Degradation of seventeen contaminants of emerging concern in municipal wastewater effluents by sonochemical advanced oxidation processes

A Review on Additives-assisted Ultrasound for Organic Pollutants Degradation

In the past 2 decades, considerable attentions have been paid to the sonochemical advanced oxidation processes (SAOPs) in the fields of pollutants removal. SAOPs are powerful methods for refractory pollutants degradation due to the free radicals (e.g., •OH and •H) generated by water pyrolysis and extremely high temperature and pressure in and around cavitation bubbles. Reports on various additives for the improvement of sonochemical pollutants degradation including oxidants, inorganic anions, etc. have been made. This paper presents a comprehensive review on the ultrasound (US) alone and sono-hybrid systems for various pollutants degradation. In this paper, the degradation efficiency of various pollutants in sono-hybrid systems are elucidated in detail, and particular emphasis is placed on the reaction mechanism of additives in US for the enhancement of pollutants degradation. The problems on the applications of the current sono-hybrid systems are identified and discussed, and the outlooks for further in-depth studies on the challenges and some research needs for the applications of SAOPs for the removal of organic pollutants from aquatic systems are made at the end.

Surface modification of zero-valent iron nanoparticles with β-cyclodextrin for 4-nitrophenol conversion

Environmental pollution causes irreversible damage to ecosystems and their structure. Therefore, the development of novel remedial techniques is a must for an effective response to emerging contaminants and those already persisting in the environment. The nanosized zero-valent iron (nZVI) is considered as an important nanostructure for the degradation of toxic compounds. Furthermore, the degradative potential of nZVI may be improved by surface modification. In this work nZVI was functionalized with β-cyclodextrin (β-CD), which is considered to be an environmentally-friendly and cheap adsorbent for toxic pollutants. Such a 'green' improvement not only enhances the activity of nZVI but also enables the conversion of 4-nitrophenol to 4-aminophenol, which under standard conditions is persistent and does not significantly react with bare nZVI. This research may help to find a solution to treat persistent organic pollutants (POPs) in aqueous environment.

Label-Free Ultrasensitive and Environment-Friendly Immunosensor Based on a Silica Optical Fiber for the Determination of Ciprofloxacin in Wastewater Samples

Emerging contaminants, including pharmaceutical compounds, are receiving research attention as a result of their widespread presence in effluents and wastewater treatment plants (WWTPs). The antibiotic ciprofloxacin (CIP) is extensively employed to treat infections in animal and human medicine. Both CIP and its metabolites are common contaminants found in WWTPs. In this study, a label-free ultrasensitive U-bent optical fiber-based immunosensor for the determination of CIP in wastewater samples was developed using the properties of the conducting polymer polyaniline (PANI). The anti-CIP immunoglobulin G (IgG) was deposited on a silica optical fiber surface previously functionalized with PANI. Scanning electron microscopy and micro-Raman spectroscopy were used to investigate the surface of the immunosensor. The analysis of CIP in wastewater was performed without the use of an organic solvent or sample preparation steps, with only the sample dilution in saline buffer (pH = 7.4). The linear range for CIP was from 0.01 to 10,000 ng L^-1. The detection limit was 3.30 × 10^-3 ng L^-1 and the quantification limit was 0.01 ng L^-1. The immunosensor provided a high average recovery of 91% after spiking wastewater samples with CIP at a concentration of 9,100 ng L^-1. The method was applied in triplicate to wastewater samples from Quebec (Canada), obtaining concentrations of 549 and 267 ng L^-1. A comparison with a reference method showed no significant difference (t-test at 95% confidence). The new technique developed is selective, allowing a quantitative analysis of CIP in wastewater.

Sonochemical degradation of trimethoprim in water matrices: Effect of operating conditions, identification of transformation products and toxicity assessment

The sonochemical degradation of trimethoprim (TMP), a widely used antibiotic, in various water matrices was investigated. The effect of several parameters, such as initial TMP concentration (0.5-3 mg/L), actual power density (20-60 W/L), initial solution pH (3-10), inorganic ions, humic acid and water matrix on degradation kinetics was examined. The pseudo-first order degradation rate of TMP was found to increase with increasing power density and decreasing pH, water complexity (ultrapure water > bottled water > secondary wastewater) and initial TMP concentration. TMP degradation is accompanied by the formation of several transformation products (TPs) as evidenced by LC-QToF-MS analysis. Nine such TPs were successfully identified and their time-trend profiles during degradation were followed. An in silico toxicity evaluation was performed showing that several TPs could potentially be more toxic than the parent compound towards Daphnia magna, Pimephales promelas and Pseudokirchneriella subcapitata.

