A novel antibiotic wastewater degradation technique combining cavitating jets impingement with multiple synergetic methods

The effect of the combined system of hydrodynamic cavitation, ozone, and hydrogen peroxide on chlorophyll a and organic substances removal in the raw water

Increased levels of nutrients and algae can cause drinking water problems in communities. Harmful algal blooms affect humans, fish, marine mammals, birds, and other animals. In the present study, we investigated the use of a combined system [Hydrodynamic Cavitation, Ozone (O₃), and Hydrogen Peroxide (H₂O₂)] on the removal of Chlorophyll a and Organic substances in the raw water was investigated. The Effect of different operating conditions such as pH, cavitation time, pressure, distance, flow rate, ozone dose, and hydrogen peroxide concentration was studied. Utilizing the Taguchi design method, experiments were planned and optimized. The combined system treatment yielded a maximum reduction in Chlorophyll a and Total Organic Carbon (TOC) at an optimum condition of pH 5, cavitation pressure 5 bar, flow rate of 1 m³/h, a distance of 25 cm from the orifice plate, O₃ 3 g/h and 2 g/l of H₂O₂ concentrations. The most efficient factor in the degradation of TOC and Chlorophyll a, was cavitation pressure based on the percentage contributions of each parameter (38.64 percent and 35.05 percent, respectively). H₂O₂ was found to have the most negligible impact on degradation efficiency (4.24 percent and 4.11 percent, respectively).

In-situ degradation of Amphotericin B in a microbial electrochemical cell containing wastewater

Antimicrobial resistance raises serious medical implications and is primarily caused by indiscriminate usage and environmental contamination with antimicrobial agents. To prevent microbes from developing resistance against antimicrobial agents, they must be effectively degraded. This is the first study that investigates the degradation of Amphotericin B(AmB) with simultaneous wastewater treatment in a Microbial Peroxide producing cell (MPPC). Two sets of MPPCs (A and B) were used to degrade AmB oxidatively, one with H₂O₂ and the other with the microbial electro Fenton process in a catholyte containing 0.1% AmB. MPPC A and B had voltage outputs of 0.356 ± 3 V and 0.411 ± 2 V, producing 26 ± 0.04 mM and 44 ± 0.8 mM of H₂O₂ respectively. The structural changes of treated samples were analyzed using Fourier Transformed Infrared Spectroscopy, which revealed the disappearance of major characteristic bands such as the NH band (1556 cm^-1), the CH band Polyene ring (3358 cm^-1), and others, implying the disruption of multiple double bonds in polyene, resulting in the structure's lactone ring breakdown. Liquid chromatography quadrupole time-of-flight revealed the changes in retention time and peak area of treated samples in comparison to native AmB which also confirmed its structural changes. Such structural disruption induced the drug to lose its antifungal action since no zones of inhibition were detected in an antimicrobial susceptibility test against Candida albicans. The degradation of 57.05% and 69.83% of AmB by H₂O₂ and the Fenton process was also correlated with a reduction in COD. Simultaneously the anodic wastewater treatment in both the MPPCs had COD removal efficiency of 78% and 82% and the BOD removal efficiency was 75.38% and 90% respectively. The MPPC system's process conditions and reactor design could be optimized further to enhance antimicrobial degradation and wastewater treatment. This research offers a sustainable and efficient method for expediting antimicrobial degradation while simultaneously treating wastewater.

Low Intensity Focused Ultrasound Ignited “Deep-Penetration Nanobomb” (DPNB) for Tetramodal Imaging Guided Hypoxia-Tolerant Sonodynamic Therapy Against Hypoxic Tumors

Background

Sonodynamic therapy (SDT) has been regarded as a novel therapeutic modality for killing tumors. However, the hypoxic tumor microenvironment, especially deep-seated tumors distant from blood vessels, severely restricts therapeutic efficacy due to the oxygen-dependent manner of SDT.

