Comparative study on the microbial quality in the swimming pools disinfected by the ozone-chlorine and chlorine processes in Tabriz, Iran.

Applying a desirable disinfestation process is necessary to control the pathogenic microorganisms in the swimming pools and prevent both dermal and intestinal effects. Therefore, the present study was conducted to compare the bacterial community and diversity in the two swimming pools disinfected by the chlorine and ozone (O3)-chlorine processes. A total of 24 samples were taken from the two swimming pools in three distinct seasons to analyze the bacterial and physico-chemical indicators. Culture and molecular methods were used to evaluate the microbial quality. Two sets of sample taken from the pools with the maximum swimmer load in the summer were investigated by the next-generation sequencing (NGS) technique. In total, 410 and 406 bacterial species were identified in the chlorine- and ozone-chlorine-disinfected pools, respectively. Among the eight dominant bacterial species in each swimming pool, Pseudomonas alcaliphila, Pseudomonas stutzeri, and Pseudomonas acnes were common species between the two studied pools. Oleomonas sagaranensis (350 reads/18593), Staphylococcus caprae (302 reads /18593), and Anaerococcus octavius (110 reads/18593) were among the dominant bacteria in the chlorine-disinfected pool. Bacterial diversity was lower in the ozone-chlorine-disinfected pool than the other one, and the highest bacterial sequencing belonged to the genus Pseudomonas (85.79%). Results showed that water quality of in O3-chlorine-disinfected pool was more desirable than the chlorine-disinfected pool. Molecular methods along with conventional culture methods would be advantageous for microbial assessment in the swimming pools.

Phototoxicity of environmental radiations in human lens: revisiting the pathogenesis of UV-induced cataract.

The magnitude of cataract pathology is indeed significant as it is the principal cause of blindness worldwide. Also, the prominence of this concept escalates with the current aging population. The burden of the disease is more tangible in developing countries than developed ones. Regarding this concern, there is a gap in classifying the pathogenesis of the ultraviolet (UV) radiation-induced cataracts and explaining the possible cellular and subcellular pathways. In this review, we aim to revisit the effect of UV radiation on cataracts categorizing the cellular pathways involved. This may help for better pharmaceutical treatment alternatives and their wide-reaching availability. Also, in the last section, we provide an overview of the protecting agents utilized as UV shields. Further studies are required to enlighten new treatment modalities for UV radiation-induced pathologies in human lens.

Monitoring, mapping and health risk assessment of fluoride in drinking water supplies in rural areas of Maku and Poldasht, Iran.

The aim of this study was to investigate and determine fluoride concentrations in drinking water supplies in rural areas of Maku and Poldasht in West Azerbaijan Province, the northwest of Iran. Fluorosis risk assessment and characterization was also investigated. Fluoride concentrations mapping was accomplished by using the GIS system. Totally, 356 water samples, including one sample in each season, were collected from 89 water supplies providing water for 95 and 61 rural areas of Maku and Poldasht, respectively. According to the results, in Maku and Poldasht, 25 and 30 rural areas had contaminated water sources, respectively. Average annual fluoride concentrations ranged from 3.04 to 7.31 mg/l in the contaminated villages of Maku, which is about 2-4.8 times higher than the maximum standard level of the Iranian drinking water standard, and 4.52-8.21 mg/l in the contaminated areas of Poldasht, which is about 3-5.47 times higher than the maximum standard level. The maximum fluoride level was determined 11.12 mg/l and 10.98 mg/l in one of villages of Maku and Poldasht Counties in summer, respectively. Neither in Maku nor in Poldasht, water resources showed dental cavity risk, while dental fluorosis risk and skeletal fluorosis risk were very significant in some villages of both cities. Children were at most risk of fluorosis. New alternative water supplies for the contaminated villages if possible, consumption of bottled water and application of reverse osmosis are recommended as remedial actions in the contaminated areas.

Haloacetic acids degradation by an efficient Ferrate/UV process: Byproduct analysis, kinetic study, and application of response surface methodology for modeling and optimization.

