[Objective] This study aimed to determine the optimal technical parameters for the swine wastewater treatment by struvite precipitation. [Method] Central composite design （CCD） and response surface method （RSM） we...[Objective] This study aimed to determine the optimal technical parameters for the swine wastewater treatment by struvite precipitation. [Method] Central composite design （CCD） and response surface method （RSM） were employed to study the effects of struvite precipitation on removing the ammonia nitrogen in the swine wastewater. Quadratic model was developed to describe the mathematical relationships between the investigated factors of pH value, reaction time, magnesium to nitrogen molar ratio （Mg/P）, nitrogen to phosphorus molar ratio （N/P）, the investigated indicators of NH 4 -N removal efficiency and residual PO 4 3 -P concentration. Contour overlay plot was proposed to predict the optimal experimental conditions with the NNH 4 -N removal efficiency of 75% and residual PO 4 3-P concentration of 3.0 mg/L as the desired values. [Result] At pH of 10.0, mixing time of 30 min, Mg/N of 1.11, N/P of 1.14, the NH 4 -N removal efficiency （Y 1 ） was the maximum of 79.0% , and the residual PO 4 3-P concentration （Y 2 ） at this time was 0.35 mg/L. The verification test of the optimal conditions proved that the verification data and model predictions agreed well. [Conclusion] The optimized parameters for the chemical struvite precipitation used to treat swine wastewater with central composite experimental design and response surface method are scientific, rational and efficient.展开更多
Objective： To determine the changes of gastrointestinal migrating motor complex （MMC） during the early stage of cholesterol gallstone formation. Methods：Totally 45 healthy adult guinea pigs were randomly and equal...Objective： To determine the changes of gastrointestinal migrating motor complex （MMC） during the early stage of cholesterol gallstone formation. Methods：Totally 45 healthy adult guinea pigs were randomly and equally divided into 3 groups, that is, normal control, group B （1% cholesterol diet for 2 weeks） and group C （1% cholesterol diet for 4 weeks）. Three pairs of silver electrodes were inserted into the gastric antrum, duodenum and jejunum of every animal respectively. Record of gastrointestinal MMC of these guinea pigs were recorded and analyzed. Gallbladder bile was taken to detect the formation of cholesterol gallstone. Results： There were only 29 guinea pigs living. The MMC cycle time and the duration of phase Ⅱ were prolonged significantly and gradually compared with the control group （P〈0.01）, but the duration of phase Ⅲ became significantly and gradually shorter. Conclusion： During the early stage of cholesterol gallstone formation, the MMC cycle time and the duration of phase Ⅱ are prolonged and the duration of phase Ⅲ is shortened.展开更多
基金Supported by the Special Fund for the Environmental Protection Research in the Public Interest, China (201009063, 2011467024)the Fundamental Research Fund for the Welfare Scientific Research Institutes, China (ZX-200809-06)the Major Science and Technology Program for Water Pollution Control and Treatment, China (2008ZX072110010)~~
文摘[Objective] This study aimed to determine the optimal technical parameters for the swine wastewater treatment by struvite precipitation. [Method] Central composite design （CCD） and response surface method （RSM） were employed to study the effects of struvite precipitation on removing the ammonia nitrogen in the swine wastewater. Quadratic model was developed to describe the mathematical relationships between the investigated factors of pH value, reaction time, magnesium to nitrogen molar ratio （Mg/P）, nitrogen to phosphorus molar ratio （N/P）, the investigated indicators of NH 4 -N removal efficiency and residual PO 4 3 -P concentration. Contour overlay plot was proposed to predict the optimal experimental conditions with the NNH 4 -N removal efficiency of 75% and residual PO 4 3-P concentration of 3.0 mg/L as the desired values. [Result] At pH of 10.0, mixing time of 30 min, Mg/N of 1.11, N/P of 1.14, the NH 4 -N removal efficiency （Y 1 ） was the maximum of 79.0% , and the residual PO 4 3-P concentration （Y 2 ） at this time was 0.35 mg/L. The verification test of the optimal conditions proved that the verification data and model predictions agreed well. [Conclusion] The optimized parameters for the chemical struvite precipitation used to treat swine wastewater with central composite experimental design and response surface method are scientific, rational and efficient.
文摘Objective： To determine the changes of gastrointestinal migrating motor complex （MMC） during the early stage of cholesterol gallstone formation. Methods：Totally 45 healthy adult guinea pigs were randomly and equally divided into 3 groups, that is, normal control, group B （1% cholesterol diet for 2 weeks） and group C （1% cholesterol diet for 4 weeks）. Three pairs of silver electrodes were inserted into the gastric antrum, duodenum and jejunum of every animal respectively. Record of gastrointestinal MMC of these guinea pigs were recorded and analyzed. Gallbladder bile was taken to detect the formation of cholesterol gallstone. Results： There were only 29 guinea pigs living. The MMC cycle time and the duration of phase Ⅱ were prolonged significantly and gradually compared with the control group （P〈0.01）, but the duration of phase Ⅲ became significantly and gradually shorter. Conclusion： During the early stage of cholesterol gallstone formation, the MMC cycle time and the duration of phase Ⅱ are prolonged and the duration of phase Ⅲ is shortened.
