Background: Titanium dioxide (TiO₂)-mediated photocatalysis has been found to be an efficient method of water treatment and is capable of degrading a wide range of organic pollutants and microbial agents with high efficiency. The microorganism Pseudomonas aeruginosa is resistant to chemicals and UV irradiation. Bacteria which are resistant to UV-induced oxidative damage of the cell membrane are susceptible to photocatalytic technology. The main objective of this research was to examine the photocatalytic removal of P. aeruginosa upon UV irradiation in the presence of TiO₂ nanoparticles.
Methods: Polluted water samples were prepared by the addition of P. aeruginosa colonies into water, followed by contact with UV, TiO₂, or a combination of the two in separate stages. The effect of various parameters, including contact time, pH, and TiO₂ concentration, on reaction efficiency was examined.
Results: The highest efficiency of bacterial disinfection was achieved with UV irradiation in the presence of TiO₂ nanoparticles, with complete (100%) removal of P. aeruginosa observed upon irradiation for 60 min in the presence of 0.4 g/L TiO₂ under conditions of neutral pH.
Conclusions: The results of this study suggest that from a technical and economic perspective, the UV/TiO₂ process may be effectively applied for the disinfection of polluted water. This process could be considered a promising method of cleaning and purification, and applicable for water disinfection.

Background: Bio aerosols include airborne micro-organisms such as bacteria, fungi, viruses, etc and their products. Exposure to a bio aerosol is linked with a broad spectrum of health problems, including infectious diseases, acute toxic effects, allergies, and cancer. The aim of this study was to evaluate the quality and quantity of bio aerosols found in the air of different wards in Valiasr Hospital, Zanjan, in summer and fall 2012.
Methods: Air samples were collected from six wards including: operating room, infectious, ear, nose, and throat (ENT), surgery, adult intensive care unit (ICU), oncology and administrative with a single-step Anderson sampler. The type and number of colonies were determined in the laboratory, and then the bio aerosol density were calculated in terms of cfu/m³ and compared with the recommended limits.
Results: The most common genera of isolated bacteria and fungi were Staphylococcus and Penicillium, respectively. In the infectious ward bacterial density was higher than the recommended limit of WHO (100cfu/m³) in the visiting times (afternoon). The fungal density in the meeting time (afternoon) in the ICU, ENT, and general surgery, infectious and administrative wards, and in non-visiting times (morning) in the infectious ward was higher than the recommended limit of WHO (50 cfu/m³).
Conclusion: From the findings of this study it can be concluded that the density of fungi and bacteria in the hospital air in some times of working period are higher than recommended levels and therefore, the condition of existing air filtration and ventilation systems should be appropriated according to the international standards of hospitals buildings.

Background: Qual2k is a stream water quality model and was used to evaluate the water quality of the Kine-Vars River and assess the response of the river to nutrient management strategies.
Methods: For that purpose, 7 sample stations were selected and surface water samples were collected in the winter and summer of 2012 and were analyzed for temperature, dissolved oxygen, biological oxygen demand, ammonia–nitrogen, nitrate–nitrogen, organic nitrogen, organic phosphorus, and inorganic phosphorus.
Results: Results showed that the Kine-Vars River is saturated with N and P and is classified as eutrophic. The simulated data showed that the total nitrogen and total phosphorus loads of the studied river need to be reduced by 76% and 93%, respectively, to reach water quality objectives.
Conclusion: Application of nutrient control strategies can reduce the nutrient loads significantly but is not sufficient to change the river classification from eutrophic to oligotrophic in a short time; thus, additional nutrient control measures are necessary.

Background: Various industries produce and discharge wastes containing different heavy metals into the environment. Apart from using living biomass, dead and dried biomasses have been introduced as a new field of biotreatment technology.
Method: The cadmium (Cd) (II) removal characteristics of live (growing), dead (autoclaved), and oven-dried biomasses of Aspergillus versicolor were examined as a function of initial pH, contact time, and initial Cd concentration.
Result: Maximum bioaccumulation of Cd for live biomass [11.63 (mg g⁻¹)] occurred at an optimal pH of 4 and incubation time of 4 days. Themaximum biosorption of 27.56 (mg g⁻¹) for dead biomass occurred at 1.5 h and at a pH of 4. The maximum biosorption [18.08 (mg g⁻¹)] with dried biomass was reached at an equilibrium time of 3 h at a pH of 6.
Conclusion: The present study confirmed that heat treatment promoted the removal capacity of fungi. Cd removal was increased by decreasing the pH in live and dead-mode experiments. Inversely, Cd removal was increased with increasing pH for the dried biomass of A. versicolor. Varying responses to environmental conditions (pH and contact time) clearly proved the different removal mechanisms used by three biomasses of A. versicolor. Higher Cd concentration increased the removal ability of three types of biomasses. The results indicated that all biomasses of A. versicolor used in this study, particularly dead biomass, are a suitable biosorbent for the removal of Cd (II) ions from aqueous solution.
 