Haloacetic acids (HAAs) after trihalomethanes are the second main group of chlorination byproducts. In this study, decomposition of the two most common HAAs in drinking water was studied by an advanced oxidation process using a combination of Ferrate [Fe(VI)] and UV irradiation. The decomposition rate was measured, and the byproducts formed during the process and the mass balances were also analyzed. HAAs were quantified by GC-ECD, and the final products including acetate and chloride ions were measured by ion chromatography (IC). A central composite design was used for the experimental design, and the effect of four variables including the initial HAA concentration, pH, Fe(VI) dosage, and contact time were investigated by response surface methodology (RSM). Dichloroacetic acid decomposed more easily than TCAA. Results show that when TCAA and DCAA were studied individually, the degradation rates were 0.0179 and 0.0632 min-1, respectively. When the HAAs were simultaneously placed in the reactor, the decomposition rates of both TCAA and DCAA decreased dramatically. In this case their decomposition rate constants decreased by 67% and 49%, respectively. In the mixture, the decomposition rate of DCAA was 2.5 times higher than that of TCAA. In summary, Fe(VI)/UV process can be used as a promising treatment option for the decomposition of recalcitrant organic pollutants such as HAAs, and RSM can be used for modeling and optimizing the process.

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.

Oxidative degradation of sulfamethoxazole from secondary treated effluent by ferrate(VI): kinetics, by-products, degradation pathway and toxicity assessment.

Sulfamethoxazole (SMX) is a typical antibiotic in the world, which is frequently detected in the aquatic environment. The current study was aimed to investigate the SMX degradation in secondary treated wastewater using potassium Ferrate [Fe(VI)]. The effects of various experimental conditions, EDTA and phosphate as chelating agents, and toxicity assessment were also considered. Secondary treated effluent was spiked with predefined SMX concentrations, and after desired reaction time with Fe(VI), residual SMX was measured using HPLC. Results indicated that SMX degradation by Fe(VI) was favored under acidic condition, where 90% of SMX degradation was achieved after 120 min. Fe(VI) and SMX reaction obeyed first-order kinetic; meantime, the SMX degradation rate under pH 3 was 7.6 times higher than pH 7. The presence of phosphate (Na2HPO4) and EDTA declined SMX degradation, while Fe (III) effect was contradictory. In addition to promising demolition, 10% TOC removal was achieved. Eighteen major intermediates were identified using LC-MS/MS and the degradation pathways were suggested. Transformation products (TPs) were formed due to hydroxylation, bond cleavage, transformation after bond cleavage, and oxidation reactions. The ECOSAR analysis showed that some of the SMX oxidation products were toxic to aquatic organisms (fish, daphnia and green algae). Supplementary Information: The online version contains supplementary material available at 10.1007/s40201-021-00769-9.

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.

Arsenic health risk assessment and the evaluation of groundwater quality using GWQI and multivariate statistical analysis in rural areas, Hashtroud, Iran.

Arsenic (As) is a toxic metalloid that can cause significant health issues through drinking water. The present study was aimed to evaluate As distribution and the related health risks from drinking groundwater in rural areas of Hashtroud, Iran. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were also applied to better explain relationship pattern between different resources. The samples were taken from 51 locations in 37 villages. Arsenic concentration was determined by a polarograph device, and the corresponding carcinogenic and non-carcinogenic health risks were calculated based on US Environmental Protection Agency (EPA) guideline. PCA analysis extracted four main components that explained nearly 62% of data variance. Results pointed severe As contamination in the studied area, where As was detected in 78% of the samples ranging from less than 0.001 to 0.250 mg/L. Forty percent of the contaminated places violated guideline value of 10 µg/L suggested by EPA and institute of standards and industrial research of Iran (ISIRI). Based on our findings, 1329 people including 239 children were living in the areas with higher As contamination. Hazard quotient (HQ) in 72%, 59%, and 33% of the samples was higher than one for children, adolescent, and adult age groups, respectively. Excess life time cancer risk (ELCR) in almost 80% of all age groups was significantly higher than EPA recommended guideline (10-4 or 10-6). In summary, from the view point of arsenic HQ and ELCR, water resources in the studied areas were not appropriate for drinking and hygienic purposes; necessary and urgent management strategies to guarantee water supply and health safety for local residents should be considered.

