Environmental health engineering

A questionnaire survey consisting of 2400 householders was performed on Abadan residents to evaluate their knowledge, attitudes, and practices (KAP) towards solid waste (SW) reduction, source separation and recycling, collection and willingness to pay (WTP) for SW services. The study has also covered the relationship between demographic variables and KAP towards SW management. The data analyzed suggests that the studied community had a very positive attitude to take part in SW source separation and recycling plans. However, the respondents not only showed low intimate knowledge of different steps of SW management, but were also weak to take practices about these steps. The KAP of SW source separation and recycling was influenced by demographic factors of age, education level, gender and occupation. It was further found that education level and occupation were two significant factors affecting residents' WTP (2 = 24.083, p-value <0.0001). In conclusion our study found that providing public with MSW infrastructures and improving citizens' awareness about SW source separation and recycling to promote SW recycling programs hold great promise for developing effective public campaigns and behavior-changing interventions. This has important implications in that the usual KAP of public proved inadequate in the case of SW source separation and recycling. The implementation of needs-based training programmes considering females as one of the main audience groups and determination of municipality needs are thereby highly advocated.

Although the removal of colloidal particles continues to be an important reason for using coagulation, a newer objective, the removal of natural organic matter (NOM) to reduce the formation of disinfection by-products (DBPs), is growing in importance. Enhanced coagulation is thus introduced to most water utilities treating surface water. Bench-scale experiments were conducted to compare the effectiveness of alum and ferric chloride in removing DBPs precursors from eight synthetic water samples, each representing a different element of the USEPA's 3×3 enhanced coagulation matrix. The effect of enhanced coagulation on the residual metal (aluminum/iron) concentration in the treated water was assessed as well. The removal of total organic carbon (TOC) was dependent on the coagulant type and was enhanced with increasing coagulant dose, but the latter had no further considerable effect in case of increasing to high levels. For all the treated samples coagulation with ferric chloride proved to be more effective than alum at similar doses and the mean values of treatment efficiencies were 51% and 32% for ferric chloride and alum, respectively. Ferric chloride was therefore considered the better chemical for enhancing the coagulation process. Besides, due to less production of sludge by this coagulant, it would be predicted that treatment plants would be confronted to fewer problems with respect to final sludge disposal. Measurements of residual metal in treated water indicated that iron and aluminum concentrations had been increased as expected but the quality of water concerning the residual metal deteriorated much more in cases of under-dosing. Despite expecting high residual Al and Fe concentrations under enhanced coagulation, metal concentrations were frequently remained low and were not increased appreciably.

Two laboratory-scale column-type sequencing batch reactors (SBRs) were used to investigate the inhibition of suspended flocs and aerobic granular biomass at COD 4CP /COD Total ratios ranging from 0 to 1. The inhibitory concentrations of 4-chlorophenol (4CP) were determined as a function of substrate consumption rate (q max) and specific oxygen uptake rate (SOUR), as well as of chemical oxygen demand (COD) and 4CP removal efficiencies. Monoethylene glycol was used as a biogenic substrate to simulate industrial wastewater. Granular SBR (GSBR) showed high efficiency in both COD and 4CP removal, at concentrations of up to 620 mg/L; however, the process ceased at 200 and 550 mg-4CP/L in the suspended flocs SBR (FSBR). Other than dosing various concentrations of 4CP in the system, the lack of sufficient dedicated time led to the accumulation of inhibitory compounds over time. At inhibitory concentration levels, only partial degradation of 4CP occurred, which resulted in 5-chloro-2-hydroxymuconic semialdehyde accumulation in the system. Assimilatory removal of 4CP was negligible at the normal performance of FSBR, but reached considerable values in GSBR, or at the time of cessation of FSBR performance. The bulk liquid color evolution in the case of repeated feast and famine conditions, both after process cessation and in the absence of 4CP in the feed, emphasized the crucial role of the biodegradable organic compound to enhancement of 4CP removal. An increasing trend of q max was not only observed at any definite concentration of 4CP as the cycles proceeded, but also with the feed ratio of 4CP/COD Total in both reactors. In comparison with FSBR, higher q max was observed in GSBR, as biomass completely adapted to 4CP, suggesting that the granular bioreactor is limited by diffusion rather than biomass.

