Optimizing ozone dose and contact time for removal of antibiotic-resistant P. aeruginosa, A. baumannii, E. coli, and associated resistant genes in effluent of an activated sludge process in a municipal WWTP.

This study aimed to investigate the impact of ozonation on inactivation of antibiotic-resistant bacteria (ARB) including E. coli, P. aeruginosa, and A. baumannii, as well as on removal of 16S-rRNA gene and their associated antibiotic-resistant genes (ARGs) indigenously present in effluent of municipal wastewater treatment plant. The Chick-Watson model was used to describe bacterial inactivation rates at specific ozone doses. Maximum reduction of total cultivable A. baumannii, E. coli, and P. aeruginosa were found to be 7.6, 7.1, and 4.7 log, respectively, with the highest ozone dose of 0.48 gO3/gCOD at 12 min contact time. According to the study results, complete inactivation of ARB and bacterial regrowth was not observed after 72 h incubation. The culture methods overestimated the performance of disinfection processes and propidium monoazide combined with qPCR, and showed the presence of viable but non-culturable bacteria after ozonation. ARGs were more persistent to ozone than ARB. The results of this study highlighted the significance of specific ozone dose and contact time in ozonation process considering the bacterial species and associated ARGs as well as the wastewater physicochemical characteristics, in order to help diminish the entrance of the biological microcontaminants into the environment.

Characterization of antibiotic resistance genes and bacteria in a municipal water resource recovery facility.

Municipal water resource recovery facilities (WRRFs) are important sources of antibiotic-resistant bacteria and genes (ARB and ARGs). In this study, antibiotic-resistant total heterotrophic bacteria (THBR ) counts (CFU/ml) cultivated from influent, effluent of activated sludge process, and outflow of disinfection unit of an urban WRRF were investigated for the presence of 16, 32, 64, and 128 µg/ml of nine antibiotics. The isolates of Pseudomonas spp., Acinetobacter spp., and Escherichia coli obtained from effluent of activated sludge process were subjected for molecular identification by detecting the 16S rRNA gene sequences. Additionally, using the polymerase chain reaction method (PCR), the isolates were investigated for the presence of blaSHV , blaTEM , blaCTX-M , blaVIM , sul1, and qnrS genes. According to the results, the abundance of THBR counts was not significantly reduced by the biological treatment except for cefixime and sulfamethoxazole; it also increased for some antibiotics after disinfection unit. The average removal efficiency of THBR resistant to ciprofloxacin, sulfamethoxazole, and ceftazidime were 7.9 ± 1.7%, 41.8 ± 2.1%, and 14.4 ± 6.2%, respectively. Also, all the tested isolates were resistant to at least four antibiotics. For all antibiotics, the resistance ratio (THBR /THB) significantly increased in the effluent and after chlorination unit. Among 12 resistant isolates, blaTEM and sul1 genes were the most frequently detected ones involved in 92% and 83% of the isolates, respectively. Both blaTEM and sul1 genes were found in 100% of E. coli, and 83% and 67% of Pseudomonas spp. isolates, respectively. Further efforts are necessary to limit the transmission of ARB and ARGs from WRRFs into the environment and prevent human health threats. PRACTITIONER POINTS: The ratio of resistance significantly increased after biological treatment. Up to 40% of heterotrophic bacteria in the effluent was antibiotic resistant. blaTEM and sul1 genes were more prevalent (92%) in all isolates of bacteria. Both blaTEM and sul1 genes were found in 100% of E. coli isolates. Pseudomonas spp. holds blaTEM and sul1 genes in 83% and 67% of isolates, respectively.

Distribution of fluoride contamination in drinking water resources and health risk assessment using geographic information system, northwest Iran.

