Sustainable Fertilizers: Publication Landscape on Wastes as Nutrient Sources, Wastewater Treatment Processes for Nutrient Recovery, Biorefineries, and Green Ammonia Synthesis.

The ability of modern agriculture to meet future food demand imposed by accelerating growth of the world's population is a major challenge, and fertilizers play a key role by replacing nutrients in agricultural soil. Given the need for fertilizers, their cost in nonrenewable resources and energy, and the consequences of the greenhouse gas emissions required to make them, people have begun to explore ways to make fertilizer manufacturing and use more sustainable. Using data from the CAS Content Collection, this review examines and analyzes the academic and patent literature on sustainable fertilizers from 2001 to 2021. The breakdown of journal and patent literature publication over time on this topic, country or region of publications, the substances included in published research, among other things allow us to understand the general progress in the field as well as the classes of materials and concepts driving innovation. We hope that this bibliometric analysis and literary review will assist researchers in relevant industries to discover and implement ways to supplement conventional fertilizers and nutrient sources while improving the efficiency and sustainability of waste management and ammonia production.

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.

Elucidate microbial characteristics in a full-scale treatment plant for offshore oil produced wastewater.

Oil-produced wastewater treatment plants, especially those involving biological treatment processes, harbor rich and diverse microbes. However, knowledge of microbial ecology and microbial interactions determining the efficiency of plants for oil-produced wastewater is limited. Here, we performed 16S rDNA amplicon sequencing to elucidate the microbial composition and potential microbial functions in a full-scale well-worked offshore oil-produced wastewater treatment plant. Results showed that microbes that inhabited the plant were diverse and originated from oil and marine associated environments. The upstream physical and chemical treatments resulted in low microbial diversity. Organic pollutants were digested in the anaerobic baffled reactor (ABR) dominantly through fermentation combined with sulfur compounds respiration. Three aerobic parallel reactors (APRs) harbored different microbial groups that performed similar potential functions, such as hydrocarbon degradation, acidogenesis, photosynthetic assimilation, and nitrogen removal. Microbial characteristics were important to the performance of oil-produced wastewater treatment plants with biological processes.

Application of a fast and sensitive method for the determination of contaminants of emerging concern in wastewater using a quick, easy, cheap, effective, rugged and safe-based extraction and liquid chromatography coupled to mass spectrometry.

The inefficiency of wastewater treatment plants (WWTPs) to remove contaminants of emerging concern (CECs) leads to their continuous release to the environment. Consequently, CECs are present at low concentrations in the treated wastewater (TWW), producing unpredicted and unwanted effects on living organisms as they are discharged into water receiving bodies. This work presents a fast and reliable method for the determination of CECs in TWW based on the innovative application of a QuEChERS (quick, easy, cheap, effective, rugged and safe) method for water extraction and determination by sensitive liquid chromatography coupled to quadrupole-linear ion trap tandem mass spectrometry (LC-QqLIT-MS/MS). The scope of the proposed QuEChERS-based method allows the monitoring of 107 CECs, including pharmaceuticals (58), antibiotics (16) and pesticides (33). The proposed method was successfully validated in urban TWW at two concentration levels (50 and 500 ng L-1) and it is a feasible alternative to conventional and time-consuming solid-phase extraction (SPE) methodologies. 89% of the CECs presented mean recovery values in the 70-120% range with relative standard deviations (RSDs) always < 20% (intra and inter-day precision), and limits of quantification (LOQs) in the range 5-500 ng L-1 (89% of the compounds showed a LOQ ≤ 50 ng L-1). The applicability of the method was demonstrated by the analysis of urban TWW samples (7 sampling events). In total, 35 CECs (23 pharmaceuticals, 2 antibiotics and 10 pesticides) were detected in the monitored samples with concentrations ranging from 5 to 677 ng L-1.

SARS-CoV-2 in wastewater: Challenges for developing countries.