Epidemiological and laboratory studies have suggested that polychlorinated biphenyls (PCBs) and methyl mercury (MeHg) may have additive or synergistic effects on CNS function. Aim of this study was to characterize the effects of exposure to low levels of MeHg (0.5 mg/kg day in drinking water) and PCB126 (100 ng/kg day in food), alone and in combination, on neurobehavioral development in Wistar rats. Dams were treated from gestational day 7 to post-natal day (PND) 21. Animals were tested for developmental landmarks and reflexes (PND1-21), attention deficits (PND40), locomotor activity (PND30, 110), spatial learning (PND75), coordination and balance (PND90), object discrimination (PND80), anxiety (PND100), and conditioned learning (PND110). Parameters related to pregnancy, sex ratio at birth, and physical development (at weaning) did not differ among groups, though PCB126 decreased number of pups at birth. A slight delay in negative geotaxis was found in female rats in all treatment groups. No significant effects were seen in attention, coordination and balance, object discrimination, and spatial and conditioned learning. Increased motor activity was present in PCB126-treated male and in MeHg + PCB-treated female rats in the elevated plus maze test, and in PCB126-treated male rats in the open field test (PND110). The results do not support the hypothesis that co-exposure to MeHg and PCB126 results in additive or synergistic effects. This finding is in agreement with more recent in vitro and in vivo studies.

Jar-test experiments were conducted to study enhanced coagulation effectiveness in removal of disinfection by products (DBPs) from Zayandehrud River at Isfahan Province-the center part of Iran-in 2004. In this study, the removal of suspended and colloidal particles and natural organic matter (NOM) at various coagulant doses and coagulation pHs was assessed through raw and treated water measurements of turbidity, UV 254 absorbance, TOC, and dissolved organic carbon (DOC). The trihalomethane formation potential (THMFP) was also determined by a mathematical relationship with TOC. Results indicated that NOM removal was a function of coagulant type, coagulant dose, and pH of coagulation. In general, TOC, DOC, and UV 254 absorbance removal enhanced with increasing coagulant dose. However, further increases in coagulant dosage had little effect on disinfection by-products precursors removal. Ferric chloride was consistently more effective than alum in removing NOM. Coagulation pH was appeared to be a determining factor for maximum NOM removal and the removal of DBPs precursors by enhanced coagulation was significantly enhanced at pH 5.5 in comparison with initial pH of water. Furthermore, it is specified that preadjustment of pH with sulfuric acid reduced the coagulant dosage and thus, production of sludge. The reduction in THMFP was consistent with the trends observed for DBPs precursors removal data (i.e. UV 254 and TOC data).

The performance of a horizontal roughing filter (HRF) and a downflow roughing filter (DRF) in the removal of Ascaris and Fasciola hepatica eggs was investigated. The experiments were performed at three filtration rates of 0.5, 1.0 and 1.5 m/h and different influent concentrations of Ascaris and Fasciola hepatica eggs. Alteration of the filtration rate in the range of 0.5-1.5 m/h did not have significant influence on the effectiveness of the roughing filters. The HRF had higher efficiency in the removal of both Fasciola hepatica and Ascaris eggs in comparison with the DRF, so that the average efficiencies of the HRF for the removal of Fasciola hepatica and Ascaris eggs at filtration rate of 1.0 m/h were determined to be 89.0 and 57.3%, respectively, whereas the same values of the DRF were 77.2 and 52.5%, respectively. The straining was confirmed to be the main mechanism of helminth eggs removal by the roughing filters, because Fasciola hepatica eggs with larger size were removed more effectively than Ascaris eggs. The results of this study indicate that the roughing filters, especially the HRF, had promising performance in the removal of helminth eggs and could be used for water and secondary effluent treatment.