This paper considers exposure to the concentration of fluoride in drinking water resources of Showt city in West Azerbaijan Province in, Iran, and its related potential health risk assessment issues to the resident populations. For this purpose, 88 drinking water samples were analyzed in 2016 by using the spectrophotometric method. Non-carcinogenic health risks due to F exposure through consumption of drinking water were assessed using the US EPA method. In addition, the associated zoning maps of the obtained results were presented using a geographic information system (GIS). The results indicated that fluoride concentration in drinking water ranged from 0.0 to 5.5 mg L-1 of the study area. Based on this research, 36.36% of the samples had a fluoride level higher than the permissible level, 13.63% had less than the permissible limit, and 50% of the samples had a level within the optimum limit of 0.5-1.5 mg L-1. The Hazard Quotient index (HQ) for children, teenager and adults had health hazards (HQ > 1) in 54.55%, 31.82%, and 22.73% of samples, respectively. Groundwater resources having a risk of more than one were located in the villages of Khilajajam, Kolos, and Shorboulagh. So, in these study areas, there are potential risks of dental and skeletal fluorosis.

Spatial Distribution Variation and Probabilistic Risk Assessment of Exposure to Fluoride in Ground Water Supplies: A Case Study in an Endemic Fluorosis Region of Northwest Iran.

Prevalence of fluorosis is a worldwide public health issue, especially in the West Azerbaijan province of Iran. The aim of this study was to investigate fluoride concentration in drinking water resources within Maku city, in both the warm and cold seasons, to perform a health risk assessment. Fluoride were measured using UV-visible spectrophotometry. The spatial distribution was calculated by the software ArcGIS and Hazard Quotients (HQs) were calculated according to the US EPA method. The fluoride concentrations ranged between 0.29 to 6.68 and 0.1 to 11.4 mg/L in the cold and warm seasons, respectively. Based on this report, 30.64 and 48.15% of the samples revealed a fluoride level higher than the permissible level in the cold and warm seasons, respectively. Moreover, results showed that the HQ value in the warm season for different age groups was higher than the HQ value in the cold season. In both seasons, the non-carcinogenic risks of fluoride for the four exposed populations varied according to the order: children > teenagers > adults > infants. The HQ values for three age groups (children, teenager and adults) for both seasons were higher than 1 with a high risk of fluorosis. The results of this study, support the requests that government authorities better manage water supplies to improve health quality.

Carcinogenic and Non-carcinogenic Risk Assessment of Heavy Metals in Groundwater Wells in Neyshabur Plain, Iran.

The present work reports the As, Cr, Cu, Pb, Zn, and Fe concentrations of drinking water samples in Neyshabur Plain, Iran. This study aimed also to ascertain the potential consumers' health risk of heavy metal intake. Heavy metal concentrations were analyzed by inductively coupled plasma optical emission spectrometry. The highest and lowest average values in the analyzed water samples were observed for Fe (9.78 ± 5.61 µg/L) and As (1.30 ± 2.99 µg/L), respectively. These values were well below the limits recommended by the World Health Organization and the Iranian national standard. Heavy metal pollution index and heavy metal evaluation index were used to evaluate drinking water quality. The risk index was calculated by chronic daily intake and hazard quotient according to the United States Environmental Protection Agency approach. Heavy metal pollution index in all the samples was less than 100, indicating that it is a low-level heavy metal. The total risk of all heavy metals in the urban environment varied from 40.164 × 10-7 to 174.8 × 10-7. In this research, the maximum average of risk belonged to lead and copper with the respective values of 60.10 × 10-7and 33.99 × 10-7 from the selected wells. However, considering the toxic effect of some elements, including Pb and As, in the chronic exposure of consumers, we suggest a continuous evaluation and monitoring of drinking water resources.

Data on quality indices of groundwater resource for agricultural use in the Jolfa, East Azerbaijan, Iran.

The aim of this study was to evaluate the groundwater quality Indices of Groundwater resource for Agricultural Use in jolfa city (Iran) during one decade (2003-2013). Data showed in the first and end year of the study period, the Mean±SD of Sodium Adsorption Ratio (SAR) and Sodium Percentage (Na%) indices 5455.77±3878.02, 3638.69±3565.19 and 51.49±15.65, 41.58±17.69, respectively. The data indicate that the, in terms of sodium percentage and sodium adsorption ratio, the water quality in this area is not suitable for irrigation.

