Aeration plays an important role in the treatment of activated sludge due tothe interactions among bubbles, sewage and activated sludge in an aeration tank. The aerationperformance is directly concerned with the effic...Aeration plays an important role in the treatment of activated sludge due tothe interactions among bubbles, sewage and activated sludge in an aeration tank. The aerationperformance is directly concerned with the efficiency of sewage disposal. So the three-dimensionaltwo-fluid model was established with emphasis on the phase interaction terms in this paper. Thismodel, as an extension of the two-phase flow model, involved the motion laws of three-phases, andwas compared with experimental studies. The finite volume method was used in the numericalsimulation of gas-liquid two-phase flow and gas-liquid-solid three-phase flow. In order to discussthe influence of gas-phase, liquid-phase and solid-phase motions in an aeration tank on the sewagedisposal, three kinds of boundary and initial conditions were adopted. The simulated results of theflow structure show qualitatively good agreement with the experimental data. And the theoreticalbasis for designing the best aeration tank was discussed according to the simulated results.展开更多
Instream aeration has been used as a supplement to secondary treatment or a substitute for tertiary treatment for meeting dissolved oxygen （DO） standards in rivers. Many studies have used water quality models to det...Instream aeration has been used as a supplement to secondary treatment or a substitute for tertiary treatment for meeting dissolved oxygen （DO） standards in rivers. Many studies have used water quality models to determine the number, location, and capacity of instream aeration stations （IASs） needed to meet DO standards in combination with other pollution control measures. DO concentrations have been improved in the North Shore Channel and North Branch Chicago River by the Devon Avenue IAS for more than 35 years. A study was initiated to determine whether it was better to rehabilitate or relocate this station and to determine appropriate operational guidance for the IAS at the selected location. A water quality model capable of simulating DO concentrations during unsteady flow was used to evaluate the proper location for an IAS and operational guidance for this IAS. Three test years, a dry year, a wet year, and an extreme year, were considered in the evaluation. The study found that the Devon Avenue IAS should be rehabilitated as this location performed as well as or better than any of 10 alternative locations. According to the new operational guidance for this IAS, the amount of time with blowers operating could be substantially reduced compared to traditional operations while at the same time the attainment of the DO standards could be increased. This study shows that a carefully designed modeling study is key to effective selection, location, and operation of IASs such that attainment of DO standards can be maximized while operation hours of blowers can be minimized.展开更多
文摘Aeration plays an important role in the treatment of activated sludge due tothe interactions among bubbles, sewage and activated sludge in an aeration tank. The aerationperformance is directly concerned with the efficiency of sewage disposal. So the three-dimensionaltwo-fluid model was established with emphasis on the phase interaction terms in this paper. Thismodel, as an extension of the two-phase flow model, involved the motion laws of three-phases, andwas compared with experimental studies. The finite volume method was used in the numericalsimulation of gas-liquid two-phase flow and gas-liquid-solid three-phase flow. In order to discussthe influence of gas-phase, liquid-phase and solid-phase motions in an aeration tank on the sewagedisposal, three kinds of boundary and initial conditions were adopted. The simulated results of theflow structure show qualitatively good agreement with the experimental data. And the theoreticalbasis for designing the best aeration tank was discussed according to the simulated results.
文摘Instream aeration has been used as a supplement to secondary treatment or a substitute for tertiary treatment for meeting dissolved oxygen （DO） standards in rivers. Many studies have used water quality models to determine the number, location, and capacity of instream aeration stations （IASs） needed to meet DO standards in combination with other pollution control measures. DO concentrations have been improved in the North Shore Channel and North Branch Chicago River by the Devon Avenue IAS for more than 35 years. A study was initiated to determine whether it was better to rehabilitate or relocate this station and to determine appropriate operational guidance for the IAS at the selected location. A water quality model capable of simulating DO concentrations during unsteady flow was used to evaluate the proper location for an IAS and operational guidance for this IAS. Three test years, a dry year, a wet year, and an extreme year, were considered in the evaluation. The study found that the Devon Avenue IAS should be rehabilitated as this location performed as well as or better than any of 10 alternative locations. According to the new operational guidance for this IAS, the amount of time with blowers operating could be substantially reduced compared to traditional operations while at the same time the attainment of the DO standards could be increased. This study shows that a carefully designed modeling study is key to effective selection, location, and operation of IASs such that attainment of DO standards can be maximized while operation hours of blowers can be minimized.