The COVID-19 pandemic that has engulfed the world, has affected the human lives in several aspects. The detection of SARS-CoV-2 in faeces and urine of the infected person, even after viral clearance in the respiratory tract, and its presence in untreated wastewater raises the possibility of fecal-oral transmission in future. The situation is likely to be more aggravated in developing and least developed countries struggling with the problem of ineffective waste disposal system, open defecation, poor sanitation, and limited access to clean drinking water. In this review, the available data on wastewater treatment, sanitation status and healthcare infrastructure from middle- and low-income countries is collected and correlated with the risk associated with the fecal-oral transmission of SARS-CoV-2. The review also highlights the limitation of COVID-19 surveillance through sewage monitoring in these countries owing to the absence of proper sewerage system. An inclusive approach of awareness, prevention, and mitigation from global to the local levels is required to overcome this challenging situation in developing countries.

Virus recovery by tangential flow filtration: A model to guide the design of a sample concentration process.

A simple model is developed to describe the instantaneous (rv ) and cumulative (Rv ) recovery of viruses from water during sample concentration by tangential flow filtration in the regime of constant water recovery, r. A figure of merit, M = rv r, is proposed as an aggregate performance metric that captures both the efficiency of virus recovery and the speed of sample concentration. We derive an expression for virus concentration in the sample as a function of filtration time with the rate-normalized virus loss, η=1-rvr , as a parameter. A practically relevant case is considered when the rate of virus loss is proportional to the permeation-driven mass flux of viruses to the membrane: dmaddt∼QpCf≫QpCp . In this scenario, the instantaneous recovery is constant, the cumulative recovery is decreasing as a power function of time, Rv=1-QpV0tη , η mediates the trade-off between r and rv , and M is maximized at r=ropt=12η . The proposed model can guide the design of the sample concentration process and serve as a framework for quantification and interlaboratory comparison of experimental data on virus recovery.

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.

Virus and chlorine adsorption onto guanidine modified cellulose nanofibers using covalent and hydrogen bonding.

Unsafe drinking water leads to millions of human deaths each year, while contaminated wastewater discharges are a significant threat to aquatic life. To relieve the burden of unsafe water, we are in search of an inexpensive material that can adsorb pathogenic viruses from drinking water and adsorb toxic residual chlorine from wastewater. To impart virus and chlorine removal abilities to cellulosic materials, we modified the primary hydroxyl group with a positively charged guanidine group, to yield guanidine modified cellulose derivatives. Microcrystalline cellulose (MC) bearing covalently bonded guanidine hydrochloride (MC-GC) and hydrogen-bonded guanidine hydrochloride (MC-GH) were synthesized, and electrospun into nanofibers after blending with the non-ionogenic polyvinyl alcohol (PVA), to produce large pore sized, high surface area membranes. The MC-GC/PVA and MC-GH/PVA nanofibers were stabilized against water dissolution by crosslinking with glutaraldehyde vapor. The water-stable MC-GC/PVA mats were able to remove more than 4 logs of non-enveloped porcine parvovirus (PPV) and enveloped Sindbis virus and reached 58% of chlorine removal. The MC-GC/PVA nanofibers demonstrated better performance for pathogen removal and dechlorination than MC-GH/PVA nanofibers. This first study of MC-GC/PVA electrospun mats for virus removal shows they are highly effective and merit additional research for virus removal.

Distributions of enterococci and human-specific bacteriophages of enterococci in a tropical watershed.