Methods

Herein, we report a novel ultrasonic cavitation effect-based therapeutic modality that is able to facilitate the hypoxia-tolerant SDT for inducing hypoxic tumor death. A tLyP-1 functionalized liposomes is fabricated, composed of hematoporphyrin monomethyl ether gadolinium as the sonosentizer and perfluoropentane (PFP) as the acoustic environment regulator. Moreover, the tLyP-1 functioned liposomes could achieve active tumor homing and effective deep-penetrating into hypoxic tumors. Upon low intensity focused ultrasound (LIFU) irradiation, the acoustic droplet vaporization effect of PFP induced fast liquid-to-gas transition and quick bubbles explosion to generate hydroxyl radicals, efficiently promoting cell death in both normoxic and hypoxic microenvironment (acting as deep-penetration nanobomb, DPNB).

Results

The loading of PFP is proved to significantly enhance the therapeutic efficacy of hypoxic tumors. In particular, these DPNB can also act as ultrasound, photoacoustic, magnetic resonance, and near-infrared fluorescence tetramodal imaging agents for guiding the therapeutic process.

Conclusion

This study is the first report involving that liquid-to-gas transition based SDT has the potential to combat hypoxic tumors.

Rapid Degradation of Chlortetracycline Using Hydrodynamic Cavitation with Hydrogen Peroxide

Chlortetracycline (CTC), which has been frequently detected in surface water, is generated primarily by the discharge of high-concentration CTC wastewater from pharmaceutical and livestock plants. The development of effective CTC degradation technology is critical. In this study, the extent of CTC degradation at 80 mg/L was investigated by combining hydrodynamic cavitation (HC) and hydrogen peroxide (H₂O₂). The results indicate degradation ratios of 88.7% and 93.8% at 5 and 30 min, respectively. Furthermore, the possible mechanisms of CTC degradation were determined via HPLC-MS. The CTC degradation pathways include ring openings, C–N bond cleavage, demethylation, dehydroxylation, and desaturation in the sole system of HC, and a series of additional reactions, such as glycine conjugation and the cleavage of C–C double bonds, occurs in the binary system of HC + H₂O₂. Nevertheless, the treated water poses ecological risks and cannot be directly discharged into the environment. Therefore, HC + H₂O₂ treatment may be a rapid and effective primary method for the degradation of high-concentration CTC in pharmaceutical factories.

Biodegradation performance and anti-fouling mechanism of an ICME/electro-biocarriers-MBR system in livestock wastewater (antibiotic-containing) treatment

Livestock wastewater is an important reservoir of antibiotic resistance genes (ARGs) and antibiotic residues. Membrane fouling is one of the most challenging problems confining the operation and application of membrane bioreactor (MBR). In this work, a novel iron-carbon micro-electrolysis (ICME)/electro-biocarriers-MBR system was established to explore the performance of pollutant removal and anti-fouling for an actual livestock wastewater. A light-weight porous ceramsite (bulk density 0.98 g/cm³) was used as the MBR biocarriers. The electrons generated from iron corrosion in the ICME tank traveled through external wires to the stainless steel membrane modules of MBR and the protons were transferred from the MBR tank to the ICME tank through a salt bridge, thus producing a spontaneous electric field. Under the optimized conditions, the system exhibited chemical oxygen demand removal of 76.0%, total suspended solids removal of 100%, antibiotic removal of 86.4%, NH₄⁺-N removal of 91.1%, and ARGs reduction of 6-8 orders of magnitude. The quality of the final effluent can reach the national Class I-A discharge criteria. Adding ceramsite could not only effectively improve biodegradation performance but also alleviate membrane fouling through the migration and enrichment of microbial flora to the ceramsite. The self-generated electric field had no significant improvement effect on pollutant removal, but exhibited good anti-membrane fouling behavior which could be ascribed to (i) oxidization of membrane foulants by the electrochemical products (such as H₂O₂ and •OH radicals), and (ii) electrostatic repulsion of negatively charged foulants and bacterial cells. The bacterial community structure and diversity were studied using high-throughput pyrosequencing, and the results demonstrated the roles of electric field and biocarriers in enrichment of anti-fouling communities and repulsion of biofouling-creating communities.

