A critical review on antibiotics and hormones in swine wastewater: Water pollution problems and control approaches

A review on non-thermal plasma treatment of water contaminated with antibiotics

Large amounts of antibiotics are produced and consumed worldwide, while wastewater treatment is still rather inefficient, leading to considerable water contamination. Concentrations of antibiotics in the environment are often sufficiently high to exert a selective pressure on bacteria of clinical importance that increases the prevalence of resistance. Since the drastic reduction in the use of antibiotics is not envisaged, efforts to reduce their input into the environment by improving treatment of contaminated wastewater is essential to limit uncontrollable spread of antibiotic resistance. This paper reviews recent progress on the use of non-thermal plasma for the degradation of antibiotics in water. The target compounds removal, the energy efficiency and the mineralization are analyzed as a function of discharge configuration and the most important experimental parameters. Various ways to improve the plasma process efficiency are addressed. Based on the identified reaction intermediates, degradation pathways are proposed for various classes of antibiotics and the degradation mechanisms of these chemicals under plasma conditions are discussed.

Dual-imprinted mixed matrix membranes for selective recognition and separation: A synergetic imprinting strategy based on complex initiation system

Molecularly imprinted membranes (MIMs) with sufficient and even-distributed recognition sites that can break the permeability-selectivity trade-off phenomenon are desirable in chemical field of selective separation. Herein graphene oxide (GO)/TiO₂-loaded nanocomposite fibrous membranes were prepared by developing two kinds of tetracycline (TC)-imprinted systems in the same MIMs-based material. Thereinto, polydopamine-based and sol-gel-based imprinting processes were applied to the synthesis of GO/TiO₂-loaded dual-imprinted mixed matrix membranes (GT-DIMs). The as-prepared GT-DIMs encompassed innovative GO/TiO₂-based nanocomposite fibrous channels and two kinds of TC-imprinted systems, and critical comparisons regarding the fluxes, rebinding capacities and permselectivity were provided and studied. Importantly, dual-imprinted system of GT-DIMs could not only allow for largely enhanced rebinding result (70.63 mg/g) and fast adsorption equilibrium rate within 30 min, but also facilitate the high permselectivity of TC in complex separation systems and lab-simulated wastewater samples. The permselectivity factors were all around 5.0, which strongly demonstrated the efficiently selective recognition and separation performance of GT-DIMs. Overall, based on testing results of practical separation and scalability, excellent structural stability and separation continuity had been successfully obtained for selective separation applications of pollutants.

ZnCDs/ZnO@ZIF-8 Zeolite Composites for the Photocatalytic Degradation of Tetracycline

Considering the photocatalytic performance of CDs, ZnO, and the unique porous nanostructure and stability of ZIF-8, we prepared ZnCDs/ZnO@ZIF-8 zeolite composites. The resultant material represented an enhanced ability for the photodegradation of TC compared with that of ZnCDs and ZnO. The photocatalytic degradation efficiency reached over 85%. The catalytic activity of the composites was maintained after four cycles. The experimental result indicated that ⋅O2 radical was the active species in the reaction.

Effects of long-term exposure to oxytetracycline on phytoremediation of swine wastewater via duckweed systems

The effects of antibiotics on phytoremediation systems have attracted widespread attention to high concentrations of antibiotics in livestock wastewater. In this work, the effects of oxytetracycline (OTC) whose concentration was 0.05-1.00 mg/L on swine wastewater treatment by a duckweed-based phytoremediation systems were explored, including oxidative stress, nutrient production, bioconcentration, and community-level physiological profile. Results showed that the levels of H₂O₂ and peroxidases (PODs) of duckweed increased with an increase of OTC in the first 8 days. However, oxidative stress of duckweed disappeared after 18 days of exposure, except for 0.05 and 1.00 mg/L. Although OTC has negative effects on the production of high-value nutrients in duckweed, 0.05 and 0.25 mg/L OTC promoted the synthesis of starches and flavonoids, and the synthesis of vitamin C could restore after 28 days of exposure. In addition, a community-level physiological profile revealed that 0.05 mg/L OTC could significantly enhance the duckweed associated microorganisms metabolic activity. Therefore, this investigation adds to the understanding of antibiotics stress on high-value nutrients production in hydrophyte when was used to livestock wastewater management and also helps to clarify the metabolism profile of the phyllosphere and rhizosphere microbes; thereby providing new insight into effects of antibiotic on livestock wastewater phytoremediation.

