NPA-Cu2+ Complex as a Fluorescent Sensing Platform for the Selective and Sensitive Detection of Glyphosate.

Glyphosate is a highly effective, low-toxicity, broad-spectrum herbicide, which is extensively used in global agriculture to control weeds and vegetation. However, glyphosate has become a potential threat to human and ecosystem because of its excessive usage and its bio-concentration in soil and water. Herein, a novel turn-on fluorescent probe, N-n-butyl-4-(3-pyridin)ylmethylidenehydrazine-1,8-naphthalimide (NPA), is proposed. It efficiently detected Cu2+ within the limit of detection (LOD) of 0.21 µM and displayed a dramatic turn-off fluorescence response in CH3CN. NPA-Cu2+ complex was employed to selectively and sensitively monitor glyphosate concentrations in real samples accompanied by a fluorescence turn-on mode. A good linear relationship between NPA and Cu2+ of glyphosate was found in the range of 10-100 µM with an LOD of 1.87 µM. Glyphosate exhibited a stronger chelation with Cu2+ than NPA and the system released free NPA through competitive coordination. The proposed method demonstrates great potential in quantitatively detecting glyphosate in tap water, local water from Songhua River, soil, rice, millet, maize, soybean, mung bean, and milk with mild conditions, and is a simple procedure with obvious consequences and no need for large instruments or pretreatment.

Electrochemically controlled solid phase microextraction based on a conductive polyaniline-graphene oxide nanocomposite for extraction of tetracyclines in milk and water.

BACKGROUND: Tetracycline antibiotics are employed for human and animal health and for speeding up growth rates. However, their presence in food products and environmental waters has been a concern for some years. Therefore, a variety of sample preparation methods have been developed for the analysis of tetracycline residues in these matrices. RESULTS: An electrochemically controlled solid phase microextraction based on a modified copper electrode with polyaniline/graphene oxide (PANI/GO) conductive nanocomposite was developed for the extraction of oxytetracycline, tetracycline and doxycycline before high-performance liquid chromatography-UV analysis. PANI/GO was synthesized by in situ chemical oxidative polymerization, characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy, and bound on the electrode using high purity conductive double-sided adhesive carbon glue. The significant factors affecting the performance of microextraction were investigated and optimized. Under the optimized conditions [sample, 15 mL; sorbent, 10 mg; pH, 3.0; electroextraction voltage, -0.9 V; electroextraction time, 20 min; eluent (MeOH/NH3 ), 500 µL; and desorption time, 5 min], the limits of detection for target analytes were in the ranges 0.32-1.01 and 2.42-7.59 µg L-1 in water and milk samples, respectively. The linear ranges were 1.06-750 µg L-1 for water and 8.05-750 µg L-1 for milk samples. The intra-day and inter-day precisions were 2.32-3.80 and 3.29-4.25, respectively. The method was applied to the determination of analytes in milk and water samples with different fat contents, and the recoveries were obtained in the range 71-104%. CONCLUSION: The developed electro-microextraction method provides a facile, rapid, cost-effective, sensitive and efficient promising procedure for the extraction of antibiotics in complex matrices. © 2020 Society of Chemical Industry.

Microbial pathogen removal from domestic effluent using coral sand in Kiribati.

