Rejection of pharmaceutical compounds from surface water by nanofiltration and reverse osmosis

Abstract

Pharmaceutical compounds represent a diverse set of biologically active molecules used in human and veterinary medicine. The increase in the consumption of these drugs contributes to the constant occurrence of these compounds in aquatic environments.The situation is even more serious in conditions of absence of sewage treatment system.This is the case of the city of Governador Valadares, located in the state of Minas Gerais, thus discharging all its effluent to the Doce river that supplies the region. In order to guarantee the quality of water, especially for human consumption, investments in additional treatments are necessary. Among these technologies, the use of membranes, which combine the stability of the process with the excellent quality of the treatment, stands out. Thus, nanofiltration (NF) and reverse osmosis (RO) membranes were tested aiming at the pharmaceutical compounds retention in the Doce river raw water. This study was divided into three steps. In the first one, pharmaceutical compounds occurrence in all samples of the Doce river raw water was investigated. Among the pharmaceutical compounds that were found, the following stand out: Phenylbutazone and Prednisone that were rejected in 98 and 80%, respectively, by the DK membrane, whereas Betamethasone was 40.85 removed by this membrane. In addition, the efficiency of Governador Valadares central water treatment plantwas also assessed, which showed a reduction in the concentration of the pharmaceutical products in the potable water when compared to the Doce river raw water. The second part investigated five NF and two RO membranes that were tested to evaluate the physico-chemical quality and the presence of pharmaceutical compounds in permeates. Additionally, the resistance, permeability and specific energy consumption (SEC) for each membrane were assessed. It was observed a removal high efficiency of the parameters evaluated for the RO membranes, however, these membranes presented the highest resistance, energy demandand lower permeate fluxes. Dense NF membranes presented abetter set of results. The third phase refers to the choice of the best operational condition, evaluating the best transmembrane pressure and feed flow for permeates production with high quality in the physical and chemical parameters, as weel asthe drugs removal compareted with the Doce river raw water. The best operational condition obtained in the study was 10 bar of pressure and feed flow of 3.2 L/min which presented permeates flow at 45.99 L / m².h and a SEC of 0.44 KWh.m³ m².

Using Pressure-Driven Membrane Processes to Remove Emerging Pollutants from Aqueous Solutions

“…A new experimental series using different membranes (NF99HF, RO90, and RO99) was carried out in order to make a comparative study. The high rejection coefficient of metformin, similar to that obtained by other authors [18], can be related to the presence of a net positive charge in its molecule under the experimental conditions assayed. Charged molecules are solvated in water, which enlarges their effective size and increases their rejection [14].…”

“…These drugs had similar volumes and molecular weights, but the dissociation and hydrophobicity constants, which are important in membrane separation, were different. The results obtained for metformin showed an elimination coefficient close to 94%, which reinforces the idea that membrane separation is the optimal technology [18].…”

Formation and Fate of Nitromethane in Ozone-Based Water Reuse Processes

“…The rejection of an RO membrane for an organic solute depends on the membrane material, molecular weight cutoff, surface charge, and surface morphology, as well as solute properties (i.e., structure, molecular weight, molecular geometry, p K a , and K ow ) . The low molecular weight of nitromethane (61.04 g/mol), its neutral charge (with a p K a of 10.2 at a feedwater pH of 8.37), and its low log K ow (−0.35) are consistent with poor rejection by RO membranes. − The bench-scale results generally agree with the data collected from the full-scale RO processes, which show nitromethane rejections of 37, 29, 31, and 34% for plants A, B, C, and D, respectively, suggesting that poor nitromethane rejection is generally low during RO, both in clean and fouling environments. The higher rejections observed at the full scale are likely due to fouling deposition on the RO membranes.…”

Assessing the Performance of Thin-Film Nanofiltration Membranes with Embedded Montmorillonites

“…These processes are often combined, depending on the type of wastewater [5][6][7]. Among these, NF is widely used for its applicability to various industries, such as water purification and desalination [8,9], food and beverages [7,10,11], semiconductor [12,13], petroleum [14,15], pharmaceutical and biotechnology [16,17] and the textiles industry [18,19].…”