Inhibition of acid rock drainage with iron-silicate or phosphate film: in rainy and submerged environments.

Iron phosphate-based coating and iron silicate-based coating were used to inhibit the oxidation of sulfide minerals in rainy and submerged environments. The inhibiting effectiveness of coating agents on the oxidation of iron sulfide minerals was investigated using pyrite and rock samples resulting from acid drainage. The film formed with both surface-coating agents was identified by pyrite surface analysis. It was also confirmed that the formation of coatings varies depending on the crystallographic orientation. The inhibitory effects under rainy and submerged conditions were investigated using column experiments. Submerged conditions accelerated deterioration compared to that under rainy conditions. Iron phosphate coating had a significantly better oxidation-inhibitory effect (84.86-98.70%) than iron silicate coating (56.80-92.36%), and at a concentration of 300 mM, H+ elution was inhibited by more than 90% throughout the experiment. Furthermore, methods for effective film formation were investigated in terms of producing Fe3+; (1) application of coating agents mixed with oxidant (H2O2), (2) application of coating agent after the use of the oxidant. In a rainy environment, applying iron phosphate-based coating using the sequential method showed oxidation inhibition effects for cycles 1-9, whereas applying the mixed material showed effects for cycles 9-13. The use of a surface-coating agent after applying an oxidant did not inhibit oxidation. The surface coating agent and the oxidizing agent should be applied as a mixture to form a film.

Removal of Mn via coprecipitation and sorption by Fe(II), Fe(III), and Al in mine drainage.

In mine drainage, Fe and Mn are the two most abundant elements exceeding the discharge criteria. Although Mn removal generally requires a pH exceeding 9.5-10.0, its coprecipitation and sorption by Fe and/or Al can significantly reduce the required pH. In this study, Mn removal efficiencies, mechanisms, and required pH were investigated by experiments involving varying concentrations of Mn, Fe, and Al at different pH, and X-ray photoelectron spectroscopy (XPS) analyses. At pH > 7.9, precipitation as Mn (hydr)oxides was the principal Mn removal process, as indicated by the Mn removal plots, geochemical modeling, and XPS results. The precipitation was highly promoted by the heterogeneous oxidation of Fe and Al hydroxides. Coprecipitation-sorption experiments showed 65-80% lower Mn concentrations than those of sorption experiments at similar dosages and pH near 7.5. Fe(III) exhibited higher coprecipitation efficiency than Fe(II), possibly due to the prior oxidation of Fe(II). Fe(III) also displayed a coprecipitation-sorption efficiency five times more than Al. To decrease the Mn concentrations from 17-25 mg L-1 to <2 mg L-1 by coprecipitation-sorption, Fe(III)/Mn and Fe(II)/Mn ratios of ∼10 and ∼20, respectively, at pH 9.0 were required. Similarly, an Al/Mn ratio of ∼7 at pH 9.0 was required to reduce the Mn concentration to <5 mg L-1. Furthermore, the required Fe/Mn ratio decreased significantly when the initial Mn concentration decreased to 8-11 mg L-1. Utilizing the deduced relationships, required pH for Mn removal could be estimated and the design of Mn treatment facilities can be more efficient.

Water defluorination using granular composite synthesized via hydrothermal treatment of polyaluminum chloride (PAC) sludge.

In this work, we newly synthesized granular composite (GASA) via hydrothermal treatment of polyaluminum chloride (PAC) and subsequently granulation pelleting with starch gel as an organic binder. The resulting composite was characterized with analytic instruments, and the feasibility of utilizing GASA as adsorbent for the removal of fluoride (F-) was tested in the batch and column experiments. The characterization results revealed that GASA possessed a spherical/porous framework consisting of aluminosilicate (i.e., ordered albite, NaAlSiO3O8). The results of final pH effect experiments and XRD/XPS analyses showed the dominant adsorption mechanisms of F- on GASA were electrostatic attraction by protonated surface Al-OH, ligand exchange between surface hydroxyl groups and F ions, and surface precipitation (i.e., cryolite formation). Based on the results of adsorption kinetics and adsorption isotherm, granulation resulted in the relatively slow kinetics of F adsorption compared to the powder type, but was preferred to retain good adsorption capacity. The regeneration possibility of GASA was also proven with the adsorption/desorption cyclic test. In the column study, 15-cm length of the GASA layer and the flow rate less than 0.85 mL min-1 were proposed to keep the satisfactory level of F in water. The experimental results offer a potential of PAC sludge-derived composite as adsorbent for the removal of F from water.

