Abstract
In recent years, there has been an increase in studies regarding nanofiltration-based processes for removing antibiotics and other pharmaceutical compounds from water and wastewater. In this work, a 2k factorial design with five control factors (antibiotic molecular weight and concentration, nanofiltration (NF) membrane, feed flow rate, and transmembrane pressure) was employed to optimize the NF performance on the treatment of antibiotic-containing wastewater. The resulting multiple linear regression model was used to predict the antibiotic rejections and permeate fluxes. Additional experiments, using the same membranes and the same antibiotics, but under different conditions of transmembrane pressure, feed flow rate, and antibiotic concentration regarding the 2k factorial design were carried out to validate the model developed. The model was also evaluated as a tertiary treatment of urban wastewater for removing sulfamethoxazole and norfloxacin. Considering all the conditions investigated, the tightest membrane (NF97) showed higher antibiotics rejection (>97%) and lower permeate fluxes. On the contrary, the loose NF270 membrane presented lower rejections to sulfamethoxazole, the smallest antibiotic, varying from 65% to 97%, and permeate fluxes that were about three-fold higher than the NF97 membrane. The good agreement between predicted and experimental values (R2 > 0.97) makes the model developed in the present work a tool to predict the NF performance when treating antibiotic-containing wastewater.
Highlights
Antibiotics are a class of pharmaceutical compounds with a huge input into the environment, a fact that is associated with their high consumption
50% greater than those predicted by the model (Table 6). These results show that rejection and permeate flux were influenced by the wastewater background matrix, once it contains organic and inorganic compounds (Table 3), in which the loose membrane (NF270) is the most affected, especially regarding the rejection of the antibiotic (SMX) with lower molecular weight (MW)
(65–97%) to the smallest antibiotic (MW approximately 253 Da), in which the rejection was dependent on aqueous matrix and permeate fluxes about three-fold higher than the ones achieved with the
Summary
Antibiotics are a class of pharmaceutical compounds with a huge input into the environment, a fact that is associated with their high consumption. A great concern regarding antibiotics is that after administration, it is only partially absorbed by the patient, being the rest excreted in the urine or feces [2], reaching the urban sewage network and the urban wastewater treatment plants (UWWTPs). These have conventional treatment processes, which are inefficient in removing antibiotics and other micropollutants [2,3,4]; the discharged wastewater ends up contaminating the different ecosystems [5]. In a survey on the occurrence of antibiotics in wastewater treatment plants, Wang et al [14]
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