Background: Dyes can cause many problems in environment. Therefore, removal of these contaminants before discharging wastewater to environment can reduce the environmental hazards. Adsorption is one of the usual processes for decolorizing from wastewater. Nanotubes are new adsorbents that can adsorb different compounds. This work aimed to investigate Acid violet 17 dye removal by adsorption using multi-walled carbon nanotubes as adsorbent from aqueous solution.
Methods: This experimental study was conducted in the batch mode and to investigate effects of parameters such as contact time, initial concentration of dye, pH and Multi-walled carbon Nanotubes dose on decolorization process.
Results: Results showed that the maximum dye decolorization was achieved in 3 hours. With increasing adsorbent dose, the removal efficiency was increased up to 95.9%. It was found that the maximum adsorption capacity of multi-walled carbon nanotubes occurred in acidic pH conditions. With decreasing the initial concentration of dye, removal efficiency increase up to 83.4%. Adsorption equations were described by Freundlich isotherm and Pseudo-Second order kinetic.
Conclusion: The optimal conditions for decolorization efficiency ware equilibrium time of 3 hours, pH of 4, and nanotube dose of 0.4 g /L. The high R² value of greater than 0.90 obtained showed that the experimental data agreed well with Freundlich isotherm and Pseudo-second order kinetic models.

Background: Dithiocarbamates, the main group of fungicides, are used to control about 400 pathogens in more than 70 crops. These pesticides are widely applied to crops including potato, cereal, apple, pear and leafy vegetables throughout the world since 1960. From the late 1980s, using these fungicides has caused much debate among regulators about their long-term effects on consumers and occupational users.
Method:  In this study the residues of Dithiocarbamates in cucumber and tomato using the colorimetric method (Keppel method) was measured. Respectively 80 and 45 samples of greenhouse cucumber and tomato were collected from Zanjan vegetables center in autumns and winter 2013. The samples were analyzed in 4 treatments of: unwashed, washing with water, washing whit detergent and peeling.
Result: The results showed that the average concentration of Dithiocarbamates residues in unwashed greenhouse cucumber and tomatoes were 384.5 µg/kg and 65 µg/kg respectively. 35% and 5% of unwashed and water washed cucumber and tomato   samples (respectively) had higher Dithiocarbamates residue than MRL recommended by Institute of Standards and Industrial Research of Iran (0.5mg/kg).
Conclusion: The treatments of washing and peeling had significant effect on the reduction of Dithiocarbamates residues in the all samples.

Background: Turbidity removal using inorganic coagulants such as iron and aluminum salts in water treatment processes causes environmental and human health concern. Historically, the use of natural coagulant to purify turbid water has been practiced for a long time. Recent research indicates that Descurainia Sophia seed can be effectively used as a natural coagulant to remove water turbidity.
Method: In this work, turbidity removal efficiency of Descurainia Sophia seed extract was compared with Ferric chloride. Experiments were performed in laboratory scale. The coagulation experiments were done with kaolin as a model soil to produce turbidity in distilled water. The turbidity removal efficiency of Descurainia Sophia seed extract and Ferric chloride were conducted with jar test apparatus. In all experiments, initial turbidity was kept constant 100(NTU). Optimum combination of independent variables was used to compare two different types of coagulants.
Result: The obtained results showed that Ferric chloride could remove 89.75% of the initial turbidity, while in case of Descurainia Sophia this value was 43.13%. The total organic carbon (TOC) analysis of the treated water using seed extract showed an increased concentration of TOC equal to 0.99 mg/L.
Conclusions:This research has shown that Descurainia Sophia seed extract has an acceptable potential in the coagulation/flocculation process to treat turbid water.