Cavitation based treatment of industrial wastewater: A critical review focusing on mechanisms, design aspects, operating conditions and application to real effluents

Acoustic cavitation (AC) and hydrodynamic cavitation (HC) coupled with advanced oxidation processes (AOPs) are prominent techniques used for industrial wastewater treatment though most studies have focused on simulated effluents. The present review mainly focuses on the analysis of studies related to real industrial effluent treatment using acoustic and hydrodynamic cavitation operated individually and coupled with H₂O₂, ozone, ultraviolet, Fenton, persulfate and peroxymonosulfate, and other emerging AOPs. The necessity of using optimum loadings of oxidants in the various AOPs for obtaining maximum COD reduction of industrial effluent have been demonstrated. The review also presents critical analysis of designs of various HCRs that have been or can be used for the treatment of industrial effluents. The impact of operating conditions such as dilution, inlet pressure, ultrasonic power, pH, and operating temperature have been also discussed. The economic aspects of the industrial effluent treatment have been analyzed. HC can be considered as cost-efficient approach compared to AC on the basis of the lower operating costs and better transfer efficiencies. Overall, HC combined with AOPs appears to be an effective treatment strategy that can be successfully implemented at industrial-scale of operation.

Degradation of norfloxacin wastewater using kaolin/steel slag particle electrodes: Performance, mechanism and pathway

In this work, kaolin/steel slag particle electrodes (KSPEs) were synthesized using a calcination method, and they were used to degrade norfloxacin (NOR) wastewater in three-dimensional (3D) reactor. Characterization methods used by KSPEs included SEM, XRF, XRD and BET. The effects of cell voltage, initial pH, KSPEs dosage and initial NOR concentration on NOR degradation were studied in the optimization experiment of operating parameters. The NOR degradation rate and COD removal rate can reach 96.02% and 93.45% under the optimal parameters within 30 min, and energy consumption is 0.99 kWh m^-3. As a result, KSPEs shows excellent catalytic performance and cycling, and still has high electrocatalytic activity after 10 cycles. Finally, the degradation mechanism and degradation pathways of KSPEs to treat NOR are proposed.

Treatment of rhodamine B with cavitation technology: comparison of hydrodynamic cavitation with ultrasonic cavitation

This paper presents the use of hydrodynamic cavitation and ultrasonic cavitation technologies for treating rhodamine B (RhB) in simulated wastewater. Various parameters of each technology that influence the RhB degradation rate were compared and optimized. The results showed that the optimal conditions for the hydrodynamic cavitation determined by the single-factor method were as follows: inlet pressure, 0.4 MPa; initial concentration, 10 mg L⁻¹; reaction temperature, 30 °C; and pH value, 3. The RhB degradation rate was 38.7%. In addition, the optimal conditions for the ultrasonic cavitation determined by the response surface methodology were as follows: initial RhB concentration, 10 mg L⁻¹; ultrasonic power, 850 W; ultrasonic time, 100 min; addition amount of H₂O₂, 0.6%; and pH value, 3. The RhB degradation rate was 84.06%. We also found that the degradation of RhB by both cavitation technologies conformed to the first-order kinetic reaction model. The rate constant of UC was 5.22 × 10⁻³ min⁻¹ and that of HC was 4.35 × 10⁻³ min⁻¹. The ultrasonic cavitation has a stronger cavitation effect than hydrodynamic cavitation.

This paper presents the use of hydrodynamic cavitation and ultrasonic cavitation technologies for treating rhodamine B (RhB) in simulated wastewater.

