The competitive adsorption of pharmaceuticals on granular activated carbon in secondary effluent

Abstract

The competitive adsorption characteristics of four pharmaceutical compounds, including clofibric acid (CA), carbamazepine (CBZ), naproxen (NAP), and diclofenac (DCF), were evaluated on granular activated carbon in secondary effluent. In ultrapure water (UW), the adsorption efficiencies of CA, CBZ, NAP, and DCF on coconut shell-based carbon were 63.0, 85.5, 79.1, and 68.8%, respectively, at initial concentration of 500 μg/L and carbon dosage of 133 mg/L. All the substrates could be removed completely when carbon dosage was increased to 250 mg/L. In the secondary effluent from a real wastewater treatment plant, the removal of four pharmaceuticals were decreased to 26.9, 57.9, 44.7, and 31.0%, respectively, with carbon dosage of 250 mg/L, which recovered to 39.6, 67.1, 53.4, and 48.1% after solution filtration by 0.22-μm hydrophilic membrane. The suspended solids and soluble organic compounds in wastewater were considered as the key inhibited factors for pharmaceuticals adsorption by activated carbon. The differences of adsorption efficiency between spiked UW and secondary effluent demonstrate that further purification for secondary effluent is necessary in practical wastewater treatment, when activated carbon is used as adsorbent for pharmaceuticals removal and wastewater advanced treatment.

Keywords:

• Pharmaceutical compounds
• Granular activated carbon
• Competitive adsorption
• Ionic strength
• Secondary effluent

Acknowledgments

The study is supported by the special scientific research project from education department of Shaanxi province (Grant No. 12JK0640) and innovative research team of Xi’an University of Architecture and Technology.