Background: Water treatment sometimes needs a coagulation and flocculation process to remove suspended and colloidal materials. Inorganic coagulants used create concerns about pollution of the environment and harmful effects on the human’s health. The studies carried out previously indicated the capability of an active coagulant agent extracted from Descurainia Sophia seed to remove turbidity of water.
Methods: The purpose of this study was to investigate the effect of NaCl (0.05-1 gL^-1), NaOH (0.01-0.1 gL^-1), extraction duration (1-25 min) and the ultrasound frequency (0-45-75 kHz), used in the extraction of Descurainia Sophia seed, on the generation of color in purified water and to provide a model to predict the effects of the studied variables on color generation. Extraction was performed using water as solvent, supplemented with NaCl and NaOH and irradiated by ultrasound. Design of experiments and analysis of results were conducted by the D-optimal method based on the response surface methodology (RSM).
Results: The results demonstrated that only the effect of concentration of NaOH is significant in color generation (with p&It;0.05).
Conclusion: The effect of NaOH on color generation in purified water is predictable by the use of a statistically valid linear model at a confidence level of 95%.

Background: Conventional chemical coagulation is considered as the old method to color and COD removal in textile effluent. Electrocoagulation (EC) process is a robust method to achieve maximum removal.
Methods: This work was designed to compare the result of operational parameters including optimum pH and coagulant concentration for chemical coagulation with ferric chloride and alum. Also, the effect of voltage, electrolysis time, initial pH, and conductivity for EC with iron electrodes on removal of reactive red 196 (RR 196).
Results: The results show that ferric chloride and alum at optimum concentration were capable of taking away color and COD equal to 79.63 %, 84.83%, 53%, and 55% respectively. In contrast, EC process removed the color and COD equal to 99.98% and 90.4%, respectively.
Conclusion: The highest treatment efficiency was obtained by increasing the voltage, electrolysis time, pH and conductivity. Increase in initial dye concentration reduces removal efficiency. Ultimately, it could be concluded that EC technology is an efficient procedure for handling of colored industrial wastewaters.

Background: Brucellosis (Malta fever) is a major contagious zoonotic disease, with economic and public health importance.
Methods: To assess the effect of meteorological (temperature, rainfall, humidity, and wind) and climate parameters on incidence of brucellosis, brucellosis distribution and meteorological zoning maps of Zanjan Province were prepared using Inverse Distance Weighting (IDW) and Kriging technique in Arc GIS medium. Zoning maps of mean temperature, rainfall, humidity, and wind were compared to brucellosis distribution maps.
Results:Correlation test showed no relationship between the mean number of patients with brucellosis and any of the four meteorological parameters.
Conclusion: It seems that in Zanjan province there is no correlation between brucellosis and meteorological parameters.

Background: Environmental gamma ray refers to the gamma radiation from terrestrial sources and building materials. In enclosed spaces radiation can become a health hazard leading to potential increase in the rates of lung cancer. The goal of this study is to assess the exposure to natural gamma radiation of children in the schools of Zanjan province.
Method:The natural gamma radiation was assessed in 46 primary schools of Zanjan province. A total number of 75 classrooms were studied. The measurements were performed in classrooms and schoolyards using a Geiger–Muller detector (RDS-110). Alongside radiation measurements, all the data corresponding to the characteristics of each school building were collected.

Results: The results showed that the outdoor dose rate ranged from 82 to 106nSv h^-1 while gamma dose rate due to inside classrooms ranged from 106 to 137nSvh^-1. The findings represented that the highest indoor gamma dose rate belonged to the buildings of more than 30 years and metal frame and brick (P<0.05).

Conclusion: We concluded that the effective dose due to gamma radiation from terrestrial sources and building materials for students of primary schools in Zanjan province (0.83 mSv) was higher than worldwide average of the annual effective dose (0.48 mSv).

Background; Contamination of water and soil through non-point sources such as road runoff causes environmental concern. The aim of this study is to determine the effect of Zanjan – Chavarzagh road on the total organic carbon (TOC) content of sediments in tributaries and the river that lead to Taham Lake.
Methods; In tributaries and the river 69 soil and sediment samples were taken and the Total organic carbon (TOC) was measured according to Walkely-Black method. Also, Taham Dam Basin area and its hydrologic properties were calculated by Global Information System (GIS) software.
Results; Results showed that, TOC concentration has a significant negative relationship with the distance from the lake. TOC in soil samples taken from hillside of the road had significantly lower mean and median concentration ( median= 3262 , mean = 4083 ± 3461  mg/kg) than the valley side ( median = 5324 , mean = 6178 ± 3980  mg/kg). The check dams across the tributaries and the river have not been effective in the reduction of TOC in sediments.
Conclusion; Roads in the Taham Dam Basin, increases TOC content of soil and sediments in Taham dam basin. TOC moves toward Taham dam lake.

