جستجوی مقالات مرتبط با کلیدواژه « activated sludge » در نشریات گروه « پزشکی »

Azo dyes are present in the wastewater of most textile factories, and if they enter water resources, they pose risks to the health of humans and the living environment due to the effects of toxicity, biological accumulation, and mutagenicity. This study aimed to determine the removal of azo dye by a biological method using wastewater treatment plant sludge in aerobic and anaerobic conditions and isolation and identification of bacteria.

This experimental study, was conducted in the faculty of health, at Mazandaran University of Medical Sciences. In this study, the removal of reactive red azo dye 195 in the wastewater of textile factories was investigated using the activated sludge of the wastewater treatment plant. Experiments were carried out in batch mode in both aerobic and anaerobic conditions with 192 samples. The concentrations of azo dye in the range available in the wastewater of textile factories were 50, 65, and 80 mg/liter. The culture medium used in this study was a mineral medium containing glucose. Bottles containing culture medium, sludge, and azo dye were kept at 30°C in an incubator in aerobic and anaerobic conditions for 8 days. The effect of factors including contact time, amount of sludge, and concentration of color was investigated. Sampling was done at the contact times of 1, 2, 4, and 8 days and after centrifuge, the color concentration was measured by spectrophotometric method at a wavelength of 545 nm. The total organic carbon (TOC) concentration of the samples was measured by a TOC analyzer. After removing the color, the bacteria in the bottles were identified by the differential diagnosis method and using special culture media, gram staining techniques, and biochemical tests.

In anaerobic conditions and contact time of 8 days, the removal of azo dye in concentrations of 50 and 80 mg/liter by using 5 ml of biomass was obtained by 93 and 82%, respectively. In the aerobic condition, the removal of the dye was achieved to more than 90% within two days, and after that, the removal efficiency reached 100% with a gently increasing slope up to 8 days. By increasing the concentration of dye from 50 to 80 mg/liter, the removal efficiency decreased by about 10%. Increasing the volume of sludge from 5 to 10 ml in both cases did not have a significant effect on increasing the amount of dye removal. The amount of azo dye removal was higher in aerobic than in anaerobic conditions. In aerobic conditions, for all dye concentrations, the TOC removal rate was about 85-90%. There was no significant difference in the amount of TOC removal for 5 and 10 ml of sludge. The average TOC removal in aerobic was about 10% higher than in anaerobic conditions. In the aerobic condition, the identified bacteria included Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aerogenosa, and in the anaerobic condition, the identified bacterial species were Lactobacillus, Enterococcus faecalis, and Bacillus cereus.

Complete removal of azo dye from textile wastewater by sludge biomass under microaerophilic culture conditions is possible with a contact time of 8 days or more. The dye removal efficiency was higher in partial aerobic than in absolute anaerobic conditions. The identified azo dye-removing bacteria were mainly facultative anaerobic and microaerophilic.

The tension and crisis caused by the lack of water is one of the major problems in Iran and the world. The available water resources are under threat with the increase in population and the water per capita is constantly decreasing. The use of wastewater treatment plant effluents for irrigation of green spaces, agriculture and other purposes as an alternative and suitable source is very necessary and must be given more attention. This problem shows the importance of proper operation and maintenance of wastewater treatment plants, especially the activated sludge method as a very efficient process with the production of wastewater with suitable quality for use in irrigation of green spaces and agriculture. Achieving this importance depends on the adequate training of local operators and the existence of necessary incentive and monitoring programs and policies. This article is presented with the aim of introducing one of the most important and practical techniques in the operation of wastewater treatment plants using the activated sludge method. This article is presented with the aim of introducing one of the most important and practical techniques in the operation and maintenance of wastewater treatment plants using the activated sludge method.

In 2015, the European Union placed estrogen hormones on the list of compounds with a possible real risk to living organisms and emphasized the need for environmental research. The aim of this study was to determine the occurrence and effect of activated sludge process and chlorination on the fate of 17-beta estradiol and testosterone in hospital wastewater.

