مجله تحقیقات نظام سلامت
سال ششم شماره 4 (زمستان 1389)

Nitrate and nitrite compounds are considered as groundwater’s contamination factors, which in recent years, their densities have been growing in these resources. This study was conducted aiming to measure nitrate and nitrite density in drinking water wells in villages around the industrial estate, city of Orumieh, and to compare them to the approved standards.

This was a descriptive, analytical, cross section study. The samples were taken from 30 wells in different parts of the surrounding areas of the industrial estate within a year period and the densities of nitrate and nitrite were measured.

Based on the findings of the experiments, the annual mean density of nitrate and nitrite were respectively 17.46 mg/L and 0.008 mg/L. The highest nitrate concentration was related to the winter. ANOVA was used to compare the mean density of nitrite and nitrate in different seasons. The assessment showed that the average nitrate density was significantly different comparing spring and summer and also spring and autumn (P<0.05), but there was not any significant differences in nitrite’s mean density in different seasons (P<0.05). Also, a statistically significant relationship were established between nitrate levels and the water depth (P<0.001, r=0.76), with increasing the water depth, the wells nitrate density decreased.

Based on the findings of the study it can be concluded that studied water quality is currently in accordance with drinking water standards in Iran with regards to nitrate and nitrite concentration; however, continuous control of water resources is essential. Hence, monitoring, treatment and disposal of production waste water should also be considered.

In this study, the inhibition rate of different oil concentrations containing PCBs (1242 and 1254 PCB Arochlors) on the anaerobic biomass was investigated by Specific Methanogenic Activity using the vials with volume of 120 ml.

Original samples were divided into two groups: with soil containing PCBs and without PCBs and the control samples in both cases were just contained substrate, without adding oil. The concentrations were evaluated in three categories: low, moderate and high values, classified and compared together and with the control samples.

the findings of this study indicated that 70% of the COD removal occurred in vials containing only two grams of soil. Biodegradation of PCBs containing oil was occurred by microorganisms without any delay in absence of oil containing 0.02 to 0.3 ml PCBs and without using oil containing PCBs.

Maximum specific methane building happened in vials containing 0.1 ml oil. Thus optimal concentrations of oil containing PCBs vials that had maximum specific methanognic activity were equal to 0.1 ml with 0.1 ml of acetic acid as auxiliary substrate. And in the 1.5 ml oil input together with the Acetic acid as auxiliary substrate the concentration was inhibitor.

Removing heavy metals from industrial wastewaters by iron nanoparticles has been much noticed in the recent years. Chromium is considered as one of the emphasis environmental pollutants. There are high concentrations of chromium in the wastewater of electroplating industries. Magnetic iron nanoparticles are used to control and eliminate the heavy metals from industrial effluents through the mechanisms of adsorption, ion exchange and electro-static forces. The aim of this study was to evaluate the efficiency of magnetic nanoparticles for hexavalent chromium’s (VI) removal from the simulated electroplating wastewater and the parameters that influence its removal.

The maghemite nanoparticles were prepared by sol-gel method and addition of two and trivalent iron chloride in the water environment under alkaline conditions. Then the factors influencing this process, including nano-particle concentration, initial concentration of chromium, pH, mixing rate, and retention time were studied.

The findings of this study showed that in the conditions of pH 2, initial chromium concentration of 10 mg/L, synthesized magnetite nanoparticles with a dose of 1 g/ L, retention time of 5 minutes, and mixing rate of 250 rpm, about 86% of chromium (VI) is removed. In addition, characteristics of nanoparticles including, particles structure, composition, size and zeta potential was determined using analytical devices such as XRD, XRF, Zeta potential and particle seizer.

It is concluded that magnetite nanoparticles have high performance for removal of chromium (VI) from the simulated electroplating wastewater, and removal efficiency is reversely related with pH.

The purpose of this study was to investigate the efficiency of flat sheet membrane bioreactor (FS-MBR) in BOD5 and COD removal of Isfahan south municipal wastewater treatment plant.

In this study a submerged FS-MBR, with 140 liters volume was fed using microfiltration membrane (MF) during 109 days and hydraulic retention time of 20 hours.

The MBR application in MLSS concentration of 7800 mg/L achieved an average efficiency removal of 95% and 99 % in COD and BOD5, respectively.

It is concluded that FS-MBR could be used in the large scales of municipal wastewater treatment plants due to the removal effluent high quality and the removal of the COD, BOD5 in accordance with effluent discharge standards.

One of the major sources of drinking water contamination is nitrate. Nitrate concentrations of more than the standard levels (45mgl-1 based on nitrate) could cause methemoglobinemia in children. The aim of this study is to investigate the nitrate adsorption on granular ferric hydroxide (GFH). Also in this study, the effect of factors such as initial concentration of nitrate, contact time, adsorbent mass and particle size of adsorbent were determined.

This study was conducted in a laboratory-scale in which the synthetic nitrate solutions were placed in a batch reactor, in contact with the adsorbent to model the adsorption kinetics.

The findings of the study indicated that by increasing Nitrate‘s initial concentration, sorption capacity reaches to the maximum level in a short time of two to three minutes. Increasing the amount of adsorbent and decreasing the adsorbent particle size could reduce the adsorption capacity. Also, the absorption kinetics followed the pseudo-degree reaction model.

This removal method could decrease nitrate concentrations to less than the standard level (45mgl-1 based on nitrate). Easy operation and high adsorption capacity of GFH are the advantages of this removal method.

The antibiotics are excreted after their effect on the host body and together with other waste disposal are entered the treatment plant processes. Antibiotics prevent the biological sewage treatment in the plant which consequently causes hazards to the environmental and human health. The purpose of this study was to investigate the effect of some popular antibiotics used by human and livestock on the anaerobic wastewater treatment process.