Background; Enzymes are well known as sensitive catalysts in the laboratory and industrial scale. To improve their properties and for using their significant potential in various reactions as a useful catalyst the stability of enzymes can often require improvement. Enzymes Immobilization on solid supports such as epoxy- functionalized ferric silica nanocomposite can be effective way to improve their characteristics.
Methods; In this study silica coated magnetite nanoparticles were Functionalized with GPTSM as a linker, then immobilization reaction performed by using  various amounts of lipase B from Candida Antarctica (CALB), for the next step immobilization effects on thermal stability and optimum pH were investigated in comparison with free CALB.
Results; Results illustrated enzyme was successfully immobilized on nano particles and immobilized derivative retains 100% of its activity by 55°C while free CALB loss its activity at the same condition.
Conclusion; Immobilization of CALB on Fe₃O₄@SiO₂ particles resulted in significant improvements in its characteristics such as thermal stability and methanol tolerance compared to the free CALB.

Background; Pollution of drinking water and ice is one of the most serious ways of water borne diseases spread. The purpose of this study was to investigate the bacterial contamination of the ice produced by ice factories in Bandar Abbas.
Methods; In this descriptive ,cross-sectional study samples were collected from seven ice factories in Bandar Abbas. Sampling was done by standard method.    Amount of the Contamination of ice and water to coliforms was investigated by the Multiple Tube method to determine the MPN, isolate bacteria and identify the microorganisms using conventional bacteriological techniques and counting the total count of bacteria by the Plate Count method on a nutrient agar medium. The data was analyzed by the SPSS software.
Results; In this study, a total of 84 samples were investigated. Gram-positive bacteria (65.5%) and gram-negative bacteria(34.5%) were separated from each other. The MPN rate in samples and total count of bacteria were 0->1100 and 2×10¹×10⁴ CFU/mL, respectively.
Conclusion;The results suggest that necessary precautions be taken by environmental health specialists and other public health authorities in production, transportation and distribution of the ice blocks to reduce the rate of bacterial contamination.

Background; Recently, there has been a great concern about the consumption of dyes because of their toxicity, mutagenicity, carcinogenicity, and persistence in the aquatic environment. Therefore, the aim of this study was to determine the feasibility of using Lemna minor for Acid Blue 292 (AB292) dye removal from aqueous solution and to determine the optimal conditions.
Methods; This experimental study was conducted in the batch systems to investigate the effects of parameters such as contact time, initial concentration of dye, pH and Lemna minor biomass dose. Isotherms and kinetic studies of dye adsorption were performed using equilibrium data.
Results; According to the results, a maximum removal efficiency of 98.5% was obtained at pH of 3 and the contact time of 90 min; initial dye concentration 10 mg/L and adsorbent dose 3g/L. The adsorption data was best fitted to the Langmuir isotherm and pseudo-second order kinetic model.
Conclusion; The results showed that Lemna minor could be used as a cost-effective adsorbent for removing AB292 dye from textile wastewater efficiently.

Background; The aim of this study is to compare UV, ferrate (VI) and UV/ferrate (VI) methods for removal of hydrogen sulfide and chemical oxygen demand (COD) from municipal wastewater under a continuous condition.

Methods; The experiment was divided into three parts: 1) pollutants removal by using ferrate (VI) alone; 2) pollutants removal using UV alone; 3) pollutants removal using a combination of UV/ferrate (VI). The electrolysis process was utilized to generate ferrate (VI).

Results;The results showed that UV had the highest pollutants removal, so that 89% and 85% of hydrogen sulfide and COD were removed from the wastewater, respectively. UV/ferrate (VI) ranked as the next most efficient method. This method removed 65% and 73% of hydrogen sulfide and COD, respectively from the wastewater.

Conclusion; Using ferrate (VI) alone had the lowest pollutant removal efficiency, with 41% and 48% of hydrogen sulfide and COD removal from wastewater, respectively. UV has a higher ability to remove hydrogen sulfide and COD from wastewater, compared with UV/ferrate (VI) and ferrate (VI) alone.

