فصلنامه سلامت و محیط زیست
سال چهارم شماره 3 (پیاپی 13، پاییز 1390)

One of the complete treatment processes for industrial and municipal wastewater treatment is membrane bioreactor process which has dominant potential in process and operation sections. This study was conducted to compare the performance of extended aeration activated sludge (EAAS) with submerged membrane bioreactor (SMBR) systems in the treatment of strength wastewater, in the same condition. The initial activated sludge was brought from the Plascokar Saipa wastewater plant. The Plexiglas reactor with effective volume of 758 L was separated by a baffle into the aeration and secondary sedimentation parts with effective volumes of 433 L and 325 L, respectively. The chemical oxygen demand (COD) concentration of the influent wastewater of the EAAS and SMBR systems were between 500-2700 and 500-5000 mg/L, respectively. Results showed that the SMBR system produced a much better quality effluent than EAAS system in terms of COD, biochemical oxygen demand (BOD5), total suspended solids (TSS) and ammonium. By increasing the COD concentration, the concentration of mixed liquor suspended solids (MLSS) and the removal efficiency of organic matter in the SMBR system, were increased regularly, however the removal efficiency of COD in the EAAS system was irregular. The average BOD5/COD ratio of effluent in the EAAS and SMBR systems were 0.708±0.18 and 0.537±0.106, respectively. These show that the organic matters in the effluent of the SMBR system was less degradable and thereupon more biological treatment was achieved. Nitrification process was completely done in the SMBR system while the EAAS system could not achieve to complete nitrification.

Backgrounds and Selection of proper coagulants for turbidity removal and determination of effective methods to reduce coagulants dose and related costs in water treatment plants is of critical importance. The present study investigates the effect of returned sludge on improving the performance of poly-aluminum chloride (PAC) in turbidity, coliform bacteria, heterotrophic bacteria removal from drinking water during rapid mixing phase. In order to determine the optimal returned sludge volume injected during rapid mixing with PAC for turbidity, total coliform and hetrophic bacteria, experiments were conducted based on variables such as injected silt volume (from 0 - 125 ml), and varying turbidities from 58 - 112 NTU. At the end of each JAR experiments, remaining turbidity, microbial parameters of samples were measured. Coagulant efficiency in turbidity removal and microbial parameters were determined by Covariance, Duncan analyses and graphs were drawn by MS Excel. The results statistically showed significant among variables (P<0.05). The results showed that the maximum turbidity removal efficiency of 98.92 at 30 ppm was 10 ml while the maximum turbidity removal efficiency of 98.31 at 10 ppm was 4 ml. The maximum total coliform removal efficiency of 95.68 obtained for 10 ppm in 10 cc injected sludge volume. This study shows that addition of returned sludge to flash mixing can reduce the turbidity of samples.

Water pollution by pesticides has adverse effects on the environment and human health, as well. In recent years, advanced oxidation processes, have been gone through to a very high degree for pesticides removal. Poly-Aluminum chloride (PAC) used for water treatment, can be effective on pesticides removal. The aim of this research was to study the use of UV/O3 and PAC in the removal of pesticides from drinking water. In this descriptive- analytical survey, specific concentrations of pesticides (1,5,10,15,20 ppm);namely Diazinon, Chlorpyrifos, Carbaril were prepared through addition to deionized water. Dichloromethane was used for sample's extraction, samples extracted with Liquid- Liquid & Solid-phase extraction, finally entered bath reactor at pH (6,7,9). The samples then exposed to UV/O3at contact time of (0.5,1,1.5 and 2 hours). In the PAC pilot, the effects of various concentrations of pesticides, and PAC - ranging (12/24 and 36 ppm) were investigated for the efficacy of pesticides removal. All samples analyzed by GC/MS/MS and HPLC. It was found that in UV/O3 reactor, with the rise of pH, decrease in pesticides concentration, and rise of contact time, the efficiency of removal increased too. In the PAC pilot, increase in PAC concentration and decrease in pesticides concentration, both increased the efficiency. Besides, both of the methods showed high efficiencies in the removal of both pesticides,i-e. halogenated Organophosphorus (Chlorpyrifos), non- halogenated Organophosphorus (Diazinon) at the degree of over (%80); In case of carbamate pesticides (e.g. Carbaril) efficiency was over (>%90). One-Way Anova & Two -Way Anova were used to analyze the obtained data. According these results these two methods are suggested for the removal of pesticides from aqueous solutions.

Industrial wastewater included the cyanide is one of the important sources of environmental pollution which founded in Industrial wastewater which are harmful for human health and environment. Therefore, the purpose of this research that was fundamental designed is investigation of Removal of cyanide from aquatic solution by using of iron and copper powder in experimental scale. At first, pilot was designed. Then, acquired pH optimum equal to 2,7 for copper and iron by variation pH= (2,4,6,8,12) and constant other parameters. The effect of initial cyanide concentration (40,60,80 mg/l), initial iron and copper dosage (0.08-1 g/100CC) and contact time (15-12 min) studied at the constant of optimum pH. The result showed removal efficiency Increased from 46.6% to 90.56% and 31% to 93.78% for copper and iron by increasing of contact time from 15to 120 minute in constant conditions, respectively. Also result showed Removal efficiency decreased and increased by increasing initial cyanide concentration and initial iron and copper dosage. The results showed equilibrium data were explained acceptably by Langmuir isotherms and kinetic parameters were obtained by application of Langmuir&Hinshelwood equation. The results showed that removal of cyanide can be quick and effective done by iron and copper in experimental scale.