Optimization of coagulation process for efficient removal of Natural Organic Matters (NOM) has gained a lot of focus over the last years to meet the requirements of enhanced coagulation. NOM comprises both particulate and soluble components which the latter usually comprises the main portion. Removal of soluble NOM from low turbidity waters by coagulation is not a successful process unless enough attention is paid to stages of formation and development of both micro and macro-flocs. This study, which presents experimental results from pilot scale research studies aimed at optimizing coagulation process applied to synthetic raw waters supplemented by adding commercial humic acid with low turbidity levels, explains how pH and turbidity can be controlled to maximize soluble NOM removal. The removal of NOM at various coagulant doses and coagulation pHs has been assessed through raw and treated (coagulated-settled) water measurements of total organic carbon (TOC). For low turbidity waters, essential floc nucleation sites can be provided by creating synthetic turbidities, for example by adding clay. Adjusting the initial pH at 5.5 or adding clay before coagulant addition allows the formation of micro-flocs as well as formation of the insoluble flocs at low coagulant doses.

The majority of anthraquinone dye released to the environment come from antrapogenic sources. Several techniques are available for dyes' removal. In this study removal of reactive blue 29 (RB29) by an advanced oxidation process sequenced with single wall carbon nanotubes was investigated. Advanced oxidation process was optimized over a period of 60 minutes by changing the ratio of acetic acid to hydrogen peroxide, the compounds which form peroxy acid. Reduction of 20.2%-56.4% of reactive blue 29 was observed when the ratio of hydrogen peroxide/acetic acid/dye changed from 344/344/1 to 344/344/0.08 at different times (60, 120 and 180 min). The optimum ratio of acetic acid/hydrogen peroxide/dye was found to be 344/344/0.16 over 60 min. The resultant then was introduced for further removal by single wall carbon nanotubes(SWCNTs) as adsorbent. The adsorption of reactive blue 29 onto SWCNTs was also investigated. Langmuir, Freundlich and BET isotherms were determined and the results revealed that the adsorption of RB29 onto SWCNTs was well explained by BET model and changed to Freundlich isotherm when SWCNTs was used after the application of peroxy acid. Kinetic study showed that the equilibrium time for adsorption of RB 29 on to SWCNT is 4 h. Experiments were carried out to investigate adsorption kinetics, adsorbent capacity and the effect of solution pH on the removal of reactive blue29. The pseudo-second order kinetic equation could best describe the sorption kinetics. The most efficient pH for color removal (amongst pH=3, 5 and 8) was pH= 5. Further studies are needed to identify the peroxy acid degradation intermediates and to investigate their effects on SWCNTs.

We reconsidered the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) to achieve an efficient drinking water quality index (DWQI) for assessment of drinking source water quality in rural communities of Khuzestan Province, Iran in 2009-2013. In contribution with a panel of water quality experts, the CCME WQI was mainly modified by four changes: (1 and 2) assigning weight factors for input parameters and index factors, (3) modifying excursion concept for carcinogens and bioaccumulative pollutants and (4) removing effect of unequal measurements of input parameters. The DWQI characterizes the drinking source water quality through comparing the measured values of input parameters with relevant benchmarks. The DWQI score (from 0 to 100) classifies the water quality in five categories as poor (0-54.9), marginal (55.0-69.9), fair (70.0-84.9), good (85.0-94.9) and excellent (95.0-100). Based on the DWQI, the temporal changes of the rural drinking source water quality were not significant; while the spatial variations of the water quality were considerable across the province, so the DWQI scores in the northern counties were higher than that in the southern ones. At the county level, the highest and lowest average scores of the DWQI (±standard deviation: SD) were observed in Izeh and Shadegan to be 90 ± 5 and 69 ± 10, respectively. Based on the DWQI, proportions of the drinking water sources with the excellent, good, fair, marginal and poor qualities were determined to be 6.7, 59.1, 26.2, 7.8 and 0.1%, respectively. Turbidity and Ryznar Index (RI) were introduced respectively as the healthbased and esthetic parameters with the most violations (22.7 and 63.2%, respectively). The results of the case study and sensitivity analysis indicated that the DWQI is a simple, flexible, stable and reliable index and could be used as an effective tool to characterize drinking source water quality.