To evaluate the inhibitory effect of the antibiotics on biomass activity, particularly methane production (specific methanogenic activity; SMA) using anaerobic biomass Batch, the 90ml vials were filled by 15 percent volume and 70 mg biomass L substrate including volatile fatty acids, mainly acetic acid, or glucose and then various concentrations of antibiotics were added including amoxicillin, tetracycline and tylosin. To provide the optimum temperature of 35 ° C in vials the hot water bath was used, and to mix the contents of the vial fully, the magnetic mixer was used. The methane gas produced was measured through its replacement with KOH 2 N solution as CO2 absorber and bromine thymol blue as indicator. Each batch lasted for 10 days. COD tests were carried out before and after each test on the samples.

Based on the findings of each batch, oxy tetracycline, amoxicillin and tylosin in 8000, 9000 and 9000 mg/ L concentrations, respectively, had a complete inhibitory effect on the specific methanogenic activity of anaerobic biomass.

The results of this study indicated that by increasing the antibiotics concentrations, the produced biogas volume as per biomass weight per unit is decreased. On the other hand, COD removal was 42% to 82% due to long retention time and the groups adsorption.

Ocsillator system is recognized by many water plant treatment designers for having many advantages, such as combination of mixing processes, flocculation and sedimentation processes in the same unit, the possibility of softening and lucidity simultaneously, and relatively acceptable efficiency. Despite using this process in number of the regions in the country, enough researches have not been under taken on the actual performance and the pilot-scale.

In this study, to investigate the ocsillator system performance in turbidity removal a system was designed in pilot scale and operated in controlled condition (25oC and pH=7.2) using chemical coagulants (PACL and FeCl3) and different conditions of turbidity, coagulant dose and detention time.

The results indicated that there was significant deference between the detention time and turbidity of outlet water (r=0.98 and P<0.05). Maximum efficiency of the system in turbidity removal was 95% while the injected coagulant dose (FeCl3) was 10 mg / l after detention time of 240 minutes. So the inlet turbidity of 100NTU decreased to 5NTU.

FeCl3 efficiency in the turbidity removal is more than PACL.

Production of solid waste is the result of the human’s different activities that today has changed a lot in comparison to the past due to the changing life styles and pervasive expansion. In Isfahan province lots of wastes are produced daily. Due to the importance of the waste and its recycling, the purpose is determining the production scopes of different wastes in order to find a proper place for recycling.

In order to analyze the zoning of industrial and urban waste, the waste production status in different groups were studied and evaluated in this province. According to the type of industry the wastes can be divided into ten groups of metal, glass, construction and masonry wastes, rubber and plastic, paper and card board, electronic waste, decayed automobile, textile, wood and so on…. In this article the composed map of produced waste in different groups in the industrial towns, dispersed industries and the provinces were drown by Arc GIS software, so based on the wastes distributions, a proper recovering place wastes are considered by the related industries.

The distribution of recyclables are shown on the maps prepared include organic metal material (i.e. glass), cellulosic material (wood), chemical (rubber and plastic) and textiles, electronic and electric wastes and decayed automobile; in order that according to their accumulation, the proper places to recycle different wastes are recognized.

In this study, adsorbentn process performance was assessed using nickel oxide nanoparticles for wastewater treatment containing mono azo Orange II dye in a laboratory scale.

The effects of various factors such as adsorbent dosage, contact time, pH and initial dye concentration were investigated.

Based on the obtained results, the optimum pH range to dye removal is acidic pH and under these conditions, complete removal of the 50 mg/L dye can be achieved by using 0.6 g/L of nickel oxide. This concentration of nickel oxide was determined as the optimum concentration. Although increasing dye concentration caused a decrease in the efficiency process, but a considerable efficiency was obtained in 100 mg/L dye concentration.

The data showed that the nickel oxide nanoparticles could be used as an efficient adsorbent for the decolorization of azo dyes.

The high percentage of consumed antibiotics by humans and animals is excreted with other residues from the body after its performance. By entering these compounds to the wastewater, they can disrupt the anaerobic treatment process. In this study, deterrent behavior of two Ampicillin and Gentamicin antibiotics are investigated on specific methanogenic activity (SMA) of anaerobic biomass.

A total of 18 SMA (Specific Methanogenic Activity) tests were done using 120-mLvials in batch mode. In each vial 40%, 37% and 23% (v/v) of substrate, biomass and biogas were placed respectively. Each test lasted in range of 20 to 25 days. Produced methane was measured by gas replacement with 2N KOH solution as CO2 absorbent. Three Volatile fatty acids (VFAs) including Acetic, Propionic, and Butyric acids were used as co-substrate.

In this study, in the concentrations of 200, 500 and 1000 mg/L of Ampicillin, the cumulative SMA were 25, 35, and 46 ml CH4/g VSS.d for Propionic acid, 66, 101, and 154 CH4/g VSS.d for Acetic acid and 198,140, and 245 CH4/g VSS.d for Butyric acid, respectively. Also, in the concentrations of 100, 500 and 1000 mg/L of Gentamicin the cumulative SMA were 54, 72, and 71 mL CH4/g VSS.d for Propionic acid, 141, 204, and 257 mL CH4/g VSS.d for Acetic acid, and 139, 74, and 85.5 mL CH4/g VSS.d for Butyric acid, respectively.

At the same concentrations, Ampicillin has more deterrence effect on anaerobic biomass than Gentamicin. On VFAs, the deterrence of Propionic acid is greater than Acetic and Butyric acids.