AIM: Infiltration experiments aimed to show the effectivity of coral sand to remove micro-organisms in septic tank wastewater treatment system, in South Tarawa, Kiribati. METHODS AND RESULTS: Laboratory experiments evaluated effective microbial removal properties of a packed bed of coral beach sand conditioned with domestic effluent. Bacterial and viral indicators Escherichia coli J6-2, Enterococci faecalis and f-RNA (MS2) bacteriophage, along with viral pathogens adenovirus, echovirus, norovirus and rotavirus, were dosed (at 106 -107  CFU, PFU or genome copies per ml concentration) with effluent to unsaturated coral sand-packed columns. For the conditions simulated, all organisms showed removal efficiencies of >4-Log Removal Values (LRVs) (i.e. >99·99% effective reduction in number). Results revealed that the conditioned coral sand had a higher affinity for attenuating viruses than the bacteria tested. MS2 phage, adenovirus, echovirus, norovirus and rotavirus were absent in leachate from the base of the sand columns. E. coli J6-2 and E. faecalis were recovered at 100 -101  CFU (colony forming units) per ml in the column effluent, following a dosage of 106  CFU per ml. Destructive sampling of the columns after experiments revealed that a high proportion of viral pathogens were retained in the top 30 mm of the sand. CONCLUSIONS: On the basis of the relative spatial distribution of trace organisms in the sand, we speculate that adsorption processes likely dominated attenuation of the viral pathogens, more so than physical straining effects. Further study is required to fully elucidate the removal mechanisms. SIGNIFICANCE AND IMPACT OF THE STUDY: To the best of our knowledge this is the first study of the effective microbial removal capacity of coral sand under unsaturated conditions. The work represents an initial exploratory step of developing some standardized design practice of on-site wastewater treatment systems in Kiribati, to offer enhanced protection of groundwater resources and reduce diarrhoeal disease.

Evaluation of degradation behavior over tetracycline hydrochloride by microbial electrochemical technology: Performance, kinetics, and microbial communities.

Tetracycline hydrochloride (TCH), as a typical antibiotic-pollutant, is desired to enhance its removal from public environment, due to its toxicity and persistence. Microbial electrochemical technology (MET) is a series complex microorganisms-driven processes with characteristics of simultaneous wastewater treatment and electricity generation. The study was presented to evaluate the TCH removal behavior and power generation performance through the co-metabolism under constant glucose with different TCH concentrations using MET. It was found that the TCH removal efficiency arrived at 40% during the first 6 h, when TCH concentrations ranged from 1 to 50 mg/L. It was interesting that TCH degradation rate increased to a maximum of 4.15 × 10-2 h-1 with its concentrations varying from 1 to 20 mg/L, however, the further increase to 50 mg/L in TCH concentration resulted in a reverse 66% reduction. In the meantime, the generated bioelectricity declared a similar fluctuation trend with a maximum power density of 600 mW/m2 under the condition of 20 mg/L TCH co-degradation with glucose. What's more, the TCH inhibition effect fitted well with Haldane's model, indicating that the microbial electrochemical system had a better potency toward TCH toxicity than that reported (EC50 = 2.2 mg/L). Thauera as mainly functional aromatics-degrading bacteria and Bdellovibrio against bacterial pathogens, only existed in the mixed cultures with TCH and glucose, indicating extremely remarkable changes in bacterial community with TCH addition. In summary, a new approach for the anaerobic biodegradation of TCH was explored through co-metabolism with glucose using MET. The results should be useful for antibiotics wastewater disposal of containing TCH.

A nanocomposite consisting of etched multiwalled carbon nanotubes, amino-modified metal-organic framework UiO-66 and polyaniline for preconcentration of polycyclic aromatic hydrocarbons prior to their determination by HPLC.

A polyaniline composite doped with etched multi-walled carbon nanotubes and UiO-66-NH2 was prepared by electropolymerization. It was used as a sorbent to extract the polycyclic aromatic hydrocarbons (PAHs) phenanthrene, fluoranthene and pyrene. Its surface morphology, crystal structure and capability of adsorbing PAHs were characterized by scanning electron microscopy, X-ray photoelectron spectrometry, Fourier transform infrared spectrometry and zeta potentiometry. The π stacking and anion-π interactions are shown to play dominant roles in the sorption mechanism. Coupled with high performance liquid chromatography, the composite-modified fiber was applied to detect PAHs in lake water samples by direct immersion extraction. The method excels by (a) wide linear range (0.05-20 ng mL-1), (b) low limits of detection (10 pg mL-1), (c) satisfactory recovery from spiked samples (84.7-113.8%), and (d) good reproducibility (relative standard deviations of <6.5%). The method is superior in terms of costs and reproducibility compared to some pretreatment methods with mass spectrometric detection. Graphical abstractSchematic representation for interaction between PANI-etched MWCNT/UiO-66-NH2 and polycyclic aromatic hydrocarbons (phenanthrene, fluoranthene, pyrene).