The bacteriophages of E. faecalis strains AIM06 (DSM100702) and SR14 (DSM100701) have previously been validated as human-specific microbial source tracking (MST) markers in Thailand. In this study, their spatial and temporal distribution in a freshwater river was investigated for the first time (n = 48). The abundance of enterococci as a standard microbial water quality parameter was evaluated by both the qPCR detection assay with primers and a hydrolysis probe according to the US EPA Method 1611 and the US EPA Method 1600 membrane filtration culture method. AIM06 and SR14 phages were detected by a double layer agar assay and were present in 87.5% and 81.3% of all samples with a co-presence of 92.9% of phage-positive samples. After spiking the representative phages, the ranges of recovery efficiencies were 57.9-99.6% and 49.6-99.9% (n = 48) for AIM06 and SR14 phages, respectively. The absolute abundance of AIM06 and SR14 phages ranged from 0.25 to 221.94 and from 0.25 to 76.66 PFU/100 mL, respectively. Enterococci DNA copies and CFU were detected in all samples ranging from 3.24 to 6.32 log10 copies/100 mL and 100.00 to 1593 CFU/100 mL, respectively. Enterococci in the qPCR assay also showed a moderate correlation with the culture method. The AIM06 and SR14 phage results indicated continuing human faecal pollution along the river with no significant different levels among stations. Interestingly, the higher levels of enterococci in downstream stations for both the qPCR and culture methods along with the significant correlation with other faecal indicator organisms and non-human MST markers implied non-human faecal pollution. In conclusion, this study provides insightful information that could lead to effective water quality management and public health risk reduction from exposure to faecally-contaminated water.

Assessment of microbial risks by characterization of Escherichia coli presence to analyze the public health risks from poor water quality in Nepal.

The combination of natural disasters and inadequate infrastructure introduce unique challenges in providing safe drinking water in low-income countries. For example, Nepal faces several challenges in managing sporadic diarrheal outbreaks across the country, given its complex geographic terrain, and its susceptibility to extreme natural events like earthquakes, floods, and landslides. To assess the risks of diarrheal diseases caused by fecal contamination in several water sources in different geographical regions of Nepal, we conducted a two months cross-sectional study throughout 37 out of 75 districts in Nepal, including the ones affected by Nepal 2015 earthquake. Quantitative Microbial Risk Assessment (QMRA) was applied to estimate the human health risk based on Escherichia coli (E. coli) count for 2,822 water samples collected at source and households. Disease burden calculations suggested that Hilly and Terai (low-land) regions are at the highest risk with 0.27 and 0.16 DALYs per person per year (DALYpppy), respectively, whereas mountain region disease burden was 0.02 DALYpppy. The risk comparison among exposure pathways indicated that the water used in households, including drinking water and water for washing, posed higher risks than from source water, reservoir water or tap water, suggesting deteriorated sanitation conditions in households. These findings suggest that the combination of QMRA and spatial analysis can help to prioritize intervention activities after a major natural disaster.

Microbial indicators and molecular markers used to differentiate the source of faecal pollution in the Bogotá River (Colombia).

Intestinal pathogenic microorganisms are introduced into the water by means of faecal contamination, thus creating a threat to public health and to the environment. Detecting these contaminants has been difficult due to such an analysis being costly and time-intensive; as an alternative, microbiological indicators have been used for this purpose, although they cannot differentiate between human or animal sources of contamination because these indicators are part of the digestive tracts of both. To identify the sources of faecal pollution, the use of chemical, microbiological and molecular markers has been proposed. Currently available markers present some geographical specificity. The aim of this study was to select microbial and molecular markers that could be used to differentiate the sources of faecal pollution in the Bogotá River and to use them as tools for the evaluation and identification of the origin of discharges and for quality control of the water. In addition to existing microbial source markers, a phage host strain (PZ8) that differentiates porcine contamination was isolated from porcine intestinal content. The strain was identified biochemically and genotypically as Bacteroides. The use of this strain as a microbial source tracking indicator was evaluated in bovine and porcine slaughterhouse wastewaters, raw municipal wastewaters and the Bogotá River. The results obtained indicate that the selected microbial and molecular markers enable the determination of the source of faecal contamination in the Bogotá River by using different algorithms to develop prediction models.

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).

Fabrication of iron-dipicolinamide catalyst with Fe-N bonds for enhancing non-radical reactive species under alkaline Fenton process.