Current Applications of Magnetic Nanomaterials for Extraction of Mycotoxins, Pesticides, and Pharmaceuticals in Food Commodities

Environmental pollutants, such as mycotoxins, pesticides, and pharmaceuticals, are a group of contaminates that occur naturally, while others are produced from anthropogenic sources. With increased research on the adverse ecological and human health effects of these pollutants, there is an increasing need to regularly monitor their levels in food and the environment in order to ensure food safety and public health. The application of magnetic nanomaterials in the analyses of these pollutants could be promising and offers numerous advantages relative to conventional techniques. Due to their ability for the selective adsorption, and ease of separation as a result of magnetic susceptibility, surface modification, stability, cost-effectiveness, availability, and biodegradability, these unique magnetic nanomaterials exhibit great achievement in the improvement of the extraction of different analytes in food. On the other hand, conventional methods involve longer extraction procedures and utilize large quantities of environmentally unfriendly organic solvents. This review centers its attention on current applications of magnetic nanomaterials and their modifications in the extraction of pollutants in food commodities.

Radical Scavenging and Catalytic Activity of Fe-Cu Bimetallic Nanoparticles Synthesized from Ixora finlaysoniana Extract

Iron–copper bimetallic nanoparticles (Fe-Cu BNPs) were prepared via a green synthesis route. Ixora finlaysoniana has been used in this study as a capping and stabilizing agent in the modification of Fe-Cu BNPs. As-synthesized BNPs were characterized using different techniques including UV/Vis spectrophotometry, FTIR, XRD and SEM. A particle size analyzer and SEM studies indicated the particle size to be in the range of 50–200 nm. In addition, degradation of MB dye in an aqueous system and radical-scavenging potential in a DPPH assay were also examined using BNPs. Methylene blue dye degradation in 17 min was monitored with UV/Vis spectrophotometry, which exhibited the efficiency of Fe-Cu BNPs. Bimetallic nanoparticles were also found to be efficient in neutralizing DPPH free radicals. Furthermore, kinetic studies of both dye degradation and radical scavenging potential are reported in this article. Subsequently, Fe-Cu BNPs synthesized via a green and sustainable method can be employed for dye degradation and free radical-scavenging activities.

Application of TiO2-Based Photocatalysts to Antibiotics Degradation: Cases of Sulfamethoxazole, Trimethoprim and Ciprofloxacin

The extensive application of antibiotics in human and veterinary medicine has led to their widespread occurrence in a natural aquatic environment. Global health crisis is associated with the fast development of antimicrobial resistance, as more and more infectious diseases cannot be treated more than once. Sulfamethoxazole, trimethoprim and ciprofloxacin are the most commonly detected antibiotics in water systems worldwide. The persistent and toxic nature of these antibiotics makes their elimination by conventional treatment methods at wastewater treatment plants almost impossible. The application of advanced oxidation processes and heterogeneous photocatalysis over TiO2-based materials is a promising solution. This highly efficient technology has the potential to be sustainable, cost-efficient and energy-efficient. A comprehensive review on the application of various TiO2-based photocatalysts for the degradation of sulfamethoxazole, trimethoprim and ciprofloxacin is focused on highlighting their photocatalytic performance under various reaction conditions (different amounts of pollutant and photocatalyst, pH, light source, reaction media, presence of inorganic ions, natural organic matter, oxidants). Mineralization efficiency and ecotoxicity of final products have been also considered. Further research needs have been presented based on the literature findings. Among them, design and development of highly efficient under sunlight, stable, recyclable and cost-effective TiO2-based materials; usage of real wastewaters for photocatalytic tests; and compulsory assessment of products ecotoxicity are the most important research tasks in order to meet requirements for industrial application.

Enhancing biochar sorption properties through self-templating strategy and ultrasonic fore-modified pre-treatment: Characteristic, kinetic and mechanism studies

The traditional anaerobic sewage treatment facilities are unsuitable for the widely uncontrolled spread of antibiotic residues in hospital or on livestock farm, which have raised the risk levels of high concentrations of antibiotic residues leakages and seriously threatened the aquatic ecology safeties. Thus, to develop an effective adsorbent with safe, low cost, and high firmly adsorptive capacity are imminent required. In this investigated, a self-templating hydrothermal alkali fore-modified & ultrasonic treatment was developed to achieve the highly adsorptive capacity and low desorption rate of biochar. As expected, the prepared biochar adsorbents present plenty of surface functional groups and micro pores. The BET value is raised up 1452 cm²·g^-1 for biochar treated by the associated alkali fore-modified and ultrasonic treatment (UFB), whereas it is only 415.8 cm²·g^-1 for the biochar treated by traditional carbonization (AC) and 1205 cm²·g^-1 for the biochar by further hydrothermal alkali fore-modification (FB). Congruously, UFB exhibits the removal abilities of 397.70 mg·g^-1 of levofloxacin (LEV) and 320.99 mg·g^-1 of chlorotetracycline (CTC), 3.5-6.3 times absorbability towards familiar antibiotics than traditional biochar. Moreover, the corresponding the lowest desorption of 1.30 mg·g^-1 (LEV) and 0.43 mg·g^-1 (CTC) mg·g^-1 by UFB have been confirmed. Meanwhile, Furthermore, both the adsorption and desorption mechanisms have been addressed by kinetic studies, pore width distributions, XPS and FTIR surveys. It is proposed the fore-modified treatment is more helpful for carbon functionalization while the ultrasonic treatment dedicates to the largely microporous structures. Consequently, the adsorption's capacity and stability of UFB adsorbents is large promoted due to its more micro- and meso-porous structure through a jointly hydrothermal alkali fore-modified and ultrasonic treatment. The present investigation will provide a novel alternative preparation strategy of the highly efficient adsorbent for emergency medical wastewater treatment.

