Sun-Joon Kim

Enhancement of microalgal growth and biocomponent-based transformations for improved biofuel recovery: A review

Microalgal biomass has received much attention as feedstock for biofuel production due to its capacity to accumulate a substantial amount of biocomponents (including lipid, carbohydrate, and protein), high growth rate, and environmental benefit. However, commercial realization of microalgal biofuel is a challenge due to its low biomass production and insufficient technology for complete utilization of biomass. Recently, advanced strategies have been explored to overcome the challenges of conventional approaches and to achieve maximum possible outcomes in terms of growth. These strategies include a combination of stress factors; co-culturing with other microorganisms; and addition of salts, flue gases, and phytohormones. This review summarizes the recent progress in the application of single and combined abiotic stress conditions to stimulate microalgal growth and its biocomponents. An innovative schematic model is presented of the biomass-energy conversion pathway that proposes the transformation of all potential biocomponents of microalgae into biofuels.

Redox reaction of Fe(0) with As(V) sorbed onto goethite-coated sand under anoxic conditions

The objective of this study was to determine the applicability of reductive immobilization of As(V) by Fe(0) [zero valent iron (ZVI)] to the As contaminated soil. The experiments comprised reactions between ZVI and As(V) absorbed onto goethite-coated sand (GCS) simulating heterogeneous soil environment, and reactions between ZVI and dissolved As(V) simulating homogeneous environment. Arsenic(III+V) removal ratio in the heterogeneous system was lower than in the homogeneous system, which was due to the incomplete reduction of As(V) adsorbed onto GCS. Incomplete reduction might be caused by difficulty of desorption of As(V) or lower accessibility of ZVI to As(V) adsorbed onto GCS to react. Almost half of As(V) adsorbed onto GCS was instantly desorbed. Arsenic(III) produced by reaction between As(V) and ZVI was quickly removed by iron hydroxide including As(III). Effect of air injection for As removal in the heterogeneous system was smaller than in the homogeneous system because of difficulty in the oxidation of adsorbed Fe(II) on GCS in the heterogeneous system.