Degradation of gaseous volatile organic compounds (VOCs) by a novel UV-ozone technology.

In this study, a UV-assisted ozonation (UV/O3) process for the degradation of VOCs emissions with a final scrubbing phase was implemented to evaluate the removal efficiency of toluene and to prevent the release of polluting intermediates of the single-step process. Inlet toluene concentration and applied voltage were varied in order to investigate several operating conditions. The results highlighted that at higher inlet concentration the abatement of toluene was lower, while increase in ozone concentration led to an increase of the degradation efficiencies. The additional water scrubbing step enhanced the abatement of UV/O3 up to 98.5%, due to the solubilisation of ozone and by-products in the process water and, thus, the further oxidation of the contaminants within this phase. A maximum Elimination Capacity (ECmax) of 22.6 g m-3 h-1 was achieved with the UV/O3 + Scrubbing. The combined system boosted higher performance and stability compared to the stand-alone (UV/O3) process along with a more economical and environmental sustainability.

Next-generation of instrumental odour monitoring system (IOMS) for the gaseous emissions control in complex industrial plants.

Odour emissions from complex industrial plants may cause potential impacts on the surrounding areas. Consequently, the validation of effective tools for the control of the associated environmental pressures, without hindering economic growth, is strongly needed. Nowadays, senso-instrumental methods by using Instrumental Odour Emissions Systems (IOMSs) is among the most attractive tool for the continuous monitoring of environmental odours, allowing the possibility of obtaining real-time information to support the decision-making process and proactive approach. The systems complexity and scarcity of real data limited their wider full-scale employment. The study presents an advanced prototype of IOMS for the continuous classification and quantification of the odours emitted in ambient air by complex industrial plants, to continuously control the plants emissions with backwards approach. The IOMS device was designed and optimized and included the system for the automatic control of the conditions inside the measurement chamber. The designed operational procedures were presented and discussed. Results highlighted the influence of temperature and air flow rate for the measurement repeatability. Accurate prediction model was created and optimized and resulted able to distinguish 3 different industrial odour sources with accuracy approximately equal to 96%. The models were optimized thanks to the software features, which allowed to automatically apply the designed statistical procedures on the identified dataset with different pre-processing approach. The usefulness of having a fully-developed and user-friendly flexible system that allowed to select and automatically compare different settings options, including the different feature extraction methods, was demonstrated in order to identify the best prediction model.

Effect of curing conditions on physical and chemical properties of MTA.

AIM: To evaluate setting time, pH, solubility and surface roughness of MTA+ and ProRoot MTA and characterize their hydration under several curing conditions. METHODOLOGY: Specimens were prepared to evaluate setting time (n = 6 for each group, specimen dimensions 10 × 8 × 5 mm), solubility (n = 6 for each group, specimen dimension 20 mm in diameter and 1.5 mm thick) after 1 and 28 days, pH (n = 10 for each group, specimen dimensions 10 mm in diameter and 1 mm thick) after 1, 7, 14, 21 and 28 days and surface roughness (n = 10 for each group, specimen dimensions 4 mm in diameter and 3 mm high) after 28 days when cements were cured at 95% humidity or immersed in saline or HBSS at 37 °C. The powder and liquid were mechanically mixed by an amalgamator. The set materials were characterized using X-ray diffraction analysis, scanning electron microscopy and X-ray energy-dispersive analysis. Statistical comparisons were employed using one-way anova. The level of significance was set at P = 0.05. RESULTS: Setting time was significantly shorter when cements were cured at 95% humidity compared to those in saline (P < 0.001) and HBSS (P < 0.001). Setting time of MTA+ was significantly shorter than that of ProRoot MTA (P < 0.001), which had a significantly higher pH than MTA+ (P < 0.05) for all periods and immersion liquids. After immersion in saline, MTA+ was significantly less soluble than ProRoot MTA (P < 0.001); when immersed in HBSS, no significant difference was found (P = 1.00). The surface roughness of both cements was affected when exposed to HBSS (P < 0.001 for both cements) and saline (P < 0.001 for both cements). Storage in HBSS created a homogenous surface; incubation in saline or humidity created a biphasic surface. The main crystalline phases in both cements were tricalcium silicate, bismuth oxide and calcium hydroxide. CONCLUSIONS: MTA+ had a shorter setting time than ProRoot MTA, promoted lower pH and had lower solubility in saline. Curing conditions affected the surface roughness and microstructure of the cements.

Skin reactions amongst Greek endodontists: a national questionnaire survey.

