Tropical-based EBPR process: The long-term stability, microbial community and its response towards temperature stress

Area of Science:

• Environmental Microbiology
• Wastewater Treatment
• Biotechnology

Background:

• Operational efficiency of enhanced biological phosphorus removal (EBPR) systems is sensitive to temperature fluctuations.
• Tropical regions present unique challenges for maintaining optimal performance of wastewater treatment processes due to higher ambient temperatures.

Purpose of the Study:

• To investigate the impact of thermal stress exceeding 30°C on the performance of an EBPR community sourced from tropical inoculum.
• To determine the threshold temperature at which EBPR efficiency fails under elevated thermal conditions.

Main Methods:

• An EBPR system was established using tropical inoculum and maintained at 30°C for 210 days to confirm stability.
• The system was then subjected to cyclic temperature increases to 35°C and 40°C under anaerobic-aerobic phases to assess performance.
• Microbial community composition, specifically the abundance of Accumulibacter and Competibacter, was monitored in response to thermal stress.

Main Results:

• The EBPR system demonstrated stability and high phosphorus removal efficiency at 30°C, with Accumulibacter being the dominant genus.
• At 35°C, high phosphorus removal was maintained for a short period (2 days) before gradual failure, coinciding with Competibacter outcompeting Accumulibacter.
• Complete EBPR failure was observed at 40°C, indicating a critical temperature threshold for this tropical microbial community.

Conclusions:

• EBPR systems utilizing tropical inoculums are robust at 30°C but show limited tolerance to short-term thermal stress at 35°C.
• Sustained operation above 35°C leads to performance deterioration, with the failure threshold identified between 35°C and 40°C.
• The dominance shift from Accumulibacter to Competibacter under thermal stress is a key indicator of EBPR system failure.