Akiyoshi Sakoda

Biological efficiency and nutritional value of Pleurotus ostreatus cultivated on spent beer grain.

Unpretreated spent beer grains were successfully used as a basic substrate material for the cultivation of Pleurotus ostreatus. The effects of spent grain types, additives, substrate moisture content, and substrate packing density on the yield and nutrition of fruit bodies were investigated. The cultivation results showed that few fruit bodies were formed on spent grain alone; however, a significantly high biological efficiency (19.1%) was obtained with the addition of wheat bran to (45%). The chemical analysis of fruit bodies indicated that P. ostreatus cultivated on spent grain substrate had a higher nutritional value than those grown on other reported types of substrates. The total amino acid content in the fruit bodies was 347.5 mg/g dry matter, and the crude protein content was as high as 53.3% on a dry weight basis. It was also found that the cultivation of P. ostreatus increased the crude protein content, while it decreased the ratio of lignin to cellulose, of the spent grain substrate.

Gramine-induced growth inhibition, oxidative damage and antioxidant responses in freshwater cyanobacterium Microcystis aeruginosa

In recent years, the exploration and development of the effective methods of treatment and prevention to algal blooms, especially Microcystis aeruginosa blooms has been an important issue in the field of water environment protection. Allelochemicals (natural plant toxins) are considered promising sources of algicides to control algal blooms. The objective of this study is to determine the inhibitory effects and potential mechanisms of a well-known allelochemical gramine (N,N-dimethyl-3-amino-methylindole) on bloom-forming cyanobacterium M. aeruginosa. The results showed that this indole alkaloid effectively inhibited the growth of M. aeruginosa. The effective concentration causing a 50% inhibition at 3 d (EC(50, 3 d)) increased with the initial algal density (IAD) increasing. When IAD increased from 5x10(4) to 5x10(5)cellsmL(-1), the values of EC(50, 3 d) increased from 0.5 to 2.1mgL(-1). In the cells of M. aeruginosa, gramine caused an obvious increase in the level of reactive oxygen species (ROS). The lipid-peroxidation product malondialdehyde (MDA) increased significantly in gramine-treated cells. The effects of gramine on enzymatic and non-enzymatic antioxidants were in different manners. The activity of superoxide dismutase (SOD) was decreased after gramine exposure. The catalase (CAT) activity was increased after 4h but decreased from 60h. Both the contents and the regeneration rates of ascorbic acid (AsA) and reduced glutathione (GSH) were increased after 4h of exposure to gramine. However, only GSH content was still increased after 40h of exposure. These results suggested that the activation of antioxidants in M. aeruginosa played an important role to resist the stress from gramine at initial time, the inactivation of SOD is crucial to the growth inhibition of M. aeruginosa by gramine, and the phytotoxicity of gramine on M. aeruginosa may be due to oxidative damage via oxidation of ROS.

Modelling a global biogeochemical nitrogen cycle in terrestrial ecosystems

Abstract An integrated global model developed mechanistically based on nitrogen transformation processes and nitrogen fluxes between the terrestrial biosphere and the atmosphere is described in this paper. This model was designed in conjunction with our previous global carbon model on the compartments of vegetation and organic-soil, a third compartment, inorganic-soil, comprising ammonium and nitrate was also incorporated. We divided the global terrestrial biosphere into 60156 grid cells, each cell being 0.5° latitude by 0.5° longitude in size, whereas we simplified the atmosphere by regarding it as a well-mixed reservoir. Each grid cell was fixed as one of the five types of ecosystems: tropical forest, temperate forest, boreal forest, crops/grassland, or no vegetation (desert, ice). Geographical information system (GIS) data on climate, soils, and vegetation for each grid cell was used to drive the model in monthly time steps. Almost all of the key processes governing nitrogen cycling in the natural ecosystem were defined based on their respective mechanisms and specific relationships to environmental factors, then integrated into a highly aggregated dynamic model. Parameters required by the model were derived from published information or determined by model calibrations such as curve fitting. Our model-based estimate of potential nitrogen storage in vegetation was 16 Pg, which is of similar magnitude to estimates found in other studies (e.g. 10, 11–14 and 12–15 Pg), while nitrogen storage in global soil was 280 Pg according to our model, which also shows good agreement with previously reported values, which range from 70 to 820 Pg, with intermediate estimates of 170, 175, 300 and 760 Pg. Of the 280 Pg of nitrogen in soil, 25 Pg was in inorganic forms such as ammonium and nitrate, and 255 Pg was in organic forms such as detritus and humus. Thus, more than 90% of the soil nitrogen was present in organic forms, a finding that agrees very well with other fields research. A sensitivity analysis on the uncertainties of the initial conditions of the model and the parameter values determined by model calibrations was also performed. Although additional work on model validation is still necessary, this models ability to simulate the nitrogen cycle in the natural ecosystem and to quantitatively estimate potential nitrogen storage in global vegetation and soil has been documented. We therefore can conclude at this stage that the basic framework of a global biogeochemical nitrogen cycle, which can be used as a tool for quantitative evaluation of anthropogenic disturbances, has been developed.