Enhanced activated persulfate oxidation of ciprofloxacin using a low-grade titanium ore under sunlight: influence of the irradiation source on its transformation products

In this work, the activated persulfate oxidation of ciprofloxacin (CIP) using a low-grade titanium ore under sunlight or simulated sunlight were conducted to analyze the CIP degradation efficiency and to identify the transformation products (TPs) generated during oxidation under both types of irradiation sources by using liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). All advance oxidation process experiments were performed in a 2700-mL raceway reactor at a pH value of ~ 6.5 and an initial CIP concentration of 1 mg/L, during 90 min of reaction time. The control experiments carried out under simulated sunlight achieved a 97.7 ± 0.6% degradation efficiency, using 385 W/m² of irradiation with an average temperature increase of 11.7 ± 0.6 °C. While, the experiments under sunlight reached a 91.2 ± 1.3% degradation efficiency, under an average irradiation value of 19.2 ± 0.3 W/m² in October-November 2019 at hours between 11:00 am and 3:00 pm with an average temperature increase of 1.4 ± 0.8 °C. Mass spectrometry results indicated that 14 of the 108 possible TPs reported in the literature were detected. The calculated exact mass, measured accurate mass, and its characteristic diagnostic fragment ions were listed, and two new TPs were tentative identified. The TP generation analysis showed that some specific compounds were detected in different time intervals with kinetic variations depending on the irradiation used. Consequently, two CIP degradation pathways were proposed, since the type of irradiation determines the CIP degradation mechanism. Graphical abstract.

Preparation of Pd–Ni Nanoparticles Supported on Activated Carbon for Efficient Removal of Basic Blue 3 from Water

Pd–Ni nanoparticles supported on activated carbon (Pd–Ni/AC) were prepared using a phase transfer method. The purpose of synthesizing ternary composites was to enhance the surface area of synthesized Pd–Ni nanoparticles, as they have a low surface area. The resulting composite was characterized by scanning electronic microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) for investigating its surface morphology, particle size, percentage of crystallinity and elemental composition, respectively. The XRD data and EDX analysis revealed the presence of Pd–Ni alloys impregnated on the AC. Pd–Ni/AC was used as an adsorbent for the removal of the azo dye basic blue 3 from an aqueous medium. Kinetic and isotherm models were used to calculate the adsorption parameters. The most suitable kinetic model amongst the applied models was the pseudo-second-order model, confirming the chemisorption characteristics of the process, and the most suitable isotherm model was the Langmuir model, with a maximum adsorption capacity of 333 mg/g at 333 K. Different experimental parameters, such as the adsorbent dosage, pH, temperature and contact time, were optimized. The optimum parameters reached were: a pH of 12, temperature of 333 K, adsorbent dosage of 0.01 g and optimum contact time of 30 min. Moreover, the thermodynamics parameters of adsorption, such as Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°), showed the adsorption processes being exothermic with values of ΔH° equal to −6.206 kJ/mol and being spontaneous with ΔG° values of −13.297, −13.780 and −14.264 kJ/mol, respectively at 293, 313 and 333 K. An increase in entropy change (ΔS°) with a value of 0.0242 kJ/mol K, indicated the enhanced disorder at a solid–solution interface during the adsorption process. Recycling the adsorbent for six cycles with sodium hydroxide and ethanol showed a decline in the efficiency of the selected azo dye basic blue 3 up to 79%. The prepared ternary composite was found effective in the removal of the selected dye. The removal of other pollutants represents one of the possible future uses of the prepared adsorbent, but further experiments are required.

The performance of aerobic granular sludge for simulated swine wastewater treatment and the removal mechanism of tetracycline

In this study, aerobic granular sludge (AGS) cultivated in a sequencing batch reactor (SBR) was employed to investigate its ability on the decontamination of tetracycline (TC) from swine wastewater (SWW). The removal mechanism of TC by AGS was studied. Results showed that the AGS process could effectively remove chemical oxygen demand (COD), ammonium nitrogen (NH_{+ 4}-N), total phosphorus (TP), and TC during operation. The removal of TC by AGS was mainly due to adsorption and biodegradation, and the contribution rate of biodegradation increased after AGS adaptation to TC. Twenty-two by-products were detected during biodegradation of TC, and accordingly the degradation pathway of TC was speculated. Compared to the control reactor, the microbe diversity in different levels of classification was richer in the TC fed reactor according to the LefSe analysis. The results revealed that enzymes that participated in the metabolic pathway of microbial biodegradation of polycyclic aromatic compounds were enriched and may have played a key role in the biodegradation of TC.

