Pentachlorophenol aerobic removal in a sequential reactor: start-up procedure and kinetic study

Area of Science:

• Environmental Microbiology
• Biotechnology
• Wastewater Treatment

Background:

• Pentachlorophenol (PCP) is a highly toxic pollutant found in industrial wastewater.
• Conventional treatment methods often struggle with PCP removal due to its recalcitrance and toxicity.
• Developing efficient and cost-effective biodegradation technologies for PCP is crucial.

Purpose of the Study:

• To demonstrate the applicability of sequencing batch reactors (SBRs) for aerobic biodegradation of pentachlorophenol (PCP).
• To enrich and acclimate a microbial consortium capable of degrading PCP.
• To characterize the kinetic and stoichiometric parameters of the acclimated biomass.

Main Methods:

• Enrichment of microbial consortium from urban wastewater treatment plant biomass.
• Operation of sequencing batch reactors (SBRs) with suspended biomass for PCP biodegradation.
• Kinetic modeling using classical and modified Haldane equations to describe substrate-inhibited kinetics.
• Evaluation of growth yield coefficient (Y) and endogenous respiration rate (b).

Main Results:

• Achieved approximately 90% removal efficiency of PCP within 70 days of start-up.
• Sustained removal efficiencies ≥90% at influent PCP concentrations of 10-20 mg/L.
• Haldane models provided reliable predictions for substrate-inhibited kinetics (R² > 0.99).
• Determined growth yield coefficient (Y = 0.075) and endogenous respiration rate (b = 0.054 d⁻¹).

Conclusions:

• Aerobic SBRs with mixed microbial cultures are effective for PCP biodegradation.
• The technology demonstrates superior performance compared to continuous systems for PCP removal.
• Achieved removal rates are suitable for practical application in wastewater treatment.