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Monitoring and modeling 4-chlorophenol biodegradation kinetics by phenol-acclimated activated sludge by using open
Cintia C Lobo1, Nora C Bertola2, Edgardo M Contreras3
1Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA), CONICET, Facultad de Ciencias, Exactas, UNLP, 47 y 116, B1900AJJ, La Plata, Argentina. cintiacecilialobo@hotmail.com.
Summary
This study analyzed 4-chlorophenol (4CP) biodegradation by activated sludge, finding high 4CP removal but incomplete chemical oxygen demand (COD) reduction due to intermediate buildup. A model predicted biodegradation dynamics in wastewater treatment.
Area of Science:
- Environmental microbiology
- Biochemical engineering
- Wastewater treatment technologies
Background:
- 4-chlorophenol (4CP) is a persistent pollutant in industrial wastewater.
- Activated sludge is commonly used for biological wastewater treatment.
- Understanding biodegradation kinetics is crucial for optimizing treatment processes.
Purpose of the Study:
- To investigate the biodegradation kinetics, mechanisms, stoichiometry, and stability of 4-chlorophenol (4CP) using phenol-acclimated activated sludge.
- To determine the oxygen consumption stoichiometry during 4CP aerobic oxidation.
- To develop a mathematical model for predicting 4CP biodegradation dynamics.
Main Methods:
- Open respirometry was employed to monitor oxygen consumption and substrate degradation.
- Stoichiometric ratios (YO2/4CP) were calculated from respirometric data.
- A mathematical model was fitted to experimental data to predict key parameters over time.
Main Results:
- Over 98% removal of 4CP was achieved, but chemical oxygen demand (COD) removal was limited (69-79%) due to intermediate metabolite accumulation.
- The stoichiometric ratio of oxygen consumed to 4CP removed (YO2/4CP) was determined to be 1.95 ± 0.04 mol/mol.
- 4CP degradation activity decreased with successive 4CP additions, indicating potential inhibition or saturation.
- The developed mathematical model accurately predicted oxygen consumption, total phenols, and soluble COD concentrations.
Conclusions:
- The study elucidated the aerobic biodegradation pathway of 4CP, highlighting the role of oxygenases.
- Intermediate metabolite accumulation limits overall COD removal efficiency in biological treatment.
- The developed model provides a valuable tool for predicting and managing chlorophenol biodegradation in wastewater treatment systems.