Double surfactants-assisted electromembrane extraction of cyromazine and melamine in surface water, soil and cucumber samples followed by capillary electrophoresis with contactless conductivity detection.

BACKGROUND: Cyromazine (CYR) and its main degradation product melamine (MEL) are attracting wide attention due to their potential hazards to the environment and humans. In this work, double surfactants-assisted electromembrane extraction (DS-EME) by Tween 20 and alkylated phosphate was firstly used for purification and extraction of CYR and MEL, and the extract was directly analyzed by capillary electrophoresis with capacitively coupled contactless conductivity detection. RESULTS: Under the optimum conditions, two targets could be well separated from the main interferences, including common biogenic amines and inorganic cations within 14 min. This developed method was successfully applied to the analyses of surface water, soil and cucumber samples, and the average recoveries were in the range 93.3-112%. DS-EME provided a synergistic purification and enrichment effect for CYR and MEL by adding Tween 20 and alkylated phosphate into donor phase and supporting liquid membrane, respectively. Satisfactory limits of detection [0.2-1.5 ng mL-1 , signal-to-noise ratio (S/N) = 3] could be obtained in the tested sample matrices, and the corresponding enrichment factors were up to 115∼123 times. CONCLUSION: This developed method provides an alternative for the simultaneous analysis of CYR and MEL in complex real-world samples. © 2019 Society of Chemical Industry.

Biosynthesis of silver nanoparticles by cell-free extracts from some bacteria species for dye removal from wastewater.

OBJECTIVES: To investigate the biosynthesis of silver nanoparticles (AgNPs) using extracts of some bacterial isolates Bacillus pumilus, Bacillus paralicheniformis and Sphingomonas paucimobilis. The formation of AgNPs was detected by the change in color into yellow and confirmed by the UV-Vis spectroscopy. The nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). RESULTS: The obtained AgNPs were spherical to oval in shape with particle size ranged from 4 to 20 nm and surface area 118 m2/g. The AgNPs have been used as nanocatalyst for the removal of malachite green dye (MG) from aqueous solution. The dye was chosen as a model dye released in wastewater. The AgNPs showed excellent nanocatalyst for the removal of MG. The dye removal process was observed by the continuous decrease in dye absorbance at 617 nm until it vanished over 160 min. The removal kinetics followed closely the pseudo-first-order kinetic model. CONCLUSION: The B. paralicheniformis strain KJ-16 was the most effective isolated bacteria to give extract for biosynthesis of AgNPs and dye removal. This method may be considered easy and eco-friendly, and could be applicable for large-scale decontamination of wastewater from harmful dyes.

Detection of pathogenic Leptospira in ornamental water fountains from urban sites in Cali, Colombia.

Leptospirosis is a disease endemic to both rural and urban areas of tropical countries and resource-poor communities. Little information is available on the presence of Leptospira spp. in urban water sources. A study was conducted to detect pathogenic Leptospira in ornamental water fountains in Cali, Colombia. Twenty-seven water fountains were tested for pathogenic Leptospira using a multiplex PCR assay targeting the secY and the flaB genes. Pathogenic Leptospira was confirmed in 11 (41%) ornamental water fountains. Plazas, building exteriors, and sidewalks presented the highest proportion (67%) of pathogenic Leptospira-positive water fountains. Urban ornamental water fountains might be sources of pathogenic Leptospira and might pose a risk to humans who come into close contact, although relevance from a public health perspective is yet to be established.

Parametric optimization of domestic wastewater treatment in an activated sludge sequencing batch reactor using response surface methodology.

In this work, the parametric optimization of real domestic wastewater treated in an activated sludge sequencing batch reactor (SBR) was performed by means of the response surface methodology (RSM). The influences of influent organic matter concentration as chemical oxygen demand (CODinf), biomass concentration (Xs) and aeration time (t) on the COD, organic matter removal efficiency as COD (η) and sludge volume index (SVI) were determined to evaluate the performance of activated sludge SBR. The results showed that organic matter efficiency and maximum SVI were obtained at a t of 12 h, 300 mg L-1 of CODinf and 2000 mg L-1 of Xs. The SBR-activated sludge exhibited a η of 73% and an SVI of 119 mL g-1. Both values indicated a very good performance. Furthermore, the COD of the effluent under these conditions complied with Mexican regulations for wastewater discharged into water bodies.

