Mathematical modeling of Fe(II), Cu(II), Ni(II) and Zn(II) removal in a horizontal rotating tubular bioreactor

Abstract

Industrial wastewaters polluted with toxic heavy metals are serious ecological and environmental problem. Therefore, in this study multi-heavy metals (Fe(2+), Cu(2+), Ni(2+) and Zn(2+)) removal process with mixed microbial culture was examined in the horizontal rotating tubular bioreactor (HRTB) by different combinations of process parameters. Hydrodynamic conditions and biomass sorption capacity have main impact on the removal efficiency of heavy metals: Fe(2+) 95.5-79.0%, Ni(2+) 92.7-54.8%, Cu(2+) 87.7-54.9% and Zn(2+) 81.8-38.1%, respectively. On the basis of experimental results, integral mathematical model of removal heavy metals in the HRTB was established. It combines hydrodynamics (mixing), mass transfer and kinetics to define bioprocess conduction in the HRTB. Mixing in the HRTB was described by structured cascade model and metal ion removal by two combined diffusion-adsorption models, respectively. For Langmuir model, average variances between experimental and simulated concentrations of metal ions were in the range of 1.22-10.99 × 10(-3) and for the Freundlich model 0.12-3.98 × 10(-3), respectively. On the basis of previous facts, it is clear that developed integral bioprocess model with Freundlich model is more efficient in the prediction of concentration of metal ions in the HRTB. Furthermore, the results obtained also pointed out that the established model is at the same time accurate and robust and therefore it has great potential for use in the scale-up procedure.

Biosorption of Mn (II), Co (II) and Cr (VI) in a horizontal rotating tubular bioreactor: experiments and evaluation of the integral bioprocess model

“…In this model, it was also assumed that the biofilm is submerged in the stagnant liquid layer (L g , Figure 1b). The mass transfer processes in the liquid phase and inside the microbial biofilm on the inner surfaces of the HRTB were defined as described earlier (Rezić et al, 2011b).…”

“…For the compartments with biofilm layer in the state of dynamic equilibrium at time (t), the model was derived from mass balance equations (Equations (5), (6)- (8)) and the second-order polynomial correlation for description of the metal ion concentrations (Equation (9)) across the biofilm layer. For more details see Rezić et al (2011b).…”

“…) with mixed microbial culture was also studied in the HRTB (Rezić et al, 2011a) and the integral bioprocess model was established that combines a mixing model and a metal ion diffusion-adsorption model (Rezić et al, 2011b). In recent years, many mathematical models have been established to represent the biosorption of different metal ions in different bioreactor systems (Lesmana et al, 2009;Ong et al, 2013).…”

“…Furthermore, in this study for bioprocess monitoring in the HRTB a more efficient and sensitive analytical method (ICP-MS) was used. Bioprocess performance in the HRTB was described by the integral bioprocess model that combines mixing and diffusion-adsorption models (Rezić et al, 2011b) in order to confirm its ability to describe different heavy metals removal processes in the HRTB, as well as to prove its potential for the use in the scaleup procedure.…”

“…The established integral bioprocess model combines the mixing model and a metal ion diffusion-adsorption model. A diffusive biofilm concept was introduced in order to detect changes of metal ion concentration inside the microbial biofilm attached to the inner surfaces of the HRTB (Rezić et al, 2011b).…”