The study was conducted to investigate the effect of sludge retention on bacterial community composition of membrane bioreactor(MBR)treating synthetic hospital wastewater.The removal of four pharmaceuticals,namely car...The study was conducted to investigate the effect of sludge retention on bacterial community composition of membrane bioreactor(MBR)treating synthetic hospital wastewater.The removal of four pharmaceuticals,namely carbamazepine,estradiol,venlafaxine,and ibuprofen in MBR,was studied at varying sludge retention time(SRT)duration of 100,45,and 15 days and hydraulic retention time(HRT)of 18 h.The removal of ibuprofen and estradiol was constant at varying SRT;however,a negligible removal of carbamazepine and low removal of venlafaxine was observed(<20%).The study suggested that the SRT of 45 days in MBR could provide maximum treatment efficiency via decreasing membrane clogging.The effect of sludge age and pharmaceutical presence on the bacterial community was investigated via high-throughput sequencing.The study reveals that the variation in SRT affects the dynamics of the bacterial community significantly.For instance,the dominant bacterium Caldimonas of SRT 100 was disappeared at lower SRTs.Moreover,the profile of the dominant genus of the SRTs varied greatly from each other.展开更多
The purpose of this work is to prepare better activated carbons from the shells of Ricinodendron Heudelotii by chemical activation with sulfuric acid (H<sub>2</sub>SO<sub>4</sub>) and sodium hy...The purpose of this work is to prepare better activated carbons from the shells of Ricinodendron Heudelotii by chemical activation with sulfuric acid (H<sub>2</sub>SO<sub>4</sub>) and sodium hydroxide (NaOH). The process was optimized by a full factorial design (2<sup>K</sup>) based on the analysis of the external specific surface area of sixteen (16) activated carbons prepared according to the parameters of the preparation. This active analysis reveals that under the preparation conditions, good carbons are obtained for a sodium hydroxide concentration equal to 1 M, an impregnation time of 24 h and carbonization at 500˚C for 1 h. The external specific surface of this carbon is 358 m<sup>2</sup><sup> </sup>•<sup></sup> g<sup>-1</sup>. The characteristics of this prepared carbon are as follows: a pH at zero point charge (pHpzc) of 8.2, a predominantly amorphous structure, a basic character and a low ash content (4.2%). It also has surface functions;the lactonic and carbonyl groups (C=O) at 1600 cm<sup>-1</sup> and the carboxylate groups (O-H or C-O) at 1340 cm<sup>-1</sup>.展开更多
Photocatalytic degradation of paraquat (PQ) aqueous solutions was studied in a fixed bed photoreactor under UV irradiation at 368 nm. This contained β-SiC alveolar foams coated with TiO2 P25 by dip-coating method. SE...Photocatalytic degradation of paraquat (PQ) aqueous solutions was studied in a fixed bed photoreactor under UV irradiation at 368 nm. This contained β-SiC alveolar foams coated with TiO2 P25 by dip-coating method. SEM analyses revealed that the surface of the film did not exhibit cracks in the presence of TTIP as a binder in the TiO2 P25 suspension. The following parameters were studied in continuous mode operation: the flow rate in the reactor, the initial concentration of the paraquat, the pH of the solution, the weight of photocatalytic material with the number of foams in the reactor and the weight of the catalyst deposited onto the support. The results showed that by working under optimal operating conditions at natural pH (pH = 6.7), low paraquat (Co = 10 ppm), and flow (26 mL/min), we recorded approximately (43.16 ± 1.00)% oxidation of paraquat and a decrease in total organic carbon (TOC) of (27.13 ± 1.00)% after about 70 minutes. The apparent rate constant is in the order of (0.0656 ± 0.0010) min-1. In addition, by increasing the amount of β-SiC foams coated with TiO2, we improve the degradation of paraquat in the same order. The study of aging of the material showed its stability over time. However, photocatalytic activity was limited after 20 minutes of UV irradiation due to the limitation of the diffusion of the paraquat molecules towards the surface of the photocatalyst. As an outcome, we obtained an efficient TiO2/β-SiC material for photocatalytic degradation of organic compounds in water.展开更多
基金The authors thank the Natural Sciences and Engineering Research Council of Canada,Canada(NSERC-STPGP-479160 Strategic grant,Premier Tech Ltée,Canada Research Chair)for financial support.