Advanced oxidation processes for chlorpyrifos removal from aqueous solution: a systematic review.

Chlorpyrifos (CPF), an organophosphate insecticide, due to its high efficiency and low cost is widely used in the agricultural industry. CPF may lead to lung deficiency, central nervous system damage, developmental and autoimmune disorders. In recent decades, the advanced oxidation processes (AOPs) have been considered in water and wastewater treatment due to their high efficiency in decomposition of organic and inorganic compounds, specially hardly biodegradable or non-biodegradable compounds. In the present review study, the most common AOPs (such as Fenton and Photo-Fenton processes, UV/H2O2 photolysis, UV/TiO2 heterogeneous photo catalysis, electrochemical processes, sonolysis technology, gamma irradiation technology and sulfate-based AOPs) applied for CPF removal from aqueous matrices has been investigated. It can be concluded that the use of AOPs are effective for CPF removal from aqueous media. In addition, Fenton and photocatalytic processes appear to be the most common techniques for CPF degradation.

Abundance and distribution of microplastics in the sediments of the estuary of seventeen rivers: Caspian southern coasts.

Given the increase in plastic production, persistence, and toxicity in the environment, understanding the probability of microplastics (MPs) accumulation in the sediments of the rivers' estuary is urgently needed. In this study, sediments of the estuary of 17 rivers, ending to the Caspian Sea, were evaluated at two depths (0-5 cm and 5-15 cm). Plastic particles were categorized into two groups in terms of size: small MPs and large MPs. The combination of observational techniques, FTIR, and SEM analysis was applied to identify MPs. The mean of MPs in 17 rivers was obtained at a depth of 0 to 15 cm of sediments 350.6 ± 232.6 MP/kg. The fiber was identified as the predominant particles in sediments, and foam-shaped particles were the least amount in the sediment. In terms of polymer structure, polyethylene (PE) (20%) and polyvinyl chloride (PVC) (2%) showed the highest and lowest prevalence, respectively. In the current study, the number of MPs was higher than the average of MPs in sediments of recreational-tourist areas and non-tourist areas of the southern Caspian coast. Results from this study indicate that sediments of the rivers' estuary are a hotspot of plastic particle pollution. Therefore, plastic management in the path of the Caspian catchment area of Iran, and cleaning rivers coast and rivers mouth from plastic is recommended.

Tendencies towards bottled drinking water consumption: Challenges ahead of polyethylene terephthalate (PET) waste management.

Background: The main objective of this study was to investigate the logics behind tendencies towards bottled drinking water usage in spite of availability of treated tap water. The amount of waste bottle is also estimated in Iran and managing principles for resolving the issue presented. Methods: A questionnaire was used to survey the logics behind tendencies toward bottled drinking water consumption among 120 participants. In order to estimate the quantities of the PET wastes produced in the country, data about bottled water production rate as well as volume of the imported and exported drinking bottled water were collected from 1962 to 2015 and applied in the calculations. Results: Findings suggested that about 0.026 to 3.86 billion liters (about 1.04 billion literson average) of bottled water was consumed annually between 2000 and 2015. Furthermore, bottled water consumption increased from 0.41 to 48.9 L/capita-year within the same time period. In the meantime, the plastic bottle waste generation rate rose from 12.84 to 1519.38 g/capita-year. There is no efficient and suitable system for managing and recycling waste bottles in the country. The perceived unreliability of tap water quality was the main reason of bottled water consumption among 74% of the respondents. Conclusion: To reduce bottled water consumption and the associated harmful environmental and health consequences, measures such as informing people, validating public water supply quality, preventive rules enactment, and establishing extended producer responsibility (EPR) are highly recommended.

Temporospatial variation and health risk assessment of trihalomethanes (THMs) in drinking water (northwest Iran).

