Trimethoprim removal from wastewater: Adsorption and electro-oxidation comparative case study

Trimethoprim (TMP) is among the emerging pollutants that cause harmful effects on the aquatic environment and human health if not accurately controlled. This antibiotic is one of the most regularly administered drugs, thus, its contamination of water bodies has received much concern in recent years. In this case study, a comparison between adsorption and electrochemical oxidation was carefully performed to identify the best treatment for removing TMP from impacted water. Adsorption with commercial activated carbon F400 as an adsorbent showed higher TMP removal efficiencies (70.6%) than natural zeolites (17.6%). The experimental data for TMP adsorption onto F400 were well-fitted by the linear form of the Langmuir isotherm (R2 = 0.986). The values of qmax and KL were 18.40 mg g−1 and 1.40 L mg−1, respectively. The pseudo-second order model provided the best correlation with the experimental data. Electrochemical oxidation over two platinum-coated titanium electrodes led to 70.1% TMP removal after 330 min of treatment. The optimal operative conditions were achieved at a concentration of NaCl of 0.04 M and an applied current density of 120 A m−2. Cost estimates for both technologies indicated that electrochemical oxidation of TMP is comparable to adsorption if operating at low current density. Each process presents several advantages and limitations, and the choice of the right approach needs to consider different factors, including the composition of the wastewater and the cost and availability of resources.