Degradation of Antibiotics in Wastewater: New Advances in Cavitational Treatments

Over the past few decades, antibiotics have been considered emerging pollutants due to their persistence in aquatic ecosystems. Even at low concentrations, these pollutants contribute to the phenomenon of antibiotic resistance, while their degradation is still a longstanding challenge for wastewater treatment. In the present literature survey, we review the recent advances in synergistic techniques for antibiotic degradation in wastewater that combine either ultrasound (US) or hydrodynamic cavitation (HC) and oxidative, photo-catalytic, and enzymatic strategies. The degradation of sulfadiazine by HC/persulfate (PS)/H2O2/α-Fe2O3, US/PS/Fe0, and sono-photocatalysis with MgO@CNT nanocomposites processes; the degradation of tetracycline by US/H2O2/Fe3O4, US/O3/goethite, and HC/photocatalysis with TiO2 (P25) sono-photocatalysis with rGO/CdWO4 protocols; and the degradation of amoxicillin by US/Oxone®/Co2+ are discussed. In general, a higher efficiency of antibiotics removal and a faster structure degradation rate are reported under US or HC conditions as compared with the corresponding silent conditions. However, the removal of ciprofloxacin hydrochloride reached only 51% with US-assisted laccase-catalysis, though it was higher than those using US or enzymatic treatment alone. Moreover, a COD removal higher than 85% in several effluents of the pharmaceutical industry (500-7500 mg/L COD) was achieved by the US/O3/CuO process.

Experimental and numerical studies on the cavitation in an advanced rotational hydrodynamic cavitation reactor for water treatment

Hydrodynamic cavitation (HC) has emerged as one of the most potential technologies for industrial-scale water treatment. The advanced rotational hydrodynamic cavitation reactors (ARHCRs) that appeared recently have shown their high effectiveness and economical efficiency compared with conventional devices. For the interaction-type ARHCRs where cavitation is generated from the interaction between the cavitation generation units (CGUs) located on the rotor and the stator, their flow field, cavitation generation mechanism, and interaction process are still not well defined. The present study experimentally and numerically investigated the cavitation flow characteristics in a representative interaction-type ARHCR which has been proposed in the past. The cavitation generation mechanism and development process, which was categorized into "coinciding", "leaving", and "approaching" stages, were analyzed explicitly with experimental flow visualization and computational fluid dynamics (CFD) simulations. The changes in the cavitation pattern, area ratio, and sheet cavitation length showed high periodicity with a period of 0.5 ms/cycle at a rotational speed of 3,600 rpm in the flow visualization. The experimental and CFD results indicated that sheet cavitation can be generated on the downstream sides of both the moving and the static CGUs. The sheet cavitation was induced and continuously enlarged in the "leaving" and "approaching" stages and was crushed after the moving CGUs coincided with the static CGUs. In addition, vortex cavitation was formed in the vortex center of each CGU due to high-speed rotating fluid motion. The shape and size of the vortex cavitation were determined by the compression effect produced by the interaction. The findings of this work are important for the fundamental understanding, design, and application of the ARHCRs in water treatment.

A review on hydrodynamic cavitation disinfection: The current state of knowledge

Disinfection, which aims to eliminate pathogenic microorganisms, is an essential step of water treatment. Hydrodynamic cavitation (HC) has emerged as a promising technology for large-scale disinfection without introducing new chemicals. HC, which can effectively induce sonochemistry by mechanical means, creates extraordinary conditions of pressures of ~1000 bar, local hotspots with ~5000 K, and high oxidation (hydroxyl radicals) in room environment. These conditions can produce highly destructive effects on microorganisms in water. In addition, the enhancements of chemical reactions and mass transfers by HC produce the synergism between HC and disinfectants or other physical treatment methods. HC is generated by hydrodynamic cavitation reactors (HCRs), therefore, their performance basically determines the effectiveness, economical efficiency, and applicability of HC disinfection. Therefore, developing high-performance HCRs and revealing the corresponding disinfection mechanisms are the most crucial issues today. In this review, we summarize the fundamental principles of HC and HCRs and recent development in HC disinfection. The energy release from cavitation phenomenon and corresponding mechanisms are elaborated. The performance (effectiveness, treatment ratio, and cost) of various HCRs, effects of treatment conditions on performance, and applicability of HC disinfection are evaluated and discussed. Finally, recommendations are provided for the future progress based on the analysis of previous studies.

