Packed-bed reactor for the integrated biodegradation of cyanide and formamide by immobilised Fusarium oxysporum CCMI 876 and Methylobacterium sp RXM CCMI 908

Experiments were carried out to develop the technological basis for the integrated biodegradation of cyanide and formamide. The ability of both Fusarium oxysporum CCMI 876 and Methylobacterium sp. RXM CCMI 908 to transform cyanide and formamide was analysed and characterised. The K-m, for cyanide hydratase in the immobilised Fusarium oxysporum CCMI 876 was 19 +/- 4 mM of cyanide and the V-maxi was 21 +/- 5 mu mol min(-1) g(-1) (DW) cells. For the entrapped Methylobacterium sp. RXM CCMI 908 the values of the apparent reaction kinetics were K-m,K- = 1.7 +/- 0.3 mM of cyanide and the V-max,V- = 20 +/- 2 mu mol min(-1) g(-1) (DW) cells. These data were used to design and operate a two-catalyst system to balance cyanide and formamide transformations and assess the system stability. The cyanide was degraded by Fusarium oxysporum CCMI 876 at a rate of 0.059 mM h(-1) leading to 96% cyanide conversion and leaving a residual 0.21 mM. Average 3.76 mM of formamide and 0.34 mM of formate, were formed. This effluent is contacted with Methylobacterium sp. RXM CCMI 908 which used 84% of formamide. Then this compound drops to an average value of 0.62 mM. In parallel, formate builds up to nearly 12-fold the initial concentration, correlating with the amount of formamide used. The two systems were merged in a single system which design involved a scale-up criterion and the degradation profiles along the system were determined. (c) 2005 Elsevier Inc. All rights reserved.