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Abstract
The compositions of odor gases in Jizhuangzi sewage treatment plant of Tianjin in the summer of 2011 and 2012 were monitored by GC-MS. Meanwhile 24 subjects (11 male, 13 female) were selected for acute exposure experiment by HOLTER. 67 kinds of odors were detected out, the concentration of odor gases emitted from grid was the highest, sulfide and oxygen-contained were major species of odor gases; the acute exposure experiment at the grid showed that blood pressure reacted normal, maximum heart rate was significantly higher than normal value, mostly in the field test period, while the HRV parameters all deviated from normal range, which indicated that malodorous gases induced the subjects' sympathetic nerve activity. According to health risks assessment of odor gases from sewage treatment plan, methylene chloride and benzene of malodorous gases in the sludge dewatering had potential risk, non-carcinogenic hazard index (HI) was less than 1, within an acceptable range.
In order to evaluate the potential adverse health effects of odor emissions from wastewater pump stations (WWPSs) to human, a health risk assessment was performed to study the odors emitted from an urban WWPS in a residential area, Tianjin (in North China). First, 15 types of volatile organic compounds in the WWPS were collected and analyzed using gas chromatography-mass spectrometry. Next, Monte Carlo probabilistic modeling was applied to evaluate the potential health effects of four odors (chlorobenzene, dichloromethane, hydrogen sulfide, and carbon disulfide), which had higher concentrations. The results revealed that the 95th percentile of the total non-carcinogenic risk was approximately 1.73, which poses a threat to human health. In addition, hydrogen sulfide had the highest non-carcinogenic risk value of the four; the hazard quotient of hydrogen sulfide was estimated to be 1.60 at the 95th percentile, higher than the upper confidence limit (1.0). The 95th percentile of the carcinogenic risk was approximately 5.47E-08, much lower than the maximum acceptable level (1.0E-06). Finally, the influence of the input variables on the output was evaluated using sensitivity analysis, and contaminant concentration, reference concentration, and inhalation unit risk were the most influential variables.
While various volatile organic compounds (VOCs) are known to show neurotoxic effects, the detailed mechanisms of the action of VOCs on the autonomic nervous system are not fully understood, partially because objective and quantitative measures to indicate neural abnormalities are still under development. Nevertheless, heart rate variability (HRV) has been recently proposed as an indicative measure of the autonomic effects. In this study, we used HRV as an indicative measure of the autonomic effects to relate their values to the personal concentrations of VOCs measured by a real-time VOC monitor. The measurements were conducted for 24 hours on seven healthy subjects under usual daily life conditions. The results showed HF powers were significantly decreased for six subjects when the changes of total volatile organic compound (TVOC) concentrations were large, indicating a suppression of parasympathetic nervous activity induced by the exposure to VOCs. The present study indicated these real-time monitoring was useful to characterize the trends of VOC exposures and their effects on autonomic nervous system.
Wastewater Treatment plants can cause odour emissions that may lead to significant odour annoyance in their vicinity. Thus, over the past 20 years, several measurements were taken of the odour emissions that occur at WWTPs of different sizes, treatment technology, plant design and under different operating conditions. The specific aspects of odour sampling and measurement have to be considered. I presented some of the results of my odour emission measurements 11 years ago. However, it is now necessary to update the figures by evaluating newer measurement results obtained from measurements taken from 1994 to 2003. These are presented in this paper.
Also, the paper highlights the odour emission capacity (OEC) measurement technique which characterises liquids and can be used to assess the results achieved by different types of treatment in the liquid phase, e.g. in a sewerage system. In addition, the OEC is a suitable parameter to set standards for the odorant content of industrial wastewaters that are discharged into the publicly owned sewerage system.
GDX-502 sampling tubes, two-stage thermal desorption and gas chromatography coupled with mass spectrometry were used to investigate the composition and the content of malodor volatile organic compounds (MVOC) emitted from different processing units and the ambient sites of a typical municipal sewage treatment plant in Guangzhou. The molecular markers, atmospheric chemical reactivity, source profiles were studied. The results show that 40 volatile organic compounds (VOCs) were detected in the plant and were composed of alkanes, halogenated hydrocarbons, alkenes, aromatic hydrocarbon, OVOC and mercaptans. 34 MVOC species were detected, accounting for more than 95% of the total VOCs in each processing units. Benzenes, 2-Butanone, ethyl acetate, butyl acetate and dimethyl sulfide were found to be the MVOC molecular markers of the plant, while benzenes were the dominant components with the contribution of 75.89% to the measured MVOC. A strong correlation was found between the reconciliated source profile and the measured MVOC composition at the ambient receptor site.