Data on microbiological quality assessment of rural drinking water supplies in Tiran County, Isfahan province, Iran.

A lack of access to safe drinking water can lead to adverse health effects such as infection, disease, and undesirable aesthetic problems. The current study focused on the investigation of groundwater quality in Tiran's villages (Isfahan province, Iran). To determine essential microbiological quality, water samples were collected from 46 randomly-selected water wells during a one-year period. The parameters of pH and chlorine were measured on-site. Turbidity was measured at 420 nm using a DR5000 spectrophotometer. Microbiological tests including general thermoforms, Escherichia coli, and thermophiles were carried out according to the National Iranian Standard Method 3759. Data showed that 1.8% of the villages under study had contaminated water resources. The turbidity values for 94.5% of the resources were within recommended limits (<5NTU). In 20.6% of the samples, the residual free chlorine was in the range of 0 to 0.2 mg/L, 8.79% of samples had values greater than the recommended limits, and18.5% had no free residual chlorine.

Groundwater quality assessment for drinking and agriculture purposes in Abhar city, Iran.

The main objective of this study is to assess the quality of groundwater for drinking consume and agriculture purposes in abhar city. The analytical results shows higher concentration of electrical conductivity (100%), total hardness (66.7%), total dissolved solids (40%), magnesium (23%), Sulfate (13.3%) which indicates signs of deterioration as per WHO and Iranian standards for drinking consume. Agricultural index, in terms of the hardness index, 73.3% of the samples in hard water category and 73.3% in sodium content were classified as good. Therefore, the main problem in the agricultural sector was the total hardness Water was estimated. For the RSC index, all 100% of the samples were desirable. In the physicochemical parameters of drinking water, 100% of the samples were undesirable in terms of electrical conductivity and 100% of the samples were desirable for sodium and chlorine parameters. Therefore, the main water problem in Abhar is related to electrical conductivity and water total hardness.

Data on assessment of groundwater quality with application of ArcGIS in Zanjan, Iran.

The aim of this study was to Monitoring of physical and chemical characteristics of ground water including Ca2+, Mg2+, EC, pH, TDS, TH, HCO3- , Na+, K+, Cl-, SAR, %Na and SO42- in Zanjan city, Iran. For assessing the physic-chemical parameters from 15 wells, water samples 4 times at different times were collected and examined. Data were analyzed using R and Arc GIS software. According to the calculated correlation coefficients, the highest correlation Coefficient belonged to TDS-EC while HCO3- and Cl- showed low and weak correlations. However, Na+, Mg2+, K+, Ca2+ exhibited good positive correlations with EC and TDS. The results show that the water in the study area at the time of the study was based on the WHO standards and appropriate for drinking.

Surveillance of Legionella species in hospital water systems: the significance of detection method for environmental surveillance data.

Monitoring of hospital water systems to prevent and control nosocomial legionellosis is important from a public health perspective. This study was conducted to survey the prevalence of Legionella contamination of hospital waters. A total of 44 water samples from the hot-water system of 11 hospitals were tested for Legionella by a culture method and a nested polymerase chain reaction (PCR) assay with Legionella-specific primers to identify the more sensitive method. Some physicochemical parameters and heterotrophic plate counts of water samples for possible association with Legionella contamination were also determined. The contamination rate of hospitals in our study varied between 64% (eight of 11)-100% based on culture method and nested PCR, respectively. Of the 44 water samples examined, 23% were positive for Legionella spp. by the culture method, while the nested PCR assay using the primers LEG448-JRP revealed 66% of the water samples being positive. Given the importance of monitoring hospital water systems for the presence of Legionella spp., the present PCR assay proved highly applicable for practical and sensitive surveillance of Legionella in such water systems. In addition, rapid monitoring of Legionella contamination could eliminate the potential exposure of high-risk patients through effective control measures.