In this descriptive-analytical study, for each hormone, 18 samples were taken from different parts of a real scale treatment plant in a three months period. Hormone extraction was performed by solid phase extraction using selective C18 cartridge. The extracted hormones were assayed by ELISA specific kits (IBL, Germany). Data analysis was performed using SPSS software version 22 and Mann-Whitney and Wilcoxon statistical tests.

The minimum concentration observed in raw wastewater was related to 17β-estradiol and in the final effluent was related to testosterone. The mean concentration of testosterone in raw wastewater (6.08 ng/l) was significantly higher than the 17β-estradiol concentration (4.13 ng/l), but the difference in the mean concentrations (around 1 ng/l) of the two hormones in the final effluent was not significant. The overall efficiency of the activated sludge and chlorination processes in the removal of testosterone and 17β-estradiol was observed to be about 85% and 76%, respectively.

Although the treatment processes can reduce considerably the concentration of 17β -estradiol and testosterone, but the final hormones concentrations indicated that the type of effluent reuse and capacity of the receiving water resources must be considered.

Aerobic granules as a novel type of bio-sorbent have an excellent settling ability and high-porosity structure. This study investigated the feasibility of aerobic granules for chromium (VI) removal from synthetic aqueous solution and compare it with conventional activated sludge.

In this research the effect of some important parameters including pH (5, 7, and 9), initial chromium (VI) concentration (25, 50, and 100 mg/l), and equilibration time (30, 60, 120, 180, 240, and 360 minutes) in removal of chromium (VI) from synthetic aqueous solution in batch system have been studied. The amount of chromium (VI) was determined using Spectrophotometer at 540 nm.

The results indicated that at pH=5, initial chromium concentration of 25 mg/L  and equilibration time of 120 minutes, 97.65 % of chromium (VI) was found by aerobic granules. In the second stage, chromium (VI) removal was examined using conventional activated sludge which the efficiency of chromium (VI) were obtained 58% in the optimum conditions (pH=5, initial chromium (VI) concentration =25 mg/l, and retention time=120 minutes).

Totally, it can be concluded that aerobic granules sludge as an effective and low-cost biodegradable adsorbent has a good performance for the removal of chromium (VI) from aqueous solutions.

Nowadays, soil pollution with total petroleum hydrocarbons (TPH) is one of the major environmental issues caused serious problems to human and other living organisms. One of the best and most reliable methods of bioremediation is the use of earthworms known as vermin-remediation. In this study, bioremediation of gasoline-contaminated soil using Eisenia Fetida, the mixture of activated sludge and compost was evaluated.

In order to determine the efficiency of bioremediation to removal gasoline from contaminated soil, cow compost and urban sewage sludge with a weight ratio of 1: 0.35:0.25, was used. Experiments were carried out in 6 reactors with different concentrations of diesel (10 and 30 g / kg soil), a different number of Eisenia Fetida earthworm (10 and 20) at ambient temperature during 90 days. To compare the performance of biodegradation of gasoline using Eisenia Fetida earthworm, two control reactors that contained only contaminated soil with two ratios of gasoline, vermicompost and activated sludge, were used. The (TPH) decomposition rate was measured by GC-FID. Results of this study were analyzed by Minitab version 17 software.

Results indicated reactor No.3 has the best removal efficiency of light hydrocarbons during 90 days. the removal efficiency of average hydrocarbons was  70% and heavy hydrocarbons with the highest removal efficiency of 68% in reactor No. 4 with characteristics Soil polluted with 10 g / kg of soil + 20 number of Eisenia Fetida, With a significant difference of other reactors.

Based on the results of this study, the degradability of hydrocarbons has increased significantly with the addition of organic modifying materials and the increase in the number of earthworms.