Zirconia-Assisted Pyrolysis of Coffee Waste in CO2 Environment for the Simultaneous Production of Fuel Gas and Composite Adsorbent.

This work newly employed monoclinic zirconia (ZrO2) as a promoter to improve CO2 pyrolysis of coffee waste (CW). The CO2 pyrolysis of CW presented the high level of CO production (14.3 mol%) during two stages of non-isothermal (280 to 700 °C) and isothermal pyrolysis (kept at 700 °C). At the same condition, the incorporation of ZrO2 improved the CO generation up to about twice that of CW (29.5 mol%) by possibly inducing more conversion of pyrolytic oil into gas. The characterization results exhibited that ZrO2-impregnated biochar (ZrB) possessed the distinctive surface morphology that highly graphitic- and porous carbon layers were covered by ZrO2 nanoparticle clusters. In a series of adsorption experiments, ZrB composite showed pH-dependent As(V) adsorption and pH neutralization ability. The adsorption proceeded relatively rapid with 95% removal during 120 min in the early stage, followed by 5% removal in the remaining 240 min. The maximum adsorption capacity was found to be 25.2 mg g-1 at final pH 8. The reusability and stability of ZrB were demonstrated in the 6 consecutive cycles of adsorption/desorption. As a result, ZrO2-assisted CO2 pyrolysis can potentially produce fuel gas with high CO fraction and composite adsorbent suitable for As(V) removal in acidic wastewater.

Waste sludge derived adsorbents for arsenate removal from water.

Aqueous arsenate [As(V)] was removed using an aluminum-based adsorbent (ABA) and coal mine drainage sludge coated polyurethane (CMDS-PU) prepared using alum and coal mine sludge, respectively. Their As(V) removal efficiencies were compared with each other and granular ferric hydroxide (GFH). The mineralogy and surface chemistry of materials were determined using wavelength dispersive X-ray fluorescence (WD XRF) and Fourier transform infrared spectroscopy (FTIR), respectively. The angle-resolved X-ray photoelectron spectroscopy (AR-XPS) studies confirmed As(V) retention on the adsorbent surfaces. The adsorption kinetics data were fitted to pseudo second-order rate equation. The faster As(V) uptake kinetics of GFH and ABA (GFH > ABA > CMDS-PU) were attributed to their large pore volume and mesoporous nature. Langmuir adsorption capacities of 22, 31 and 10 mg/g, were achieved for GFH, ABA and CMDS-PU, respectively. As(V) adsorption on GFH, ABA and CMDS-PU was endothermic. GFH and ABA were efficient over a wide pH range (3-10). In column studies, GFH, ABA, and CMDS-PU successfully treated 23625, 842, and 158 bed volumes (BVs) and 2094, 6400, and 17 BVs of As(V)-contaminated water with 9.5 and 27 EBCT, respectively (at pH = 6.0, Asi = 600 µg/L). The GFH and ABA have a potential to be used at large-scale aqueous phase As(V) remediation.

Primary care clinics can be a source of exposure to virulent Clostridium (now Clostridioides) difficile: An environmental screening study of hospitals and clinics in Dallas-Fort Worth region.

C. difficile is an endospore-forming pathogen, which is becoming a common cause of microbial health-care associated gastrointestinal disease in the United States. Both healthy and symptomatic patients can shed C. difficile spores into the environment, which can survive for long periods, being resistant to desiccation, heat, and disinfectants. In healthcare facilities, environmental contamination with C. difficile is a major concern as a potential source of exposure to this pathogen and risk of disease in susceptible patients. Although hospital-acquired infection is recognized, community-acquired infection is an increasingly recognized health problem. Primary care clinics may be a significant source of exposure to this pathogen; however, there are limited data about presence of environmental C. difficile within clinics. To address the potential for primary care clinics as a source of environmental exposure to virulent C. difficile, we measured the frequency of environmental contamination with spores in clinic examination rooms and hospital rooms in Dallas-Fort Worth (DFW) area of Texas. The ribotypes and presence of toxin genes from some environmental isolates were compared. Our results indicate primary care clinics have higher frequencies of contamination than hospitals. After notification of the presence of C. difficile spores in the clinics and an educational discussion to emphasize the importance of this infection and methods of infection prevention, environmental contamination in clinics was reduced on subsequent sampling to that found in hospitals. Thus, primary care clinics can be a source of exposure to virulent C. difficile, and recognition of this possibility can result in improved infection prevention, potentially reducing community-acquired C. difficile infections and subsequent disease.