Outbreaks of legionellosis may be a side effect of institution-water treatment. However, the long-term outcomes and the predictive factors of Legionella prevalence in such systems have still not been fully studied. This study was therefore conducted to investigate the prevalence of Legionella spp. and to evaluate the role of bacteriological water quality parameters on its prevalence and removal in hospital water systems. A total of 45 samples were collected from distinct sites at seven hospitals in Tehran, Iran. The prevalence of this bacterium was assayed through a sensitive and specific technique for DNA detection using PCR. Multivariable stepwise regression analysis was used to explore the independent effects of the baseline factors on the incidence of Legionella. Two positive samples were also identified for species by DNA sequencing. Legionella were detected in 31.1% of samples. Showerheads and cold-water taps were the most and the least contaminated sources with 55.3 and 9 per...

Chemical coagulation with metallic salts has traditionally been used in water treatment for turbidity removal. However, coagulation is also capable of some degree of natural organic matter (NOM) removal, with NOM functioning as a precursor to disinfection by-products (DBPs) formation. Enhanced coagulation is thus introduced to most water utilities treating surface water. Jar-test experiments were conducted to compare the effectiveness of alum and ferric chloride in removing DBPs precursors from eight synthetic water samples, each representing a different element of the USEPA's 3×3 enhanced coagulation matrix, and the residual metal (aluminum/iron) concentration in the treated water was assessed. Coagulant type influenced the removal of total organic carbon (TOC) and which was enhanced with increasing coagulant dose. For all the treated samples coagulation with ferric chloride proved to be more effective than alum at similar doses and the mean values of treatment efficiencies were 51% and 32%, respectively. Ferric chloride was therefore considered the better chemical for enhancing the coagulation process. The results of residual metal concentration measurements in treated water showed that iron and aluminum concentrations had been increased as expected but the quality of water concerning the residual metal deteriorated much more in cases of under-dosing. Despite expecting high residual Al and Fe concentrations under enhanced coagulation, metal concentrations were frequently remained low and were not increased appreciably.

Background and purpose: Cancer is a noteworthy cause of morbidity and mortality worldwide, especially in developing countries. It is more often caused by the environment of a person lives in, rather than his or her innate biology. The highly significant and rapid changes in cancer incidence in the last decades are generally attributed to equally dramatic changes in population exposure to environmental factors. Methods: The available evidence on the role of environmental factors and their relevant effects in cancer rates has been studied. Results: Major of cancer risk factors are include tobacco, overweight and obesity, physical activity, diet and body composition, food, air and water contamination, and viral chronic infections. Exposure assessment and research methodology has been the Achilles heel for studies on environmental contaminants and cancer. Thus, it should not be looked at cancer merely as a disease, since cancer is beyond a disease and must be considered through different aspects. Conclusion: The scientific community effort to increase public awareness, winning the support of policy makers as well as intersectoral coordination in order to lifestyle modifications, reducing highrisk behaviors and confronting food, air and water contamination have strategic importance in cancer prevention. Basic and clinical studies as well as interdisciplinary research thence are necessary for a better understanding of the pathophysiology and finding more effective and cheaper ways to prevent, early diagnosis and treatment of cancer. Accordingly, this requires the investment of governmental and non-governmental democrats.

