Biofouling reduction in recirculating cooling systems through biofiltration of process water

Area of Science:

• Environmental Engineering
• Industrial Microbiology
• Water Treatment Technologies

Background:

• Biofouling poses significant challenges in industrial recirculating cooling systems, leading to equipment damage (biocorrosion) and reduced efficiency (clogging, decreased heat transfer).
• Assimilable organic carbon (AOC) in process water serves as a primary nutrient source for microbial growth, driving biofouling processes.

Purpose of the Study:

• To develop and evaluate a fixed-bed biofilter for removing AOC from industrial cooling water.
• To assess the efficacy of biofiltration in mitigating biofouling in a model recirculating cooling water system.

Main Methods:

• A fixed-bed biofilter was integrated into a laboratory model recirculating cooling water system with a heat exchanger and cooling tower.
• The system was challenged with organic carbon (sucrose, yeast extract) to induce biofouling, with a parallel system without a biofilter serving as a reference.
• Key water quality parameters (AOC, ATP, bacterial numbers, turbidity) and biofouling indicators (protein, heat transfer resistance, chlorine demand) were monitored.

Main Results:

• The biofilter significantly reduced AOC content, ATP concentration, bacterial numbers (30-40 fold reduction), and turbidity (OD660) in the cooling water.
• Biofouling was substantially lower in the system equipped with the biofilter compared to the reference system.
• Improvements were observed in heat exchanger performance and reduced maintenance chlorine demand.

Conclusions:

• AOC removal via biofiltration is an effective and environmentally friendly strategy for controlling biofouling in industrial recirculating cooling systems.
• Biofiltration offers a sustainable approach to enhance operational efficiency and prolong equipment lifespan in cooling water applications.