AIM: To investigate amongst Greek endodontists in the past 5 years the prevalence, aetiologic factors, severity and treatment for skin reactions. METHODOLOGY: One hundred and 47 endodontists met the inclusion criteria and were invited to participate in the survey. Participants were asked for personal/professional data, prevalence, aetiologic factors, symptoms, severity and treatment for skin reactions in the past 5 years. The type of gloves used and frequency of hand washing as well as information on history of atopy and eczema were also recorded. Data were analysed using chi-square test and independent samples t-test. The level of significance was set at P = 0.05. RESULTS: The response rate was 84%. Skin reactions were reported by 32.5% of participants. Hands were the body part most frequently affected (66% of cases); glove powder accounted for 73% of skin reactions. Medical care was sought by 28.2% of the affected participants. Endodontists with a history of atopy (P < 0.001) and dermal eczema (P < 0.001) as well as females (P = 0.023) were more likely to report skin reactions. Replacement of powdered latex gloves with powder-free or vinyl/nitrile gloves, avoidance of potential allergens and use of pharmaceutical ointments were adopted by 48.7%, 23.1% and 2.6% of the affected endodontists, respectively, to manage skin reactions. CONCLUSIONS: Approximately one-third of participants reported skin reactions. History of atopy and dermal eczema as well as gender was significantly associated with such reactions. The use of powder-free latex gloves instead of powdered ones was the measure most frequently adopted to manage reactions.

Musculoskeletal disorders amongst Greek endodontists: a national questionnaire survey.

AIM: To investigate amongst Greek endodontists the prevalence and characteristics of musculoskeletal disorders (MSDs) in the past 12 months, the treatment followed, their postures during practice and the adoption of ergonomic standards. METHODOLOGY: One hundred and forty-seven endodontists met the inclusion criteria and were invited to participate in the survey. Participants were asked for personal/professional data, prevalence, characteristics and treatment for MDSs in the past 12 months. Endodontists' postures during practice as well as ergonomic factors were also recorded. Data were analysed using chi-square test, independent samples t-test and logistic regression. The level of significance was set at P = 0.05. RESULTS: The response rate was 84%. MSDs were reported by 61% of the participants. Of them, 69% reported pain to more than one body part. The prevalence of disorders was highest in the lower back (30%) and neck (30%). Medical care was applied in 53% of the disorders. A sitting position was always used by 83% of endodontists. Awkward postures during practice (OR:4.561, 95% CI:1.341-15.512), regular stretching exercises (OR:0.032, 95% CI:0.010-0.110) and number of patients day(-1) (OR:3.524, 95% CI:1.686-18.100) were significant predictors for MSDs. Properly adjusted stools, sufficient lighting and space in the operating room were reported by 71%, 96% and 93% of participants, respectively. CONCLUSIONS: A high percentage of endodontists reported MSDs. Adoption of correct/neutral postures, regular performance of stretching exercises and reduced number of patients/day were associated with a low prevalence of disorders. The majority of endodontists had adopted ergonomic innovations/standards to control disorders.

Occupational ocular accidents amongst Greek endodontists: a national questionnaire survey.

AIM: To investigate amongst Greek endodontists, the incidence of ocular accidents during practice, the circumstances associated with them, the therapeutic measures taken after the accidents, their compliance with the use of eye protection and their eye care behaviour. METHODOLOGY: One hundred and forty-seven endodontists met the inclusion criteria and were invited to participate in the survey. Data were gathered through interviews based on a questionnaire. Participants were asked for personal/professional data, information on ocular accidents in the past 5 years, post-accident actions and the type of eye protection used. Their eyesight status and frequency of ocular examination were also recorded. Data were analysed using chi-square test, independent samples t-test and logistic regression. The level of significance was set at P = 0.05. RESULTS: The response rate was 84%. Ocular accidents were reported by 73% of the participants. Amalgam and NaOCl were the foreign bodies most frequently associated with ocular accidents. Medical assistance was sought in 16% of the most recent accidents. No permanent eye damage was reported. Regular use of magnification (OR:0.305, 95%CI:0.123-0.754) and years of clinical experience (OR:0.191, 95%CI:0.066-0.551) were significant predictors for the incidence of ocular accidents. Adequate eye protection was utilized by 82% of endodontists. Endodontists with eyesight deficiencies attended more frequently for ocular examination (P = 0.018). CONCLUSION: A high percentage of endodontists experienced ocular accidents. Regular use of magnification and increasing years in practice were associated with a reduced risk of ocular accidents. The majority of endodontists reported using adequate eye protection.

