A new wastewater treatment equipment, the bi-external recycling biological fluidized bed (BRBFB), which is an effective equipment, was investigated. Anaerobic digestion, aerobic aeration and settlement processes with a fixed sequential procedure were compacted into this reactor. By five different treatment courses, the optimization of the combined operation procedure in the system was determined to be a 12-hour cycle including an inflow process, a 4 h anaerobic digestion process, a 4 h aerobic aeration process, a 2 h settlement process and a 2 h recess process including effluent discharge process. By utilizing BRBFB to treat a synthetic dyeing wastewater, 90% of COD_ Cr is removed for a higher-concentration water (COD_ Cr 1 000-1 200 mg/L), and 82% of COD_ Cr is removed for a lower-concentration water (COD_ Cr 400-600 mg/L). Near 100% color is removal and discharging standards for industry wastewater are achieved.
This paper aims to investigate exact solutions for a second-grade fluid flow with the inverse method.By assuming the relation between the vorticity field and the streamfunction,the exact solutions of the motion of plane second-grade fluids are investigated and obtained.The solutions obtained include simple Couette flows,slit jet flows and uniform flows over a series of distributed obstacles.
This is a study on the mass transport of a solute or contaminant in oscillating flows through a circular tube with a reactive wall layer.The reaction consists of a reversible component due to phase exchange between the flowing fluid and the wall layer,and an irreversible component due to absorption into the wall.The short-time dispersion characteristics are numerically investigated,incorporating the coupling effects between the flow oscillation,sorption kinetics,and retardation due to phase partitioning.The effects of various dimensionless parameters e.g.,Da(the Damk&o&h lernumber),α(phase partitioning number),Γ(dimensionless absorption number),and δ(dimensionless Stokes boundary layer number) on dispersion are discussed.In particular,it is found that there exist trinal peaks of the breakthrough curves in some cases.
