Use of the disc fermenter to examine production of citric acid by Aspergillus niger

Continuous citric acid fermentation in a supported biomass reactor

“…The main problem encountered with the technology proposed in this study is a fall off in citric acid productivity observed after about one month of continuous working, like those previously reported for similar disk immobilized A . niger mycelium [14]. This drawback suggests a periodical washing of the disks and a renewal of mycelium, which can be automatically and simply performed in this reactor configuration, as described in detail in a previous paper for a different fermentation system [33], but would imply activity losses due to the wait for a new mycelial growth.…”

“…niger [4- 101 and solid state culture [ l l , 121. In order to increase citric acid productivity, a semi-submerged biodisk (RBS) reactor provided with entrapped cells is proposed to ensure a careful dosage of dissolved oxygen in the culture broth as well as a high biomass level. Similar equipments were previously used for citric acid production [13] and for biomass production [14] from low strength sugar solutions (10 to SOg/l).…”

Simulation of citric acid production by rotating disk contactor

“…The mathematical model of itaconic acid production by RDC was discussed by Ju and Wang (1986), but the oxygen distribution in the biofilm was not taken into consideration. As reported in the literature (Anderson et al, 1980;Ju and Wang, 1986), RDC has advantages in it's ease of operation for the repeated batch or continuous culture which results in high productivity. When the microorganism is cultivated with the RDC, there are other advantages: (a) the energy requirement is low compared with the submerged culture (conventional stirred tank reactor and airlift reactor), as it needs no aeration apparatus; and (b) the foaming which accompanies aeration in the medium does not exist.…”

“…As for the application of RDC to the production of useful materials, there have been only a few reports (Anderson et al, 1980;Ju and Wang, 1986). The mathematical model of itaconic acid production by RDC was discussed by Ju and Wang (1986), but the oxygen distribution in the biofilm was not taken into consideration.…”

“…In waste water treatment, the kinetics for the removal of the organic substrate by the microbial film using the RDC was examined both experimentally and theoretically taking into consideration the oxygen distribution within the biofilm (Gonenc and Harremoes, 1990). However, the concentration of the organic substrate in the waste water was much lower than that in the medium for the production of such useful materials as citric acid (Anderson et al, 1980). In addition, the growth of the biofilm was scarcely taken into consideration.…”