Background; Providing Safe drinking water is a prime concerninany community. This analytical study was carried out to evaluate the microbial quality of drinking water in rural areas of northeastern Iran.

Methods;The water microbial quality was determined in all villages (a population of 53047 people), in 3 rounds and based on 3 measurements, i.e. Total Coliform, Fecal Coliform, and Heterotrophic Plate Count. Census method was used for studying water distribution system too.

Results; Results of heterotrophic plate counts of over 500 were positive in 19 (19.8%) of the villages.Total coliforms were also detected in 37 (38.5%) of the villages. Water in villages receiving the services of Water and Wastewater Company had significantly lower levels of total and fecal coliforms contamination (p<0.05) compared to villages deprived of these services. In 4.3% of the villages where the Company delivered services, the HPC≥ 500 results were positive, while this percentage rose to 24.7% in other villages ( p = 0.03).

Conclusion; Comparison of  the results of this study with guidelines published by WHO, regarding the microbial quality of water in 2006, indicated that the the microbial quality of the drinking water in rural areas in Maraveh Tappeh is desirable but lower than the Iranian standard.

Background; Fluoride is an essential nutrient for the human body. The major routes of fluoride intake include food and drinking water, though the absorption of fluoride from food is much easier. The aim of this study was to evaluate the amount of fluoride in the soil and tomato and onion crops on farms of Zanjan.

Methods; Three farms of each crop (tomato and onion) were selected randomly. Each farm was divided into 10 sections, and one sample of soil and crop of each section was taken which means 120 samples in total. Fluoride concentrations in the soil and crops were measured using the Ion Selective Electrode (ISE) and repeated 3 times.

Results; The mean concentration of fluoride in soil samples from studied farms in Zanjan was 0.83 ± 0.17 mg/kg. The mean concentrations of fluoride in tomatoes and onions of Zanjan were observed 2.10 ± 0.80 and 2.23 ± 0.64 mg/kg, respectively.

Conclusion;There was no significant difference between fluoride concentration in tomatoes and onions, although there was a significant difference between the amount of fluoride in the soils of studied farms (Pv < 0.024). No significant correlation was observed between the fluoride levels of soils and the fluoride levels of tomatoes (R² = 0.126) and onions (R² = 0.008).

Background: Safe drinking water is one of the main factors in improving health status of the population. The aim of this study was assessment of the microbiological quality, determination of pH and residual chlorine in water coolers’ drinking water in educational centers of Zanjan University of medical Sciences in 2015 and comparing the results with the Iranian national standards.

Methods: In this cross-sectional study, water samples of all used water cooler apparatuses were sampled and transferred rapidly to the laboratory. pH and residual free chlorine were measured by pH meter and  Chlorine Residual Testing kit, respectively. Total coliforms, Escherichia coli, Mold and yeasts count were enumerated according to the Iranian national standards No. 1011, 3759, 5271 and 10899-1, respectively. Data were analyzed through the statistical softwares.

Results:The obtained results indicated that 44.44% of the samples were non-standard because of low residual chlorine. 44.44% and 27.8% of the taken water samples of water cooler dispensers were contaminated with mold or yeast and Escherichia coli, respectively.

Conclusion: According to some microbial contamination in water samples of water cooler devices to ensure availability clean water to consumers (students and hospital’s visitors) continuous monitoring, proper maintenance and regular inspection of the water cooler dispensers seems necessary.

Background: Iran is located in the global arid zone. With an average rainfall of less than 250 mm. 25 percent is Iran of located in hyper-dry area and 40 percent in the arid area. In 2007, the World Bank report declared the annual reduction of freshwater resources in Iran 6 times more than global standards and indicators. Since at present, in Iran most available fresh water enters the water ecosystems, their management is vitally important due to climate changes and water quality parameters.

Methods: In this study, long- term changes of some parameters including hardness, dissolved solids and EC, pH, HCO₃, Ca, Na, Mg, Cl and SO₄ were investigated for a period of 44 years in two key rivers (Neka and Tajan rivers) in the north of Iran.

Results: The results show that there was the same changes pattern in all parameters in both rivers. The highest level of correlation was between electrical conductivity and dissolved solids in both rivers. Also, due to the similarity of the hydrological characteristics of the rivers, the impact of area development by local people is playing a major role in the environmental health.

Conclusion: Although Iran's northern regions have high rate of precipitation, status of water quality parameters is an indicator of low levels of water quality and its pollution.