Influence of geometry and solids concentration on the hydrodynamics and mass transfer of a rectangular airlift reactor for marine sediment and soil bioremediation

Hydrodynamics and mass transfer characteristics of a three-phase airlift re actor were studied in a rectangular split-vessel reactor and using an air-s eawater-marine sediment system. Experiments were conducted over a range of downcomer to riser cross-sectional area ratios (A(D)/A(R) = 0.65 to 1.0) fo r two-phase systems and for five sediment concentrations (5 to 25% w/v) usi ng marine sediments. The influence of higher sediment concentrations (30 to 50% w/v) was examined for A(D)/A(R) = 1. The presence of fine sediment par ticles in the system had little effect on hydrodynamic and mass transfer pa rameters compared to the two-phase systems up to 25% loading, decreasing at higher loadings. The airlift reactor was found to meet the dissolved oxyge n demand needed For a contaminated sediment treatment process. Axial distri bution of the particles was uniform along the riser and the downcomer. Corr elations were developed that described the hydrodynamic and mass transfer b ehaviour for all experimental conditions examined.