FUMARIC-ACID PRODUCTION IN AIRLIFT-LOOP REACTOR WITH POROUS SPARGER

Airlift loop reactors with porous spargers were investigated and used in the process of fumaric acid production by Rhizopus oryzae ATCC 2034 4. In order to enhance oxygen mass transfer, which is very important f or organic acid production, two kinds of porous spargers (stainless st eel membrane tube and porcelain tube) were examined. Gas holdup, liqui d circulation velocity, mixing time, bubble size, and bubble rise velo cities were measured in a 50 L rectangular airlift loop reactor with d ifferent ratios of the cross-sectional area of the riser and downcomer . The local volumetric mass transfer coefficient (K(L)a) was also meas ured in the gas sparger zone. The results indicated that high K(L)a an d excellent hydrodynamics can be obtained in the airlift loop reactor with a porous sparger. A 10 L laboratory airlift loop reactor was empl oyed for the fumaric acid fermentation. Results showed that the turbul ence of two-phase flow in the airlift loop reactor not only produced f avorable conditions for mass transfer, but was also useful for forming and suspending small, well-distributed mycelial pellets (1 similar to 2 mm). A production rate of up to 0.814 g/L/h and efficiency yield of 50.1% (w/w) was obtained in the airlift loop reactor. The performance was compared with the typical stirred tank fermenter fermentation res ults.