Trihalomethanes (THMs) are one of the most common classes of disinfection by-products. In this study, the temporospatial trends and health risks due to exposure to THMs in the Tabriz water distribution network were investigated. THM series were analyzed using gas chromatography equipped with electron capture detector. The non-carcinogenic and carcinogenic risks due to exposure to THMs were calculated using Monte Carlo simulations. Mean concentrations of THMs in winter and spring were 10.2 ± 9.3 µg/l and 252 ± 185.9 µg/l, respectively. More than 80% of THMs identified were bromodichloromethane. The mean values of lifetime cancer risk (LTCR) of THMs were calculated as 4.23E-06 and 2.38E-04 for winter and spring, respectively. This study showed that there were noticeable levels of THMs in Tabriz water distribution network, especially in the center of the city. Although the non-cancer risk through THMs was below permissible recommended levels, the cancer risk likely remains due to high levels of THMs in some locations.

Contamination of the Caspian Sea Southern coast sediments with microplastics: A marine environmental problem.

Marine ecosystem pollution with microplastics (MPs) is a global problem. The current study aimed to assess the occurrence of MPs in the sediments of the Caspian Sea southern coasts. For sampling, two distinct areas were selected including recreational-tourism areas (No = 24), and non-tourist areas (No = 24). MPs were studied in 5 and 5-15 cm from the top sediment surface. All 96 samples were taken and analyzed according to the methodology provided by the US national oceanic and atmospheric administration (NOAA). The combination of observational techniques, FTIR, and SEM analysis was applied to identify MPs. MPs were classified into two categories in terms of size: small MPs and large MPs. The average, maximum, and minimum abundance of MPs (based on dry weight) in sediments of the southern coast of the Caspian Sea was 183.5 ± 154.4 MP/kg, 542 MP/kg, and 13 MP/kg, respectively. On the basis of morphology, fragment-shaped (30.3%) MPs showed the highest prevalence, while film-shaped (18.7%) MPs were the least contributory. Polyethylene (PE) and polyethylene terephthalate (PET), each of them with a 20% share, were the most common MPs found in the studied samples. The distribution of MPs on the southern coasts of the Caspian Sea revealed a sporadic and irregular spatial pattern. Correspondingly, it can be concluded that probably environmental factors (the current of the sea surface water from west to east), enclosed environment of the Caspian Sea, anthropogenic activities (e.g., industrialization and urbanization, improper waste management, fishing, and tourism activity, residential wastewater), and also discharging of rivers (which can carry plastics) into the sea, have all influenced the abundance and polymer diversity of MPs in the sediments of the southern coast of the sea. More attention should be paid to the health and environmental effects of MPs and to the protection of this sensitive marine ecosystem through implementing proper waste management system by all surrounding littoral countries.

Estimation of plastic waste inputs from land into the Persian Gulf and the Gulf of Oman: An environmental disaster, scientific and social concerns.

It has been reported that, the huge amount of plastic waste is present in marine environments. This study evaluated solid waste generation, management, disposal approaches, and the amount of plastic waste entered into the Persian Gulf and the Gulf of Oman in 2016. The findings showed that waste in the Persian Gulf and the Gulf of Oman regions has been mismanaged by 65% and 81%, respectively. According to our estimates, about 1634.9 k-tons (Kt) and 204.6 Kt of plastic waste have been, respectively, generated by the Persian Gulf and the Gulf of Oman littoral states in 2016. Most likely, the mass of plastic waste entering the Persian Gulf and the Gulf of Oman in 2016 was ranged from 155 to 413.4 Kt and 29.2-77.9 Kt, respectively. Without implementation of effective waste management strategies, it is estimated that by 2030, the mass of plastic waste entering the Persian Gulf will increase to 199.4-531.6 Kt, while in the Gulf of Oman it would be about 40.4-107.7 Kt. The entry of plastic waste into the Persian Gulf and the Gulf of Oman has been expected to increase by 29% and 38% in 2030, respectively. As a result, the related cumulative environmental and health effects can be more intensive. It can be emphasized that all countries located in the coastal areas of the Persian Gulf and the Gulf of Oman need to modify their solid waste management, plastic waste in particular, policies to conserve sensitive marine ecosystems.