Underestimated effects of sediments on enhanced startup performance of biofilm systems for polluted source water pretreatment.

In order to evaluate the enhancement mechanisms of enhanced startup performance in biofilm systems for polluted source water pretreatment, three lab-scale reactors with elastic stereo media (ESM) were operated under different enhanced sediment and hydraulic agitation conditions. It is interesting to found the previously underestimated or overlooked effects of sediment on the enhancement of pollutants removal performance and enrichment of functional bacteria in biofilm systems. The maximum NH4+-N removal rate of 0.35 mg L-1 h-1 in sediment enhanced condition was 2.19 times of that in control reactor. Sediment contributed to 42.0-56.5% of NH4+-N removal and 15.4-41.2% of total nitrogen removal in different reactors under different operation conditions. The enhanced hydraulic agitation with sediment further improved the operation performance and accumulation of functional bacteria. Generally, Proteobacteria (48.9-52.1%), Bacteroidetes (18.9-20.8%) and Actinobacteria (15.7-18.5%) were dominant in both sediment and ESM bioiflm at  phylum level. The potentially functional bacteria found in sediment and ESM biofilm samples with some functional bacteria mainly presented in sediment samples only (e.g., Genera Bacillus and Lactococcus of Firmicutes phylum) may commonly contribute to the removal of nitrogen and organics.

Porous MnFe2O4@SiO2 magnetic glycopolymer: A multivalent nanostructure for efficient removal of bacteria from aqueous solution.

The focuses of this research is to prepare an efficient magnetic glycopolymer for bacteria removal from aqueous solution. To perform this idea; porous MnFe2O4@SiO2 was functionalized with glucose and or maltose as an anchors to adhere onto bacteria cell surface. Aminopropyltriethoxysilane was employed to link the saccharides on magnetic nanoparticle surface. The hybrid materials were characterized with XRD, VSM, FT-IR, FESEM, TEM, zeta potential measurement and elemental mapping. Microscopic image showed that MnFe2O4 is in cluster form composed from tiny nanoparticles. After saccharide functionalization hybrid composite generate hyper-crosslinked porous structure as a result of polysilicate formation due to hydrolysis of silica source. Escherichia coli and bacillus subtilis were selected as sample pathogens to evaluate the bacteria capturing ability of the magnetic glycopolymer. At the optimum conditions (pH = 6, time of 20 min, dosage of 15 mg) removal efficiency was more than 99% using both saccharide.

Removal of mercury from contaminated saline wasters using dithiocarbamate functionalized-magnetic nanocomposite.

In this study, an efficient adsorbent was proposed for the removal of mercury from saline water contaminated with mercury ions. Fe3O4 nanoparticles were modified using tetraethylenepentamine and carbon disulfide to incorporate dithiocarbamate functional group on the surface of the adsorbent. CHNS analysis confirmed successful modification of magnetic nanoparticles. The XRD pattern of adsorbent indicated a proper match with the standard XRD pattern of cubic Fe3O4. The saturation magnetization of final adsorbent was 27 emu g-1. The morphology of bare and silica-coated Fe3O4 and final product were investigated using FE-SEM analysis. For optimizing the adsorption process, response surface methodology was applied, which was resulted in a significant quadratic model. The effect of adsorbent dosage and initial concentration of Hg (II) was much more significant than that of pH. Different concentrations of dissolved solids up to 2000 mg L-1 had no adverse effect on the adsorption process due to the strong interaction between dithiocarbamate functional group of adsorbent and Hg (II). The least values of RMSE (0.0950) and χ2 (0.0009) were observed for Radke-Prausnitz, Redlich-Peterson, and UT isotherms. Maximum adsorption capacities calculated using Langmuir and UT models were 109.5 and 95.07 mg g-1, respectively. The investigation of adsorption isotherm was conducted at the pH range of 2.0-6.5. The results showed an increase in the adsorption capacity by increasing pH. Thermodynamic studies demonstrated that the nature of the adsorption process was spontaneous and endothermic. Recovery of adsorbent was successfully carried out using HCl 0.5 mol L-1. The prepared adsorbent was successfully applied for mercury removal from a real groundwater.