Hydrodynamic Cavitation: A Promising Technology for Industrial-Scale Synthesis of Nanomaterials

One of the most challenging issues for the large-scale application of nanomaterials, especially nanocarbons, is the lack of industrial synthetic methods. Sonochemistry, which creates an extreme condition of high pressure and temperature, has been thereby applied for synthesizing a wide variety of unusual nanostructured materials. Hydrodynamic cavitation (HC), characterized by high effectiveness, good scalability, and synergistic effect with other physical and chemical methods, has emerged as the promising sonochemistry technology for industrial-scale applications. Recently, it was reported that HC can not only significantly enhance the performance of biochar, but also preserve or improve the respective chemical composition. Moreover, the economic efficiency was found to be at least one order of magnitude higher than that of conventional methods. Due to the great potential of HC in the industrial-scale synthesis of nanomaterials, the present perspective focuses on the mechanism of sonochemistry, advances in HC applications, and development of hydrodynamic cavitation reactors, which is supposed to contribute to the fundamental understanding of this novel technology.

Enhanced degradation of antibiotics by photo-fenton reactive membrane filtration

Micropollution such as pharmaceutical residuals potentially compromises water quality and jeopardizes human health. This study evaluated the photo-Fenton ceramic membrane filtration toward the removal of sulfadiazine (SDZ) as a common antibiotic chemical. The batch experiments verified that the photo-Fenton reactions with as Goethite (α-FeOOH) as the photo-Fenton catalyst achieved the degradation rates of 100% within 60 min with an initial SDZ concentration of 12 mg·L^-1. Meanwhile, a mineralization rate of over 80% was obtained. In continuous filtration, a negligible removal rate (e.g., 4%) of SDZ was obtained when only filtering the feed solution with uncoated or catalyst-coated membranes. However, under Ultraviolet (UV) irradiation, both the removal rates of SDZ were significantly increased to 70% (no H₂O₂) and 99% (with H₂O₂), respectively, confirming the active degradation by the photo-Fenton reactions. The highest apparent quantum yield (AQY) reached up to approximately 25% when the UV₂₅₄ intensity was 100 μW·cm^-2 and H₂O₂ was 10 mmol·L^-1. Moreover, the photo-Fenton reaction was shown to effectively mitigate fouling and prevent flux decline. This study demonstrated synchronization of photo-Fenton reactions and membrane filtration to enhance micropollutant degradation. The findings are also important for rationale design and operation of photo-Fenton or photocatalytic membrane filtration systems.

Enhanced Degradation of Sulfamethoxazole (SMX) in Toilet Wastewater by Photo-Fenton Reactive Membrane Filtration

Pharmaceutical residuals are increasingly detected in natural waters, which made great threat to the health of the public. This study evaluated the utility of the photo-Fenton ceramic membrane filtration toward the removal and degradation of sulfamethoxazole (SMX) as a model recalcitrant micropollutant. The photo-Fenton catalyst Goethite (α-FeOOH) was coated on planar ceramic membranes as we reported previously. The removal of SMX in both simulated and real toilet wastewater were assessed by filtering the feed solutions with/without H₂O₂ and UV irradiation. The SMX degradation rate reached 87% and 92% respectively in the presence of UV/H₂O₂ for the original toilet wastewater (0.8 ± 0.05 ppb) and toilet wastewater with a spiked SMX concentration of 100 ppb. The mineralization and degradation by-products were both assessed under different degradation conditions to achieve deeper insight into the degradation mechanisms during this photo-Fenton reactive membrane filtration. Results showed that a negligible removal rate (e.g., 3%) of SMX was obtained when only filtering the feed solution through uncoated or catalyst-coated membranes. However, the removal rates of SMX were significantly increased to 67% (no H₂O₂) and 90% (with H₂O₂) under UV irradiation, respectively, confirming that photo-Fenton reactions played the key role in the degradation/mineralization process. The highest apparent quantum yield (AQY) reached up to approximately 27% when the H₂O₂ was 10 mmol·L⁻¹ and UV254 intensity was 100 μW·cm⁻². This study lays the groundwork for reactive membrane filtration to tackle the issues from micropollution.

