Sludge reduction by a micro-aerobic hydrolysis process: A full-scale application and sludge reduction mechanisms

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies
• Microbial Ecology

Background:

• Conventional activated sludge processes generate significant sludge volumes, increasing operational costs and environmental burden.
• Developing efficient sludge reduction strategies is crucial for sustainable wastewater treatment.
• Industrial park wastewater presents complex treatment challenges requiring robust solutions.

Purpose of the Study:

• To investigate the long-term performance of a full-scale sludge process reduction activated sludge (SPRAS) system.
• To evaluate the sludge reduction efficiency and pollutant removal capabilities of the SPRAS.
• To analyze the microbial community and operational mechanisms driving sludge reduction in the SPRAS.

Main Methods:

• Implementation and long-term operation of a full-scale SPRAS system incorporating a micro-aerobic tank and clarifier.
• Batch tests to determine sludge decay rates and microbial activity.
• Analysis of microbial communities to identify key bacteria involved in sludge reduction.
• Techno-economic analysis to assess cost-effectiveness and footprint.

Main Results:

• The SPRAS achieved efficient pollutant removal and a low observed sludge yield (0.074 g SS/g COD).
• Micro-aerobic conditions favored sludge reduction, with a sludge decay constant of 0.168 d⁻¹.
• The system enriched slow-growing, hydrolytic, and floc-forming bacteria, enhancing sludge reduction, simultaneous nitrification-denitrification, and settleability.
• Process configuration supported enhanced metabolism and uncoupled processes for effective sludge reduction.

Conclusions:

• The SPRAS configuration is highly effective for industrial wastewater treatment, significantly reducing sludge production.
• The system's microbial ecology and operational dynamics contribute to efficient sludge reduction and improved treatment performance.
• The SPRAS offers a cost-effective and space-saving solution for sustainable wastewater management.