Rheological tests for raw and conditioned activated sludge （AS） or anaerobic digested sludge （ADS） show that power-law relationships can be used to describe the evolution of several rheological parameters, i.e., l...Rheological tests for raw and conditioned activated sludge （AS） or anaerobic digested sludge （ADS） show that power-law relationships can be used to describe the evolution of several rheological parameters, i.e., limiting viscosity （η∞）, yield stress （τy）, cohesion energy of the sludge network （Ec）, and storage modulus （G＇）, with total suspended solid （TSS） content in raw and conditioned sludge. A gel-like structure that behaves similar to weak-link flocs/aggregates was observed in AS and ADS. As derived from the double-logarithmic plots of G＇-TSS content, the mass fractal dimensions of the raw and conditioned AS or ADS flocs/aggregates were 2.70 and 2.53 or 2.85 and 2.79, respectively. The theological tests also indicate that both polymer conditioning and increased TSS content led to improved elastic behavior, cohesion energy, and yield stress of the sludge network, as well as expanded the corresponding linear viscoelastic range. The porosity of AS or ADS flocs/aggregates will be improved by polymer conditioning.展开更多
Universal Soil Loss Equation (USLE) is the most comprehensive technique available to predict the long term average annual rate of erosion on a field slope. USLE was governed by five factors include soil erodibility fa...Universal Soil Loss Equation (USLE) is the most comprehensive technique available to predict the long term average annual rate of erosion on a field slope. USLE was governed by five factors include soil erodibility factor (K), rainfall and runoff erodibility index (R), crop/vegetation and management factor (C), support practice factor (P) and slope length-gradient factor (LS). In the past, K, R and LS factors are extensively studied. But the impacts of factors C and P to outfall Total Suspended Solid (TSS) and % reduction of TSS are not fully studied yet. Therefore, this study employs Buffer Zone Calculator as a tool to determine the sediment removal efficiency for different C and P factors. The selected study areas are Santubong River, Kuching, Sarawak. Results show that the outfall TSS is increasing with the increase of C values. The most effective and efficient land use for reducing TSS among 17 land uses investigated is found to be forest with undergrowth, followed by mixed dipt. forest, forest with no undergrowth, cultivated grass, logging 30, logging 10^6, wet rice, new shifting agriculture, oil palm, rubber, cocoa, coffee, tea and lastly settlement/cleared land. Besides, results also indicate that the % reduction of TSS is increasing with the decrease of P factor. The most effective support practice to reduce the outfall TSS is found to be terracing, followed by contour-strip cropping, contouring and lastly not implementing any soil conservation practice.展开更多
基金supported by the Fundamental Research Funds for the Central Universities (No. JC2011-1,TD2010-5)the National Natural Science Foundation of China (No. 51078035,21177010)+2 种基金the Ph.D. Programs Foundation of the Ministry of Education of China (No.20100014110004)the High-Tech Research and Development Program (863) of China (No. 2007AA06Z301)the Major Projects on the Control and Rectificationof Water Body Pollution (No. 2008ZX07422-002-004,2008ZX07314-006)
文摘Rheological tests for raw and conditioned activated sludge （AS） or anaerobic digested sludge （ADS） show that power-law relationships can be used to describe the evolution of several rheological parameters, i.e., limiting viscosity （η∞）, yield stress （τy）, cohesion energy of the sludge network （Ec）, and storage modulus （G＇）, with total suspended solid （TSS） content in raw and conditioned sludge. A gel-like structure that behaves similar to weak-link flocs/aggregates was observed in AS and ADS. As derived from the double-logarithmic plots of G＇-TSS content, the mass fractal dimensions of the raw and conditioned AS or ADS flocs/aggregates were 2.70 and 2.53 or 2.85 and 2.79, respectively. The theological tests also indicate that both polymer conditioning and increased TSS content led to improved elastic behavior, cohesion energy, and yield stress of the sludge network, as well as expanded the corresponding linear viscoelastic range. The porosity of AS or ADS flocs/aggregates will be improved by polymer conditioning.
文摘Universal Soil Loss Equation (USLE) is the most comprehensive technique available to predict the long term average annual rate of erosion on a field slope. USLE was governed by five factors include soil erodibility factor (K), rainfall and runoff erodibility index (R), crop/vegetation and management factor (C), support practice factor (P) and slope length-gradient factor (LS). In the past, K, R and LS factors are extensively studied. But the impacts of factors C and P to outfall Total Suspended Solid (TSS) and % reduction of TSS are not fully studied yet. Therefore, this study employs Buffer Zone Calculator as a tool to determine the sediment removal efficiency for different C and P factors. The selected study areas are Santubong River, Kuching, Sarawak. Results show that the outfall TSS is increasing with the increase of C values. The most effective and efficient land use for reducing TSS among 17 land uses investigated is found to be forest with undergrowth, followed by mixed dipt. forest, forest with no undergrowth, cultivated grass, logging 30, logging 10^6, wet rice, new shifting agriculture, oil palm, rubber, cocoa, coffee, tea and lastly settlement/cleared land. Besides, results also indicate that the % reduction of TSS is increasing with the decrease of P factor. The most effective support practice to reduce the outfall TSS is found to be terracing, followed by contour-strip cropping, contouring and lastly not implementing any soil conservation practice.
