A review on pharmaceuticals removal from waters by single and combined biological, membrane filtration and ultrasound systems

Abstract

Contaminants of emerging concern (CEC) such as pharmaceuticals commonly found in urban and industrial wastewater are a potential threat to human health and have negative environmental impact. Most wastewater treatment plants cannot efficiently remove these compounds and therefore, many pharmaceuticals end up in aquatic ecosystems, inducing problems such as toxicity and antibiotic-resistance. This review reports the extent of pharmaceutical removal by individual processes such as bioreactors, advanced oxidation processes and membrane filtration systems, all of which are not 100% efficient and can lead to the direct discharge of pharmaceuticals into water bodies. Also, the importance of understanding biotransformation of pharmaceutical compounds during biological and ultrasound treatment, and its impact on treatment efficacy will be reviewed. Different combinations of the processes above, either as an integrated configuration or in series, will be discussed in terms of their degradation efficiency and scale-up capabilities. The trace quantities of pharmaceutical compounds in wastewater and scale-up issues of ultrasound highlight the importance of membrane filtration as a concentration and volume reduction treatment step for wastewater, which could subsequently be treated by ultrasound.

Keywords: Activated sludge; Biotransformation; Membrane filtration; Pharmaceutical waste; Ultrasound.

Fig. 1

Average removal of pharmaceuticals in WWTP processes. Acetaminophen (ACT), diclofenac (DCF), ibuprofen (IBP), ketoprofen (KTP), naproxen (NPR), mefenamic acid (MFN), carbamazepine (CBZ), clofibric acid (CLF), gemfibrozil (GFB), caffeine (CAF), atenolol (ATN), metoprolol (MTP), triclosan (TCN), sulfamethazine (SMZ), sulfamethoxazole (SMX), trimethoprim (TMP), lincomycin (LIN), estrone (ESN), estriol (ESL), estradiol (ETL). Reprinted from , Copyright (2011), with permission from Elsevier.

Fig. 2

Pharmaceutical removal routes of sulfamethazine (SMT), sulfamethoxazole (SMX), ibuprofen (IBP), diclofenac (DCF), norfloxacin (NOR), cephalexin (CLX) and tetracycline (TC) in the ASP. Adapted after Peng et al. .

Fig. 3

Biodegradation products and pathways of iopromide by conventional activated sludge and nitrifying activate sludge. Reprinted from , Copyright (2016), with permission from Elsevier.

Fig. 4

Proposed pathways for biotransformation of ketoprofen. Reprinted from , Copyright (2005), with permission from Elsevier.

Fig. 5

Correlation between electrophilic index (ω) and the natural logarithm of biodegradation constant rate (ln k_bio) for metronidazole, sulfamethoxazole, bezafibrate and ibuprofen. Reprinted from , Copyright (2018), with permission from Elsevier.

Fig. 6

Removal percentage of ibuprofen (IBP) as a function of the sludge retention time (SRT). Reprinted from , Copyright (2005), with permission from Elsevier.

Fig. 7

Relationship between initial concentration and biodegradation rate constant (k_bio) for metronidazole (MTZ), sulfamethoxazole (SMX), bezafibrate (BZF) and ibuprofen (IBU). Reprinted from , Copyright (2019) with permission from Elsevier.

Fig. 8

Effect of solution pH on the degradation of acetaminophen (AAP) and naproxen (NPX) and the production of H₂O₂ at 580 kHz and 15 ± 1 °C. Reprinted from , Copyright (2014) with permission from Elsevier.

Fig. 9

Degradation rate of cefadroxil (CDX), ciprofloxacin (CIP), norfloxacin (NOR), cephalexin (CPX), oxacillin (OXA) and cloxacillin (CLX) as a function of octanol–water partition coefficient (log P), which is correlated with hydrophobicity . Note: Distribution coefficient and partition coefficient are different (but related) concepts. The first one refers to the concentration ratio of all species of the compound (ionized plus un-ionized). Meanwhile, the partition coefficient refers to the concentration ratio of non-ionized species of the compound .

Fig. 10

The impact of concentration on the initial rate of DCF degradation by ultrasound irradiation. 861 kHz, pH 5.7 and 40 min treatment. Reprinted from , Copyright (2011) with permission from Elsevier.

Fig. 11

Pulse enhancement (PE) as a function of molar volume of five pharmaceuticals: acetaminophen (ATP), ibuprofen (IBU), carbamazepine (CBZ), ciprofloxacin (CIPRO) and sulfamethoxazole (SFT). Reprinted with permission from Copyright 2013 American Chemical Society.

Fig. 12

Typical primary transformations induced by the sonogenerated hydroxyl radical (HO•) on pharmaceuticals.

Fig. 13

Schematic sequence of phases during pharmaceutical degradation by sonochemistry.

Fig. 14

Removal of antibiotics and antimicrobials in membrane bioreactor (MBR) and conventional activated sludge (CAS) processes. Trimethoprim (TMP), lincomycin (LIN), erythromycin (ERY), sulfamethoxazole (SMX), clarithromycin (CLAR), triclocarban (TCC), minocycline (MIN), tetracycline (TET), sulfamethazine (SMZ), chlortetracycline (CTC), meropenem (MER), clindamycin (CLI), azithromycin (AZT), ciprofloxacin (CIPX), oxytetracycline (OXY), triclosan (TCS), vancomycin (VCM), chloramphenicol (CAP), amoxicillin (AMX). Reprinted from , Copyright (2016) with permission from Elsevier.

Fig. 15

Schematic diagram of the OMBR setup. Reprinted from , Copyright (2018) with permission from Elsevier.

Fig. 16

Concentration of organic contaminants in the feed and the permeate, as well as the removal efficiencies by the OMBR system. Reprinted from , Copyright (2012) with permission from Elsevier.

Fig. 17

Schematic diagram of the ultrasound, activated carbon and ultrafiltration membrane treatment unit. Reprinted from , Copyright (2014) with permission from Elsevier.

Fig. 18

A schematic diagram of US coupled with an anaerobic membrane bioreactor. Reprinted from , Copyright (2013) with permission from Elsevier.

Fig. 19

(a) TMP of the MBR for a given permeate flux as a function of time with and without O₃/US pre-treatment prior to MBR and (b) The removal of pharmaceutical compounds (DCF, CBZ and SMX) after different treatments: O₃/US treatment, MBR process and O₃/US followed by MBR in series .