2,4,6-trichlorophenol (TCP) photobiodegradation and its effect on community structure.

Area of Science:

• Environmental Science
• Environmental Biotechnology
• Chemical Engineering

Background:

• 2,4,6-trichlorophenol (TCP) is a persistent organic pollutant requiring effective remediation strategies.
• Photolytic circulating-bed biofilm reactors (PCBBRs) offer a potential solution for treating recalcitrant compounds.
• Understanding the synergistic mechanisms in PCBBRs is crucial for optimizing treatment efficiency.

Purpose of the Study:

• To investigate the mechanisms of TCP degradation in a PCBBR under different treatment conditions.
• To compare the efficacy of photodegradation alone, biodegradation alone, and combined photodegradation-biodegradation (P&B).
• To assess the impact of P&B on TCP mineralization and microbial community structure.

Main Methods:

• Batch experiments were conducted using three protocols: photodegradation (P), biodegradation (B), and combined P&B.
• TCP removal rates and chemical oxygen demand (COD) were monitored.
• Microbial community analysis was performed using clone libraries.

Main Results:

• The P&B approach demonstrated the highest TCP removal efficiency, with concentrations approaching zero.
• The initial TCP removal rate in P&B equaled the sum of individual P and B rates.
• P&B achieved 95% COD removal, indicating significant TCP mineralization, and led to dramatic shifts in microbial communities.

Conclusions:

• Intimately coupled photodegradation and biodegradation in PCBBRs synergistically enhance TCP removal and mineralization.
• The P&B process alters microbial community composition, favoring biofilm formation and non-chlorinated aromatic degradation.
• PCBBRs represent a promising technology for the effective treatment of chlorinated phenolic compounds.