Backgrounds and

Improvement of water quality standards and inability of mono layer filters in producing such quality caused researchers attended to multi layer filters. Due to specific characteristics of anthracite and leca can improve removal of organic materials and Surface over flow rate. The aim of this research was evaluation performance of dual media filters (anthracite/leca) in removing of organic materials and turbidity from Ahvaz Water treatment plant

In this study two pilots built for investigation of mono layer filter and dual media filter performance. The researcher used sand in structure's media of mono layer filter and composition of anthracite, sand and leca in structure's media of dual media filter, respectively. In this study single and dual layer filter pilot examined in term of organic matter and turbidity removal efficiency.

Results indicated that removal of organic matter by single layer filter (sand), dual media filter (anthracite, and sand), dual media filter (leca and sand) was 7%,12%,4/2% respectively. And also Turbidity removal by single layer filter(sand), dual media filter (anthracite and sand), dual media filter (leca and sand) was also 69%, 80%, 74% respectively.

Results of this study showed that upgrading of Single layer to dual layer with anthracite and leca media can‘t show a significant affect in TOC removal.

New studies indicate that nitrate concentration in groundwater is increasing in most cities. High concentrations of nitrate in water increase the potential health risk in the community and the environment. In infants, No3 _ is reduced to No2 _, which combines with hemoglobin in the blood to form met hemoglobin leading to blue-tinged blood for babies under six months old in particular, Namely, so-called ‘‘blue baby syndrome'' and it also produce carcinogenic compounds. Therefore high nitrate concentration is important. The aim of the present study is removing nitrate from water using zero_valent iron. Analyses were conducted on synthetic samples. These samples were analyzed considering reaction times, pH, initial nitrate and sulfate concentration. Results showed that at Nitrate with an initial concentration of 200mg L1- after 60 min of reaction at pH(s) 7, 6 and 5 about 67.8%, 72.5 % and 88% was reduced, respectively in concentration of 100 and 300 mgL- (pH=6) the removal efficiency is 60 and 83 percent, respectively. In sodium sulfate and nitrate with concentration of 300, the removal efficiency reached from 72 to 70 percent. Results show that the initial pH is important to achieve maximum efficiency of nitrate removal. So the lower pH levels increases removal efficiency of nitrate. All of the experiments indicated that removal is the highest in the first 5 min. Generally with an increasing initial nitrate concentration the removal efficiency of nitrate increases.

Industrial processes are the major sources of environmental pollutants. Oil & gas processing are one of the industries which emitting several air pollution matters in to the atmosphere. The obtained results of CO2 emission in one of the Gas Sweetening unit of Iranian south oil company based on the field and deskwork calculations is presented in this paper. Fuel analysis method is the best method for CO2 estimation from combustion sources. In this paper, CO2 emission factor for gas sweetening plants is estimated based on this method. The obtained results showed that total CO2 emission in selected unit is about 922212/97 (kg/d) and CO2 emissions for the separate parts of this unit are 579661/75, 12921/93 and 329629/29 for acid gas flare, gas flare and boilers respectively. comparison between the separated parts of the studied units showed that emission of acid gas flare is higher than other sources (i.e about 63% of total CO2 emission), and by using the EPA default CO2 emission factors the CO2 emitted 1/2 % lower than the actual emission in the mentioned unit.

with the developments of technology, contact with various frequencies of electromagnetic fields (EMF) has significantly increased, while the abundant benefits of using microwaves in routine life cannot be neglected. During recent years there have been reports of adverse effects caused by contact with electric and magnetic fields of these waves that spread from BTS antennas. The purpose of this study is the measurement of microwaves spreading around BTS antennas in Tehran. according to the location of BTS antennas in Tehran, power density of electromagnetic waves around 63 antennas in near and distant fields in different distances was measured. The measurements were performed using the standard method of IEEE Std C95.1 by Hi-4333 device. in order to analysis data we used spss 16 and descriptive and deductive statistical tests. results of this study show that in the near field, with increase of distance from the foot of antenna, the average power density of electromagnetic waves increase in a way that in the distance of 10 meters from the antenna foot, the increase of average power density is hardly conceivable and from 10 to 15 meters distance is perfectly noticeable. But in the distant field, with increase of distance from 20 meters, the average power density of the electromagnetic waves decreases; and from 100 meter and further, the gradient of the diagram will get almost linear and the rate of power density reaches the base limit in a way that with the increase of distance there would be no significant decrease. All the measures of power density of electromagnetic waves caused by BTSs are about 0.06% of recommended measures of environmental standards and 0.0000013% of occupational standards. The results of this study are close to the results of other studies.