An Estimation of Potential Vector Control Effect of Gravid Mosquito Trapping in Fort Worth, Texas.

Entomological surveillance is an essential component for integrated vector management (IVM), the current best practice for West Nile virus (WNV) prevention and control. The significance of vector mosquito surveillance, however, is not always recognized by the public, which increases vulnerability of IVM programs to elimination or downsizing when virus activities are low, particularly during interepidemics of WNV. In order to increase public recognition, the unrecognized contribution of mosquito surveillance with gravid (egg-carrying) mosquito trapping to WNV vector control was estimated using a novel approach. This approach includes development of a quantitative model to estimate the number of female progeny from a gravid mosquito and application of the model with mosquito surveillance data to estimate the potential vector control effect of gravid mosquito trapping. Applying this approach, the potential WNV vector control effect of 2013 surveillance activities in Fort Worth, Texas, was estimated to almost 1,590,000 female mosquitoes by capturing 44,654 females.

A potential risk assessment of a dengue outbreak in north central Texas, USA. (Part 1 of 2): Abundance and temporal variation of dengue vectors.

In response to three imported dengue cases in north central Texas as well as increased case numbers in Texas and adjoining Mexican states in 2005, the authors assessed the potential risk of a dengue outbreak in north central Texas by investigating abundance and temporal variation of dengue vectors in 2006. Dengue vector abundance was monitored from 54 sites in Dallas County, Texas, from June to November 2006, using oviposition traps. Both dengue vectors--the yellow fever mosquito, Aedes aegypti, and the Asian tiger mosquito, Aedes albopictus--were present. Of the two, Ae. albopictus was more abundant and its abundance appeared to be positively affected by temperature and precipitation. Potential risk of a dengue outbreak was predicted based on the abundance and temporal variation of dengue vectors and a long-term trend of breeding season precipitation and warmer winter temperatures.

A potential risk assessment of a dengue outbreak in north central Texas, USA. (Part 2 of 2): Development of a practical prevention strategy.

In response to three dengue cases in north central Texas in 2005, the authors assessed the potential risk of a dengue outbreak in Dallas County in 2006. As a part of the assessment, habitat factors for dengue vector mosquitoes were quantified and associated with their abundances. In addition, percent population originated from endemic countries (Hispanic origin in the Census data) was associated with vector abundances and habitat factors of the vectors. Percent population data were obtained from publicly accessible databases. The areas with higher Hispanic populations had more Aedes aegypti and container numbers and also appeared to have more shade, which is attractive to this species. The methodology of this study may help to devise a practical strategy to reduce the risk of dengue outbreak in areas where dengue vector activity is present and a potential source of infection.

Analysis of foodborne disease outbreaks for improvement of food safety programs in Seoul, Republic of Korea, from 2002 to 2006.

Foodborne disease (FBD) is a common food safety problem in Seoul, Republic of Korea. To identify target areas for improvement of the food safety programs, FBD outbreaks from 2002 to 2006 were analyzed with regard to facility, monthly occurrences, and causative agents. A total of 147 FBD outbreaks were reported, with an average of 29.4 FBD outbreaks per year and 49 cases per outbreak. Restaurants and school lunches were two main facilities associated with 76.2% of the outbreaks. A majority of FBD cases (73.1%) were from school lunches. The highest number of outbreaks and cases occurred in June, followed by March. Among the seven identified causative agents, norovirus was the most significant in the number of outbreaks and cases. Among the outbreaks and cases with causative agents identified, norovirus and Staphylococcus aureus were responsible for 61.7% of outbreaks and 81.5% of cases. The analysis indicates that the efficiency of current food safety programs could be enhanced if critical control points in school lunch programs are identified and incorporated in the training and inspection. Identifying risk factors for contamination of norovirus and Staphylococcus aureus would also be beneficial.

Host-feeding patterns of Culex mosquitoes in relation to trap habitat.

Mosquito feeding patterns identify vertebrate species potentially involved in the amplification of West Nile virus. In New York, northern cardinals (Cardinalis cardinalis) were the predominant hosts in most habitats. Crow (Corvus sp.) blood meals were most frequently identified from sewage treatment plant and storm water catch basin habitats.

Detection of Babesia microti DNA in Ixodes scapularis (Acari: Ixodidae) by use of Chelex 100 resin and polymerase chain reaction.