  Anoxic-oxic (A/O) is a new method of wastewater treatment and is being used in Mahdishahr wastewater plant. considering the lack of studies in this area, it seemed necessary to study the performance of A/O system in wastewater treatment. This study was carried out to evaluate the efficiency of Mahdishahr wastewater Treatment Plant. The present cross sectional study was conducted in 2014 during 8 months. Sampling was performed two times per week from the incoming wastewater, aeration pond and effluent. Overall, 200 samples were collected. The efficiency of Treatment Plant was measured by TSS, BOD5, COD, MLSS, MLVSS, and SVI indices in aeration ponds based on standard method. Then the datas were analyzed by statistical analysis. The mean concentrations of BOD5, TSS and COD in influent were 221.6 mg/l, 203.8mg/l and 321 mg/l respectively. The mean concentrations of BOD5, TSS and COD in effluent were 23.65 mg/l, 16.79 mg/l and 34.9 mg/l respectively. According to the results the average removal efficiency of BOD5, TSS and COD were about 87.25%, 91.77% and 87.29% respectively. These results are in accordance with standards of Iranian Department of Environment to be used for agricultural purposes. During the study, the monthly mean for SVI was 67.3 ml/g and the mean for MLSS and MLVSS was 1880 and 1182 mg/l respectively.   in present study, the efficiency of A/O process in COD removals is approximately 89 percent, representing high degradability of wastewater in A/O reactor. In addition, according to the results this method was efficient and the effluent complied with Iranian standards in terms of COD, TSS and BOD5, thus the flow is suitable for reuse or discharge to water courses.

Bioaugmentation is a superior technique in bioremediation of contaminated soils with petroleum hydrocarbons. The aim of this study was to evaluate the effect of isolated bacteria from activated sludge of Asalouyeh special zone municipal wastewater treatment for bioaugmentation of kerosene-contaminated soils and to study the growth of isolated bacteria in the presence of different concentrations of this product.
Sampling of activated sludge was carried out from two treatment plants in Asalouyeh zone. Isolation of degrading bacteria was performed by culturing the samples on basal mineral medium. Emulsification test and evaluating the kinetic growth of bacteria were carried out in different concentrations of kerosene. Isolated bacteria were inoculated to polluted soils with kerosene oil compound for bioaugmentation and measuring their bioremediation potentials and the rate of biodegradation were measured by InfraRed (IR) spectroscopy.
In this study, three bacterias: Pseudomonas putida, Serratia marcescens, and Proteus mirabilis were isolated and identified as kerosene degrading bacterias from activated sludge. P. putida was recognized as the most powerful degrading bacterium of this oil product according to the emulsification tests, measuring the growth of bacteria in various concentrations of kerosene, the results of bioaugmentation of contaminated column of soil with kerosene, and reducing the level of Total Petroleum Hydrocarbons (TPHs). This bacterium with emulsification rate of 3.8 could reduce 71.03% of TPHs within 30 days.
According to the adaption of Pseudomonas putida, Serratia marcescens, and Proteus mirabilis in activated sludge with variety of pollutants in sewage, they can be used as non-indigenous bacteria for bioaugmentation and cleaning up the soil contaminated petroleum hydrocarbons.

Collection and treatment of wastewater due to adverse effect of improper wastewater disposal to the environment is inevitable and necessary. So that establishing of wastewater treatment plant toward regular evaluation of treatment systems performance is necessary for achieving environmental standards. Biokinetic coefficients obtained from laboratory studies are vital factors in industrial applications. The aim of present study was performance evaluation and bio-kinetic coefficients determination of activated sludge unit in Sanandaj wastewater treatment plant.
This cross-sectional study implemented in wastewater treatment plant of Sanandaj using continuous activated sludge process. In this study 30 samples were taken from influent and effluent wastewater and experiments carried out on them. The wastewater quality parameters including BOD5, COD, TSS and MLSS were measured; removal efficiency and bio-kinetic coefficients such as yield coefficient maximum substrate utilization rate (k), endogenous decay coefficient (kd), half saturation coefficient (Ks), Yield coefficient (Y) and specific maximum growth (μ_max) were also calculated.
Mean of COD, BOD5 and TSS removal was obtained 90.3 ± 3.3, 93.9 ± 1.9 and 86.4 ± 4.2, respectively. According to MLSS/MLVSS concentration, K, Ks, Y, Kd andμ_max were calculated 2.5 d-1, 7.25 mg/L, 0.013, 0.027 d-1 and 0.03 d-1,respectively.
Effluent derived from the activated sludge treatment plant in terms of achieving to BOD5, COD and TSS standards for discharge into surface water or agricultural purposes is desirable. Results of this study resulted in calculation of bio-kinetics confections. The bio-kinetic coefficients obtained in this study can be used in designing of similar plants, especially in cold areas.