Hydrodynamic cavitation degradation of Rhodamine B assisted by Fe3+-doped TiO2: Mechanisms, geometric and operation parameters

In this paper, a novel method, hydrodynamic cavitation (HC) combined with Fe³⁺-doped TiO₂, for the degradation of organic pollutants in aqueous solution is reported. The venturi tubes with different geometric parameters (size, shape and half divergent angle) are designed to obtain a strong HC effect. The structure, morphology and chemical composition of prepared Fe³⁺-doped TiO₂ as catalyst are characterized via using XRD, SEM, TEM, XPS, UV-vis DRS and PL methods. The effects of added TiO₂ (heat-treated at different temperatures for different times) and Fe³⁺-doped TiO₂ (with different mole ratios of Fe and Ti) on the HC catalytic degradation of RhB are discussed. The influences of operation parameters including inlet pressure, initial RhB concentration and operating temperature on the HC catalytic degradation of RhB are studied by Box-Behnken design (BBD) and response surface methodology (RSM). Under 3.0 bar inlet pressure for 10 mg/L initial concentration of RhB solution at 40 °C operating temperature in the presence of Fe³⁺-doped TiO₂ with 0.05:1.00 M ratio of Fe and Ti, the best HC degradation ratio can be obtained (91.11%). Furthermore, a possible mechanism of HC degradation of organic pollutants in the presence of Fe³⁺-doped TiO₂ is proposed. Perhaps, this study may provide a feasible method for a large-scale treatment of dye wastewater.

Experimental Investigation of Sludge Treatment Using a Rotor-Stator Type Hydrodynamic Cavitation Reactor and an Ultrasonic Bath

In the present work, the sludge treatment performance of a sludge treatment using a rotor-stator type hydrodynamic cavitation reactor (HCR) was investigated. To verify the performance, a comparison with an ultrasonic bath was conducted in four experimental cases using three assessment factors. The HCR consisted of a rotor and three covers with inserted dimples resulting in variation of the cross-sectional area in a flow. The experimental cases were established using the same energy consumption for each device. Disintegration performance was analyzed with assessment factors using particle size distribution and sludge volume index (SVI), oxidation performance using total chemical oxygen demand (TCOD) and volatile suspended solids (VSS) reduction rate, as well as solubilization rate using soluble chemical oxygen demand (SCOD). As a result, the particle disintegration and oxidation performance of the HCR were generally superior to those of the ultrasonic bath. However, due to the contradictory interactions of these factors, the solubilization rate of the two devices was measured similarly as 42.3% and 41.4% for each device. Results of the current study proved that the HCR can be an effective, promising and clean sludge treatment technique for use in wastewater treatment plants.

Influence of amoxicillin after pre-treatment on the extracellular polymeric substances and microbial community of anaerobic granular sludge

A combined process coupling a Fe₃O₄ nanoparticles (Fe₃O₄ NPs) heterogeneous Fenton-like reaction and an anaerobic biological technology was investigated in order to effectively treat amoxicillin-containing wastewater. With the increase in the pretreatment degree, the average COD removal rate correspondingly increased from 84.8% to 92.4% using the anaerobic biological treatment, and the biodegradability and COD removal efficiency was improved by the pretreatment processes. During the process of amoxicillin degradation, hydroxyl free radicals tended to attack the lactamide, amide and pentacyclic rings of amoxicillin. In the excitation-emission matrix (EEM) spectra of soluble microbial products (SMPs), the absorption peak of humic acid gradually decreased with application of the pretreatment. The pretreatment products were more beneficial to the characteristics of anaerobic granular sludge. For the microbial community structure, the proportion of Methanothrix and Clostridia increased with addition the heterogeneous Fenton-like pretreatment, which favored conversion of organic contaminants to volatile fatty acids and biogas.