A propionate-oxidizing microorganism in the methanogenic granular sludge from a thermophilic (55°C) upflow anaerobic sludge blanket (UASB) process was studied by cultivation and in situ hybridization analysis. To isolate the propionate-oxidizing anaerobe, primary enrichment was made with propionate as the sole carbon source under anaerobic conditions at 55°C. After several attempts to purify the propionate-oxidizing microorganism, we finally isolated a thermophilic, syntrophic bacterium that was able to oxidize propionate in syntrophic coculture with Methanothermobacter thermautotrophicus (“Methanobacterium thermoautotrophicum”) strain ΔH. This syntrophic propionate-oxidizing bacterium, designated as strain SI, oxidized propionate as well as ethanol, lactate, 1-butanol, 1-pentanol, 1,3-propanediol, 1-propanol and ethylene glycol in syntrophic coculture. In addition, strain SI fermented pyruvate and fumarate in pure culture. The spatial distribution of strain SI in sludge granules was investigated by fluorescence in situ hybridization (FISH) with a 16S rRNA-targeted oligonucleotide probe specific for strain SI in combination with confocal laser scanning microscopy. Using these methods, strain SI was shown to be present in the middle and inner layers of the thermophilic granules and it was juxtaposed with hydrogenotrophic methanogens. In addition, strain SI-type cells were found to account for 1.1% of the total cells in the sludge by the FISH-direct count method. These results indicate that strain SI may be responsible for propionate oxidation in situ as one of the significant populations in sludge granules.

View full abstract

A boron adsorption material for treating wastewater containing boron was synthesized from various types of saccharides and polyallylamine resin. The adsorption properties of boron were investigated by the batch and column methods using model wastewater. In the synthetic reaction for the D(+)-mannose-type polyallylamine resin, the optimum mole ratio of D(+)-mannose to one unit of polyallylamine was 1.0. Furthermore, the optimum reaction time and temperature of the synthetic reaction were found to be 24 hours and 35°C, respectively. The amount of boron adsorbed on the D(+)-mannose-type polyallylamine resin exceeded 0.5 mM·g^-1 in the pH range of 2-12, and boron could be effectively adsorb onto the D(+)-mannose-type polyallylamine resin from model wastewater. At the optimum pH of 8.5, the maximum quantity of boron adsorbed was 2.06 mM·g^-1. The adsorption isotherm of boron on the D(+)-mannose-type polyallylamine resin follows Freundlich's equation in the equilibrium concentration range from 0.045 mM·l^-1 to 15.0 mM·l^-1 at 25°C. When a feed solution containing 2.0 mM·l^-1 boron was pumped into the D(+)-mannose-type polyallylamine resin column, the volume of effluent containing less than 0.02 mM·l^-1 boron was about 311 times the bed volume, which was about 3.3 times the column of Amberlite IRA-743. The boron that was adsorbed on the D(+)-mannose-type polyallylamine resin column was easily eluted with a 1.0 M·l^-1 hydrochloric acid solution, and the elution ratio was 100.6% of the adsorbed boron on the column.

View full abstract

Adsorption of organic compounds in model and real wastewater onto a hydrotalcite-like compound (HT) was performed to evaluate the adsorbability of these organic compounds and the effect of coexisting additives. The adsorption (inclusion) state of organic compounds was also discussed based on the X-ray diffraction pattern. The 1/n values obtained using the Freundlich equation for model wastewater were larger than those for dyestuff solutions, indicating the effect of coexisting additives on the adsorbability of organic compounds. Among the coexisting additives, Na₂CO₃ had the greatest effect compared to surfactants, PVA and Na₂SO₄. Dyestuffs, surfactants and PVA were assumed to be included on a plane surface between host layers of HT. A lower adsorbability was observed in real dye wastewater than in model wastewater.

View full abstract

The dominant factors of encystment in a wild strain of Peridinium bipes (Dinophyceae) were studied through encystment experiments in culture medium using natural water. The wild strain of P. biopes and the natural water sample were collected from Gogawa Reservoir in Wakayama Prefecture. Based on the results of the encystment experiments, the optimal temperature for encystment was found to be in the range of 10 to 15°C, and no encystment was observed at 25°C. In addition, natural water during the water bloom of P. bipes induced encystment of vegetative cells. Nutrients concentrations of the natural water were very low, 0.025 mgN·l^-1 of nitrate ion and 0.003 mgP·l^-1 of orthophosphate ion, because of the uptake by phytoplanktons. Accordingly, it was inferred that resting cysts of P. bipes are formed during the bloom and that the new cysts serve as a seed population for the next bloom. Therefore, it is strongly required to develop countermeasures to break the daisy chain of bloom and encystment.

View full abstract

An investigation on water quality was conducted in a small catchment of a tea field for three years, and runoff loads of total nitrogen (T-N), total phosphorus (T-P) and chemical oxygen demand (COD) were estimated. Runoff quantity was estimated using a water-balance equation. The annual runoff loads of T-N were estimated to be 61.0 kg·ha^-1 for the first year, 193 kg·ha^-1 for the second year, and 88.1 kg·ha^-1 for the third year, and the average load for the three years was 114.1 kg·ha^-1. The ratio of the nitrogen load to the amount of applied nitrogen fertilizer was 17.1%, being much lower than in previous studies. The main reason for the low ratio obtained in this study was the lower concentration of nitrogen. The annual runoff loads of T-P and COD were estimated to be 0.68 kg·ha^-1 and 59 kg·ha^-1, respectively, and both were affected by the flushing effect on rainy days. This result suggests the importance of monitoring of phosphorus and COD as well as nitrogen in upland fields.

View full abstract