Gamma rays, the most energetic photons within the any other wave in the electromagnetic spectrum, pose enough energy to form charged particles and adversely affect human health. Provided that the external exposure of human beings to natural environmental gamma radiation normally exceeds that from all man-made sources combined, environmental gamma dose rate and corresponding annual effective dose were determined in the cities of Ardabil and Sar Ein.

Outdoor environmental gamma dose rates were measured using an Ion Chamber Survey Meter in 48 selected locations (one in city center and the remaining in cardinal and ordinal directions) in Ardabil and Sar Ein. Ten more locations were monitored along the hot springs effluent in Sar Ein. Measurements of gamma radiation dose rate were performed at 20 and 100 cm above the ground for a period of one hour.

Average outdoor environmental gamma dose rate were determined as 265, 219, and 208 for Ardabil, Sar Ein, and along the hot spring effluent, respectively. The annual affective dose for Ardabil and Sar Ein residents were estimated to be 1.45 and 1.39 mSv, respectively.

Calculated annual effective dose of 1.49 and 1.35 are appreciably higher than the population weighted average exposure to environmental gamma radiation worldwide and that analysis of soil content to different radionuclide is suggested.

Particular importance of hazardous wastes is due to having characteristics such as toxicity, flammability, corrosively and reactivity. Some of the chemical wastes due to having hazardous materials must be collected and managed in a proper manner, since they are potentially harmful to the environment. Owing to the fact that educational centers have important roles in developing countries, so the main objective of the present study was to investigate, hazardous waste management in chemistry laboratories of Ministry of Science universities, in Tehran, Iran. Study area of this research includes all chemistry laboratories in Tehran universities which were covered by Ministry of Science. To obtain the number of samples, based on Scientific Principles and identification formula, 64 samples were calculated. In addition, sampling was done by Stratified sampling. Validated checklists were used for data gathering. Data analysis were done by Descriptive statistics (mean, frequency and etc.) and inferential statistics (kruskal- wallis test). results obtained in this study indicate that Sharif University by obtaining the mean score of 60.5 and Tehran University by obtaining the mean score of 4.5-6 are placed in best and worst rank, respectively. Beheshty, Alzahra and Tarbiat Moallem univesities by acquiring the mean score of 20-28.5 have a same position in ranking table. Results show that most of the studied laboratories do not have any collection program and only 26.5 percent of them have acceptable programs.The separation and storing program observed in about 12.5 percent. Hazardous waste's management in chemistry laboratory of Tehran Universities was not in good status. And from the standpoint of management, only 12.5 percent of studied cases are in good status, while 75 percent was in undesirable status.

Nowadays, most countries of the world have shortage of water due to many reasons such as population growth, rising of living standards, indiscriminate water use, and so on. Besides, in absence of adequate water resources, desalination of brackish and saline waters have been used to supply potable water. Freezing process is one of the methods which can be used to desalinate saline waters.The aim of this study was to survey freezing process to produce potable water from saline water of Persian Gulf shores. This study was conducted in lab-scale by using indirect contact freezing. Three samples of 50 liter were provided from Bushehr shores. The implemented process steps were freezing (crystallization), separation of crystals, surface washing, and thawing. Freezing of the samples (each in 0.5 liter containers) were performed by a refrigerator at -20°C and 0.1KW/h energy consumption. The removal efficiencies of TDS in the first, second, and third samples by first freezing process were 56, 56, and 51 percent, respectively. Moreover, the removal efficiencies by EC were 42, 44, and 40 percent, respectively. Meanwhile, the removal efficiencies of TDS in first, second, and third samples by second freezing process observed 69, 69, and 68 percent, respectively. Moreover, the removal efficiencies by EC were 61, 60, and 63 percent, respectively. Also, the removal efficiencies of TDS in first, second, and third samples by third freezing process were 72, 73, and 72 percent, respectively. Moreover, the removal efficiencies by EC were 77, 78, and 77 percent, respectively. The production of the potable water by this method was 15-20 percent of the entry water. According to the obtained results, potable water was obtained after third freezing of the saline water. Meanwhile, TDS of the produced water was less than maximum allowed concentration of Iranian standards.

Over the last three decades environmental pollutions became a more noticeable problem in all around of the world. In many countries, noise pollution as a basic problem has a great importance.Development of the city, increasing of industrial centers, increasing vehicles, other annoying noise resources and also little information about the noise pollution of Tabriz city, has led to the doing of this research. Sampling and measuring of noise pressure levels was done 180 times According to the EPA standards, measuring was done simultaneously in two stations(commercial-residential areas), three times a day (morning 7:30 -9:30 am, midday 12:30-14:30 pm and night 19:00-21:00 pm) and 30 days in month. Sound pressure level in both stations was higher than the standards and the highest average level with 71.4 db was recorded in Raste-koche station at midday. Also lowest calculated average value with 68.5 db was measured in Golbad station at the morning time that is 8.5 db higher than the standards. Average measured sound pressure level in two stations was higher than the standards. The results show that Tabriz has a noise pollution in commercial and residential - commercial areas. It is suggested that other noise pollution resources identified and the proper management actions for its reduction be done.