文摘The study was conducted to investigate the effect of sludge retention on bacterial community composition of membrane bioreactor(MBR)treating synthetic hospital wastewater.The removal of four pharmaceuticals,namely carbamazepine,estradiol,venlafaxine,and ibuprofen in MBR,was studied at varying sludge retention time(SRT)duration of 100,45,and 15 days and hydraulic retention time(HRT)of 18 h.The removal of ibuprofen and estradiol was constant at varying SRT;however,a negligible removal of carbamazepine and low removal of venlafaxine was observed(<20%).The study suggested that the SRT of 45 days in MBR could provide maximum treatment efficiency via decreasing membrane clogging.The effect of sludge age and pharmaceutical presence on the bacterial community was investigated via high-throughput sequencing.The study reveals that the variation in SRT affects the dynamics of the bacterial community significantly.For instance,the dominant bacterium Caldimonas of SRT 100 was disappeared at lower SRTs.Moreover,the profile of the dominant genus of the SRTs varied greatly from each other.
文摘The purpose of this work is to prepare better activated carbons from the shells of Ricinodendron Heudelotii by chemical activation with sulfuric acid (H<sub>2</sub>SO<sub>4</sub>) and sodium hydroxide (NaOH). The process was optimized by a full factorial design (2<sup>K</sup>) based on the analysis of the external specific surface area of sixteen (16) activated carbons prepared according to the parameters of the preparation. This active analysis reveals that under the preparation conditions, good carbons are obtained for a sodium hydroxide concentration equal to 1 M, an impregnation time of 24 h and carbonization at 500˚C for 1 h. The external specific surface of this carbon is 358 m<sup>2</sup><sup> </sup>•<sup></sup> g<sup>-1</sup>. The characteristics of this prepared carbon are as follows: a pH at zero point charge (pHpzc) of 8.2, a predominantly amorphous structure, a basic character and a low ash content (4.2%). It also has surface functions;the lactonic and carbonyl groups (C=O) at 1600 cm<sup>-1</sup> and the carboxylate groups (O-H or C-O) at 1340 cm<sup>-1</sup>.
文摘Photocatalytic degradation of paraquat (PQ) aqueous solutions was studied in a fixed bed photoreactor under UV irradiation at 368 nm. This contained β-SiC alveolar foams coated with TiO2 P25 by dip-coating method. SEM analyses revealed that the surface of the film did not exhibit cracks in the presence of TTIP as a binder in the TiO2 P25 suspension. The following parameters were studied in continuous mode operation: the flow rate in the reactor, the initial concentration of the paraquat, the pH of the solution, the weight of photocatalytic material with the number of foams in the reactor and the weight of the catalyst deposited onto the support. The results showed that by working under optimal operating conditions at natural pH (pH = 6.7), low paraquat (Co = 10 ppm), and flow (26 mL/min), we recorded approximately (43.16 ± 1.00)% oxidation of paraquat and a decrease in total organic carbon (TOC) of (27.13 ± 1.00)% after about 70 minutes. The apparent rate constant is in the order of (0.0656 ± 0.0010) min-1. In addition, by increasing the amount of β-SiC foams coated with TiO2, we improve the degradation of paraquat in the same order. The study of aging of the material showed its stability over time. However, photocatalytic activity was limited after 20 minutes of UV irradiation due to the limitation of the diffusion of the paraquat molecules towards the surface of the photocatalyst. As an outcome, we obtained an efficient TiO2/β-SiC material for photocatalytic degradation of organic compounds in water.