Iron dipicolinamide (Fedpa), as an efficient Fenton-like catalyst, was fabricated to excite hydrogen peroxide (H2O2) for the removal of 2,4-dichlorophenol (2,4-DCP). The unique structures and the electronic properties of Fedpa were contributed to its excellent catalytic performance in alkaline Fenton process. Fe was chelated with dpa by four Fe-N bonds leaved two labile sites, which reduced the oxidation potential of dpa[FeIII/FeII], dpa[FeV/FeIII] or dpa[FeIV/FeII] to 0.316 V and 1.189 V respectively, and made it easily be bound with H2O2 to initiate the reaction. The results showed that 99.5% removal rate of 2,4-DCP (0.58 mM) was achieved by using 0.027 g/L Fedpa and 5.8 mM H2O2 in 60 min at pH 9.9. The coordination between Fe and dpa enhanced the catalytic efficiency of FeII. The active species generated in Fedpa/H2O2 system contained the iron-oxo species (dpaFeV = O or dpaIV = O), O2- and HO. The iron-oxo species was the main non-radical reactive species for the degradation of 2,4-DCP and some degradation intermediates were detected by GC-QTOF. Furthermore, the influence of factors, such as Fedpa loading, solution pH, temperature and anions (F-, Cl-, SO42-, NO3- and PO43-) on the catalytic performance of Fedpa were also discussed. This process of complexation between Fe and dpa combined with a green oxidant H2O2 presents a new insight for the use of Fenton-like system in the degradation of refractory organics.

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.

In-situ characterization of dissolved organic matter removal by coagulation using differential UV-Visible absorbance spectroscopy.

Removing dissolved organic matter (DOM) is of great concern due to its adverse effects on water supplies. Great effort has been given to studying DOM removal by coagulation, while the mechanism of DOM removal and the changes in its properties during coagulation have not been clearly illustrated due to the limitations of detection methods under practical environmental conditions. In this paper, the changes in DOM during coagulation were quantified using differential UV-Visible absorbance spectroscopy, and the differential spectra of DOM in the wavelength range of 200-600 nm could be deconvoluted into six Gaussian bands with maxima at approximately 200, 240, 276, 316, 385, and 457 nm after coagulation, respectively. The intensity of these maxima decreased with the type and dosage of coagulants. These observations should reflect the difference in the removability of DOM by coagulation, and this perspective was further confirmed by examining the deprotonation-protonation properties of DOM before and after coagulation. The affinity sites of DOM in coagulated waters, quantified by spectra parameter DlnA400 (differential log-transformed spectra at wavelength 400 nm) in combination with the revised NICA model, increased as the coagulant dosage, which indicates that coagulation is inclined to remove the DOM fraction with fewer functional groups. Polyaluminum chloride (PAC) and Al-aggregate (Al13) were more efficient than Alum for removing DOM due to their high efficiency for removing DOM fractions with fewer functional groups. The residual dissolved Al concentration depended on the total amount of reactive binding sites in DOM, and there was a strong linear correlation between residual dissolved Al and the total amount of reactive binding sites in DOM for Alum, while a weaker correlation was presented for PAC and Al13. This indicates that Ala was the dominant species to bind with the affinity sites in DOM to form residual dissolved Al.

Plasmonic Ag decorated graphitic carbon nitride sheets with enhanced visible-light response for photocatalytic water disinfection and organic pollutant removal.

