k L a determination: comparative study for a gas mass balance method

Abstract

The determination of k(L) a by a gas balance method coupled with sulphite oxidation is compared for three kinds of processes (stirred tank, bubble column and fixed-bed column reactors) with a gassing-in and with a classical chemical sulphite oxidation method. The mathematical relations required for the determination of the k(L) a value are detailed. In coalescing gas-liquid conditions, the values calculated by the three methods are shown to be comparable. The gas balance method is more rapid than either the steady-state gassing-in or the chemical sulphite reaction rate measurement methods. It is also well adapted for three-phase systems (gas-liquid-solid) in which the non-coalescing effects of sulphite solution are reduced by solid interferences.

Surfactant Effects on Aeration Performance of Stirred Tank Reactors

“…As recently reported by Poughon et al [16], and Carbajal and Tecante [17], the method was found comparable to other methods, especially in fermentation liquids and at extensive foaming.…”

Oxygen transfer in intensive microbial culture

“…Our data follow the tendencies described by In fixed bed column reactors, the GB method carried out with 10 g L -1 Na 2 SO 3 instead of 50 g L -1 leads to K L a values close to those measured in water [15]. However, in our STR, K L a values obtained from the GB method with 10 and 50 g L -1 Na 2 SO 3 are alike within 10% (Fig.…”

“…With high oxygen consumption rate (cell culture, sulphite oxidation), K T can only be calculated online since any cut in the oxygen flow, required in a dynamic gassingout method, would cause oxygen limitation within a few seconds [23]. In this case, the gas balance method was used [15,[23][24][25]. When coupled with sulphite oxidation, the method proposed by Poughon et al [15] was used, at temperature and pressure conditions used for E. coli culture; it was verified that x O 2 ¼ 0 and that no enhancement occurred (variation in K L a was less than ±6%, for [Co 2+ ] = 10 -6 M, 5 9 10 -7 M and 2 9 10 -7 M).…”

“…This assumption was supported by the multi-turbine reactor configuration used in this work, and the high liquid height to diameter ratio (between 1.3 and 2.4 during microbial culture) [26]. The axially dispersed plug flow model took into account heterogeneities of the gas phase composition due to oxygen depletion in bubbles crossing the reactor from bottom to top [15]. 3.…”

“…An aqueous solution of 50 g L -1 Na 2 SO 4 was the non-coalescing ionic reference [13,14]. An aqueous solution of 10 g L -1 Na 2 SO 4 was an intermediate coalescing ionic reference [15]. Additionally, the medium R3 containing the three major salts of the E. coli culture medium (8 g K 2 HPO 4 , 8 g (NH 4 ) 2 HPO 4 , 2 g Na 2 HPO 4 ) was used.…”