Hazardous wastes treatment technologies

A review of the literature published in 2019 on topics related to hazardous waste management in water, soils, sediments, and air. The review covered treatment technologies applying physical, chemical, and biological principles for the remediation of contaminated water, soils, sediments, and air. PRACTICAL POINTS: This report provides a review of technologies for the management of waters, wastewaters, air, sediments, and soils contaminated by various hazardous chemicals including inorganic (e.g., oxyanions, salts, and heavy metals), organic (e.g., halogenated, pharmaceuticals and personal care products, pesticides, and persistent organic chemicals) in three scientific areas of physical, chemical, and biological methods. Physical methods for the management of hazardous wastes including general adsorption, sand filtration, coagulation/flocculation, electrodialysis, electrokinetics, electro-sorption ( capacitive deionization, CDI), membrane (RO, NF, MF), photocatalysis, photoelectrochemical oxidation, sonochemical, non-thermal plasma, supercritical fluid, electrochemical oxidation, and electrochemical reduction processes were reviewed. Chemical methods including ozone-based, hydrogen peroxide-based, potassium permanganate processes, and Fenton and Fenton-like process were reviewed. Biological methods such as aerobic, anoxic, anaerobic, bioreactors, constructed wetlands, soil bioremediation and biofilter processes for the management of hazardous wastes, in mode of consortium and pure culture were reviewed. Case histories were reviewed in four areas including contaminated sediments, contaminated soils, mixed industrial solid wastes and radioactive wastes.

Critical Perspective on Advanced Treatment Processes for Water and Wastewater: AOPs, ARPs, and AORPs

Emerging contaminants’ presence in water, wastewater, and aquatic environments has been widely reported. Their environmental and health-related effects, and the increasing tendency towards wastewater reuse require technology that could remove to a greater degree, or even mineralize, all these contaminants. Currently, the most commonly used process technologies for their removal are advanced oxidation processes (AOPs); however, recent advances have highlighted other advanced treatment processes (ATPs) as possible alternatives, such as advanced reduction processes (ARPs) and advanced oxidation-reduction processes (AORPs). Although they are not yet widely diffused, they may remove contaminants that are not readily treatable by AOPs, or offer better performance than the former. This paper presents an overview of some of the most common or promising ATPs for the removal of contaminants from water and wastewater, and their application, with discussion of their limitations and merits. Issues about technologies’ costs and future perspectives in the water sector are discussed.

Cohesive strength changes of sewer sediments during and after ultrasonic treatment: The significance of bound extracellular polymeric substance and microbial community

Sewer flushing is widely used to remove sewer sediment from drainage systems; however, its performance and cleaning efficiency are limited by the cohesive strength of sewer sediment. To address this, ultrasound, as a clean technology, is proposed to reduce the cohesive strength of sewer sediment. This study investigated the variations in the cohesive strength, extracellular polymeric substances (EPSs), and microbial community of sewer sediment with ultrasonic treatment. During ultrasonic conditioning, the degradation process of the cohesive strength followed the first-order kinetic model and was positively related to the degradation of bound-EPSs. Field emission scanning electron microscopy, particle diameter, and three-dimensional excitation emission analyses suggested that ultrasound reduced the cohesive strength by decreasing the bound-EPS concentration, which reduced the particle size of sewer sediment, and by destroying the structure of tryptophan proteins, which impaired the stability of agglomerated particles. Following ultrasonic treatment, the cohesive strength of the treated sediment was reduced to 69.3% of that of the raw sewer sediment after storage for 21 days; this result could be ascribed to the improvements in polysaccharide transport, amino acid transport, and the cell wall biogenesis functions of the microbial community, as indicated by PICRUSt. Furthermore, next-generation sequencing studies suggest that the proportions of Syntrophomonadaceae, Bacteroidetes_vadinHA17, Synergistaceae, and Syntrophaceae, which are associated with anaerobic digestion and methane production in sediment, improved conspicuously after ultrasonic conditioning.