Hospital wastewater is among hazardous wastewater due to its composition of pathogens and toxic chemicals. Discharge of untreated hospital wastewater to environment is hazardous for human and environment. Aims of this study were to identify Operational and Maintenance problems of Extended Aeration Activated sludge process in Golestan Hospital wastewater treatment plant (WTP), Ahwaz, Iran, and to find their solutions.
Sampling period was 6 months of 2015. BOD5, COD, and TSS parameters analysed in the hospital WTP effluent. In addition, VLR, Qr/Q, MLSS, F/M, SVI, HRT, and θc parameters measured in aeration tank, then operational and maintenance parameters calculated.
Results shown that average of operation & maintenance parameters were: F/M = 0.35, HRT = 6 hour, Qr/Q = 64.28 %, VLR = 1.1 Kg BOD/m3.d, MLSS = 2819.36 mg/l, SVI = 144.89 ml/g, θc = 10.93 days.
Results of operational and maintenance parameters shown that biological process behavior of the hospital WTP was Extended Aeration Activated Sludge in past years, but converted to conventional activated sludge process due to increase in hospital beds of clinical and out patients departments , which increased water consumption lead to increase wastewater flow rate. High flow rate lead to increase hydraulic load and diluting organic matter load, so hydraulic retention time and sludge age decreased.

Background and Estrogen is a steroid hormone that enters water sources through urban and hospital waste water and is a serious threat to aquatic organisms, especially fish, and human health. The aim of this study was to evaluate the performance of municipal and hospital waste water treatment, especially biological treatment in removal of estrogenic compounds.
Estrogens in aqueous samples were determined by tracking. Fifty six samples were obtained from various locations in Ahwaz municipal wastewater treatment plant and hospital waste water treatment facilities within 8 months. The samples were analyzed using Electrochemiluminescence (ECL). The results were reported in units of ng/L.
The average influent and effluent hormone levels in municipal wastewater treatment plant were 58.8 ng/ L and 5.4 ng/L, respectively. In hospital treatment plant the average influent estrogen level was 61.8 ng/L and the average effluent level was 10.8 is ng/L. The results showed that biological treatment using activated sludge can remove significant amounts of estrogen and could reduce its level to a value lower than international standards.
The removal mechanism of estrogen in biological treatment system, especially activated sludge are adsorption and biological degradation. Secondary treatment of wastewater is effective in reducing hormones that could be due to wastewater biological treatment.

Acrylonitrile is widely used as the main raw material in the production of Acrylonitrile butadiene styrene (ABS). It can be considered as pollutant in ABS process effluent. Since the importance of biological systems to treatment the ABS effluents, this study aimed to identify the dominant microorganisms in biological wastewater treatment plant and to evaluate the potential for biodegradation of acrylonitrile.
Microbial populations in the biological unit were examined during 8 runs of sampling. The culture media including PCA, R2A, Sabouraud Dextrose Agar and Rose Bengal were used for bacterial and fungal culturing. Biochemical tests were used to identify bacterial genus and the culturing was used for fungal identification. The potential of acrylonitrile biodegradation was assessed through the measurement of the concentration of acrylonitrile, acrylamide and acrylic acid.
A total of 20 bacteria isolated, 7 genera including Neisseria, Moraxella, Alcaligenes, Bacillus, Pseudomonas, Shigella and Staphylococcus were identified as dominant. The fungal genera including Aspergillus, Cladosporium, Trichoderma, and Penicillium were also identified as dominant. From a total of 71% acrylonitrile in biological unit. Acrylic acid concentration as breakdown product of acrylonitrile in influent and effluent were 39 and 94 mg/l, respectively. However, acrylamide concentration as a byproduct was almost constant.
Dominant bacterium and fungi are identified as Pseudomonas and Aspergillus, respectively. Among the isolated bacteria, the genera of Alcaligenes, Pseudomonas, Bacillus and Moraxella belong to heterotrophic nitrifying bacteria that have the ability to breakdown nitrogen compounds such as acrylonitrile.