Faecal sludge treatment and utilization by hydrothermal carbonization.

Hydrothermal carbonization (HTC) is a thermal conversion process that can be applied to convert faecal sludge into carbonaceous solids, called hydrochar. In this study, the technical feasibility of hydrochar production by HTC of faecal sludge was investigated. Experimental results showed energy contents of the produced hydrochar to be about 19-20 MJ/kg, comparable to natural coals and therefore usable as a solid fuel. The produced hydrochar contained a carbon content of approximately 40%wt, which could be processed further to make it suitable as an anode in batteries. The produced hydrochar also had adsorption characteristics for removing heavy metals and micropollutants in wastewater. Liquid by-products obtained from the HTC process were found to contain high concentrations of organic matter, while the amount of gas produced was 10 L-gas/kg-FS with CO2 is the main component. The bio-methane potential tests of this liquid product suggested the methane production of about 2.0 L-CH4 per kg-faecal sludge could be obtained.

Emerging human pathogen Acinetobacter baumannii in the natural aquatic environment: a public health risk?

Bacterium Acinetobacter baumannii is an emerging human pathogen whose presence in the aquatic environment raises the issue of public health risk. Fish colonization represents the potential route of pathogen transmission to humans. The aim was to examine the colonization of A. baumannii to freshwater fish Poecilia reticulata. An extensively drug-resistant A. baumannii was tested at three concentrations in natural spring water. Additionally, 70 fish from the Sava River (Croatia) were screened for the presence of A. baumannii, which was not found in gill swabs or analysed gut. The colonization potential of A. baumannii in freshwater fish is dependent upon its concentration in surrounding water. The low concentration of A. baumannii in natural waters represents low colonization potential of freshwater fish. The risk for public health exists in closed water bodies where there is constant inflow of water polluted by A. baumannii in concentrations above 3 log CFU mL-1.

Infectious helminth ova in wastewater and sludge: A review on public health issues and current quantification practices.

Raw and partially treated wastewater has been widely used to maintain the global water demand. Presence of viable helminth ova and larvae in the wastewater raised significant public health concern especially when used for agriculture and aquaculture. Depending on the prevalence of helminth infections in communities, up to 1.0 × 103 ova/larvae can be presented per litre of wastewater and 4 gm (dry weight) of sludge. Multi-barrier approaches including pathogen reduction, risk assessment, and exposure reduction have been suggested by health regulators to minimise the potential health risk. However, with a lack of a sensitive and specific method for the quantitative detection of viable helminth ova from wastewater, an accurate health risk assessment is difficult to achieve. As a result, helminth infections are difficult to control from the communities despite two decades of global effort (mass drug administration). Molecular methods can be more sensitive and specific than currently adapted culture-based and vital stain methods. The molecular methods, however, required more and thorough investigation for its ability with accurate quantification of viable helminth ova/larvae from wastewater and sludge samples. Understanding different cell stages and corresponding gene copy numbers is pivotal for accurate quantification of helminth ova/larvae in wastewater samples. Identifying specific genetic markers including protein, lipid, and metabolites using multiomics approach could be utilized for cheap, rapid, sensitive, specific and point of care detection tools for helminth ova and larva in the wastewater.

Efflux pumps genes of clinical origin are related to those from fluconazole-resistant Candida albicans isolates from environmental water.

