Kenji Takeno

Practical Removal of Radioactivity from Soil in Fukushima Using Immobilized Photosynthetic Bacteria Combined with Anaerobic Digestion and Lactic Acid Fermentation as Pre-Treatment

Practical removal of radioactivity from polluted soil in Fukushima, Japan was done using a photosynthetic bacterium, Rhodobacter sphaeroides SSI, immobilized in alginate beads. The beads were put in a mesh bag and soaked in which soil was suspended (5 kg of soil/10 L of tap water). The radioactivity of the broth decreased by 31% after 15 d of aerobic treatment. When lactic acid bacterial culture broth was added to the suspend broth, about 50% of the radioactivity was transferred to a suspend broth fraction consisting of small particles from the soil after 3 d of fermentation and 20 s of sedimentation. The results suggest that organic matter in the soil was decomposed by anaerobic digestion and lactic acid fermentation simultaneously, and was then transferred into the liquid as small particles. With combined treatment by anaerobic digestion and lactic acid fermentation for 5 d and immobilized bead aerobic treatment for an additional 19 d, the radioactivity of suspend broth decreased by 66%. The radioactivity of the original soil (10.56 µSv/h) ultimately decreased by 67% (3.52 µSv/h) after the combined treatment.

Isolation of a Thermotolerant Photosynthetic Bacterium, Rhodobacter sphaeroides Strain, NAT, and Its Capacity for Oil and Chemical Oxygen Demand Removal at High Temperatures

A thermotolerant photosynthetic bacterium NAT identified as Rhodobacter sphaeroides was isolated. When alginate-immobilized cells of strain NAT were used in high-temperature treatment of artificial sewage wastewater containing oil, the chemical oxygen demand (COD) decreased by 80% and 76% of the oil was removed after 96 h of treatment at 55 °C. Lipase activity was observed in the culture.

Hydrogen and poly- (hydroxy) alkanoate production from organic acids by photosynthetic bacteria

Publisher Summary This chapter investigates hydrogen production by Rhodobacter sphaeroides ILl06 and R. sphaeroides S from organic acids and considers the bioremediation of sediment mud of oyster farm in Hiroshima Bay. Photosynthetic bacteria can produce hydrogen from organic acids observed the relatively high hydrogen production from Rhodobacter sphaeroides RV. Recently, several reports about hydrogen production have been reported by photosynthetic bacteria using organic wastes. Acidogenic fermentation of sediment suspension is first carried out. With the addition of small amount vitamins, acidogenic fermentation is enhanced giving about 2 g/L of acetic acid. In addition, 20 mg/L of phosphate and about 1.0 mg/L of ammonium is released into the culture broth after 7 days. Hydrogen production from acetic acid as carbon and energy source is then investigated using two strains of photosynthetic bacteria (ILl06 and S strain) with the synthetic liquor of acidogenic fermentation of sediment mud. When S strain is about 2.0 L of total, gas is evolved after 100 hours culture with acetic acid energy source. 0.01 L/L broth of total is evolved by ILl06 strain. In this case, large amount of poly-Hydroxyalkanoate (PHA) accumulates in the cells of ILl06 but about 40 % of PHA is in the cells of S strain.