Enhanced visible light photoelectrocatalytic degradation of tetracycline hydrochloride by I and P co-doped TiO2 photoelectrode

Elimination of antibiotics such as tetracycline hydrochloride (TC) from wastewater is of great significance, but still faces challenges. Herein, for the first time, I and P co-doped TiO₂ catalysts were prepared via a hydrolysis method. We also reported a simple method to prepare I and P co-doped TiO₂ photoelectrodes, which exhibited preeminent photoelectrocatalytic (PEC) performance for the decomposition of TC. The synergistic effect of I and P co-doping could significantly improve the charge separation rate and enhance the light absorption capacity of TiO₂, leading to an enhancement of PEC activity. The main factors affecting the PEC performance were investigated, and the highest degradation rate constant (4.20 × 10^-2 min^-1) was achieved when the doping content of P was 4 at% (ITP-4 photoelectrode) at pH 11.02 under visible light. The Langmuir-Hinshelwood kinetic model and active species trapping experiments were selected to investigate the degradation mechanism of TC. The results suggest that the hydroxyl radicals and photogenerated holes were the main active species that were responsible for the decomposition of TC. Moreover, the degradation pathways of TC based on the intermediates also demonstrated that the hydroxyl radicals and holes showed a principal role in degrading TC.

Anodic oxidation of ciprofloxacin using different graphite felt anodes: Kinetics and degradation pathways

Ciprofloxacin (CIP) is ubiquitous in the environment which poses a certain threat to human and ecology. In this investigation, the physical and electrochemical properties of graphite felt (GF) anodes which affected the anodic oxidation (AO) performance, and the CIP removal effect of GF were evaluated. The GFs were used as anodes for detection of ·OH with coumarin (COU) as molecule probe and removal of CIP in a 150 mL electrolytic cell with Pt cathode (AO-GF/Pt system). The results showed that hydrophilic GF (B-GF) owned higher sp³/sp² and more oxygen-containing and nitrogen-containing functional groups than the hydrophobic GF (A-GF). Moreover, B-GF possessed higher oxygen evolution potential (1.12 V), more active sites and stronger ·OH generation capacity. Above mentioned caused that B-GF exhibited more superior properties for CIP removal. The best efficiencies (96.95%, 99.83%) were obtained in the AO-B-GF/Pt system at 6.25 mAcm^-2 after 10 min (k₁, 0.356 min^-1) and 60 min (k₂, 0.224 min^-1), respectively. Furthermore, nine degradation pathways of CIP in AO-B-GF/Pt system were summarized as the cleavage of the piperazine ring, cyclopropyl group, quinolone ring and F atom by ·OH. It provides new insights into the removal and degradation pathways of CIP with GF in AO system.

Design of ultrathin nanosheet subunits ZnIn2S4 hollow nanocages with enhanced photoelectric conversion for ultrasensitive photoelectrochemical sensing

Herein, a high-efficiency photoactive material, hollow ZnIn₂S₄ nanocages (ZIS-HNCs) composed of ultrathin nanosheets were creatively synthesized via a metal-organic framework (MOF) derived solvothermal method. It had been specified the underlying mechanism of the ZIS-HNCs evolution under the MOF templated surface. Subsequently, the obtained ZIS-HNCs combined with annealing TiO₂ modified electrode (ZIS-HNCs@TiO₂), and the ZIS-HNCs@TiO₂ exhibited intense transient photocurrent. The enhanced photocurrent signal benefited from the multiple light capture effect of ZIS-HNCs, ultrathin nanosheet subunits of ZIS-HNCs, and typical type Ⅱ heterojunction, which could effectively retard the photoexcited electron-hole pairs recombination, and accelerated charge separation and transfer. Taking antibiotic lincomycin (Lin) as a model, a signal-off photoelectrochemical (PEC) aptasensor based on the ZIS-HNCs@TiO₂ was established and manifested a high sensitive detection for Lin with a linear response range from 0.0001 to 0.1 nM as well as an ultralow detection limit of 0.084 pM. Additionally, the proposed PEC aptasensor showed acceptable stability and remarkable selectivity. Therefore, this study provides a promising strategy to design nanomaterials with superior photoelectric activity for PEC sensing applications.

Occurrence, fate, and risk assessment of typical tetracycline antibiotics in the aquatic environment: A review

Tetracyclines (TCs), used as human and veterinary medicines, are the most widely used antibiotics. More than 75% of TCs are excreted in an active form and released into the environment through human and animal urine and feces, causing adverse effects on the ecological system and human health. Few articles review the environmental occurrence and behaviors of TCs, as well as their risks and toxicities. Here, we comprehensively summarized the recent advances on the following important issues: (1) Environmental occurrence of TCs. TCs are used globally and their occurrence in the aquatic environment has been documented, including surface water, groundwater, drinking water, wastewater, sediment, and sludge. (2) Environmental behaviors of TCs, particularly the fate of TCs in wastewater treatment plants (WWTPs). Most WWTPs cannot effectively remove TCs from wastewater, so alternative methods for efficient removal of TCs need to be developed. The latest degradation methods of TCs are summarized, including adsorption, photocatalytic, photochemical and electrochemical, and biological degradations. (3) Toxicities and possible risks of TCs. The toxicological data of TCs indicate that several TCs are more toxic to algae than fish and daphnia. Risk assessments based on individual compound exposure indicate that the risks arising from the current concentrations of TCs in the aquatic environment cannot be ignored.

