Hydrodynamics and mass transfer of a U-tube bioreactor were studied by measuring gas holdup, bubble diameter and intrinsic liquid side mass transfer coefficients. Gas holdup and bubble diameter were measured at three different points vertically in the downcomer and the riser respectively using an optical fiber two-phase flow meter. The results were well correlated by the following equations
U_Gd/ε_d=0.9(U_Gd+U_Ld)-0.25
U_Gr/ε_r=0.97(U_Gr+U_Lr)-0.22
B_z=7.69exp(-0.43U_L) (atmospheric pressure/pressure at water depth Zm)
Intrinsic liquid side mass transfer coefficients were measured in 4 zones of U-tube bioreactor (the gas dispersion zone and the bubbly flow zone in the downcomer, the bottom of the basin and the riser) using the chemical method of sulfite oxidation.
It was verified that the hydrodynamic and mass transfer data obtained using the chemical method of sulfite oxidation were applicable to a full scale U-tube bioreactor.

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Organophosphoric acid triesters (OPE) in various water sample at Osaka North Port Sea-Based Solid Waste Disposal Site were examined, to reveal the relation between the change of OPE concentration and the situation of waste disposal. OPE concentration rose suddenly by solid waste disposal into remained sea-surface directly (sea-surface disposal), and stopped rising on a certain level. TCEP and TCPP showed high concentration in OPE, the max of concentration of TCEP was over 30 μg·l^-1. OPE concentration decreased as the interruption of sea-surface disposal. Major source of OPE were the combustible waste such as plastics or fibers which mingled with the incombustible waste which was permitted reclamation into this disposal site. Behavior of OPE concentration was about the same as water pollution index such as BOD or COD in both of the water inside of disposal site and the surrounding seawater.

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The objective of this study is to obtain the fundamental knowledge for construction and management of tidal flats. An artificially constructed tidal flat was compared with a natural one in terms of physico-chemical and biological structures and biodegradability of organic carbon in soil. The results obtained were as follows :
1) Contents of silt and organic carbon in natural tidal flat were higher than those in artificially constructed one. Natural tidal flat was under aerobic condition only from surface to 2cm in depth, while under anaerobic condition below 2cm in depth. On the other hand, artificially constructed tidal flat was under aerobic condition in all the depths.
2) Based on water table variation during low and high tides, thickness of water-penetrable layer from surface in natural and artificially constructed tidal flat was estimated to be 2 and 9cm, respectively. This suggests that artificially constructed tidal flat had a wide water-penetrable zone compared to natural one.
3) Number of bacteria in soil surface (0 to 2cm in depth) in natural tidal flat was seven times higher than that in artificially consturcted one. Little vertical variation in number of bacteria was observed in both tidal flats.
4) Biomass of macrobenthos in natural tidal flat was 1.4 times higher than that in artificially constructed one. Different dominant specied were observed ; Polychaeta in natural tidal flat and Bivalve, Mollusca in artificially consturcted one.
5) Bacterial activity in natural tidal flat was higher in surface layer (0 to 2cm in depth) and significantly decreased with an incerasc in soil depth. On the other hand, a slight vertical decrease in bacterial activity was observed in artificially constructed tidal flat. Finally, compared with each tidal flat, bacterial activity in surface layer (0 to 2cm in depth) was high in natural tidal flat. On the contrary, in layer deeper than 2cm, artificially constructed tidal flat showed high bacterial activity.

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Quantitative sampling of sessile animals and monitoring of water quality in Dokai Bay, northern Kyushu, Japan, were carried out from 1991 to '92 for four times to evaluate the water condition in the bay, Kitakyushu heavy and chemical industry area.
In this study, seventy four species of sessile animals ware collected, which include Mytilus galloprovincialis, Limnoperna fortunei, Crassostrea gigas, Mytilopsis sallei, Balanus amphitrite, Balanus trigonus, Balanus eburneus, Ciona intestinalis, and Styela plicata. These nine reprentative species in the bay showed characteristic distribution and seasonal occurrence patterns. We noted eight immigrated species of sessile animals including an ascidian Polyandrocarpa zorritensis recorded first in Japanese coastal water.
Eutrophic level of water in Dokai Bay was classified according to the occurrence of the sessile animals in the bay. Water conditions of the inner most and central parts of the bay were classified as hyper eutrophic level, and those of the bay mouth were at intemediate one between hyper eutrophic and eutrophic levels. We suggest that six dominant species, including a mussel M. galloprovincialis, are useful as biological indicator organisms of hyper eutrophic level of coastal water.

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A continious flow method for measurement of organic substances (OS) in water has been developed on the chemiluminescent (CL) reaction between organic subustances and hydorgen peroxide in the presence of formaldehyde in alkaline solution. This CL method was characterized the CL intensity of polynucleated compounds were greater compared with saturated straightchain compounds (saturayed alcohol, acetic acid). The limit of detection for humic acid (HA) was 50 ppb (w/w) and the relative standard deviation for six measurements of 1.0 ppm (w/w) of HA was 1.6%. Cations such as Na⁺, K⁺, Mg²⁺ and Fe³⁺ and anions such as PO₄^3-, NO₃^-, CO₃^2-, SO₄^2-, Cl^- and Y^- (NaEDTA) did not interfere with the detemination of HA. Addition of Mn (II) enhanced the CL intensity. Three results measured by CL, COD_Cr, TOC methods for natural water samples were in good agreement. The correlation coefficient of CL intensity to TOC and COD_Cr were 0.85 and 0.81, respectively.

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For a reclamation system of ultra pure water, which is used for cleaning wafers in semiconductor manufacturings, we investigated the degradation characteristics of total organic carbon (TOC) in a UV-C oxidation pilot plant accompanied by hydrogen peroxide. By comparing the degradation rates of methanol, acetone and isopropyl alcohol (IPA) in a batch reactor, the TOC degradation rate of methanol was the fastest, and acetone exhibited almost the same rate as IPA.
Acetone was selected as a source of TOC, and its intial reaction rate was determined to be 0.7th order in terms of TOC concentration in the range of 0.5-2mg-C·l^-1 for TOC and 10-60ppm for hydrogen peroxide. The degradation-rate constant was observed to be the largest when hydrogen-peroxide concentration was 10-14ppm under the conditions studied. The overall degradation rate was simulated to be 0.5th order, including the high conversion of 0.9.
The rate constant was proportional to the UV output, and the different effect of internal light filtering was caused by hydrogen peroxide when number of lamps was changed.

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The removal of intermittently applied micropollutants in biological activated carbon (BAC) and sandfilter saturated by natural organic carbon (NOM) removal was examined. Bromophenol and phenol were used as target compounds for the removal of micropollutants such as pesticides. 200μg·l^-1 (0.033mg·g^-1 activated carbon) of bromophenol and phenol were independently applied to the BAC columns which have previously been used for 6-months and 20-months, and a sandfilter being used for 6-months. The 20-months-used BAC has reached breakthrough levels already.
The used BAC columns could remove almost all of the added bromophenol by adsorption. Sandfilter could remove micropollutants by biodegradation, but could not remove bromophonol applied. Phenol with lower adsorbability than bromophenol was also removed completely by BAC used for 20-months.
These results suggest that intermittently applied pesticides with similar adsorbabilities as phenol and bromophenol may be removed by used BAC which has reached breakthrough levels.

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