source. AD is crucial for food waste because it offers a way to convert discarded food, which would otherwise contribute to environmental problems, into a valuable resource, reducing waste and producing sustainable energy.

What role do Trace Elements (TEs) play in the Anaerobic Digestion process?

Trace Elements (TEs) are micronutrients essential for the health and activity of the microorganisms within the Anaerobic Digestion (AD) process. The deficiency of TEs in food waste can lead to an imbalance, particularly of volatile fatty acids (VFAs) like propionate. Supplementing the digester with TEs ensures the microorganisms, including hydrogenotrophic methanogens and Methanosarcina, have the necessary support to thrive, maintain a balanced microbial community, stabilize VFA levels, and efficiently produce methane.

How does the imbalance of Volatile Fatty Acids (VFAs) affect the Anaerobic Digestion process?

An imbalance in Volatile Fatty Acids (VFAs), particularly propionate, can strongly inhibit the Anaerobic Digestion (AD) process. When VFAs levels rise, they negatively affect the microorganisms responsible for methane production, leading to reduced efficiency and potential failure of the entire system. The accumulation of VFAs indicates the microbial community is struggling to function correctly, highlighting the importance of maintaining optimal conditions within the digester, such as providing adequate Trace Elements (TEs).

Can you explain the difference in performance between the digesters R1 and R2, and what caused those differences?

Digester R1, which did not receive Trace Elements (TEs), initially showed stability but eventually crashed due to rising Volatile Fatty Acids (VFAs) and plummeting methane production, resulting in a shift to less efficient organisms. In contrast, Digester R2, which was supplemented with TEs, maintained stable VFA levels, high methane production, and a balanced microbial community. The key difference was the presence of TEs in R2, acting as a multivitamin for the microorganisms and preventing the process imbalances that affected R1.

What are the practical implications of using Trace Elements (TEs) in food waste management through Anaerobic Digestion (AD)?

Using Trace Elements (TEs) in Anaerobic Digestion (AD) has significant implications for food waste management. By ensuring the right balance of micronutrients within the digesters, operators can stabilize the AD process, maximize biogas production, and unlock the full potential of food waste as a renewable energy resource. This approach not only reduces environmental strain by diverting waste from landfills but also contributes to sustainable energy generation, making it a critical strategy for a more circular and eco-friendly future.