VOC Profiles of Saliva in Assessment of Halitosis and Submandibular Abscesses Using HS-SPME-GC/MS Technique.

Halitosis and submandibular abscesses are examples of mouth-related diseases with the possible bacterial origin. Salivary volatile organic compounds (VOCs) are potential biomarkers of them, once they can be addressed as metabolites of bacterial activity. Healthy patients (n = 15), subjects with submandibular abscesses located in fascial deep space (n = 10), and subjects with halitosis (n = 5) were enrolled in the study. Saliva samples were subjected to headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled to mass spectrometry (GC/MS) analysis. A total number of 164 VOCs was detected by the developed methodology, 23 specific for halitosis and 41 for abscess. Halitosis' profiles were characterized by a larger number of sulfur compounds, while for abscess they had a higher variety of alcohols, aldehydes, and hydrocarbons-biomarkers of inflammatory processes. Principal components analysis allowed visualization of clusters formed according to the evaluated conditions. Kruskal-Wallis test indicated that 39 VOCs presented differentiated responses between the studied groups, with statistical relevance (p < 0.05). Random forest was applied, and a prediction model based on eight VOCs (2-butanone, methyl thioacetate, 2-methylbutanoic acid, S-methyl pentanethioate, dimethyl tetrasulfide, indolizine, pentadecane, and octadecanal) provided 100% of sensitivity, 82% of specificity, and 91% of balanced accuracy, indicating the specific presence of submandibular abscess.

Energetic assessment of fixation of CO2 and subsequent biofuel production using B. cereus SM1 isolated from sewage treatment plant.

The ongoing work on global warming resulting from green house gases (GHGs) has led to explore the possibility of bacterial strains which can fix carbon dioxide (CO2) and can generate value-added products. The present work is an effort in this direction and has carried out an exhaustive batch experiments for the fixation of CO2 using B. Cereus SM1 isolated from sewage treatment plant (STP). The work has incorporated 5-day batch run for gaseous phase inlet CO2 concentration of 13 ± 1 % (%v/v). 84.6 (±5.76) % of CO2 removal was obtained in the gaseous phase at mentioned CO2 concentration (%v/v). Energetic requirement for CO2 fixation was assessed by varying Fe[II] ion concentration (0-200 ppm) on the per-day basis. The cell lysate obtained from CO2 fixation studies (Fe[II] ion = 100 ppm) was analyzed using Fourier transformation infrared spectroscopy (FTIR) and gas chromatography-mass spectroscopy (GC-MS). This analysis confirmed the presence of fatty acids and hydrocarbon as valuable products. The hydrocarbons were found in the range of C11-C22 which is equivalent to light oil. The obtained fatty acids were found in the range of C11-C19. The possibility of fatty acid conversion to biodiesel was explored by carrying out the transesterification reaction. The yield of biodiesel was obtained as 86.5 (±0.048) % under the transesterification reaction conditions. Results of this research work can provide the valuable information in the implementation of biomitigation of CO2 at real scenario.

Comparative assessment of compost and zeolite utilisation for the simultaneous removal of BTEX, Cd and Zn from the aqueous phase: Batch and continuous flow study.

The present study focuses on the comparison of two materials, compost from municipal solid waste and natural zeolite for the simultaneous removal of petroleum hydrocarbons (benzene, toluene, ethylbenzene, xylenes - BTEX) and toxic metals from groundwater. First, batch experiments were conducted to identify the optimal removal conditions. All of the kinetic experiments were fitted to the pseudo-second-order kinetic model; equilibrium was reached within approximately 8 h for the zeolite and 12 h for the compost. An increase in the adsorbent dose and the pH value as well as a decrease in the initial concentration enhanced the pollutants' removal. The removal selectivity of both materials with slight differences follows the order Cd > Zn & toluene > ethylbenzene > m- & p-xylene > o-xylene > benzene. According, to the results derived from the continuous flow experiments the maximum adsorption capacity of the compost (90%) referred to Cd (0.88 mmol/g) whereas the minimum refers to benzene (65%) with a capacity up to 0.065 mmol/g. Zeolite had lower efficiencies for the studied pollutants with a higher performance corresponding to Cd (0.26 mmol/g), whereas the minimum zeolite capacity (63%) corresponds to toluene (0.045 mmol/g). Thus, this paper provides evidence that compost, a low cost material produced from waste, is capable for the simultaneous removal of both organic and inorganic pollutants from wastewater, and its performance is superior to zeolite.