Percutaneous injuries amongst Greek endodontists: a national questionnaire survey.

AIM: To investigate amongst Greek endodontists the incidence of percutaneous injuries, the circumstances associated with them, the therapeutic measures taken after the injuries and their compliance with infection control measures. METHODOLOGY: One hundred and forty-seven endodontists met the inclusion criteria and were invited to participate in the survey. Personal and professional data, information on percutaneous injuries in the past 5 years and on infection control practices were gathered through interviews based on a questionnaire. Data were analysed using chi-square test, independent samples t-test, one-way anova and Pearson's correlation coefficient. The level of significance was set at P = 0.05. RESULTS: The response rate was 84%. The injury rate was estimated at 1.35 per endodontist per year. Endodontic files were associated with 37% of the injuries and fingers were injured in 75% of the most recent cases. Medical assistance was sought in 36% of the most recent injuries. Endodontists who always or usually practiced 4-handed endodontics (P = 0.007) as well as those not performing surgical endodontics (P = 0.007) reported significantly fewer injuries. In 91% of the participants, a complete hepatitis B virus vaccination was reported. Gloves, masks, rubber dam isolation and puncture-resistant containers for disposal of sharp instruments were always used by 98%, 94%, 100% and 81% of the respondents, respectively. CONCLUSIONS: The injury rate was low. The practice of four-handed endodontics was associated with a reduced number of percutaneous injuries; the performance of surgical endodontics increased their incidence. Greek endodontists showed a high level of compliance with infection control measures.

Control of odour emission in wastewater treatment plants by direct and undirected measurement of odour emission capacity.

Odour emissions from wastewater treatment plants (WWTPs) are considered to be the main causes of disturbance noticed by the exposed population and have relevant impacts on both tourism economy and land costs. Odour impact from WWTPs is generated by primary and secondary odour emissions. Primary odour emissions are related especially to the wastewater type and variability discharged into the sewer and directed to the WWTP, and to the wastewater collection and sewage system. Secondary odours are related to the treatment units of the plant. Several studies describe the key role of primary odour emissions and how they are strongly related to odour impacts of WWTPs. In this way, a opportune characterization of the emission capacity of primary odour could be an effective way to control odour emission in the WWTPs. In this study the odour emission capacity (OEC) of different domestic sewers was described and investigated; a correlation between the OEC and the main physical-chemical parameters of wastewater quality was also carried out. Results of this study identify the optimum conditions for sampling and measuring OEC in wastewaters and define its dependence by wastewater quality. These results can contribute to setting the standards for the maximum odourant content of wastewater that are discharged into the publicly owned sewage system.

Instrumental characterization of odour: a combination of olfactory and analytical methods.

Odour emissions are a major environmental issue in wastewater treatment plants and are considered to be the main cause of disturbance noticed by the exposed population. Odour measurement is carried out using analytical or sensorial methods. Sensorial analysis, being assigned to the "human sensor", is the cause of a considerable uncertainty. In this study a correlation between analytical and sensorial methods was investigated. A novel tool was used to both define odour indexes and characterise the odour sources and the volatile substances that cause annoyance in a wastewater treatment plant, with the aim to remove the subjective component in the measure of the odours and define the induced impact. The sources and the main chemical substances responsible for the olfactory annoyances were identified. Around 36 different substances were detected, with more than half being smell relevant components as well as responsible. Dimethyl disulphide was identified as key compound. Results highlight the applicability of highly correlation between analytical and sensorial methods in odour emission monitoring.

Odour monitoring of small wastewater treatment plant located in sensitive environment.

Small wastewater treatment plants are often localized nearby tourist areas. Odour emissions are a major environmental issue in these plants and are considered to be the main cause of disturbance noticed by the exposed population. Odour measurement is carried out using analytical or sensorial methods. Sensorial analysis, being assigned to the "human sensor", is the cause of a considerable uncertainty.In this study, a novel procedure based on highly innovative analytical tool was used to identify and characterise the odour sources and the volatile substances that cause annoyance in a SWWTP located in a sensitive area, with the aim to remove the subjective component in the measure of the odours and define the induced impact. At the same time key odour compounds are detected, and the relationship between their concentration and the performances of the plant are investigated.The sources and the main chemical substances responsible for the olfactory annoyances were identified. Results highlight the applicability of the highly innovative tool in odour emission monitoring. Around 39 different substances were detected, with almost half being smell relevant components as well as responsible. Dimethyl disulphide was identified as key compound connected to the efficiency of the process.