In Thailand, there is a growing concern regarding the possible effects of air pollution on the health of residents living near a petrochemical complex in Map Ta Phut Industrial Estate (MTPIE), Rayong Province, Thailand. We studied exposure to selected volatile organic compounds (VOCs) in Map Ta Phut and the association between residing near the petrochemical complex and respiratory ailments. We carried out a population-based cross-sectional study, utilizing health data regarding respiratory problems among adults collected as part of a Health Effects of Air Pollution study of residents living in Map Ta Phut Municipality, Thailand, using a standardized questionnaire. The distance from the subject's residence to the center of the MTPIE was mapped using a geographical information system (GIS). A total of 15,441 adults aged > or = 13 years who lived in Map Ta Phut Municipality for at least 1 year were included in the study. Multiple logistic regression models were used to examine the relationship between the distance between the subject's residence and the MTPIE and the presence of the respiratory problems during the previous 12 months. A 5 km distance was chosen as the maximum study radius. Volatile organic compounds were observed higher concentrations at sites downwind from the MTPIE, and closer to the MTPIE. Study subjects who lived closer to the MTPIE reported an odor more frequently than subjects who lived farther from the MTPIE. Living closer to the MTPIE was associated with more acute respiratory problems, but not more chronic respiratory problems than living farther from the MTPIE. Adults aged > or = 40 years were more likely to have respiratory symptoms and eye irritation than those aged < 40 years. Females were more likely to have dyspnea, wheezing and upper respiratory symptoms than males. Living near the MTPIE for more than 5 years was associated with an increased risk of wheezing and upper respiratory symptoms.
Due to occasional complaints of odors from residential and commercial neighbors, and the projected development of adjacent vacant land, an investigation was conducted at a county wastewater treatment plant (WWTP) Utilizing a physical survey of possible odor sources, an emissions measurement study, and dispersion modeling, the site was assessed for current and future odor impacts. The main compound contributing to odors was concluded to be hydrogen sulfide (H2S). Using the EPA dispersion model Industrial Source Complex Short Term (ISCST3) and ten years of meteorological data, the H2S emissions results were analyzed to estimate potential maximum H2S concentrations, as well as the annual frequency of occurrences of H2S above certain concentrations. The chief source of odor impacts was identified as fugitive emissions from the top of the grit chamber/flow splitter building, through openings for valve stems, flow gates, and the grit removal conveyor apparatus. Another ventilation fan was added, and the H2S-laden air from the building was routed through new biofiltration units, which were being evaluated to replace an older caustic/chlorine scrubber. Since these units operated at an extremely high H2S removal efficiency, it was concluded that biofilters would replace caustic/chlorine scrubbing on a permanent basis.
Concentrations of non methane-VOCs and risk levels of employees' exposure to VOCs were determined at two Finnish waste water treatment plants. The concentration of hydrogen sulphide (H2S) reached the Finnish OEL (occupational exposure limit). The concentrations of styrene, 1,2-dichloroethane, and toluene were found to be elevated at plant A. 328.4 microg/m3 of styrene and 709.8 microg/m3 toluene was found in the sludge dewatering, and 955.8 microg/m3 of 1,2-dichloroethane was detected in the trash rake. TVOC concentrations varied from 149.8 microg/m3 in the Plant B sludge dewatering to 7719.0 microg/m3 in the Plant A sludge dewatering. Most of the detected TVOC concentrations were quite high in comparison to the indoor air regulations or recommendations. The most odorous compounds were determined by combined TD-GC-MS-sniffing analysis. Odour was mainly caused by sulphur-containing compounds, aldehydes, and butanoic acid, in addition to aromatic compounds such as styrene, toluene and 4-methylphenol.
Waste treatment processes produce odours and biological emissions to the environment, but their health effects are controversial. The aim of our study was to assess odour-associated self-reported physical symptoms among residents living near waste treatment centres. The study was conducted in the surroundings of five large-scale Finnish waste treatment centres with composting plants. In 2006, 1142 randomly selected residents living within 1.5, 3.0 and 5.0 km of these centres were interviewed by telephone. A questionnaire with 102 items asked about respondent's personal characteristics, odour exposure and symptoms during the preceding 12 months. Physical symptoms were analysed by distance to the waste treatment centre and by the respondent's perception and annoyance of waste treatment odour. The residents who were classified as "annoyed of the odour" reported following physical symptoms more than the others did: unusual shortness of breath (OR 1.5, 95% CI 1.0-2.2), eye irritation (1.5, 1.1-2.1), hoarseness/dry throat (1.5, 1.1-2.0), toothache (1.4, 1.0-2.1), unusual tiredness (1.5, 1.1-2.0), fever/shivering (1.7, 1.1-2.5), joint pain (1.5, 1.1-2.1) and muscular pain (1.5, 1.1-2.0). Moreover, the ORs for almost all other physical symptoms were elevated among the annoyed respondents. Reported odour annoyance near the waste treatment centres showed an association with many physical symptoms among residents living in the neighbouring areas.
