LOH, Kai Chee

Associate Professor

PhD (Chem. Eng.) MIT, 1995
MSCEP (Chem. Eng.) MIT, 1991
MEng (Chem. Eng.) NUS, 1991
BEng (Chem. Eng.) NUS, 1987

Contact information
Blk E5, 4 Engineering Drive 4, #02-36, Singapore 117576
Tel: (65) 6516 2174    Fax: (65) 6779 1936
Email: chelohkc@nus.edu.sg

RESEARCH

Biological Treatment of Industrial Effluents

Research in this area focuses on the biological degradation of recalcitrant organics in industrial effluents. Many of these compounds do not support cell growth and are known to be degraded through cometabolic pathways, in which primary substrates which support cell growth must be present. In our group, we are specifically investigating the cometabolic removal of chlorinated phenols and heterocyclic compounds. Work currently underway includes an investigation into the interactions among the substrates and developing suitable mathematical models to describe the growth and degradation kinetics. In addition, we are developing novel hybrid bioreactors, which incorporate hollow fiber membranes and activated carbon, for degrading cometabolic compounds.

Network Modelling for Perfusion Chromatography

It has been demonstrated that, in perfusion chromatography, the column efficiency and dynamic capacity are not compromised at high flow rates. It has long been accepted that the flattening of the HETP curve is due to the forced intraparticle convection within the macropores of the perfusive media. This has been analysed by moment analysis as well as numerical solution of the full mass transfer equation. Although microscopic network models have also been developed to evaluate the effects of this intraparticle convection on the mass transfer phenomena, the focus has been on the concept of an intraparticle convection augmented diffusivity. By averaging the network results and the assumption of a linear concentration in each pore of the network, the velocity dependence of column efficiency cannot be predicted correctly. In this research, we seek to improve on the network model by accounting for hydrodynamic dispersion, as well as surface energetic heterogeneity in order to better understand perfusion chromatography on a microscopic level.

Bioreactor Design for Wastewater Treatment

Biological degradation of phenol has been extensively studied using pure and mixed cultures. However, it has been found that these bacteria suffer from substrate inhibition, whereby growth (and consequently phenol degradation) is inhibited at high phenol concentrations. Various methods have been proposed to overcome substrate inhibition in order to treat high-strength phenolic wastewater. These include adapting the cells to higher concentrations of phenol, adding yeast extract to enhance the degradation rate and immobilisation of the cells. Our current work centres on developing an external loop inversed fluidised bed airlift bioreactor for the treatment of industrial effluents containing high concentrations of phenol.

SELECTED PUBLICATIONS

A. Geng and K. C. Loh, "Heterogeneity of Surface Energies in Reversed-Phase Perfusive Packings", Journal of Colloid and Interface Science, 239, 447 (2001).

K. C. Loh, N. T. S. Chung and W. F. Ang, "Immobilised Cell Membrane Bioreactor for High-Strength Phenol Wastewater", Journal of Environmental Engineering, 126, 75 (2000).

K. C. Loh and Y. G. Yu, "Kinetics of Carbazole Degradation by Pseudomonas putida in Presence of Sodium Salicylate", Water Research, 34, 4131 (2000).

S. J. Wang and K. C. Loh, "Growth Kinetics of Pseudomonas putida in Cometabolism of Phenol and 4-Chlorophenol in the Presence of a Conventional Carbon Source", Biotechnology and Bioengineering, 68, 437 (2000).

K. C. Loh, and D. I. C. Wang, "Characterization of Pore Size Distribution of Packing Materials Used in Perfusion Chromatography using a Network Model", Journal of Chromatography A, 718, 239 (1995).