Search

In this study, the performance of a novel configuration of the hybrid growth bioreactor in pilot-plant scale (containing of anoxic, aerobic and sedimentation sections) was investigated for Isfahan municipal wastewater treatment plants. The bioreactor performance was evaluated after primary sedimentation tanks under the inlet COD concentration of 0.27 ± 0.02 g/L, at different suspended biomass concentrations of about 3, 4, and 5 as g/L and different total hydraulic retention times 4, 8, and 12 h. An industrial moving bed packing with protected specific surface area of 350 m2/m3was used in the bioreactor with a 30% of filling ratio. The modified Stover–Kincannon and Grau models are applied to predict the bio kinetic coefficients of COD removal. According to the results obtained, the substrate removal rate constant (ks) for Grau model was in the range of 8.23–10.96 (1/d), and the saturation constant (KB) value and the maximum total substrate utilization rate (Umax) for modified Stover–Kincannon were in the range of 57.4–87.7 (g/L d) and 62.6–91.4 (g/L d), respectively. Also, the results showed that the bioreactor follows the models with 98–99% correlation coefficients. [ABSTRACT FROM PUBLISHER]

Nitrate and diazinon pesticide is among the environmental challenges which enter water resources, mostly as a result of agricultural activities. In this study, the effects of diazinon concentration, nitrate concentration and pH on the efficiency of simultaneous removal of contaminants from polluted water were investigated, applying a commercial polyamide nanofilter. Each factor was considered in three levels where diazinon concentration, nitrate concentration and solution pH were in the range of 10–1,000 μg/L, 40–160 mg/L and 5–9, respectively. The experiments were conducted at constant pressure of 6 bar. The response surface method was adopted in the experimental design to obtain the impact of mentioned factors. It was found that increasing diazinon concentration and pH enhance the pesticide removal efficiency up to 94%, while increasing nitrate concentration increases the commercial nanofilter efficiency from 80 to 85%. The diazinon removal percentage at optimum condition was estimated to be about 93% at diazinon concentration of about 90 μg/L, nitrate concentration of about 80 mg/L and pH of 9. [ABSTRACT FROM AUTHOR]

In this work, the photocatalytic degradation of Acid black 1721 (AB1721) in the presence of a novel photocatalyst (TiO2 - titanium dioxide) TiO2/CNT/BiOBr/Bi2S3 under visible light irradiation was investigated. The effect of different loadings of carbon nanotubes (CNT) (1%, 2%, 4%, 6% and 8%), BiOBr (10, 20, 30 and 40 wt.%) and Bi2S3 (5, 10, 15 and 20 wt.%) on the photocatalytic activities of the prepared nanocomposites was investigated. The structural properties of the nanocomposites have been characterized by X-ray diffraction, Brunauer-Emmett-Teller, diffuse reflectance spectra (DRS), Field-emission scanning electron microscopy, photoluminescence spectroscopy (PL) and Fouriertransform infrared spectroscopy. The results show that the photodegradation efficiency of TiO2/4-CNT/20-BiOBr/10-Bi2S3 photocatalyst was better than the samples. Results of DRS show a visible shift when TiO2/CNT was modified with BiOBr and Bi2S3. Also, PL spectra for all the prepared samples indicated that TiO2/4-CNT/20-BiOBr/10-Bi2S3 had the lowest recombining of electron and holes. The effect of independent variables including initial dye concentration (30, 60 and 90 mg/L), pH (3, 6 and 9), irradiation time (20, 30 and 40 min) and catalyst loading (0.5, 0.75 and 1 g/L) on dye removal was determined by response surface methodology. The optimum condition was AB1721 concentration of 30 mg/L, initial pH of 3, the reaction time of 40 min, and catalyst loading of 1 g/L. [ABSTRACT FROM AUTHOR]