جستجوی مقالات مرتبط با کلیدواژه « راندمان حذف » در نشریات گروه « محیط زیست »

Activated sludge process is one of the most widely used methods of urban wastewater treatment. The purpose of this study is to use nanobubbles to supply oxygen to the aeration reactor in the activated sludge process and to evaluate its performance in terms of increasing the efficiency of wastewater treatment, reducing energy consumption, reducing the amount of excess sludge and its impact on environmental factors. The results showed that the use of nano-bubble compared to the use of macro-sized bubbles increased the concentration of dissolved oxygen in the aeration reactor up to 3 mg/liter, 18% reduction in energy consumption, 10% reduction in the initial investment in the construction of the wastewater treatment plant. 15% reduction in operating costs of the sewage treatment plant. Increasing the efficiency of removing organic pollutants and reducing the hydraulic retention time in the aeration system, reducing the size of the treatment plant by 10% due to the increase in the efficiency of removing organic substances, and as a result, reducing the hydraulic time and reducing the same amount of land for the construction of the aeration reactor and facilities for the production and distribution of air in the aeration reactor. The presented model, which is obtained by using nano-bubbles in the aeration process of bioreactors, is very effective as a new and innovative technology in preserving, cleaning, and sustaining the environment.

In recent years, nanotechnology has emerged as one of the most attractive technologies for water treatment. The advantages of using nanomaterials include high surface area, high reactivity, on-site fabrication and high potential for use in water treatment. For this purpose, this research was conducted to study the effect of the application of egg shell nanostructured particles on sodium adsorption efficiency as a discontinuous system. The effect of factors such as pH, adsorbent mass, contact time, input sodium concentration on sodium uptake was tested. The results showed that for the studied adsorbent the equilibrium time was obtained after 30 minutes and the maximum sodium uptake at pH was 5. With increasing the adsorbent mass from 0.3 to 0.5 g, the removal efficiency increased from 83.35 to 92.75%, but with increasing the adsorbent from 0.5 to 1.6 g, the adsorption efficiency remained constant. With increasing the concentration of dissolved sodium (5-120 mg / l), the removal efficiency decreased from 89.01 to 68.01%. Among the synthetic models used, the Freundlich isotherm (RMSE = 0.38 and R2 = 0.99) was more suitable for describing the adsorption process and was more consistent with laboratory data.

The purpose of this study was to experimentally investigate the treatment of petroleum hydrocarbons-contaminated wastewater using UV/O3 method. To predict the degree of pollutant destruction, the initial concentrations of O3 and pollutant, pH, solution temperature, reaction time and UV intensity were designed. For this purpose, 1-liter cylindrical glass reactor was used. The radiation source was a low-pressure mercury UV lamp with 254-nanometer wavelength (30 W UV-C) placed on the top of the batch photoreactor in order to perform UV/O3 experiments. Different concentrations of O3 (5, 10, 15, 20, 25, and 30 mg/l) were tested. In a concentration of 15 mg/l petroleum and contact time of 5, 10, 30, 20, 40, 50, 60, 100, and 120 minutes, the removal rate of hydrocarbons in the UV/O3 system was 15, 28, 31, 36, 42, 52, 56, 73, and 59.5%, wheras, the COD removal efficiency at the same contact times was 22, 38, 45, 61.5, 67.5, 70, 80, 88.5, 76.5% respectively. When the initial pH was 3, 4, 5, 6, 9, 10, and 12, the approximately efficiency of hydrocarbon removal was 75, 8, 62, 63, 4, 58, 44, 8, 35, 8, and 30% respectively. The results of this study showed that 20 mg/l O3 dose at pH = 3 and UV intensity of 2.8 W/cm (254 nm), the optimal utilization conditions for mineralization of hydrocarbon provide 73% removal after

In this study, the treatability of pulp and paper wastewater has been studied using a combined method (ultrafiltration and fenton) in a laboratory scale. First, the effect of membrane filtration on the removal of turbidity and COD, as well as membrane flux and membrane fouling were investigated, and then the advanced oxidation method was used to supplement the treatment and increase the removal efficiency of the pollutants. At the end of the membrane filtration operation, the removal efficiency of turbidity was 99%. Based on the results, the average COD of the filtration process with 41.8% removal efficiency was 906 mg/ l. Under optimal pressure conditions bar-1, the amount of membrane flux in the first backwash was equal to 1/99 L.m-2.h-1 which this amount reached to 1/26 L.m-2.h-1after the fourth backwash. the Fenton process removed 862/5 mg /L COD from the pretreated wastewater by UF membrane with an optimal dose of 1.5 mM for Fe +2 and 6 mM for a hydrogen peroxide at an initial pH of 3 and at a 17minute reaction time .In these conditions, the removal efficiency of COD, BOD5 and color was 95%, 90.3% and 92.1% respectively, These results shows high efficiency of the advanced oxidation process to remove contaminants in pulp and paper wastewater

Due to the fact that in arid and semiarid areas, access to high quality water resources my have limitation, using purified wastewater for irrigation plays an important role. Although wastewater are so little comparing with needed irrigation water but using this much water can cause that we use higher quality waters for better consumption. This research has been alone in laboratory and there has been utilized the jar test set.
In this research has been attempted to analyze, the effects of moringa seed powders (Oliefera species) in comparison with Alum and Poly Aluminum Chloride (PAC) in wastewater treatment. For performing the experiments, we utilized urban wastewaters with mediun density. Efficiency of each coagulant was assessed by measuring a number of parameters including the hardness (total, Calcium and Magnesium), turbidity, electrical conductivity (EC), acidity, Coliform (fecal and total) before and after the treatment. It is noticeable that all methods of measuring the qualitative parameters were based on those described in the book of Standard Method.
This research showed that in optimum concentration Alum, PAC and Oliefera were able to decrease turbidity up to 99.5, 99 and 97.7 percent, respectively. The efficiency of eliminating total, Calcium and Magnesium hardness, fecal and total Coliforms in the best condition were 40 (100 mg Oliefera), 72.5 (100 mg Oliefera), 67(80 mg Oliefera), 99.8 (combination of 100 mg Oliefera and 15 mg Alum) and 99.7 (combination of 100 mg Oliefera and 15 mg Alum) percent, respectively.
Discussion and The results showed that the efficiency would be higher if Oliefera be combination with Alum or PAC. The Moringa seed powders decreasing sedimentation time, comparing with the Alum and PAC. So much, so that the sedimentation time was decreased from 30 min to 10 min. we have to remark that the bulk produced sludge in Moringa seed powder has less density comparing with the Alum or PAC. It also was easier to drain.