A rapid and sensitive protocol using Chelex 100 resin for DNA extraction and the polymerase chain reaction for detection of Babesia microti Franca within its vector Ixodes scapularis Say is described. The level of detection of this protocol was determined to be the approximate equivalent of one parasite.

The first record of larval collections of Ochlerotatus thibaulti in New York state.

Larvae of Ochlerotatus thibaulti Dyar and Knab have not been reported in New York State or New England, but adult records suggest that breeding populations are present. In 2003 and 2004, larval Oc. thibaulti were collected at 3 sites upstate near the Catskill Mountain region in Lomontville, NY. This is the 1st record of Oc. thibaulti collected in New York and New England. Larvae were found in a variety of subterranean habitats within and near semipermanent woodland pools, including under hummocks and in deep and shallow depressions of upturned trees. No immatures were observed after late June. Larvae of Culiseta melanura were found in the same habitats in the early spring and later in the season after Oc. thibaulti had emerged.

Babesia microti, upstate New York.

Five cases of human babesiosis were reported in the Lower Hudson Valley Region of New York State in 2001. An investigation to determine if Babesia microti was present in local Ixodes scapularis ticks yielded 5 positive pools in 123 pools tested, the first detection of B. microti from field-collected I. scapularis in upstate New York.

Field evaluation of CDC gravid trap attractants to primary West Nile virus vectors, Culex mosquitoes in New York State.

A field study was conducted to evaluate two CDC gravid trap attractants available for the West Nile virus surveillance program in New York State (NYS). According to potential attractiveness, a common lawn sod in NYS, Kentucky bluegrass (Poa pratensis) infusion and a rabbit chow infusion were compared for attractiveness to primary West Nile virus vectors, Culex mosquitoes. Attractiveness of each infusion was measured by the number of adult mosquitoes caught in CDC gravid traps and the number of egg rafts laid in ovitraps. Both gravid trap and ovitrap studies demonstrated that lawn sod infusion with a 7-day incubation period had better attractiveness to Culex restuans/Culex pipiens than rabbit chow infusion with the same incubation period. Attractiveness of lawn sod infusions was increased as they became aged within a week's period. Lawn sod infusion also attracted more Ochlerotatus japonicus, a potentially important West Nile virus vector in New York.

Toxorhynchites rutilus septentrionalis: new occurrences in upstate New York.

Records of Toxorhynchites rutilus septentrionalis findings in New York State are few, and collections north of New York City are rare. This is the 1st official documentation of Tx. rutilus found in upstate New York in the past 46 years and the farthest northern record. In 2002, immatures of Tx. rutilus were found in artificial containers in 2 locations in the Hudson Valley region, at Quarryville (Ulster County) and Blauvelt (Rockland County), NY. A study conducted at Quarryville in 2002 and 2003 found that breeding occurred continuously through the season, and that overwintering possibly could be occurring at that site.

Simultaneous detection of three mosquito-borne encephalitis viruses (eastern equine, La Crosse, and St. Louis) with a single-tube multiplex reverse transcriptase polymerase chain reaction assay.

Three mosquito-borne human encephalitis viruses (eastern equine encephalitis virus [EEE], St. Louis encephalitis virus [SLE], and La Crosse encephalitis virus [LAC]) are sympatric in the southeastern United States. However, little is known concerning the temporal and spatial pattern of the distribution of these viruses in this area. As part of surveillance activities to detect the transmission of these 3 viruses in the Tennessee Valley area, we developed a single-tube multiplex reverse transcriptase polymerase chain reaction (RT-PCR) assay capable of detecting these 3 mosquito-borne viruses in a single reaction. Three viruses were differentiated by size of amplified products. Sensitivities of the multiplex RT-PCR assay for SLE, EEE, and LAC were 1-3 log median tissue culture infective doses per pool, roughly comparable to the reported sensitivity of PCR detection assays for the individual viruses, and 1 log more sensitive than antigen-capture assays for SLE and EEE. The sensitivity of the multiplex PCR was not changed significantly when carried out in the presence of extracts prepared from 50 uninfected mosquitoes. The cost of the assay is estimated at $2.98 per test, similar to the cost of other RT-PCR-based assays for viruses. However, adaptation of the RT-PCR to a multiplex format adds less than $0.01 to the per-unit cost of an RT-PCR assay targeting a single virus species. Analysis of these data suggests that the single-tube multiplex RT-PCR assay represents a sensitive, specific, cost-effective, and rapid method for monitoring activities of the 3 endemic mosquito-borne human encephalitis viruses in mosquito populations in the southeastern United States.