Preserved granular sludge for inoculation of new UASB reactors

Area of Science:

• Environmental Microbiology
• Wastewater Treatment Engineering
• Biotechnology

Background:

• Upflow anaerobic sludge blanket (UASB) reactors are crucial for efficient wastewater treatment.
• Maintaining the integrity of granular sludge inoculum is vital for optimal reactor performance.
• Understanding sludge preservation methods can improve the start-up and operation of UASB systems.

Purpose of the Study:

• To investigate the preservation characteristics of granular sludge under different storage temperatures and durations.
• To evaluate the impact of preserved granular sludge on the granulation process in new UASB reactors.
• To determine the optimal storage conditions for maintaining sludge viability and functionality.

Main Methods:

• Granular sludge samples were collected from a mesophilic laboratory-scale UASB reactor.
• Sludge samples were stored for 6 months at three different temperatures: 4°C, 24°C (room temperature), and 35°C.
• Preservation was assessed by analyzing soluble chemical oxygen demand (COD), granular particle size, and granular surface morphology.

Main Results:

• Granular sludge stored at 4°C exhibited superior preservation of granular structure compared to storage at 24°C and 35°C.
• UASB reactors inoculated with 4°C preserved sludge reached the post-maturation stage approximately 40 days earlier than the control.
• The accelerated granulation was attributed to the elimination of the embryonic granule formation stage.

Conclusions:

• Low-temperature storage (4°C) is an effective method for preserving the structural integrity of UASB granular sludge.
• Preserved granular sludge can significantly accelerate the start-up phase of new UASB reactors.
• The use of preserved sludge as inoculum offers a viable strategy to enhance the efficiency of UASB reactor implementation.