Efflux pumps coded for by CDR1, CDR2, FLU1 and MDR1 genes could be responsible for the observed resistant phenotypes in azole-resistant Candida albicans from environmental water. This was demonstrated for clinical isolates. The aim of this study was to determine the presence and genetic similarity between efflux pump genes from clinical and environmental C. albicans isolates. Yeasts were isolated and identified using 26S rRNA gene sequencing. Disk diffusion tests were conducted. PCR was used to detect the presence of efflux genes. The fragments were sequenced and subjected to BLAST and subsequent phylogenetic analysis. Thirty seven C. albicans were identified from five selected rivers; Mooi River (19 isolates), Harts River (9 isolates), Marico River (5 isolates), Crocodile River (3 isolates) and Schoonspruit River (1 isolate). All the isolates were completely resistant to azoles. Efflux pump genes were detected in most (≥60%) of the isolates. Phylogenetic analysis showed high sequence similarity between sequences from environmental isolates and clinical isolates. Resistance to the azoles and the detection of efflux pump genes renders these antifungal agents ineffective. This is a major problem, particularly for the immune-compromised sector of the community of the North West Province and warrants further investigation.

Removal of antibiotic resistant E. coli in two Norwegian wastewater treatment plants and by nano- and ultra-filtration processes.

The effectivity of different treatment stages at two large wastewater treatment plants (WWTPs) located in Oslo, Norway, to remove antibiotic resistant Escherichia coli from municipal wastewater was investigated. The WWTPs were effective in reducing the total cultivable E. coli. The E. coli in WWTP samples were mainly resistant to ampicillin (6-27%) and trimethoprim-sulfamethoxazole (5-24%), and, to a lesser extent, tetracycline (3-14%) and ciprofloxacin (0-7%). In the first WWTP, a clear decrease in the percentage of E. coli resistant to these antibiotics was found, with the main removal occurring during physical/chemical treatment. In the second WWTP, the percentage of cultivable resistant E. coli did not display a considerable change. During laboratory-scale membrane filtration of WWTP effluents using ultrafiltration (UF) and nanofiltration (NF) membranes, all E. coli, including those resistant to antibiotics, were removed completely. The results imply that UF and NF processes are potent measures to remove antibiotic resistant bacteria (ARB) during post-treatment of WWTP effluents, thus reducing the potential spread of antibiotic resistance in the receiving aquatic environment.

Hydraulic and hydrological aspects of an evapotranspiration-constructed wetland combined system for household greywater treatment.

Constructed wetlands systems demand preliminary and primary treatment to remove solids present in greywater (GW) to avoid or reduce clogging processes. The current paper aims to assess hydraulic and hydrological behavior in an improved constructed wetland system, which has a built-in anaerobic digestion chamber (AnC), GW is distributed to the evapotranspiration and treatment tank (CEvaT), combined with a subsurface horizontal flow constructed wetland (SSHF-CW). The results show that both the plants present in the units and the AnC improve hydraulic and volumetric efficiency, decrease short-circuiting and improve mixing conditions in the system. Moreover, the hydraulic conductivity measured on-site indicates that the presence of plants in the system and the flow distribution pattern provided by the AnC might reduce clogging in the SSHF-CW. It is observed that rainfall enables salt elimination, thus increasing evapotranspiration (ET), which promotes effluent reduction and enables the system to have zero discharge when reuse is unfeasible.

Biosorption-based dispersive liquid-liquid microextraction combined with polypyrrole-coated magnetic nanoparticles as an effective sorbent for the extraction of ibuprofen from water samples using magnetic solid-phase extraction.

In this paper, biosorption-based dispersive liquid-liquid microextraction (BioDLLME) in combination with magnetic solid-phase extraction (MSPE) has been developed as a sample pretreatment method with high enrichment factor for the sensitive determination of ibuprofen in water samples. At first, magnetic Fe3 O4 /polypyrrole nanoparticles were synthesized and employed as sorbent for the MSPE of ibuprofen. After the elution of the desired compound from the sorbent by using methanol, BioDLLME technique was performed on the obtained solution. After MSPE, the eluent of MSPE was used as the disperser solvent for BioDLLME, so that the extra preconcentration factor could be achieved. The properties of the prepared magnetic sorbent were characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction methods. Experimental parameters affecting the extraction efficiency were studied and optimized. Under optimum conditions, the enrichment factor was 274. The linear dynamic range and limit of detection are 0.25-80 and 0.083 µg/L, respectively. The relative standard deviations for six replicate measurements are 3.82%.