The study on the criteria used to distinguish floc sedimentation and gel-like network sedimentation of cohesive fine-grained sediment in a turbulent flow has rarely been carried out. In this preliminary study, we deri...The study on the criteria used to distinguish floc sedimentation and gel-like network sedimentation of cohesive fine-grained sediment in a turbulent flow has rarely been carried out. In this preliminary study, we derive three criteria to distinguish these two different sedimentation phases by considering the comparison of the time that a characteristic floc takes to settle through mean distance between characteristic flocs and the time that it takes to move through the same distance under the influence of a turbulent flow. These criteria incorporate physical and chemical factors that have been verified to have some influences on the sediment flocculation in some published literatures, and a simple analysis result is found to be consistent with our qualitative understandings of flocculation phenomenon of cohesive fine-grained sediment.展开更多
An experimental unit was built which was located in the vicinity of the domestic wastewater treatment plant of the Municipality of San Marcos in the Department of Carazo. Said unit consisted of two welded metal barrel...An experimental unit was built which was located in the vicinity of the domestic wastewater treatment plant of the Municipality of San Marcos in the Department of Carazo. Said unit consisted of two welded metal barrels with a total height of 1.8 m and a diameter of 0.90 m, likewise, this unit comprised three functional zones;the first or input area composed of a collection unit, a driving unit, a flow control unit, and two distribution units;the second or packed zone, which is the axis of the system because it is there where bacterial growth takes place and where the removal of organic matter takes place;and an outlet composed of PVC pipe [1]. The main objective of this work was to determine how efficient a rocky filter turns out to be, using stabilization pond effluent as a post-treatment unit using red concrete as a filter medium. The study consisted in carrying out laboratory tests on water samples taken from the influent and effluent of a filter made up of red rock, as a filter medium, in order to determine the percentage of organic matter removal efficiency that it has used a hydraulic retention time of 19 hours, 15 hours, and 12 hours [2]. Among the aspects to be considered in the experimental study was the characterization of the effluent from the treatment system of San Marco, Carazo, to determine the quality of water that will be of interest to the study [3]. In this stage, four composite samplings were carried out, two of 12 hours and two of 24 hours, in which physical, chemical, and microbiological parameters were analyzed. Likewise, to determine the efficiency of the filter, the same parameters considered in the characterization of the lagoon effluent were analyzed, obtaining removal efficiencies of up to 55.53% in organic matter, and 64.60% in suspended solids for a hydraulic retention time of 19 hours;In the same way, the efficiency of the filter was carried out for retention times of 15 hours and 12 hours, in which organic matter removals of 67.84% and 56.59% and 82.77% and 77.51% in total suspended solids were found, respectively.展开更多
The settling and hydrodynamic properties of 3-D fractal flocs in quiescent water are investigated with a numerical model based on the Lattice Boltzmann Method （LBM）, with considering the settling velocity, hydrodyna...The settling and hydrodynamic properties of 3-D fractal flocs in quiescent water are investigated with a numerical model based on the Lattice Boltzmann Method （LBM）, with considering the settling velocity, hydrodynamic drag force and infra-floc flow. The comparisons of floc settling velocities and effective densities indicate that the numerical results present good agreements with observations in field and at laboratory. The results show that the drag force Fo increases with the floc size dr according to the relationship FD ∝ df^3. Moreover, the intra-floc flow field and movement of the pore water provide a better understanding of the intra-floc flow from the microscopic viewpoint. The results also indicate that the lattice Boltzmann method is a promising approach to reveal the mechanisms of the flocculation in aquatic environments.展开更多
文摘The study on the criteria used to distinguish floc sedimentation and gel-like network sedimentation of cohesive fine-grained sediment in a turbulent flow has rarely been carried out. In this preliminary study, we derive three criteria to distinguish these two different sedimentation phases by considering the comparison of the time that a characteristic floc takes to settle through mean distance between characteristic flocs and the time that it takes to move through the same distance under the influence of a turbulent flow. These criteria incorporate physical and chemical factors that have been verified to have some influences on the sediment flocculation in some published literatures, and a simple analysis result is found to be consistent with our qualitative understandings of flocculation phenomenon of cohesive fine-grained sediment.
文摘An experimental unit was built which was located in the vicinity of the domestic wastewater treatment plant of the Municipality of San Marcos in the Department of Carazo. Said unit consisted of two welded metal barrels with a total height of 1.8 m and a diameter of 0.90 m, likewise, this unit comprised three functional zones;the first or input area composed of a collection unit, a driving unit, a flow control unit, and two distribution units;the second or packed zone, which is the axis of the system because it is there where bacterial growth takes place and where the removal of organic matter takes place;and an outlet composed of PVC pipe [1]. The main objective of this work was to determine how efficient a rocky filter turns out to be, using stabilization pond effluent as a post-treatment unit using red concrete as a filter medium. The study consisted in carrying out laboratory tests on water samples taken from the influent and effluent of a filter made up of red rock, as a filter medium, in order to determine the percentage of organic matter removal efficiency that it has used a hydraulic retention time of 19 hours, 15 hours, and 12 hours [2]. Among the aspects to be considered in the experimental study was the characterization of the effluent from the treatment system of San Marco, Carazo, to determine the quality of water that will be of interest to the study [3]. In this stage, four composite samplings were carried out, two of 12 hours and two of 24 hours, in which physical, chemical, and microbiological parameters were analyzed. Likewise, to determine the efficiency of the filter, the same parameters considered in the characterization of the lagoon effluent were analyzed, obtaining removal efficiencies of up to 55.53% in organic matter, and 64.60% in suspended solids for a hydraulic retention time of 19 hours;In the same way, the efficiency of the filter was carried out for retention times of 15 hours and 12 hours, in which organic matter removals of 67.84% and 56.59% and 82.77% and 77.51% in total suspended solids were found, respectively.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50779046, 50279029)
文摘The settling and hydrodynamic properties of 3-D fractal flocs in quiescent water are investigated with a numerical model based on the Lattice Boltzmann Method （LBM）, with considering the settling velocity, hydrodynamic drag force and infra-floc flow. The comparisons of floc settling velocities and effective densities indicate that the numerical results present good agreements with observations in field and at laboratory. The results show that the drag force Fo increases with the floc size dr according to the relationship FD ∝ df^3. Moreover, the intra-floc flow field and movement of the pore water provide a better understanding of the intra-floc flow from the microscopic viewpoint. The results also indicate that the lattice Boltzmann method is a promising approach to reveal the mechanisms of the flocculation in aquatic environments.