Ever-increasing production and use of nanoparticles (NPs) have aroused overarching concerns for their toxic effects on the environment and human. In the present study, the toxic effects of Silver (Ag) and Iron (Fe) NPs on the performance of activated sludge were investigated under continuous aerobic/anoxic/anaerobic conditions in laboratory-scale sequencing batch reactors (SBRs).Activated sludge was exposed to various concentrations (5-100 mg/L) of Ag-Fe NPs for 60 days and its response was assessed through the enzymatic activity, COD, nitrogen (TN) and phosphorus (TP) removal, toxicity tests, as well as variations in bacterial community. Compared with the pristine control sample, the exposure to NPs suppressed TN and TP removal efficiencies. Indeed, the respiration rate and biomass concentration were significantly affected by the NPs. Although the simultaneous exposure to Ag-Fe NPs did affect the integrity of cell membrane (LDH) and key enzymes activities, the higher concentration induced an increased generation of reactive oxygen species (ROS). The metagenome analysis revealed a marked shift in the microbial community structure suggesting that both heterotrophic and autotrophic communities were affected by the presence of Ag-Fe NPs. Our results provide some evidence for compounded effects of NPs in their simultaneous presence, and generate new leads for future research efforts.

This study proposes the combination of UV/sulfite with a biological reactor (USPB) for the degradation, dechlorination and mineralization of 2, 4, 6-trichlorophenol (TCP). The effects of pH, sulfite dosage, coexisting water anions and quenchers on the performance of the UV/sulfite process (USP) were investigated. The rate of degradation, dechlorination and mineralization of TCP under optimum experimental conditions of pH, 7.0; [sulfite]/[TCP]=3.13; UV irradiation, 87 µW cm-2 ; dissolved oxygen (DO), 2 mg L-1 and an 80 min reaction time, were 100, 98 and 30.2 %, respectively (initial TCP concentration was 250 mg L-1 and initial COD was 363 mg L-1). Investigation of the reaction mechanism revealed the superiority of sulfite radicals (SO3 •-) in the degradation and dechlorination of TCP. The coexisting water anions did not significantly affect the performance of TCP degradation. The intermediates derived from TCP degradation included: 1,3-cyclohexadiene, 2-chloro-1-benzoquinone, 2-chlorophenol, benzene, 2-hydroxy benzoquinone and cyclohexene. The (BOD5)/(COD) ratio (the solution biodegradability index) was obtained as 0.57 after 80 min of UV/sulfite reaction time. The effluent obtained from UV/sulfite after 80 min of reaction time (with COD of 253 mg L-1) was efficiently posttreated in a batch biological reactor (MLSS = 5000 mg L-1), and the COD reduced to 37 mg L-1 after 720 min (12 h) of aeration. Therefore, it was found that the combination of the UV/sulfite with a biological process might be an efficient method for the treatment of wastewater containing high concentrations of toxic compounds.

Background Few studies have examined nano-sized plastic particulates (NPs) exposure in relation to oxidative stress and biochemical responses in rodents, commonly used for toxicity evaluations on which to base risk assessment for humans.Methods Here we explored possible oxidative stress and biochemical responses of five weeks oral exposure to polystyrene (PS) nanoparticles (1, 3, 6 and 10 mg/kg body weight per day) in male rats. We used variance analysis and variance explained statistic eta-squared (𝜂2) to estimate the strength of relationships worked out. The whole body scanning further provided insight into the bio-distribution of nanoplastics upon oral exposure.Results Results demonstrated the accumulation of PS-NPs through whole body and also a dose-dependent increase in the production of reactive oxygen species (ROS). Significant alterations in antioxidant responses including serum levels of catalase, superoxide dismutase (SOD), and total glutathione content were noticed, point...

Although economic growth from industrialization has improved health and quality of life indicators, however, it has intensified the release of chemicals into the environment, with severe effects on health. The present work confers toxic metals contamination levels of surface waters in Zanjan Province, Iran, encompassing several rich mines of lead and zinc. The soluble concentrations of Fe, Cu, Cd, Ni, Pb, Zn and AS in water samples were determined using ICP-MS and the level of contamination was appraised by heavy metal pollution index (HPI). Multivariate statistical methods comprising Pearson’s correlation analysis, hierarchical cluster analysis, and principal component analysis were applied to evaluate the relationships between heavy metals. Geostatistical analyses were carried out to conduct the distribution characteristics and the sources of pollution. The results showed that concentrations of studied heavy metals were higher in the spring compared to the winter, however, the cal...