The hybrid system successfully to consisting of activated sludge and biofilter process from hospital wastewater: Ecotoxicological study

This article aimed to demonstrate solution hospital wastewater due to more consumption of antibiotics, public concern has been significantly increased for usage, fates and occurrences of these emerging compounds in the environments and biota. Therefore, it does need more discoveries about occurrences and new treatment methods. Since the conventional treatment methods are low efficient on antibiotics, integration and combination of biological systems together or with an additional process has been shown that provided a better result. However, here, the potential of a full scale combined treating system with activated sludge-scoria biofilter (ASSB) was investigated for removal of ceftriaxone (CEF) and amoxicillin (AMX). To determine the potential biodegradability of proposed system, the solid-water distribution coefficient (K_d) was calculated. Overally, 118 samples were collected from three points; wastewater entering, exiting the activated sludge, and exiting the biofilter. To determine the amount of CEF and AMX antibiotics, the samples were analyzed using HPLC-UV. The results showed that the activated sludge system were able to eliminate the AMX and CEF antibiotics about 70.36 and 84.49%, respectively. In compare to activated sludge, the average mean of ASSB system for the removal efficiency were 87.53% (for AMX) and 93.17% (for CEF), respectively. As a result, it can be found that the efficiency of the combined activated sludge-biofilter system in removing of the low levels of antibiotics was more than individual activated system. The result of K_d revealed that AMX (with a K_d about 0.172) has lower tendency to biomass rather than CEF (with a K_d about 0.512). The ecological toxicity assessment guaranteed there is no risk for fish and daphnia when the activated sludge and also ASSB effluents to be discharged into the environment even without any diluting.

Phthalocyanine-Grafted Titania Nanoparticles for Photodegradation of Ibuprofen

The natural environment is constantly under threat from man-made pollution. More and more pharmaceuticals are recognized as emerging pollutants due to their growing concentration in the environment. One such chemical is ibuprofen which has been detected in processed sewage. The ineffectiveness of water methods treatment currently used raises the need for new remediation techniques, one of such is photodegradation of pollutants. In the present study, zinc(II) and copper(II) phthalocyanines were grafted onto pure anatase TiO2 nanoparticles (5 and 15 nm) to form photocatalysts for photodecomposition of ibuprofen in water. The nanoparticles were subjected to physicochemical characterization, including: thermogravimetric analysis, X-ray powder diffraction, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller surface area analysis and particle size measurements. In addition, they were assessed by means of electron spin resonance spectroscopy to evaluate the free radical generation. The materials were also tested for their photocatalytic activity under either UV (365 nm) or visible light (665 nm) irradiation. After 6 h of irradiation, almost complete removal of ibuprofen under UV light was observed, as assessed by liquid chromatography coupled to mass spectrometry. The reaction kinetics calculations revealed that the copper(II) phthalocyanine-containing nanoparticles were acting at a faster rate than those with zinc(II) derivative. The solutions after the photoremediation experiments were subjected to Microtox® acute toxicity analysis.

MOF-derived cluster-shaped magnetic nanocomposite with hierarchical pores as an efficient and regenerative adsorbent for chlortetracycline removal

The presence of large amounts of antibiotic residues can potentially threaten environmental sustainability and human health. Thus, it is imperative to develop convenient and effective technologies for eliminating antibiotics from aquatic environments, which are major contaminant reservoirs. Herein, based on Zn/Fe-MIL-88B, we designed and synthesized a magnetic nanocomposite (MC) that contains hierarchical pores and as an effective and regenerative adsorbent for the removal of chlortetracycline (CTC) from water. The characteristics of the MC and its CTC adsorption performance were investigated systematically. The synthesized MC sample pyrolyzed at 800 °C (MC-800) consisted of metallic iron and N/O-doped graphitic carbon along with cluster-like particles with a mesoporous structure. Further, the adsorption of CTC on MC-800 (maximum adsorption amount of 1158.0 mg/g) could be described using the Freundlich isotherm model and a pseudo-second-order model, indicating that the surface of MC-800 was heterogeneous. The adsorption is likely driven by weak chemical forces, including hydrogen bond formation, cation-π electron donor-acceptor (EDA), and π-π EDA interactions. Finally, MC-800 could be recovered readily through facile magnetic separation and regenerated such that its adsorption rate remained higher than 85% even after five cycles.