Utilization of recycled asphalt concrete with warm mix asphalt and cost-benefit analysis.

The asphalt paving industries are faced with two major problems. These two important challenges are generated with an increase in demand for environmentally friendly paving mixtures and the problem of rapidly rising raw materials. Recycling of reclaimed asphalt pavement (RAP) is a critical necessity to save precious aggregates and reduce the use of costly bitumen. Warm Mix Asphalt (WMA) technology provides not only the option of recycling asphalt pavement at a lower temperature than the temperature maintained in hot mixtures but also encourages the utilization of RAP and therefore saves energy and money. This paper describes the feasibility of utilizing three different WMA additives (organic, chemical and water containing) at recommended contents with different percentages of RAP. The mechanical properties and cost-benefit analysis of WMA containing RAP have been performed and compared with WMA without RAP. The results indicated that, 30%, 10% and 20% can be accepted as an optimum RAP addition related to organic, chemical and water containing additives respectively and organic additive with 30% RAP content has an appreciable increase in tensile strength over the control mix. It was also concluded that the RAP with WMA technology is the ability to reduce final cost compared to HMA and WMA mixtures.

Remediation of hydrocarbon-contaminated soils by ex situ microwave treatment: technical, energy and economic considerations.

In this study, the remediation of diesel-polluted soils was investigated by simulating an ex situ microwave (MW) heating treatment under different conditions, including soil moisture, operating power and heating duration. Based on experimental data, a technical, energy and economic assessment for the optimization of full-scale remediation activities was carried out. Main results show that the operating power applied significantly influences the contaminant removal kinetics and the moisture content in soil has a major effect on the final temperature reachable during MW heating. The first-order kinetic model showed an excellent correlation (r2 > 0.976) with the experimental data for residual concentration at all operating powers and for all soil moistures tested. Excellent contaminant removal values up to 94.8% were observed for wet soils at power higher than 600 W for heating duration longer than 30 min. The use of MW heating with respect to a conventional ex situ thermal desorption treatment could significantly decrease the energy consumption needed for the removal of hydrocarbon contaminants from soils. Therefore, the MW treatment could represent a suitable cost-effective alternative to the conventional thermal treatment for the remediation of hydrocarbon-polluted soil.

Performance assessment of pilot horizontal sub-surface flow constructed wetlands for removal of diesel from wastewater by Scirpus grossus.

One of the appropriate development technology options for the treatment of wastewater contaminated with diesel is constructed wetlands (CWs). Throughout 72 days of exposure, sampling was carried out for monitoring of physical parameters, plant growth and the efficiency of total petroleum hydrocarbon (TPH) removal, as an indication for diesel contamination, to assess the pilot-scale performance. Four pilot CWs with a horizontal sub-surface flow system were applied using the bulrush of Scirpus grossus. The CWs were loaded with different diesel concentrations of 0, 0.1, 0.2 and 0.25% (Vdiesel/Vwater). The TPH removal efficiencies were 82, 71, and 67% at the end of 72 days for diesel concentrations of 0.1, 0.2, and 0.25% respectively. In addition, the high removal efficiency of total suspended solids and chemical oxygen demand (COD) were 100 and 75.4% respectively, for a diesel concentration of 0.1%. It was concluded that S. grossus is a potential plant that can be used in a well-operated CW for restoring 0.1% diesel-contaminated water.

Plant residues--a low cost, effective bioremediation treatment for petrogenic hydrocarbon-contaminated soil.

