Complete and stable enhanced biological phosphorus removal at 30 °C using glutamate and acetate as alternating carbon sources

As utilities around the world strive to protect waterways and meet increasingly stringent nutrient limits, phosphorus removal remains a persistent challenge. Biological phosphorus removal strategies have been developed and optimized for temperate regions, focusing on the utilization of volatile fatty acids (VFAs) as carbon substrate. But what happens when temperatures are higher, or when other carbon sources dominate the wastewater stream?

A recent study published in Bioresource Technology tackles this question head-on. In the article “Complete and stable enhanced biological phosphorus removal at 30 °C using glutamate and acetate as alternating carbon sources,” Carollo’s Rogelio Zuniga-Montanez and co-authors explore how enhanced biological phosphorus removal (EBPR) can perform under tropical conditions using both conventional and non-traditional carbon sources.

Rethinking Biological Phosphorus Removal in Warm Climates

Enhanced biological phosphorus removal relies on specialized microorganisms, known as polyphosphate-accumulating organisms (PAOs), that take up phosphorus during treatment and store it inside their cells. Historically, EBPR research has focused on operating temperatures typical of temperate climates and VFAs, such as acetate, as the carbon source for PAOs, leaving questions about stability and efficiency in warmer regions.

This study examined EBPR performance at 30 °C, a temperature typical of wastewater in tropical climates, where biological phosphorus removal processes were considered to exhibit significant instability.

Using Amino Acids to Support EBPR Performance

In a laboratory-scale reactor operated for more than 400 days, the researchers alternated between two carbon sources: acetate (a traditional VFA) and glutamate (an amino acid commonly found in raw sewage and some industrial effluents). The results were striking. The system achieved complete and stable phosphorus removal for 140 consecutive days, even though glutamate produced lower phosphorus release than acetate.

As the authors note, “high phosphorus release is not a prerequisite for complete phosphorus removal,” highlighting that EBPR can be effective even when traditional performance indicators are different.

What This Means for Full-Scale Wastewater Treatment

The study found that Candidatus Accumulibacter, a key PAO, was the dominant organism during successful operation, demonstrating its ability to adapt to both carbon sources at elevated temperatures. This suggests that amino acids, such as glutamate, could help supplement VFAs in real-world treatment plants, thereby improving resilience when wastewater composition or climate conditions vary.

For utilities operating in warm regions or managing diverse influent streams, these findings offer encouraging evidence that EBPR can remain robust with thoughtful process design.

Read the full article in Bioresource Technology to explore the research methods, microbial insights, and implications for full-scale wastewater treatment systems.