Catalytic hydrolysis of β-lactam antibiotics via MOF-derived MgO nanoparticles embedded on nanocast silica

The antibiotics abuse and the proliferation of antibiotic-resistant bacteria in the environment have a severe impact on both human health and ecosystem. In this study, a silica-nanocasting method was applied in Mg-MOF-74 template to generate a series of MgO/SiO₂ catalysts for the hydrolysis of β-lactam antibiotics. The Mg-based subunits in MOF-74 were converted to highly dispersed MgO nanoparticles with controllable particle size. MgO/SiO₂-80 with the smallest MgO particle size exhibits the best catalytic performance in the hydrolysis of four β-lactam antibiotics. The kinetics study reveals the higher degradation rate and lower activation energy of MgO/SiO₂-80 than other benchmark solid base catalysts. The proposed mechanism suggests that small MgO particle size provides more accessible oxygen anions with high proton affinity for the cleavage of the β-lactam ring, so that all hydrolytic products lose antimicrobial activity. The MgO/SiO₂-80 serves as the potential high-performance solid base catalyst for the real-world antibiotic wastewater treatment.

Cellulose nanocrystals/graphene oxide composite for the adsorption and removal of levofloxacin hydrochloride antibiotic from aqueous solution

Residual antibiotics in water are often persistent organic pollutants. The purpose of this study was to prepare a cellulose nanocrystals/graphene oxide composite (CNCs-GO) with a three-dimensional structure for the removal of the antibiotic levofloxacin hydrochloride (Levo-HCl) in water by adsorption. The scanning electron microscope, Fourier transform infrared (FT-IR), energy-dispersive spectroscopy, X-ray photoelectron spectroscopy and other characterization methods were used to study the physical structure and chemical properties of the CNCs-GO. The three-dimensional structure of the composite material rendered a high surface area and electrostatic attraction, resulting in increased adsorption capacity of the CNCs-GO for Levo-HCl. Based on the Box-Behnken design, the effects of different factors on the removal of Levo-HCl by the CNCs-GO were explored. The composite material exhibited good antibiotic adsorption capacity, with a removal percentage exceeding 80.1% at an optimal pH of 4, the adsorbent dosage of 1.0 g l^-1, initial pollutant concentration of 10.0 mg l^-1 and contact time of 4 h. The adsorption isotherm was well fitted by the Sips model, and kinetics studies demonstrated that the adsorption process conformed to a quasi-second-order kinetics model. Consequently, the as-synthesized CNCs-GO demonstrates good potential for the effective removal of antibiotics such as levofloxacin hydrochloride from aqueous media.

Food-processing wastes

Literature published in 2018 and literature published in 2019 related to food-processing wastes treatment for industrial applications are reviewed. This review is a subsection of the Treatment Systems section of the annual Water Environment Federation literature review and covers the following food-processing industries and applications: general, meat and poultry, fruits and vegetables, dairy and beverage, and miscellaneous treatment of food wastes. PRACTITIONER POINTS: This article summarizes literature reviews published in 2018 and in 2019 related to food processing wastes treatment for industrial applications are reviewed. This review is a subsection of the Treatment Systems section of the annual Water Environment Federation literature review and covers the following food processing industries and applications: general, meat and poultry, fruits and vegetables, dairy and beverage, and miscellaneous treatment of food wastes.

Developmental toxicity and transcriptome analysis of 4-epianhydrotetracycline to zebrafish (Danio rerio) embryos

As a primary degradation by-product of tetracycline (TC), 4-Epianhydrotetracycline (4-EATC) has been detected frequently in the aquatic environment, which may pose a potential environmental risk to aquatic organisms. Up to now, however, the toxicology study on 4-EATC to aquatic organisms is limited. In the present study, in order to better understand the toxic mechanism of 4-EATC, developmental toxicity including lethal and sublethal effects of 4-EATC and TC were investigated. The results showed that the developmental toxicity of 4-EATC to zebrafish embryos was stronger than that of TC. The 96 h LC₅₀ value of 4-EATC to zebrafish embryos was 29.13 mg/L. Malformations seemed to be the most sensitive sublethal endpoint of 4-EATC exposure, and the 96 h EC₅₀ value was 8.57 mg/L. Transcriptome response of 4-EATC to zebrafish embryos was determined. The results showed that 430 different expression genes (DEGs) caused by 4-EATC, and most enriched in tryptophan (TRP) metabolism pathway. Annotation of DEGs in the TRP metabolism demonstrated that expression of 4 gene products in tryptophan metabolized along the kynurenine (KYN) pathway were changed. Disorder of TRP catabolism in KYN pathway was a potential mechanism of 4-EATC toxicity to zebrafish embryos.