Environmental application of monolithic carbonaceous aerogels for the removal of emerging pollutants

In this study, the performance of three commercial available monolithic carbonaceous aerogels (NQ30A, NQ60A and NQ80A) for the removal of different emerging pollutants, detected in water sources, was evaluated. More specifically, the removal of two pharmaceuticals (antipyrine and sulfamethoxazole) and an anti-fungal agent (methyl paraben), widely used in cosmetics, was studied. The NQ60A demonstrated the best adsorption characteristics and effectively adsorbed over 50 mg/g of the antipyrine and around 30 mg/g sulfamethoxazole and methyl paraben. The kinetic study of the adsorption process revealed that pseudo-first order kinetic model described very well the kinetic behaviour of the selected pollutants onto the NQ60A aerogel. After that, the regeneration of the loaded aerogel, with antipyrine alone and in presence of the other two contaminants, was evaluated. The regeneration was accomplished in two ways: (1) by using directly the loaded aerogels as cathode during the electro-Fenton treatment and (2) by its regeneration immersed in the bulk volume of electro-Fenton cell (boron doped diamond as anode and carbon felt as cathode). Both approaches can provide an effective removal of the pollutants inside the aerogel. In addition, the regenerated aerogel proved to maintain its adsorptive properties and can be successfully reused in successive cycles of adsorption-regeneration. On the basis of these promising results, it can be concluded that the proposed strategy based on aerogels adsorption and electro-Fenton regeneration is a suitable alternative for emerging pollutants removal from water streams.

Use of Ultrasound as an Advanced Oxidation Process for the Degradation of Emerging Pollutants in Water

Emerging pollutants are compounds of increased environmental importance and, as such there is interest among researchers in the evaluation of their presence, continuity and elimination in different environmental matrices. The present work reviews the available scientific data on the degradation of emerging pollutants, mainly pharmaceuticals, through ultrasound, as an advanced oxidation process (AOP). This study analyzes the influence of several parameters, such as the nature of the pollutant, the ultrasonic frequency, the electrical power, the pH, the constituents of the matrix and the temperature of the solution on the efficiency of this AOP through researches previously reported in the literature. Additionally, it informs on the application of the referred process alone and/or in combination with other AOPs focusing on the treatment of domestic and industrial wastewaters containing emerging pollutants, mainly pharmaceuticals, as well as on the economic costs associated with and the future perspectives that make ultrasound a possible candidate to solve the problem of water pollution by these emerging pollutants..

Potential formation of PCDD/Fs in triclosan wastewater treatment: An overall toxicity assessment under a life cycle approach

Wastewater may contain a diverse group of unregulated pollutants known as emerging pollutants, such as pharmaceuticals and personal care products (PPCPs). Triclosan (TCS) is a personal care product widely used as an antiseptic or preservative in cosmetics, hand wash, toothpaste and deodorant soaps. Advanced oxidation processes (AOPs) have been used as effective and alternative treatments for complex wastewater. However, an important criterion for the assessment of AOPs and their operation conditions could be the potential formation of new toxic secondary products, such as polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), especially when emerging pollutants are present in the media. If these are omitted from environmental management studies, the real environmental impacts of a WWTPs (wastewater treatment plants) may be underestimated. Consequently, the current study aims to evaluate the environmental impacts derived from electrooxidation (EOX), one of the most effective oxidation technologies, of emerging pollutants using Life Cycle Assessment. The analyses were performed for the treatment of effluents containing TCS, firstly without considering the formation of PCDD/Fs and, thereafter, considering the effects of these compounds. Total toxicity, calculated through different methods and corresponding impact factors, were evaluated for each stage of the process when different electrolytes are used, including PCDD/Fs formation. Finally, a sensitivity analysis was carried out to study i) the effect of the TCS initial concentration on the environmental impacts associated to ecotoxicity for the different life cycle methods and ii) the influence of changing the organic pollutant on PCDD/Fs formation employing 2-chlorophenol (2-CP). As a result, LCIA methods demonstrate that they are not fully adapted to the computation of PCDD/Fs in the water compartment, since only 2,3,7,8-tetraclorodibenzo-p-dioxina (2,3,7,8-TCDD) is present as a substance in the impact categories assessed, ignoring the remaining list of PCDD/Fs.

