The tangent resistance on the interface of the soil-moldboard is an important component of the resistance to moving soil . We developed simplified mechanical models to analyze this resistance. We found that it is comp...The tangent resistance on the interface of the soil-moldboard is an important component of the resistance to moving soil . We developed simplified mechanical models to analyze this resistance. We found that it is composed of two components, the frictional and adhesive resistances. These two components originate from the soil pore, which induced a capillary suction effect, and the soil-moldboard contact area produced tangent adhesive resistance. These two components varied differently with soil moisture. Thus we predicted that resistance reduction against soil exerted on the non-smooth bionic moldboard is mainly due to the elimination of capillary suction and the reduction of physical-chemical adsorption of soil.展开更多
To investigate the effect of ultrasonic pretreatment on anaerobic digestion and sludge dewaterability and further to probe into the influencing factors on sludge dewaterability,sludge flocs were stratified into four f...To investigate the effect of ultrasonic pretreatment on anaerobic digestion and sludge dewaterability and further to probe into the influencing factors on sludge dewaterability,sludge flocs were stratified into four fractions： （1） slime;（2） loosely bound extracellular polymeric substances （LB-EPS）;（3） tightly bound EPS （TB-EPS）;and （4） EPS-free pellets.The results showed that ultrasonic pretreatment increased the anaerobic digestion efficiency by 7%–8%.Anaerobic digestion without ultrasonic pretreatment deteriorated the sludge dewaterability,with the capillary suction time （CST） increased from 1.42 to 47.3 （sec·L）/g-TSS.The application of ultrasonic pretreatment firstly deteriorated the sludge dewaterability （normalized CST increased to 44.4 （sec·L）/g-TSS）,while subsequent anaerobic digestion offset this effect and ultimately decreased the normalized CST to 23.2 （sec·L）/g-TSS.The dewaterability of unsonicated sludge correlated with protein （p = 0.003） and polysaccharide （p = 0.004） concentrations in the slime fraction,while that of sonicated sludge correlated with protein concentrations in the slime and LB-EPS fractions （p 0.05）.Fluorescent excitationemission matrix analysis showed that the fluorescence matters in the LB-EPS fraction significantly correlated with sludge dewaterability during anarobic digestion.展开更多
In this work, the enhanced dewaterabing characteristics of waste activated sludge using Fenton pretreatment was investigated in terms of effectiveness and statistical optimization. Response surface method （RSM） and ...In this work, the enhanced dewaterabing characteristics of waste activated sludge using Fenton pretreatment was investigated in terms of effectiveness and statistical optimization. Response surface method （RSM） and central composite design （CCD） were applied to evaluate and optimize the effectiveness of important operational parameters, i.e., H202 concentrations, Fe2＋ concentrations and initial pH values. A significant quadratic polynomial model was obtained （R2= 0.9189） with capillary suction time （CST） reduction efficiency as the response. Numerical optimization based on desirability function was carried out. The optimum values for H202, Fe2, and initial pH were found to be 178 mg-g-1 VSS （volatile suspended solids）, 211mg.gI VSS and 3.8, respectively, at which CST reduction efficiency of 98.25% could be achieved. This complied well with those predicted by the established polynomial model. The results indicate that Fenton pretreatment is an effective technique for advanced waste activated sludge dewatering. The enhancement of sludge dewaterability by Fenton＇s reagent lies in the migration of sludge bound water due to the disintegration of sludge flocs and microbial cells lysis.展开更多
基金sup port provided by the Key Project of Ministry of Edu-cation of P.R.China(Grant No.02089)the National Key Grant Program of Basic Research De-velopment(Grant No.2002CCA01200).
文摘The tangent resistance on the interface of the soil-moldboard is an important component of the resistance to moving soil . We developed simplified mechanical models to analyze this resistance. We found that it is composed of two components, the frictional and adhesive resistances. These two components originate from the soil pore, which induced a capillary suction effect, and the soil-moldboard contact area produced tangent adhesive resistance. These two components varied differently with soil moisture. Thus we predicted that resistance reduction against soil exerted on the non-smooth bionic moldboard is mainly due to the elimination of capillary suction and the reduction of physical-chemical adsorption of soil.
基金supported by the National Key Project for Water Pollution Control (No.2008ZX07316-003)the Program of Shanghai Subject Chief Scientist (No.10XD1404200)
文摘To investigate the effect of ultrasonic pretreatment on anaerobic digestion and sludge dewaterability and further to probe into the influencing factors on sludge dewaterability,sludge flocs were stratified into four fractions： （1） slime;（2） loosely bound extracellular polymeric substances （LB-EPS）;（3） tightly bound EPS （TB-EPS）;and （4） EPS-free pellets.The results showed that ultrasonic pretreatment increased the anaerobic digestion efficiency by 7%–8%.Anaerobic digestion without ultrasonic pretreatment deteriorated the sludge dewaterability,with the capillary suction time （CST） increased from 1.42 to 47.3 （sec·L）/g-TSS.The application of ultrasonic pretreatment firstly deteriorated the sludge dewaterability （normalized CST increased to 44.4 （sec·L）/g-TSS）,while subsequent anaerobic digestion offset this effect and ultimately decreased the normalized CST to 23.2 （sec·L）/g-TSS.The dewaterability of unsonicated sludge correlated with protein （p = 0.003） and polysaccharide （p = 0.004） concentrations in the slime fraction,while that of sonicated sludge correlated with protein concentrations in the slime and LB-EPS fractions （p 0.05）.Fluorescent excitationemission matrix analysis showed that the fluorescence matters in the LB-EPS fraction significantly correlated with sludge dewaterability during anarobic digestion.
文摘In this work, the enhanced dewaterabing characteristics of waste activated sludge using Fenton pretreatment was investigated in terms of effectiveness and statistical optimization. Response surface method （RSM） and central composite design （CCD） were applied to evaluate and optimize the effectiveness of important operational parameters, i.e., H202 concentrations, Fe2＋ concentrations and initial pH values. A significant quadratic polynomial model was obtained （R2= 0.9189） with capillary suction time （CST） reduction efficiency as the response. Numerical optimization based on desirability function was carried out. The optimum values for H202, Fe2, and initial pH were found to be 178 mg-g-1 VSS （volatile suspended solids）, 211mg.gI VSS and 3.8, respectively, at which CST reduction efficiency of 98.25% could be achieved. This complied well with those predicted by the established polynomial model. The results indicate that Fenton pretreatment is an effective technique for advanced waste activated sludge dewatering. The enhancement of sludge dewaterability by Fenton＇s reagent lies in the migration of sludge bound water due to the disintegration of sludge flocs and microbial cells lysis.