Petrogenic hydrocarbons represent the most commonly reported environmental contaminant in industrialised countries. In terms of remediating petrogenic contaminated hydrocarbons, finding sustainable non-invasive technologies represents an important goal. In this study, the effect of 4 types of plant residues on the bioremediation of aliphatic hydrocarbons was investigated in a 90 day greenhouse experiment. The results showed that contaminated soil amended with different plant residues led to statistically significant increases in the utilisation rate of Total Petroleum Hydrocarbon (TPH) relative to control values. The maximum TPH reduction (up to 83% or 6800 mg kg(-1)) occurred in soil mixed with pea straw, compared to a TPH reduction of 57% (4633 mg kg(-1)) in control soil. A positive correlation (0.75) between TPH reduction rate and the population of hydrocarbon-utilising microorganisms was observed; a weaker correlation (0.68) was seen between TPH degradation and bacterial population, confirming that adding plant materials significantly enhanced both hydrocarbonoclastic and general microbial soil activities. Microbial community analysis using Denaturing Gradient Gel Electrophoresis (DGGE) showed that amending the contaminated soil with plant residues (e.g., pea straw) caused changes in the soil microbial structure, as observed using the Shannon diversity index; the diversity index increased in amended treatments, suggesting that microorganisms present on the dead biomass may become important members of the microbial community. In terms of specific hydrocarbonoclastic activity, the number of alkB gene copies in the soil microbial community increased about 300-fold when plant residues were added to contaminated soil. This study has shown that plant residues stimulate TPH degradation in contaminated soil through stimulation and perhaps addition to the pool of hydrocarbon-utilising microorganisms, resulting in a changed microbial structure and increased alkB gene copy numbers. These results suggest that pea straw in particular represents a low cost, effective treatment to enhance the remediation of aliphatic hydrocarbons in contaminated soils.

Biosurfactants production by yeasts using soybean oil and glycerol as low cost substrate

Biosurfactants are bioactive agents that can be produced by many different microorganisms. Among those, special attention is given to yeasts, since they can produce many types of biosurfactants in large scale, using several kinds of substrates, justifying its use for industrial production of those products. For this production to be economically viable, the use of residual carbon sources is recommended. The present study isolated yeasts from soil contaminated with petroleum oil hydrocarbons and assessed their capacity for producing biosurfactants in low cost substrates. From a microbial consortium enriched, seven yeasts were isolated, all showing potential for producing biosurfactants in soybean oil. The isolate LBPF 3, characterized as Candida antarctica, obtained the highest levels of production - with a final production of 13.86 g/L. The isolate LBPF 9, using glycerol carbon source, obtained the highest reduction in surface tension in the growth medium: approximately 43% of reduction after 24 hours of incubation. The products obtained by the isolates presented surfactant activity, which reduced water surface tension to values that varied from 34 mN/m, obtained from the product of isolates LBPF 3 and 16 LBPF 7 (respectively characterized as Candida antarctica and Candida albicans) to 43 mN/m from the isolate LPPF 9, using glycerol as substrate. The assessed isolates all showed potential for the production of biosurfactants in conventional sources of carbon as well as in agroindustrial residue, especially in glycerol.

In situ fluidization for peat bed rupture, and preliminary economic analysis.

This study concerns in situ fluidization (ISF), a new remediation method with potential application to the remediation of NAPL and heavy metal contaminants, by their release from the fluidized zone generated by a water jet. The present study examines the effect of ISF on layers of peat, of significance owing to its role as an important NAPL and metal contaminant trap. Once trapped, such contaminants are not readily accessible by most remedial methods, due to the low permeability and diffusivity of the peat. A simple tank experiment is used to demonstrate rupture of a peat layer by ISF, with removal of the peat as elutriated fines and segregated peat chunks. The application of ISF in the field is then examined by three field trials in uncontaminated sands, in both saturated and unsaturated conditions. Fluidized depths of up to 1.9 m in the saturated zone (with refusal on a peat layer) and 2.5 m in the unsaturated zone (no refusal) were attained, using a 1.9-m-long, 50 mm diameter jet operated at 5-13 1 s(-1). Pulses of dark turbidity and shell fragments in the effluent indicated the rupture of peat and shelly layers. The experiments demonstrate the hydraulic viability of ISF in the field, and its ability to remove peat-based contaminants. The issues of appropriate jet design and water generation during ISF are discussed, followed by a preliminary economic analysis of ISF relative to existing remediation methods.