The Influence of Photoactive Heterostructures on the Photocatalytic Removal of Dyes and Pharmaceutical Active Compounds: A Mini-Review

The diversification of pollutants type and concentration in wastewater has underlined the importance of finding new alternatives to traditional treatment methods. Advanced oxidation processes (AOPs), among others, are considered as promising candidate to efficiently remove organic pollutants such as dyes or pharmaceutical active compounds (PhACs). The present minireview resumes several recent achievements on the implementation and optimization of photoactive heterostructures used as photocatalysts for dyes and PhACs removal. The paper is focused on various methods of enhancing the heterostructure photocatalytic properties by optimizing parameters such as synthesis methods, composition, crystallinity, morphology, pollutant concentration and light irradiation.

Intervention Strategies on the Wastewater Treatment Behavior of Swine Farmers: An Extended Model of the Theory of Planned Behavior

Untreated swine wastewater pollutes rivers and harms the environment. The pollution can be minimized if swine farmers take wastewater treatment (WWT) action before the wastewater is discharged into rivers. Thus, the WWT behavior of swine farmers is key to environmental sustainability. However, WWT behavior, characterized by high costs and inconvenience, has received little attention from previous studies. Due to the high cost, some intervention strategies are helpful in ensuring that farmers behave in a pro-environmental manner. Therefore, this study compares the effects of two intervention factors, i.e., environmental knowledge and perceived effectiveness of enforcement, on the WWT behavior of swine farmers in Taiwan. The comparisons and empirical tests are based on an extended model of the theory of planned behavior (TPB). The findings reveal that all three classic factors in the TPB, i.e., attitude, subjective norms, and perceived behavioral control, had significant and positive effects on the intention of farmers to perform WWT behavior. Contradicting most previous studies, behavioral intentions did not have a significant effect on WWT behavior; however, perceived behavioral control did. The total effects of both intervention factors on WWT behavior were significant and positive. Moreover, the total effect of environmental knowledge was larger than that of the perceived effectiveness of enforcement. The findings suggest that a combination of the two strategies of increasing the environmental knowledge of individuals and enhancing the enforcement of environmental regulations will be helpful in inducing the sustained WWT behavior of farmers. Policy makers can allocate more resources to increasing farmers’ environmental knowledge than to enhancing the enforcement of environmental regulations. Finally, future research directions are discussed.

Municipal Solid Waste Landfills: An Underestimated Source of Pharmaceutical and Personal Care Products in the Water Environment

Pharmaceutical and personal care products (PPCPs) have been the focus of increasing concern in recent decades due to their ubiquity in the environment and potential risks. Out-of-date PPCPs are usually discharged into municipal solid wastes (MSWs), enter the leachates in MSW landfills, and have serious adverse effects on the surrounding water environment. However, the occurrence and removal of PPCPs from landfill leachates have rarely been examined to date. This lack of knowledge makes the landfill an underestimated source of PPCPs in the environment. In this review, we collected the relevant publications of PPCPs in landfill leachates, systematically summarized the occurrence of PPCPs in landfill leachates globally, evaluated the removal performances for various PPCPs by different types of on-site full-scale leachate treatment processes, and assessed the impacts of landfill leachates on PPCPs in the adjacent groundwater. In particular, influencing factors for PPCPs in landfill leachates, including the physicochemical properties of PPCPs, climate conditions, and characteristics of landfill sites (i.e., landfill ages) as well as sociological factors (i.e., economic development), were extensively discussed to understand their occurrence patterns. Future perspectives were also proposed in light of the identified knowledge gaps. To the best of our knowledge, this is the first review regarding the occurrence and removal of PPCPs from landfill leachates worldwide.

Facile Fabrication of Flocculent Magnesium Silicate for the Adsorption of Oxytetracycline

The discharge of antibiotics and the potential threat to organisms posed by this have received increasing attention. In this work, flocculent magnesium silicate (FMS) was fabricated by a facile hydrothermal and freeze-drying process, and its adsorption behavior for antibiotic oxytetracycline (OTC) was investigated. FMS presented a sepiolite-type structure and the alkaline solution promoted its hydroxylation. A hierarchical pore structure ranging from micropores to macropores and a high specific surface area of 660 m2/g were exhibited. FMS exhibited a higher adsorption amount in neutral solution than in acidic or alkaline conditions as the physicochemical properties of FMS and OTC were significantly affected by the pH. Adsorption isotherm could be well-described by the Langmuir model, and the calculated saturated adsorption capacity was as high as 265 mg/g. Adsorption kinetics followed the pseudo-second-order kinetic model, and the adsorption rate-controlling step was intraparticle diffusion. Thermodynamic parameters indicated that the adsorption was a spontaneous physicochemical reaction. After five cycles, around 91% of the adsorption performance was still maintained, demonstrating the excellent reusability of FMS. The sepiolite-type FMS fabricated in this work could be applied to remove OTC from wastewater.