Estimation of plastic waste inputs from land into the Caspian Sea: A significant unseen marine pollution.

It has been proven that there is an extensive bulk of plastic debris in marine ecosystems. The present study analyzed solid waste generation, its management and final disposal methods in Caspian Sea coastal countries, and the amount of plastic waste entering the Caspian Sea. The results showed that, on average, more than 90% of waste in the Caspian Sea coastal countries is mismanaged. According to our estimates, 425 kilotons (Kt) of plastic waste was generated by Caspian Sea coastal countries in 2016, of which, with high probability, 58-155 Kt find their way to the Caspian Sea. It is estimated that without improved waste management infrastructures, the amount of plastic waste entering the Caspian Sea will increase to 68-182 Kt by 2030, an increase of about 15%. Accordingly, the related cumulative environmental and health problems could be more severe. All countries located in the coastal areas of the Caspian Sea should revise their solid waste and plastic waste management programs to protect that sensitive marine ecosystem.

Hexavalent chromium removal from aqueous solution using functionalized chitosan as a novel nano-adsorbent: modeling and optimization, kinetic, isotherm, and thermodynamic studies, and toxicity testing.

Hexavalent chromium is a highly toxic metal that can enter drinking water sources. Chitosan, which contains amino and hydroxyl functional groups, is considered an appropriate candidate to remove heavy metals through absorption. In this study, a novel adsorbent, magnetic nanoparticles of chitosan modified with polyhexamethylene biguanide (Ch-PHMB NPs) was synthesized and was used to successfully remove chromium from aqueous solution. Quadratic models with independent variables including pH, adsorbent dosage, time, and the initial concentration of chromium were proposed through RSM to describe the behavior of both magnetic chitosan (M-Ch) and Ch-PHMB NPs in Cr(VI) removal. Optimized models with adjusted R2 values of 0.8326 and 0.74 for M-Ch and Ch-PHMB NPs were developed. Cr(VI) removal from aqueous solution by both absorbents followed pseudo-second-order kinetics. The experimental data were best fitted to the Temkin and Freundlich models for M-Ch and Ch-PHMB NPs, respectively. M-Ch and Ch-PHMB NPs can effectively remove the hexavalent chromium from aqueous solution with pH above 7. Ch-PHMB NPs have higher removal efficiency than M-Ch, removing up to 70% of Cr(VI) from aqueous solution. However, toxicity evaluation on Daphnia magna revealed that Ch-PHMB NPs was more toxic than M-Ch nanoparticles.

Response surface methodology as a tool for modeling and optimization of Bacillus subtilis spores inactivation by UV/ nano-Fe0 process for safe water production.

One of the most important aspects of environmental issues is the demand for clean and safe water. Meanwhile, disinfection process is one of the most important steps in safe water production. The present study aims at estimating the performance of UV, nano Zero-Valent Iron particles (nZVI, nano-Fe0), and UV treatment with the addition of nZVI (combined process) for Bacillus subtilis spores inactivation. Effects of different factors on inactivation including contact time, initial nZVI concentration, UV irradiance and various aerations conditions were investigated. Response surface methodology, based on a five-level, two variable central composite design, was used to optimize target microorganism reduction and the experimental parameters. The results indicated that the disinfection time had the greatest positive impact on disinfection ability among the different selected independent variables. According to the results, it can be concluded that microbial reduction by UV alone was more effective than nZVI while the combined UV/nZVI process demonstrated the maximum log reduction. The optimum reduction of about 4 logs was observed at 491 mg/L of nZVI and 60 min of contact time when spores were exposed to UV radiation under deaerated condition. Therefore, UV/nZVI process can be suggested as a reliable method for Bacillus subtilis spores inactivation.

A comparative study of the disinfection efficacy of H2O2/ferrate and UV/H2O2/ferrate processes on inactivation of Bacillus subtilis spores by response surface methodology for modeling and optimization.

