Multi-dimensional in-depth dissection the algae-related membrane fouling in heterotrophic microalgae harvesting: Deposition dynamics, algae cake formation, and interaction force analysis

Abstract Any single existing technique cannot monitor the overall membrane fouling behavior in heterotrophic microalgae harvesting. Herein, multi-dimensional methods, included deposition dynamic, foulants spatial distribution, chemical composition and interactive force features, were developed to dissect the fouling mechanisms. Findings indicate that particles deposition rate was the largest in the initial stage due to the high permeate flux. Protein deposition rate had greatest influence on the permeate flux decline. Cake layer condense process was confirmed by the rigid particles. And the cake layer with low porosity at the bottom and orderly deposition presented good resistance performance on algae-related fouling. 3D evolution of the cake layer was a Brownian-tree liked formation process, namely, rivet seed-cluster-monolayer-multilayers. Interaction force analysis confirmed that the interfaces with protein and the loose cake layer always presented strong attractive forces. Permeate drag force and electrical repulsion force played important role on the algae cake formation in the initial stage and cake layer formation stage, respectively. Multi-dimensional techniques shed light on foulants occurrence and accumulation as well as the cake layer evolution in the membrane microalgae harvesting process.