Synthesis of ZnO@Ag dumbbells for highly efficient visible-light photocatalysts

The photocatalytic activity (PCA) of ZnO@Ag nanocomposites for different concentrations of Ag is reported. Dumbbells shaped zinc oxide (ZnO) nanostructures with silver (Ag) nanoparticles were synthesized by a simple chemical colloidal method. The as synthesized nanocomposites (without any heat treatment) were used for optical and photocatalytic studies. The FESEM analysis shows that the composite catalysts are composed of ZnO dumbbells coated with spherical Ag nanoparticles. UV-visible spectrum of ZnO@Ag photocatalysts shows a strong absorption band of ZnO at 380 nm with a plasmonic peak of Ag at 440 nm. The PL emission intensity of the composites varies with Ag concentration and has a minimum for the catalyst containing 13.7% of Ag. A possible growth mechanism of ZnO nanostructures with hexagonal cross-section has been proposed. Photocatalytic property of the as synthesized ZnO and ZnO@Ag catalysts was studied by investigating the degradation of methylene blue (MB) dye on exposure to UV-visible radiation. A relatively faster degradation of the dye was observed for ZnO@Ag composites as compared to pure ZnO, showing an improved photocatalytic behavior in the visible region. We proposed a possible mechanism for the enhancement in photocatalytic activity of Ag coated ZnO photocatalysts.

Feasibility study on a new pomelo peel derived biochar for tetracycline antibiotics removal in swine wastewater

Removal of tetracycline antibiotics (TCs) by biochar adsorption is emerging as a cost-effective and environmentally friendly strategy. This study developed a novel pomelo peel derived biochar, which was prepared at 400 °C (BC-400) and 600 °C (BC-600) under nitrogen conditions. To enhance the adsorption capacity, BC-400 was further activated by KOH at 600 °C with a KOH: BC-400 ratio of 4:1. The activated biochar (BC-KOH) displayed a much larger surface area (2457.37 m²/g) and total pore volume (1.14 cm³/g) than BC-400 and BC-600. High adsorption capacity of BC-KOH was achieved for removing tetracycline (476.19 mg/g), oxytetracycline (407.5 mg/g) and chlortetracycline (555.56 mg/g) simultaneously at 313.15 K, which was comparable with other biochars derived from agricultural wastes reported previously. The adsorption data could be fitted by the pseudo-second-order kinetic model and Langmuir isotherm model successfully. The initial solution pH indicated the potential influence of TCs adsorption capacity on BC-KOH. These results suggest that pore filling, electrostatic interaction and π-π interactions between the adsorbent and adsorbate may constitute the main adsorption mechanism. BC-KOH can be used as a potential adsorbent for removing TCs from swine wastewater effectively, cheaply and in an environmentally friendly way.

Tetracyclines lead to ammonium accumulation during nitrification process

The effect of tetracyclines used for swine food-production (tetracycline and oxytetracycline) on enriched nitrifying bacteria cultures over time was investigated in this study. Short-term exposure assays were performed in different concentrations of each antibiotic, using ammonia oxidizing bacteria (AOB) culture and nitrifying bacteria. The results pointed out a higher inhibitory effect of tetracycline on both bacterial communities. The AOB was more sensitive to antibiotic exposure when compared to the nitrifying culture. Although high antibiotic concentrations were applied, the half maximal inhibitory concentration (IC₅₀) was achieved only for the AOB culture exposed to tetracycline at a concentration of 273 mg L^-1. Nonetheless, the long-term exposure assay demonstrated a reduction of the tetracycline inhibition effect against AOB. The exposure to 100 mg L^-1 of tetracycline (TC) did not show relevant influence over ammonium conversion efficiency; however, at 128 mg L^-1 of TC, the efficiency decreased from 94% to 72%. Further investigation revealed that TC reduced the final effluent quality due to the development of a resistance mechanism by AOB culture against this antibiotic. This mechanism involves increasing the excretion of extracellular polymeric substances (EPS) and soluble microbial products (SMP), which probably increases BOD, and reduces ammonia consumption by the bacterial culture.

Application of response surface methodology for optimization of oxytetracycline hydrochloride degradation using hydrogen peroxide/polystyrene-supported iron phthalocyanine oxidation process

Inspired by metalloporphyrin-based enzymes, a biomimetic catalyst, R-N-Fe, was prepared by grafting iron phthalocyanine (FePc) covalently onto a macroporous chloromethylated polystyrene-divinylbenzene resin (R), which was pre-functionalized using 4-aminopyridine (4-ampy) as an axial ligand. The novel catalyst was used for the degradation of oxytetracycline hydrochloride (OTCH). The response surface methodology was employed to optimize the independent operating parameters, including temperature, catalyst amount, H₂O₂ dosage, and initial pH value. The results displayed that the initial pH and temperature had the most significant effect on the removal efficiency. Under optimum conditions, the OTCH removal efficiency was 93.98%. Additionally, the classical quenching experiment and electron paramagnetic resonance (EPR) test indicated that R-N-Fe could generate hydroxyl radicals by decomposing H₂O₂, which was the main active species for eliminating OTCH. Furthermore, R-N-Fe can be easily recycled and can maintain high stability in the reusability test, rendering it a good potential for practical application.