Comparison of mass transfer efficiency in horizontal rotating packed beds and rotating biological contactors

Abstract

In this study, the mass transfer efficiencies of a novel horizontal rotating packed (h-RPB) bed and the conventional disc-type rotating biological contactor (RBC) were studied at four speeds and seven submergences. Pall rings of two different sizes (25, 38 mm), superintalox saddles and a wiremesh spiral bundle were used as packings in the h-RPB. Volumetric gas-liquid mass transfer coefficients were determined by unsteady state absorption of atmospheric oxygen in de-aerated water. Power consumption per unit liquid volume has been found for all geometries tested. The oxygen transfer efficiency values for the h-RPB were found to be 2-5 kg kWh −1 and for the disc RBC were found to be 1-2 kg kWh −1 . The performance of the h-RPB was also compared with other gas-liquid contactors such as surface aerators. The study proves that the h-RPB is a energy efficient alternative to conventional contactors.

Biosorption of heavy metals in a photo-rotating biological contactor—a batch process study

“…As it was mentioned previously, the mechanism of metal biosorption is a complicated process and depends on a variety of factors including the ambient and environmental conditions such as pH and temperature; the initial concentration of metal ions and biomass; and competition of ions for biding sites (Das et al 2009a, b;Lottermoser et al 1999;Mathure and Patwardhan 2005). In the reported study, pH as the most important factor affecting the selectivity of ions in biosorption process was implemented.…”

“…Metal bioremediation by the application of a judicious consortium of live metal-resistant cells can ensure better removal through a combination of bioprecipitation, biosorption and continous metabolic metal uptake after physical adsorption (Malik 2004). The biotreatment potential and the strength of the binding affinity of biofilms depend largely on biosorption conditions such as pH, temperature, contact time, competing ions and ion size, initial concentration of metals and the composition of extra polymeric substances (EPS) (Das et al 2009a, b;Mack et al 2007;Wang and Chen 2006;Mathure and Patwardhan 2005;Van Hullebusch et al 2003). Aguilera et al (2008) analysed the composition of EPS extracted from 12 biofilms, isolated from Rio Tinto.…”

“…High interfacial areas generated by the discs, simple and feasible design and operation, low land occupancy, low energy consumption, low cost of operation and maintenance, high reaction rate and treatment efficiency are the principal advantages of this type of reactor (Cortez et al 2008;Mathure and Patwardhan 2005). A number of studies reported the metal removal capacity of immobilised live microorganisms in a batch or continous systems using different type of reactors included rotary systems such as RBCs, with only one to three cations in solution (Akhtar et al 2008;Bayramoglu et al 2006;Travieso et al 2002;Costley and Wallis 1999, 2001aGyure et al 1987).…”

Rotating biological contactors: a review on main factors affecting performance

“…According to Mathure and Patwardhan (2005), typically rotational speeds are 1-10 rpm for RBC media in disc form with discs with 1-4 m diameter mounted on shafts around 5-10 m long.…”

“…The first RBC system was used in the early 1900s and consisted of a cylinder with wooden slats (Mathure and Patwardhan 2005). The availability of polystyrene marked the beginning of commercial application of RBCs with the first full-scale system being installed in Germany in 1958 (Rodgers and Zhan 2003).…”