Biodegradation of PhACs in the presence of humus under different redox conditions

21/04/2015

Master student: Yang Jiang

Supervisor: Yujie He

Alette Langenhoff

Introduction

Pharmaceutically active compounds (PhACs) pose physiological responses on humans, animals and plants, even at low concentration (ng-µg/L).

Low removal efficiency in wastewater treatment plants.

Low cost, easy maintenance post-treatment process—constructed wetlands.

Introduction

Microbial degradation

Carbon source (i.e. humus)

Redox conditions (i.e. aerobic, methanogenic)

Temperature

pH

Medium characteristics

presence of plants

Research objectives

To investigate the role of various redox conditions for PhACs biodegradation.

To understand PhACs biodegradation in the presence of humus.

Set-up

Tested group Humus

I. Biotic with humus (triplicate) √II. Biotic without humus (triplicate)

III. Abiotic control with humus (duplicate) √IV. Abiotic control without humus (duplicate)

Redox conditions

Aerobic respiration Aerobic Nitrification Denitrification Sulfidogenic Methanogenic

Aerobic conditions

Anaerobic conditions

(DOC = 100mg/L)

(inhibitor: 0.02 mol/L NaN3)

(inhibitor: 0.3 g/L HgCl2)

Set-up

Metoprolol

Caffeine

Propranolol

Carbamazepine

Naproxen

Ibuprofen

Diclofenac

1 mg/Lmixture

Results

Aerobic redox condition ● Aerobic respiration

● Nitrification

Anaerobic redox condition ● Denitrification

● Sulfidogenic

● Methanogenic

Aerobic respiration e-acceptor: O2

Biotic: CO2 ↑ Abiotic: CO2 →

Aerobic nitrification e-acceptor: O2

Biotic: CO2 ↑ Abiotic: CO2 →

Denitrification e-acceptor: NO3-

Biotic: NO3-

↓↓ Abiotic: NO3

- ↓

Methanogenic e-acceptor: CO2

Biotic: CO2 → CH4 ↑ Abiotic: CO2 ↑ CH4 →

Conclusion

PhACs

Redox condition

Caffeine Naproxen Metoprolol Ibuprofen Propranolol Carbamazepine Diclofenac

Aerobic respiration

Aerobic nitrification

Denitrification Sulfidogenic

Methanogenic

Fast degradable; Slightly degradable; Poorly degradable

Conclusion

Humus can increase Naproxen removal under 2 aerobic conditions and denitrification condition.

Abiotic environment was not controlled well under anaerobic conditions where some bacteria still metabolize.

Recommendation

To ensure abiotic environment for anaerobic conditions, it is suggested to use other inhibitors instead of HgCl2.

For further research in the next step, use enrichment bacteria instead of raw sediment, which could avoid sorption in the experiment.

End

Methodology &Materials

Experiment set-up

Methodology &Materials

Experiment set-up

Aerobic nitrification

Sulfidogenic

Chemical reaction