Regular articleAeration costs in stirred-tank and bubble column bioreactors

- Estimation software produces reactor costs in reasonable agreement with vendor costs.
- Bubble columns cost less to aerate than stirred-tank reactors of the same size.
- Aeration power demand is relatively independent of vessel size.
- Improved cost efficiency at larger vessel size is due to reduced capital costs.
- Higher-OTR aerobic processes are generally more cost-efficient.

To overcome knowledge gaps in the economics of large-scale aeration for production of commodity products, Aspen Plus is used to simulate steady-state oxygen delivery in both stirred-tank and bubble column bioreactors, using published engineering correlations for oxygen mass transfer as a function of aeration rate and power input, coupled with new equipment cost estimates developed in Aspen Capital Cost Estimator and validated against vendor quotations. These simulations describe the cost efficiency of oxygen delivery as a function of oxygen uptake rate and vessel size, and show that capital and operating costs for oxygen delivery drop considerably moving from standard-size (200 m3) to world-class size (500 m3) reactors, but only marginally in further scaling up to hypothetically large (1000 m3) reactors. This analysis suggests bubble-column reactor systems can reduce overall costs for oxygen delivery by 10-20% relative to stirred tanks at low to moderate oxygen transfer rates up to 150 mmol/L-h.