Adsorption and decomposition of water-dissolved ozone on high silica zeolites

The adsorption properties of water-dissolved ozone on high silica zeolites were investigated. Adsorbed ozone was desorbed almost reversibly. The adsorption equilibrium relations were described by a linear expression written as q=betaC, where q is the amount adsorbed, C is the equilibrium concentration and beta is the equilibrium constant. Also, the beta values were strongly dependent on the SiO(2)/Al(2)O(3) ratio (mol/mol) and on the pore structure of the high silica zeolites. The larger the SiO(2)/Al(2)O(3) ratio, the larger the value of beta. ZSM-5 (SiO(2)/Al(2)O(3) ratio: 3000), which gave the highest adsorption capacity of water-dissolved ozone, was able to highly concentrate water-dissolved ozone on the adsorbent. The decomposition behavior of adsorbed ozone was also investigated. Ozone adsorbed on high silica zeolite was observed to be a little more stable than ozone existing in bulk water. The decomposition rate was independent of SiO(2)/Al(2)O(3) ratios in the range of 30-3000 or a solution pH in the range of 4-6.

Adsorption of tri- and tetra-chloroethylene from aqueous solutions on activated carbon fibers

Abstract Recently the contamination of groundwater by trichloroethylene and related compounds have become a new environmental problem. As the first step to clarify the feasibility of applying newly developed adsorbent, activated carbon fiber (ACF), to adsorption treatments of water taken from such a contaminated groundwater source, the adsorption equilibrium and the adsorption rate of trichloroethylene and tetrachloroethylene from aqueous solutions on four ACFs with different pore-size distribution were investigated. The adsorption capacities of ACFs having larger volume of micropores are larger than those of granular activated carbons (GACs) usually used at present. Also, the adsorption rate on ACFs is far more rapid in comparison with GAC adsorption because of smaller diffusion path.

Decomposition of trichloroethene on ozone-adsorbed high silica zeolites

We developed a novel ozonation process for water treatment using high silica zeolites as an adsorptive concentrator of water-dissolved ozone and organic pollutants, resulting in a significant increase in reaction rate. In experiments involving trichloroethene (TCE) decomposition using a tubular flow reactor, TCE decomposition was much greater in the presence of ZSM-5 (SiO(2)/Al(2)O(3) ratio=3000) than in its absence, possibly due to the high concentrations of ozone and TCE inside the adsorbent. The TCE conversion obtained in our experiments was found to reach its theoretically maximum limit.

Trihalomethane adsorption on activated carbon fibers

Abstract Adsorption isotherms of three trihalomethanes (THMs) involving CHCl 3 , CHBrCl 2 and CHBr 2 Cl on activated carbon fibers (ACFs) were measured. Adsorption capacities of the ACFs for these THMs were found to be comparable with or slightly larger than those of granular activated carbons (GACs) which have been widely used for trihalomethane control in drinking water. Also, the breakthrough curve prediction was successfully carried out using a mathematical model on the basis of the assumption that the adsorption equilibrium is instantaneously established when a THM solution contacts the ACF. In practice, THM removal from drinking water was investigated at water works using bench-scale ACF adsorption columns. The volume of water treated at a space velocity (SV) of about 100 h −1 was approx. 401 (g-ACF) −1 .

