Efficient high-concentration dewatering of Chlorella vulgaris utilising spiral inertial microfluidics

The aim of this study was to explore an alternative mode of operation for inertial focusing systems and determine the maximum inlet volume fractions at which device performance can be maintained (i.e. cell retention efficiency remains high, here defined as >95%). Microalgae dewatering was selected as a demonstrator application, specifically using Chlorella. A spiral inertial focusing device was characterised at a range of inlet concentrations from 0.5–48.8% v/v. The modified method for operation of the spiral device through the separation of a cell free region, with volume removal decreasing as device concentration increases, alongside sample recirculation in 10 x stacked devices, maintained >95% overall recovery efficiency when concentrating from an initial inlet concentration of 1.8% v/v up to a final outlet concentration of 65.3% v/v. Power consumption was calculated to be 1.1 kWh/m3, for a concentration factor of 130, which is comparable to existing dewatering technologies. This work demonstrates the feasibility of the application of inertial focusing technology to a range of bioprocessing cell concentration applications at industrially relevant sample concentrations.