Optimal conditions for olive mill wastewater treatment using ultrasound and advanced oxidation processes

The treatment of olive mill wastewater (OMW) in Jordan was investigated in this work using ultrasound oxidation (sonolysis) combined with other advanced oxidation processes such as ultraviolet radiation, hydrogen peroxide (H₂O₂) and titanium oxide (TiO₂) catalyst. The efficiency of the combined oxidation process was evaluated based on the changes in the chemical oxygen demand (COD). The results showed that 59% COD removal was achieved within 90 min in the ultrasound /UV/TiO₂ system. A more significant synergistic effect was observed on the COD removal efficiency when a combination of US/UV/TiO₂ (sonophotocatalytic) processes was used at low ultrasound frequency. The results were then compared with the COD values obtained when each of these processes was used individually. The effects of different operating conditions such as, ultrasound power, initial COD concentration, the concentration of TiO₂, frequency of ultrasound, and temperature on the OMW oxidation efficiency were studied and evaluated. The effect of adding a radical scavenger (sodium carbonate) on the OMW oxidation efficiency was investigated. The results showed that the sonophotocatalytic oxidation of OMW was affected by the initial COD, acoustic power, temperature and TiO₂ concentration. The sonophotocatalytic oxidation of OMW increased with increasing the ultrasound power, temperature and H₂O₂ concentration. Sonolysis at frequency of 40 kHz combined with photocatalysis was not observed to have a significant effect on the OMW oxidation compared to sonication at frequency of 20 kHz. It was also found that the OMW oxidation was suppressed by the presence of the radical scavenger. The COD removal efficiency increased slightly with the increase of TiO₂ concentration up to certain point due to the formation of oxidizing species. At ultrasound frequency of 20 kHz, considerable COD reduction of OMW was reported, indicating the effectiveness of the combined US/UV/TiO₂ process for the OMW treatment.

Simple, fast and environmentally friendly method to determine ciprofloxacin in wastewater samples based on an impedimetric immunosensor

In this study an impedimetric immunosensor was developed in order to determine ciprofloxacin (CIP) in wastewater samples, an emergent contaminant widely found in wastewater. To achieve this, an anti-ciprofloxacin antibody was immobilized on the surface of a printed carbon electrode. Then, the developed immunosensor was applied in wastewater samples from Université Laval residences (Québec, Canada) through the load transfer resistance (R_ct) using [Fe(CN)₆]^3−/4− as a redox probe, and the average CIP concentration was found to be 2.90 × 10⁻⁴ μg mL⁻¹. The observed R_ct changes presented a linear relationship from CIP concentrations of 10⁻⁵ to 1.0 μg mL⁻¹, with detection and quantification limits of 2.50 × 10⁻⁶ and 7.90 × 10⁻⁶ μg mL⁻¹, respectively. The immunosensor presented high selectivity and repeatability, as well as a good recovery rate in wastewater samples (97%). Significant interference with other compounds was not observed. The proposed method requires only 30 μL of sample without the use of organic solvents or preceding sample preparation and/or extraction techniques. Moreover, the method is fast: only 20 min of incubation followed by 2 min of analysis time was sufficient to obtain the CIP concentration. The method's estimated cost is U$ 2.00 per sample.

In this study an impedimetric immunosensor was developed in order to determine ciprofloxacin (CIP) in wastewater samples, an emergent contaminant widely found in wastewater samples.

Advanced Oxidation Processes for the Removal of Antibiotics from Water. An Overview

In this work, the application of advanced oxidation processes (AOPs) for the removal of antibiotics from water has been reviewed. The present concern about water has been exposed, and the main problems derived from the presence of emerging pollutants have been analyzed. Photolysis processes, ozone-based AOPs including ozonation, O3/UV, O3/H2O2, and O3/H2O2/UV, hydrogen peroxide-based methods (i.e., H2O2/UV, Fenton, Fenton-like, hetero-Fenton, and photo-Fenton), heterogeneous photocatalysis (TiO2/UV and TiO2/H2O2/UV systems), and sonochemical and electrooxidative AOPs have been reviewed. The main challenges and prospects of AOPs, as well as some recommendations for the improvement of AOPs aimed at the removal of antibiotics from wastewaters, are pointed out.