Structural changes of lignocelluloses by a nonionic surfactant, Tween 20, and their effects on cellulase adsorption and saccharification

In this work, we found that Tween 20 treatment (0-8 mM) contributed to the cell wall collapse of most samples except for those with high lignin contents and high crystallinity. Cell wall collapse contributed to the formation of 10- to 50-nm pores and not only increased the monolayer saturation amount of adsorbed cellulase about 3-3.6 times but also increased the cellulase adsorption rate (D(e)/r(2)) about 160-880 times. Moreover, cellulose conversion at 72 h was also increased 8.7-21.5% by Tween 20 treatment. On the other hand, the adsorption of Tween 20 on Avicel (microcrystalline cellulose) hindered the cellulase reaction (adsorption and saccharification). The effect of Tween 20 treatment on the crystalline part was insignificant for both lignocelluloses and Avicel. It was found that some degree of pretreatment (e.g. lignin removal) that enhances Tween 20 diffusion into samples is necessary to obtain the structural effects of Tween 20.

Activated carbon adsorption of trichloroethylene (TCE) vapor stripped from TCE-contaminated water

Ground water contaminated with trichloroethylene (TCE) used in electronic, electric, dry cleaning and the like industries is often treated by air-stripping. In this treatment process, TCE in its vapor form is stripped from ground water by air stream and sometimes emitted into the atmosphere without any additional treatments. Activated carbon adsorption is one of the practical and useful processes for recovering the TCE vapor from the exhaust air stream. However, adsorption of the TCE vapor from the stripping air stream onto activated carbons is not so simple as that from dry air, since in the exhaust air stream the TCE vapor coexists with water vapor with relatively high concentrations. The understanding of the adsorption characteristics of the TCE vapor to be adsorbed on activated carbon in the water vapor-coexisting system is essential for successfully designing and operating the TCE recovery process. In this work, the adsorption equilibrium relations of the TCE vapor adsorption on activated carbons were elucidated as a function of various relative humidity. Activated carbon fibers (ACFs) were used as model activated carbon. The adsorption equilibrium relations were studied by the column adsorption method. The adsorption isotherms of TCE vapor adsorbed on sample ACFs were successfully correlated by the Dubinin-Radushkevich equation for both cases with and without coexistent water vapor. No effects of coexistent water vapor were found on the limiting adsorption volume. However, the adsorption characteristic energy was significantly reduced by the coexistence of water vapor and its reduction was successfully correlated with the equilibrium amount of water vapor adsorbed under the dynamic condition.

A predictive model of long-term stability after biomanipulation of shallow lakes.

Abstract The eutrophication of lakes causes serious problems, such as water-bloom consisting of the harmful blue-green algae. To prevent an unusual degree of growth of phytoplankton, various restoration methods have been tried. “Biomanipulation”, which uses zooplankton to prey on the phytoplankton, is a promising method because it can, in principle, create a desirable ecosystem. However, there are many equivocal points in the long-term stability of a newly developed ecosystem after biomanipulations. The fate prediction of a water ecosystem using a lake mathematical model is thus essential for implementing biomanipulations. There remain, however, many uncertain points in the dynamic parameters of the lake models, especially the parameters concerned with zooplankton and fish. In this study, we established a lake mathematical model based on the carbon, nitrogen and phosphorus flows among the biotic and abiotic substances in a water ecosystem. In this model, two types of phytoplankton (non blue-green algae and blue-green algae), three types of zooplankton (rotatoria, cladocera and copepoda), planktivorous fish (crucian carp), detritus and dissolved matters were considered. The dynamic parameters were estimated with a set membership estimation algorithm using random scanning based on mesocosm experiments, which can provide more rigid data than actual lake observations can. The model calculations showed good agreement with the observation data for both the non-filamentous blue-green algae dominant case and the filamentous blue-green algae dominant case. Using this model, we calculated the long-term stability of the effects of biomanipulations in a hypothetical lake. The calculation results clarified the blue-green algal species specificity in the long-term effects of biomanipulations. In the non-filamentous blue-green algal dominant case, the long-term stable suppression of algal growth was predicted under a certain threshold fish biomass, while in the filamentous blue-green algal dominant case, the suppression was not sustainable even in a no-fish-coexisting series. Model simulation is very important to the design of biomanipulations, and the model proposed in this study is suitable for this purpose.