The migration and transformation of phosphorus components in wastewater treatment plants(WWTPs)play a crucial role in the convergence and circulation of phosphorus.However,the composition and variation of dissolved or...The migration and transformation of phosphorus components in wastewater treatment plants(WWTPs)play a crucial role in the convergence and circulation of phosphorus.However,the composition and variation of dissolved organic phosphorus(DOP)in WWTPs were unclear because of its complex nature,hindering its efficient detection.In this study,the DOP species and their transformation during the treatment process in WWTP were comprehensively analyzed.First,two enrichment methods were assessed for their effectiveness at facilitating wastewater analysis:lyophilization and aluminum salt precipitation.Aluminum salt precipitation was found to be better because its application allowed 31P nuclear magnetic resonance(31P NMR)spectroscopy to identify more species in the secondary effluent:orthophosphate(Ortho-P)(81.1%–89.3%of the dissolved total phosphorus),pyrophosphates(Pyro-P)(0%–2.3%),orthophosphate monoesters(Mono-P)(7.0%–10.77%),orthophosphate diesters(Di-P)(1.0%–2.96%),and phosphonate(Phos-P)(1.7%–5.16%).Furthermore,the variation and transformation mechanism of phosphorus,particularly those of DOP,during the entire sewage-treatment process were elucidated.Among the treatment steps,biological treatment combined tertiary treatment achieved better DOP removal efficiencies.Therein,biological treatment mainly removed Mono-P and Di-P with removal efficiencies of 33.3%and 41.7%compared with the effluent of the grit chamber.Di-P has higher bioavailability and is more easily converted and utilized by microorganisms than Mono-P.However,Phos-P,with low bioavailability,was hardly utilized by microorganisms,which showed only 18.4%removal efficiency in biological treatment.In tertiary treatment,coagulation process exhibited higher removal ability of Ortho-P(69.1%)and partial removal efficiencies of DOP,resulting in an increase in the DOP proportion in TP.In addition,Phos-P could not be effectively removed through the biological treatment and was only partially reduced via the adsorption process by large particles,zoogloea or multinuclear hydroxyl complexes.The results of this study can provide a theoretical basis for efficient phosphorus removal in WWTPs.展开更多
To explore the effect of temperature on the phase transformation of HCP→FCC during compression, the uniaxial compression process of AZ31 magnesium alloy was simulated by the molecular dynamics method, and the changes...To explore the effect of temperature on the phase transformation of HCP→FCC during compression, the uniaxial compression process of AZ31 magnesium alloy was simulated by the molecular dynamics method, and the changes of crystal structure and dislocation evolution were observed. The effects of temperature on mechanical properties, crystal structure, and dislocation evolution of magnesium alloy during compression were analyzed. It is concluded that some of the Shockley partial dislocation is related to FCC stacking faults. With the help of TEM characterization, the correctness of the correlation between some of the dislocations and FCC stacking faults is verified. Through the combination of simulation and experiment, this paper provides an idea for the in-depth study of the solid-phase transformation of magnesium alloys and provides reference and guidance for the design of magnesium alloys with good plasticity and formability at room temperature.展开更多
基金support of the Major Science and Technology Program for Water Pollution Control and Treatment(No.2017ZX07106)the China Postdoctoral Science Foundation(No.2022M713469)+1 种基金the China Construction Technology Consulting Co.,Ltd.Youth Fund(No.Z2022Q15)the North China Municipal Engineering Design&Research Institute Co.Ltd.(HJ-2021-53-HJY).
文摘The migration and transformation of phosphorus components in wastewater treatment plants(WWTPs)play a crucial role in the convergence and circulation of phosphorus.However,the composition and variation of dissolved organic phosphorus(DOP)in WWTPs were unclear because of its complex nature,hindering its efficient detection.In this study,the DOP species and their transformation during the treatment process in WWTP were comprehensively analyzed.First,two enrichment methods were assessed for their effectiveness at facilitating wastewater analysis:lyophilization and aluminum salt precipitation.Aluminum salt precipitation was found to be better because its application allowed 31P nuclear magnetic resonance(31P NMR)spectroscopy to identify more species in the secondary effluent:orthophosphate(Ortho-P)(81.1%–89.3%of the dissolved total phosphorus),pyrophosphates(Pyro-P)(0%–2.3%),orthophosphate monoesters(Mono-P)(7.0%–10.77%),orthophosphate diesters(Di-P)(1.0%–2.96%),and phosphonate(Phos-P)(1.7%–5.16%).Furthermore,the variation and transformation mechanism of phosphorus,particularly those of DOP,during the entire sewage-treatment process were elucidated.Among the treatment steps,biological treatment combined tertiary treatment achieved better DOP removal efficiencies.Therein,biological treatment mainly removed Mono-P and Di-P with removal efficiencies of 33.3%and 41.7%compared with the effluent of the grit chamber.Di-P has higher bioavailability and is more easily converted and utilized by microorganisms than Mono-P.However,Phos-P,with low bioavailability,was hardly utilized by microorganisms,which showed only 18.4%removal efficiency in biological treatment.In tertiary treatment,coagulation process exhibited higher removal ability of Ortho-P(69.1%)and partial removal efficiencies of DOP,resulting in an increase in the DOP proportion in TP.In addition,Phos-P could not be effectively removed through the biological treatment and was only partially reduced via the adsorption process by large particles,zoogloea or multinuclear hydroxyl complexes.The results of this study can provide a theoretical basis for efficient phosphorus removal in WWTPs.
基金supported by the National Key Research and Development Project (2018YFB1307902)Shanxi Province Joint Student Training Base Talent Training Project(No.2018JD33)+5 种基金Shanxi young top talent projectShanxi Province Science Foundation for Youths (201901D211312)Excellent young academic leaders in Shanxi colleges and universities(No.2019045)Excellent Achievements Cultivation Project of Shanxi Higher Education Institutions(No.2019KJ028)Shanxi Province emerging industry leader talent projectShanxi Graduate Education Innovation Project(No.2019SY482)。
文摘To explore the effect of temperature on the phase transformation of HCP→FCC during compression, the uniaxial compression process of AZ31 magnesium alloy was simulated by the molecular dynamics method, and the changes of crystal structure and dislocation evolution were observed. The effects of temperature on mechanical properties, crystal structure, and dislocation evolution of magnesium alloy during compression were analyzed. It is concluded that some of the Shockley partial dislocation is related to FCC stacking faults. With the help of TEM characterization, the correctness of the correlation between some of the dislocations and FCC stacking faults is verified. Through the combination of simulation and experiment, this paper provides an idea for the in-depth study of the solid-phase transformation of magnesium alloys and provides reference and guidance for the design of magnesium alloys with good plasticity and formability at room temperature.
