We analyzed the depth profiles of phosphorous and heavy metal ions (Cr, Zn, Pb, Cd, Co, Ni, and Cu), sedimentary pigments, and fossil diatoms in the sediment cores collected from Lake Sanaru in Hamamatsu, Shizuoka Prefecture, to estimate anthropogenic effects in the lake. The concentration of P and heavy metals were significantly higher in the upper parts of the cores, indicating anthropogenic inputs into the lake. We referred their concentrations in the lower parts of the cores to the background concentrations without anthropogenic effects, and estimated the excess amounts of the elements preserved in the sediment in Lake Sanaru. The concentrations of total chlorophyll a and total carotenoids were also higher in the upper parts of the cores with dramatic changes in the relative carotenoids, suggesting eutrophication accompanying abrupt alteration in algal assemblages. Analyses of fossil diatoms and Cl⁻ ion in the interstitial waters suggest an increase in the lake salinity, probably due to the construction of the Shinkawa drainage channel and a decrease in freshwater supply into the lake by urbanization of the watershed. This study demonstrates, using multi-proxies in the sediment cores, impact of anthropogenic effects on aquatic environments and the ecosystems.

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Wastewater contaminated by edible oils (lipids) is discharged from restaurants and food-processing facilities. Lipids have a very high biological oxygen demand and notably pollute public bodies of water such as rivers, lakes and seas. In general, lipids in wastewater are removed using a grease trap, however they are not completely eliminated. Consequently, lipids comtaminate public water bodies and generate oil balls in bays. Microorganisms capable of breaking down lipids would be useful for solving the problem. Thus far, there are many reports on microbial degradation of lipids, however, many problems remains in terms of practical use. In this paper, we describe the development of lipid-degrading microorganisms and issues regarding their treatment techniques and the perspective of microbial wastewater treatment, as well as the author's work.

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Radioisotopes were released by Fukushima Daiichi nuclear power plant, which was seriously damaged by the magnitude 9.0 earthquake and the tsunami that followed. To achieve the rapid capture of cesium ions and easy processing of radioactive water, a novel potassium-cobalt-hexacyanoferrate (KCo-HCFe)-impregnated fiber was prepared by radiation-induced graft polymerization and subsequent chemical modifications. Hexacyanoferrate ions were bound to vinyl benzyl trimethylammonium chloride-grafted 6-nylon fiber. Subsequently, the bound hexacyanoferrate ions were reacted with cobalt ions to form insoluble KCo-HCFe. The resultant KCo-HCFe-impregnated fiber exhibited a high affinity to cesium ions in seawater. Such fibers can be fabricated into various fiber modules suitable for the removal of cesium at sites.

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The reverse osmosis membrane (RO) is a popular instrument for desalinating seawater and quality control of RO is an essential part of the desalination industry. The critical factor for the control of RO is fouling caused by the turbidity of seawater, such as by suspended solids, soluble salts, or biological growth. To reduce turbidity, seawater is first treated with sand, film, or other substances, resulting in so-called “pretreated seawater”. The fouling potential of this pretreated seawater should be assessed quickly and accurately.
The silt density index (SDI) and the modified fouling index (MFI) are predominantly used fouling indices, however, they do not always correctly represent the fouling potential. Thus, we sampled seawater under various environmental conditions and conducted a controlled experiment. Statistically analyzing the data, we developed a new fouling index, termed “permeation index β “ which was verified to be superior to SDI. Additionally, we found that the MFI depends upon the difference in filter holders, but not SDI and β.
Customarily, SDI is measured several times a day, although environmental conditions and characteristics of pre-treated seawater are continuously measured. Thus, regression analysis was conducted with β and those measurements, which resulted in a continuous monitoring system of the fouling potential that will tell us the fouling status of RO immediately when accidental changes in seawater or environmental conditions occur.

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The transport phenomena across an ion-exchange membrane in organic solvent and in low water content were analyzed on the basis of the Donnan equilibrium and the Nernst-Planck equation of ion flux under consideration of the Fuoss ion-pair formalism, and the theoretical predictions agreed with the experimental results. The theoretical prediction clarifies that the charge effectiveness parameter (Q-value) and the ionic mobility are the function of the dielectric constant in the membrane. This theoretical treatment can be applied to “high salt condensation”, “fuel cell system using methanol (DMFC)”, “fuel cell system in low water content”, “metal recovery from waste water with organic solvent” and “ionic transport across ionic channels”.

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Utilizing the polymorphic change in the crystallization operation under a constant temperature, the generation of local supersaturation in the regions around the gas-liquid interfaces caused by minute-bubble formation was clarified. Glycine, which has three polymorphs of stable γ-form, metastable α-form, and unstable β-form at the mild crystallization temperature, was crystallized using an antisolvent method supplying N₂ minute-bubbles. At a solution temperature of 303 K, methanol as an antisolvent was mixed into the saturated glycine solution. The mixture ratio of methanol (φ _MeOH) was varied in the range of 10 - 60 vol％. While mixing methanol with the saturated glycine solution, N₂ minute-bubbles with an average bubble size of 10 μm were continuously supplied to the mixed solution using a self-supporting bubble generator, and glycine was crystallized. For comparison, glycine crystallization with no-supplying N₂ minute-bubbles was carried out using a propeller type mixer with four blades. The results indicated that : 1) at 0.5 min crystallization, β-form glycine with no-supplying N₂ minute-bubbles was crystallized predominantly at a φ _MeOH of 60 vol％, and minute-bubble supply enabled the expansion of the generation region of β-form in the φ _MeOH range of 30 - 60 vol％; 2) N₂ minute-bubble supply resulted in the inhibition of polymorphic transformation from unstable β-form to metastable α-form with t_c increase. Moreover, the supersaturation ratio of β-form (C₀/Cs_β) in the bulk liquid was determined from the solubility of β-form (Cs_β) at various φ _MeOH values and the initial concentration of glycine (C₀). Consequently, N₂ minute-bubble supply decreased C₀/Cs_β necessary for the generation of β-form to 1.7, while the crystallization of β-form with no-supplying minute-bubbles progressed mainly in the C₀/Cs_β range over 3.0.

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