The principal health outcome of exposure to toluene is dysfunction of the central nervous system. Effects range from fatalities and severe neurological disorders in toluene abuse situations to deficits in neurobehavioral function in occupational populations. An Inhalation Reference Concentration (RfC) of 0.4 mg toluene/m3 or 0.1 ppm was developed by the U.S. EPA to protect general populations chronically exposed to toluene. The RfC was derived from results of an occupational study involving Asian workers who developed neurobehavioral deficits at a mean toluene exposure level at the time of the study of 88 ppm. The derivation incorporated several uncertainty factors, one of which was a factor of 10 to account for sensitive subpopulations. Recent evidence indicates that some Japanese and possibly other Asian populations harbor a defective gene for aldehyde dehydrogenase, and thus exhibit a decreased rate of toluene metabolism. Although it is not known if reduced metabolism by aldehyde dehydrogenase also was a factor in the occupational study, preshift blood levels of toluene were considerably higher than preshift levels from non-Asian workers exposed to similar air levels of toluene. The elevated blood levels are consistent with defective metabolism but remain to be confirmed. Inasmuch as air levels of toluene in urban environments are about 10-fold lower than the RfC, an adequate measure of protection is afforded by the RfC with or without an uncertainty factor for sensitive subgroups. However, the uncertainty factor for sensitive subgroups should be retained because there is no information regarding toluene metabolism in children.
Positive pressure pneumoperitoneum (PPP) effects on the autonomic nervous system (ANS) might be of clinical importance, as imbalance in the autonomic cardiac control might lead to serious consequences.
Fifteen healthy patients undergoing elective laparoscopic cholecystectomy were analyzed for cardiac autonomic nervous activity by spectral heart rate variability, during awake state, before and after intubation, during CO2 PPP (14 mmHg), and after CO2 evacuation. The very low, low, high and very high frequency (VLF, LF, HF, VHF respectively) bands of the spectral density of the heart rate variability (HRV) and their normalized values, as well as the LF/HF ratio, were obtained from the power spectra of R-R intervals, using the fast-Fourier transformation algorithm.
Using Friedman's nonparametric test, only the difference between the power of LF during anesthesia (median 30.74) and the middle of PPP (median 195.66) was found to be significant (p<0.012). Such change was recorded in 14 patients (p = 0.001, sign test).
Increased LF power reflects sympathetic cardiac activation. As the LF range accounts for regulation of blood pressure and baroreflex, several mechanisms may explain this activation. This in turn may predispose patients who suffer from cardiac disease to higher risk of developing ventricular arrhythmias, besides the possible adverse hemodynamic consequences of PPP.
Heart rate variability (HRV) has been used for assessment of depth of anesthesia. Alterations in respiratory rate and tidal volume modulate the sympatovagal neural drive to the heart. The changes in PaCO2 that accompany changes in breathing pattern may, through chemoreceptors in the brainstem, independently influence the autonomic control of the heart and modulate HRV.
We measured the effects of PaCO2, tidal volume and respiratory rate on HRV during spontaneous and mechanical ventilation in 22 healthy volunteers and in 25 mechanically ventilated anesthetized patients.
Adding CO2 to the inspiratory gas increased high frequency (HF) and low frequency (LF) components of HRV in awake volunteers both during spontaneous and mechanical ventilation, while this effect of CO2 was abolished in patients during anesthesia. Increase of tidal volume increased HF component of HRV only in volunteers during spontaneous ventilation. On the other hand, when respiratory rate was reduced, the balance of HF and LF power moved toward LF power in all study groups. Breathing frequency altered HRV independent on PaCO2, tidal volume and the level of consciousness. In contrast, the effect of PaCO2 appeared to be related to normal level of consciousness, suggesting that a cortical modulation of the autonomic nervous activity contributes to the effects of PaCO2 on HRV.
PaCO2, tidal volume and respiratory rate should be controlled when HRV power spectrum is measured in conscious patients or volunteers, while in anesthetized patients small changes in end-tidal CO2 or tidal volume do not modulate HRV if respiratory rate remains unchanged.
Volatile organic sulfide (VOS) causes of odors were studied at Philadelphia's Northeast Water Pollution Control Plant between September 11 and November 25, 2003. Results showed that dimethyl sulfide (DMS) dominated the VOS pool whenever VOS concentration rose above the background level (<50 microg/L). Methanethiol was generally less than 10% of VOS and it was mainly found at sites with limited or reduced dissolved oxygen (DO). Dimethyl disulfide occupied approximately 1% of the VOS and was often not detectable. Carbon disulfide was not detected. The concentrations of DMS varied by three orders of magnitude, ranging from <5 to 1260 microg/L. High concentrations of DMS, averaging 419 and ranging from <5 to 1000 microg/L, were generally found in return activated sludge. The DMS concentration in the primary effluent ranged from <5 to 729 microg/L and averaged 245 microg/L. Concentrations of DMS in the aeration tank (AT) with high DO were from <5 to 997 microg/L with an average of 250 microg/L. However, DMS concentrations in the AT representing anaerobic conditions were as high as 1260 microg/L. The estimated average purge efficiency of DMS was about 78%, which required a DMS production rate of 108 microg/Lh(-1) to keep the analyzed concentration in the AT. While a valid but weak statistical relationship between acetone and DMS was observed, there was no strong evidence to support that the methylation of hydrogen sulfide with acetone could be the mechanism for the DMS formation. Instead, DMS production was found to be associated with the characteristics of incoming wastewater. Thus, a VOS precursor was believed to be present in the incoming wastewater, which warranted a need for further investigation.