Photocatalytic disinfection with high performance is thought to be a promising way for water purification. Herein, plasmonic Ag doped urea-derived graphitic carbon nitride (g-C3N4) composites were fabricated via in-situ photo-deposition at room temperature as the visible-light photocatalyst. Scan electron microscopy and transmission electron microscopy images showed the uniform dispersion of Ag nanoparticles on the surface of g-C3N4 sheet, which facilitated the synergistic effect of antibacterial performance from Ag and photocatalytic property from Ag/g-C3N4 composites. Photocatalytic water disinfection against Escherichia coli with visible light was performed to demonstrate the improved photocatalytic property with assistance of Ag. The 3-Ag/g-C3N4 exhibited the best bactericidal performance by inactivating all bacteria within 120 min with damaged cell membranes of Escherichia coli observed by scan electron microscopy and transmission electron microscopy images. Photoluminescence spectra, steady-state surface photovoltage spectra, photocurrent response, and electrochemical impedance spectra results revealed that Ag nanoparticles inhibited the recombination of photo-generated e- and h+ pairs and further reinforced the photocatalytic performance of g-C3N4. Scavenger experiments indicated that h+ produced on valence band of g-C3N4 dominated the photocatalytic disinfection process against Escherichia coli. This work further proved Ag/g-C3N4 showed great potential in photocatalytic water disinfection under visible-light irradiation.

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.

White Eggshells: A Potential Biowaste Material for Synergetic Adsorption and Naked-Eye Colorimetric Detection of Heavy Metal Ions from Aqueous Solution.

In the present work, we have utilized a simple, no-cost, unmodified eggshell powder as a naked-eye colorimetric detector, which on simple dispersion in aqueous solution of metal ions exhibited characteristic color change from white to pale green, pale blue, yellow, pale yellow, dark yellow, pale pink, blue, and brown for metal ions V4+, Cr3+, Cr6+, Fe2+, Fe3+, Co2+, Cu2+, and Ag+, respectively. The effects of various parameters like concentration of metal ions, pH, temperature, and adsorbent dosage were investigated by batch sorption experiments. Also, Freundlich and Langmuir models were used to describe the adsorption isotherm. The eggshell powder before and after adsorption was characterized qualitatively by the naked-eye and quantitatively by diffuse reflectance spectroscopy-UV, Fourier transform infrared, atomic absorption spectroscopy, powder X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller, zeta potential, and X-ray photoelectron spectroscopy techniques. In addition, the competitive adsorption of metal ions in mixtures and the recycle experiments were carried out to prove the sustainability of the material. Further, the red, green, and blue alterations were extracted from the colorimetric array and subjected to hierarchical clustering analysis using the Ward method by calculating the Euclidean distance, which displayed facile discrimination of 10 heavy metal ions at 1 mM level. Thus, the unmodified eggshell powder has been proven to be an impressive value-added sustainable material for synergistic metal adsorption and colorimetric naked-eye detection of a series of metal ions with detection limits of 10-4 M for Fe3+, Fe2+, and Cu2+; 10-3 M for Cr3+, Cr6+, Ag+, and Co2+; and 5 × 10-3 M for V4+.

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.

First Report of Microcystis Strains Producing MC-FR and -WR Toxins in Japan.

Microcystins (MCs) are a group of cyclic heptapeptide hepatotoxins produced by Microcystis and several other genera of cyanobacteria. Many structural variants have been characterized using various methods such as liquid chromatography-mass spectrometry (LC-MS) analysis, enzyme-linked immunosorbent assay (ELISA) and protein phosphatase 2A (PP2A) inhibition assay. The representative MC, MC-LR, and related cyanobacterial toxins strongly inhibit PP2A activity and can therefore be assayed by measuring the extent of PP2A inhibition. However, these methods require reference toxin standards for the quantification and identification of known MCs. To obtain various MC-producing cyanobacterial strains, we surveyed and collected MC-producing cyanobacteria from environmental sources of water in Okinawa, Japan. Using a dual assay (LC-MS analysis and PP2A inhibition assay), we identified and isolated Microcystis strains producing five MC variants (MC-LR, -RR, -LA, -FR and -WR). Approximately 4 mg of MC-WR and -FR toxins were purified from the laboratory culture of the Microcystis isolate NIES-4344. Pure MC-WR and -FR variants were prepared for future use as toxin standards in LC-MS analysis. Phylogenetic analysis based on ftsZ revealed that the NIES-4344 strain belongs to the identified groups in Microcystis aeruginosa. This is the first report of Microcystis strains producing mainly MC-WR and -FR toxins in Japan.