Review on low- and high-frequency sonolytic, sonophotolytic and sonophotochemical processes for inactivating pathogenic microorganisms in aqueous media

Ultraviolet and ultrasound-based advanced oxidation processes (AOPs) are gaining considerable research attention for water treatment and disinfection. Compared to low-frequency ultrasound (LFUS, <100 kHz), high-frequency ultrasound (HFUS, >100 kHz and MHz range) for water disinfection remains much less investigated. The present review aims at surveying and discussing literature data on microbial inactivation in non-food aqueous media using HFUS alone and with AOPs. More specifically, the review covers sonophotolytic (US/UV) processes under sequential and simultaneous modes as well as sonophotochemical processes, where both low and high frequencies were applied. Addressing a state-of-the-art biomedical research, we have attempted to provide more insight into mechanical and sonochemical mechanisms of inactivation under ultrasonic exposure. Sonoporation, intracellular generation of reactive oxygen species (ROS), energy stimulation of aquaporins to deliver ROS, and injection of extracellular ROS into sonoporated cells have all been identified as primary ways of inactivation. Application of ultrasound in the 0.2-2 MHz range and mercury-free light sources to support the Minamata Convention on Mercury is an ongoing challenge for effective elimination of microbial pathogens from water and wastewater through sonophotolytic and sonophotochemical AOPs.

Comparative degradation of two highly consumed antihypertensives in water by sonochemical process. Determination of the reaction zone, primary degradation products and theoretical calculations on the oxidative process

This work compares the sonochemical degradation of losartan and valsartan (antihypertensives) in water. Initially, the suitable operational conditions of ultrasonic power density and frequency were established. Under such conditions, losartan was eliminated in a higher percentage than valsartan, which was associated to differences in their hydrophobicities. Additionally, degradations in presence of isopropanol and ferrous ions confirmed that losartan was closer to cavitation bubble than valsartan. The structures of primary products indicated that sonogenerated hydroxyl radical attacked biphenyl tetrazole moiety (common nucleus of both pharmaceuticals). Then, theoretical calculations were applied to the products to estimate the toxicity, degree of oxidation and probable routes of aerobic biodegradation suggesting a beneficial action of sonodegradation. Finally, the sonochemical degradation of the antihypertensives was carried out in two simulated complex matrices (i.e., seawater and hospital wastewater) and an actual wastewater. Interestingly, the losartan and valsartan eliminations in such waters were similar to the observed in distilled water. This fact indicates the high potentiality of ultrasound to degrade losartan or valsartan in waters containing other substances, even at higher concentrations than these pollutants.

Feasibility of anaerobic packed and structured-bed reactors for sulfamethoxazole and ciprofloxacin removal from domestic sewage

This study assessed the applicability of fixed bed bioreactors in two configurations - anaerobic structured bed reactor (ASBR) and anaerobic packed bed reactor (APBR) - in the removal of Sulfamethoxazole (SMX) and Ciprofloxacin (CIP), two antibiotics frequently detected in sanitary sewage. The problem of these pharmaceuticals as emerging contaminants in conventional sewage treatment systems is mainly because they encourage the development and spread of resistance genes in bacteria. Both reactors had similar performances, and the antibiotics were highly removed - APBR: 85 ± 10% for SMX and 81 ± 16% for CIP; ASBR: 83 ± 12% for SMX and 81 ± 15% for CIP. The ASBR showed to be potentially more feasible in operating and economic terms compared to the APBR, as the former presents a smaller amount of support material in the bed. SMX was completely biotransformed, while the influence of the sorption mechanism was observed for CIP, as its presence was detected sorbed onto biomass throughout the reaction bed of the reactors, with a partition coefficient (log K_D) of around 2.8 L·kg^-1TSS. The degradation kinetics of the pharmaceuticals were fitted using a first-order kinetic model, whereby the reactors behaved as plug flow ones, indicating the possibility of optimizing the operation for a hydraulic retention time of 6 h. The removal kinetics was more favorable for CIP (higher apparent constant kinetic - k_CIP^app > k_SMX^app), since its biodegradation is linked to the biomass, which is more concentrated in the bed bottom layer. The experimental results showed the potential of anaerobic fixed bed reactors in removing environmentally relevant concentrations of SMX and CIP found in sewage.