Huang Tang

Membrane fouling mechanism in ultrafiltration of succinic acid fermentation broth

The membrane fouling mechanism was studied in treating succinic acid fermentation broth during dead-end ultrafiltration. Different membranes were used and two models were applied to analyze the fouling mechanism. Resistance-in-series model was applied to determine the main factor that caused the operation resistance. Results indicated that most membranes tended to be fouled by cake layer or concentration polarization. Hermias model, which is composed of four individual sub-models, was used to analyze the predominant fouling mechanism. Results showed that the fouling of RC 10 kDa and PES 30 kDa was controlled by the complete blocking mechanism, while PES 100 kDa was controlled by the intermediate blocking and PES 10 kDa was controlled by cake layer. This conclusion was also proved by SEM photos. Membrane characteristics were monitored before and after ultrafiltration by AFM and goniometer. Both contact angle and roughness of most membranes increased after ultrafiltration.

Simultaneous Removal of Thiophene and Dibenzothiophene by Immobilized Pseudomonas delafieldii R-8 cells

Biodesulfurization (BDS) is a promising technology for deep desulfurization. In this work, PseudomonaS delafieldii R-8 cells are immobilized in calcium alginate beads and used for BDS of transportation fuels. It is found that thiophene and dibenzothiophene (DBT) can be simultaneously metabolized by immobilized R-8 cells. The initial sulfur content in the model oil is 300 mg.kg(-1) (thiophene : DBT = 1 : 1). After 10 h of treatment, the thiophene concentration is reduced by 40%, while DBT is reduced by 25%. The utilization rate of thiophene is faster than that of DBT. Moreover, the oil/water ratio of alginate immobilized cells is studied to reduce the water volume in desulfurization systems. Long-term recycling of BDS by alginate immobilized cells is carried out with oil/water ratio at 5 : 1. The immobilized cells are successfully reused over 15 batch cycles. In the last batch, the desulfurization activity remains at least 75% of the first batch.