Pharmaceuticals, or those compounds manufactured to diagnose, treat or prevent diseases, can harm terrestrial and marine life when they reach water bodies. This is why it is important to remove them from wastewater before it is discharged into water matrices.
In a study by researchers from the UP Diliman College of Engineering, University of Salreno and The Energy and Resources Institute, it was found that the electrocoagulation process was effective in treating municipal wastewater or sewage contaminated with pharmaceuticals. In electrocoagulation, electricity is applied to sacrificial anodes and cathodes to form coagulants. In this case, the coagulants are metal-hydroxo species that weaken contaminants in the wastewater and hold the dissolved compounds.
In the experiments, aluminum and stainless steel plates were used as anode and cathode, respectively. Diclofenac, carbamazepine and amoxicillin, three therapeutic drugs most frequently found in waters, were added into municipal wastewater. A total of 31 experimental runs were conducted to look at the effects of varied combinations of electricity application mode, current density, initial pharmaceutical concentration and electrolysis duration on the ability of the process to remove pharmaceutical pollutants.
Results showed that removal ability depended on the physiochemical characteristics of each pharmaceutical. Carbamazepine was more likely to adhere to coagulants while amoxicillin and diclofenac were removed more by charge neutralization and electroflotation, a process that makes solid particles stick to tiny bubbles of hydrogen and oxygen to float on water surface.
Furthermore, removal efficiencies increased when the supply of electricity was continuous rather than intermittent. This is because an uninterrupted operation also generated a continuous supply of metal-hydroxo species.
However, as the researchers noted, the difference in the removal performance between continuous operation and intermittent operation was only 15 percent, considering that the latter consumes 96 percent less energy and produces only 20 percent species. In other words, the research provides a promising alternative in the treatment of conventional water pollutants and pharmaceutical compounds in wastewater not only by proving that electrocoagulation works but also by obtaining encouraging results from intermittent application of electric field, which is more efficient in terms of cost and energy than continuous mode.
The research was published in January this year in the Journal of Hazardous Materials, an international refereed journal with an impact factor of 6.434.