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Modeling hexavalent chromium removal in a Bacillus sp. fixed‐film bioreactor
Author(s) -
NkhalambayausiChirwa Evans M.,
Wang YiTin
Publication year - 2004
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.20196
Subject(s) - hexavalent chromium , bioreactor , chromium , substrate (aquarium) , chemistry , analytical chemistry (journal) , nuclear chemistry , diffusion , effluent , kinetic energy , materials science , thermodynamics , chromatography , environmental engineering , physics , organic chemistry , oceanography , quantum mechanics , engineering , geology
A one‐dimensional diffusion‐reaction model was developed to simulate Cr(VI) reduction in a Bacillus sp . pure culture biofilm reactor with glucose as a sole supplied carbon and energy source. Substrate utilization and Cr(VI) reduction in the biofilm was best represented by a system of (second‐order) partial differential equations (PDEs). The PDE system was solved by the (fourth‐order) Runge‐Kutta method adjusted for mass transport resistance using the (second‐order) Crank‐Nicholson and Backward Euler finite difference methods. A heuristic procedure (genetic search algorithm) was used to find global optimum values of Cr(VI) reduction and substrate utilization rate kinetic parameters. The fixed‐film bioreactor system yielded higher values of the maximum specific Cr(VI) reduction rate coefficient and Cr(VI) reduction capacity ( k mc = 0.062 1/h, and R c = 0.13 mg/mg, respectively) than previously determined in batch reactors ( k mc = 0.022 1/h and R c = 0.012 mg/mg). The model predicted effluent Cr(VI) concentration well with 98.9% confidence (σ y 2= 2.37 mg 2 /L 2 , N = 119) and effluent glucose with 96.4 % confidence (σ y(w) 2= 5402 mg 2 /L 2 , N = 121, w = 100) over a wide range of Cr(VI) loadings (10–498 mg Cr(VI)/L/d). © 2004 Wiley Periodicals, Inc.