جستجوی مقالات مرتبط با کلیدواژه « extended aeration » در نشریات گروه « پزشکی »

Due to increasing the water demand and the lack of its resources, the reuse of effluents is considered as a useful option in the water resources management. The aim of this study was to evaluate the possibility of the reuse of effluents from the extended aeration process in the wastewater treatment plant of the Bojnoord city for agricultural uses.
This is a descriptive-analytical study which performed in 2013 on the quality of effluents in the wastewater treatment plant of the Bojnoord city by measuring the parameters of Electrical Conductivity (EC), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), nitrogen, phosphorus, Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Sodium Adsorption Ratio (SAR), sodium percentage, magnesium ions, potassium ions, calcium ions, sodium ions and chloride.
The results shown that, the removal efficacy of BOD and COD were 88% and 89%, respectively, and it was higher than 85 percent for TSS and VSS factors; thus, the average residual concentration of BOD, COD, TSS and phosphate in the outflow were 27, 61, 26 and 11.34 mg, respectively. The average values of pH and EC in treated effluent were obtained 7.45 and 1940 μs/cm, respectively. Moreover, the values of chloride and SAR for the effluent of the wastewater treatment plant of the Bojnoord were achieved 3.89 meq/L and 221 mg/L, respectively.
based on the results, it can be concluded that the effluents of the wastewater treatment plant of the Bojnoord city can be valuable for use in agriculture; but, due to the high concentration of chloride in treated effluent, it is recommended that this effluent used for semi-sensitive plants. Furthermore, this effluent is not suitable for feeding to groundwater and for discharging into the surface water and it is needed to advanced treatment based on the standards.

Organic compounds are one of the most important quality characteristics in wastewater treatment. The aim of this study is to make comparison of the efficiency of wetland and extended aeration activated sludge in the removal of organic compounds from sanitary wastewater based on response surface methodology.
In this experimental study 100 mixed samples were taken from wetland and extended aeration reactors. According to type of wastewater treatment and operating time, COD, BOD5 and TSS were measured. Sampling, transportation, storage and measurement performed according to standard methods. Experiment setting, modeling, removal equation of organic compounds and optimal condition was obtained by response surface methodology.
Maximum removal of COD, BOD5 and TSS (in summer) in wetland were 95.67, 93.4 and 87.41%; in extended aeration was 97, 65.1 and 80.2%, respectively. Efficiency of extended aeration was better than wetland in all seasons and all parameters. R2: 0.8- 0.89 confirms the effect of operating time on wastewater treatment efficiency. Validity and accuracy in wetland and extended aeration were 12.64-17.65 and 16.01-19.37, respectively. Removal model in both wetland and extended aeration was linear.
Efficiency of extended aeration is more than wetland. Response surface methodology properly describes organic compound removal efficacy by extended aeration and wetland.

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.

Surfactants are organic chemical compounds that increase cleaning power of water through reducing surface tension. Linear alkyl benzene sulfonate (LAS) as an anionic surfactant may cause environmental problems especially eutrophication phenomenon in surface waters. The purpose of this study is to evaluate efficiency of extended aeration process in removal of LAS in Paveh city. This descriptive cross-sectional study was carried out for 12 months in 2008. Sampling was done at 8:00 am، 10:00 am، and 12:30 pm. Methylene blue method was used to determine LAS. In total، 108 samples were taken from inlet، outlet، and return sludge during the study. All the sampling and testing methods were performed according to standard method guidelines. The results showed that efficiency of the system in removal of LAS، COD، and TSS in the warm seasons (i. e. April to September) were significantly higher than the cold seasons (p<0. 001). According to the results، the average of LAS removal in winter and summer were 94. 06% and 99. 23%، respectively. Respective values for removal of COD and TSS were 89. 1% and 72. 1% in winter and 91. 06% and 76. 36% in summer. In addition there was a direct relationship between COD and TSS parameters with LAS (R2=0. 98). It can be concluded that Paveh wastewater treatment has high performance in removal of anionic detergent in different seasons. So that، the parameters measured in all seasons (except concentration of LAS in winter) met the standards set to agriculture and surface water discharges.