Although chlorination can inactivate most of the microorganisms in water but protozoan parasites like C. parvum oocysts and Giardia cysts can resist against it. Therefore, many researches have been conducted to find a novel method for water disinfection. Present study evaluated the synergistic effect of H2O2 and ferrate followed by UV radiation to inactivate Bacillus subtilis spores as surrogate microorganisms. Response surface methodology(RSM) was employed for the optimization for UV/H2O2/ferrate and H2O2/ferrate processes. By using central composite design(CCD), the effect of three main parameters including time, hydrogen peroxide, and ferrate concentrations was examined on process performance. The results showed that the combination of UV, H2O2 and ferrate was the most effective disinfection process in compare with when H2O2 and ferrate were used. This study indicated that by UV/H2O2/ferrate, about 5.2 log reductions of B. subtilis spores was inactivated at 9299 mg/l of H2O2 and 0.4 mg/l of ferrate concentrations after 57 min of contact time which was the optimum condition, but H2O2/ferrate can inactivate B. subtilis spores about 4.7 logs compare to the other process. Therefore, the results of this research demonstrated that UV/H2O2 /ferrate process is a promising process for spore inactivation and water disinfection.

Pseudomonas aeruginosa and Heterotrophic Bacteria Count in Bottled Waters in Iran.

BACKGROUND: Nowadays, due to increased public awareness about water pollution and water borne diseases as well as water network deficiencies, bottled water consumers have increased dramatically worldwide, including Iran. Pseudomonas aeruginosa is an opportunistic human pathogen capable of causing widespread infections in burn and immune-compromised patients. The aim of this study was to investigate, P. aeruginosa in bottled waters selling in Iranian markets. METHODS: One hundred and twenty samples of five unknown (not famous) domestic bottled water brands were purchased from Tehran retailers during 2013. The samples were evaluated for the presence of P. aeruginosa. In addition, heterotrophic plate counts were determined by incubation at 37 °C for 24 h. RESULTS: P. aeruginosa was detected in 36.7% (44 samples) of all samples examined. In addition, heterotrophic bacteria in 32.5% (39 samples) of the samples were higher than 100 CFU/mL, while in 7.5% (9 samples) of the samples HPC relied between 20 and 100 CFU/ml. CONCLUSION: In contrast to public believe, bottled waters are not free of microorganisms, and it is suggested that authorities should provide stricter monitoring and control plan for water resources and plants. Concerning HPC and P. aeruginosa brands B and D were not suitable for drinking.

Disinfection of raw wastewater and activated sludge effluent using Fenton like reagent.

BACKGROUND AND OBJECTIVES: Water shortage problems have led to find either new water resources or improve wastewater treatment technologies in order to reuse. Due to less performance of previous units in microbial removal, disinfection has become a necessary step in wastewater treatment plants. In the present study performance of hydrogen peroxide (HP) and modified Fenton's reagent (HP + Cu(++)) was considered for the disinfection of raw wastewater (RW) and activated sludge effluent (ASE). MATERIALS AND METHODS: Plastic containers of 10-liter volume each were used for RW and ASE sampling. Microbiological analyses of the RW and ASE were performed in triplicate; before and after the disinfection process. Fecal coliforms were analyzed by the direct (without enrichment) multiple fermentation tube procedure. RESULTS: The results showed that using HP alone did not have any significant disinfection capability. In RW and ASE, the highest dose used in this study could reduce fecal coliforms (FC)s by only 1.54 and 1.16 log-inactivation, respectively. However, Maximum removal efficiency of modified Fenton in RW and ASE was 4.63 and 3.41 log-inactivation, respectively. The results suggested that Cu(++) ions used in combination with H2O2 produced very rigorous synergistic effect, and HP disinfection capacity increased significantly. CONCLUSION: Hydrogen peroxide, when applied alone, was not successful in disinfecting of either RW or ASE, and neither the WHO guideline nor the Iranian standard could be met. However, modified Fenton showed very significant disinfection potential and could reduce FCs under World Health Organization (WHO) guideline and Iranian national standard for agricultural irrigation.