The effect of sludge retention time (SRT) on chemical and biological leaching of heavy metals from anaerobically digested sewage sludge was investigated by using afill and draw reactor. The reactor was operated at SRTs of 0.75, 1, 1.5 and 3 days. Cu was effectively eluted in the biological leaching than the chemical one. The optimum SRT for the removal percent of heavy metals was obtained at SRT of 1.5 days in the biological leaching: 70% of Cd, 95% of Ni, 1% of Pb, 5% of Cr, 50% of Cu, 95% of Mn and 70% of Zn.
Metal forms in sludge were studied by a sequential selective extraction method. The major form of Cu in the sludge was sulfide. Cu was not eluted by the chemical leaching but eluted by the biological one. Then, the elutional mechanism of Cu from CuS was investigated by batch experiments. Elution of Cu was not carried out by the decrease of pH to 3. However, the addition of ferric sulfate or the inoculation of Thiobacillus ferrooxidans resulted in about 60% of elution

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Several Leaching Tests were applied to incinerated ashes, melted slags and their re-products of sewage sludge for investigating their release characteristics.
It was found that final pH after leaching tests was affected by major components of samples, such as CaO, K₂O, MgO and Na₂O, and also affected by CO₂condition during leaching test periods. The lower the final pH of leachates after leaching tests for incinerated ashes became, the higher the As and Se concentrations were observed. The concentration of other heavy metals in leachateswas also measured and found to be very low. The 10 kinds of re-products made from incinerated ashesand melted slags by sintering, cement consolidation, crystallization and so on were examined by several leaching tests. The release of heavy metals from re-products was found to be much lower than those of raw materials.

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A new activated sludge process which produces no excess sludge has been developed and operated successfully in a full-scale plant. The process is composed of ozonation stage and biological treatment stage. Ozone treatment enhances biological degradation of activated sludge, which is decomposed in a subsequent biological treatment. Sludge is mineralized by the recirculation between the stages. The process has been eliminating excess sludge completely for more than one and half years. The MLVSS concentration was kept about 4, 000mg/L consistently without withdrawing excess sludge. The accumulation of inert materials in the activated sludge was not observed for both inactive organics and inorganic substances, such as Fe, Al and SiO2. The inorganic substances contained in the influent water was thought to be solubilized through the treatment. The ratio of MLVSS to MLSS decreased slightly at initial phase of operation, and was kept constant afterward. The acceleration test was carried out to clarify whether inactive organics were built up in a long term operation. It was verified that the inactive organics will not be accumulated in the activated sludge for more than 7 years.

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Thermophilic oxic process was applied to treat the dredged sedimentary mud of lakes and river which contain approximately 15% of organic materials. Organic wastes such as waste food oil and rice bran were added as an energy source. Cedar chips were added as a media to adjust moisture content. Physical and chemical characteristics of mixture after the treatment of thermophilic oxic process indicate that it became a good soil conditioner for growth of the plants. Compared with conventional natural land drying and dumping disposal method, it can save space and time, prevents odor production, make no worrisome about secondary pollution to environments.

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Thermophilic Contact Oxidation Process is suited for the treatment of high concentration wastewater. The mechanism used here is as follows. Wastewater penetrates into wood chips, which are used as media.Air is supplied to ensure aerobic conditions.The system is operated at around 50°C for high performance of the microorganisms.Sludge decomposition was conducted using this process.
Operating conditions were as follows.The reactor was operated in the batch mode with 4% concentrated sludge being fed everyday. The loading was 0.9 kg as C/m³/d.
Approximately 90% of the carbon was released as CO₂ for 80 days.Thus, this process shows promise in the area of sludge treatment and disposal. Half of the nitrogen was released as NH₃, and 40% of nitrogen accumulated in the reactor was converted to NH₃.
Relationship between the moisture content of the chips and removal rate was also examined. It showed that higher moisture content reduced the lag time at start-up, and that it improved the removal rate.

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The remediation technologies of soil venting and groundwater extraction were applied to repair the volcano ash contaminated with trichloroethylene. At first taking account of the areal distribution of vaporized trichloroethylene obtained in surface soil gas of a firm, fourteen borings were achieved, and revealed that the maximum concentration in soil reached 138 mg/kg at the depth of 46m, and the groundwater concentration of 294 mg/l at the same location. In particular the highly residual part of trichloroethylene is standing over both in vadose and groundwater zones, hence the soil venting was employed for the vadose zone remediation with pumping the groundwater up. The remediation operation resulted in removing the trichloroethylene amounts of 472 kg by soil venting and 1764 kg by groundwater extraction during the period of 27700 hours (1154 days). In addition it appears that at the initial stage of the remediation, the soil venting is much prominent in the removal rate of trichloroethylene at one order as high as the groundwater extraction, however, the remediation progression is going to reverse the removal rates of both technologies. This is because the existing form of trichloroethylene has changed with the time passage of the remediation. It is of great importance to keep the flexible operation in changing the remediation technologies, corresponding to the transformation of the contaminant existing form in subsurface environment.

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The Effects of plastic compounds contained in municipal solids waste on unburned carbon content of fly ash were investigated using small-scale fluidized bed type incinerator. To establish the quantitative influences of plastic on combustion, synthetic waste was prepared. According to the results, the HDPE and PVC may increase the unburned carbon content of fly ash that needs high temperature over 450°C to be oxidized (carbon type II), but little increment was observed on the unburned carbon content oxidized at the temperature lower than 450°C (carbon type I). The ABS, however, may have potential to increase the both types of unburned carbon content. The carbon content oxidized at low temperature, shows higher correlation with carbon monoxide and chlorobenzene concentration of emission gas from secondary combustion chamber than that at high temperature.

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Effects of the Global Warming on water resources systems have to be studied both to water demand system and water supply system. Up to this time, many studies were performed only for the supply system. But water demand system is also affected directly or indirectly. The change of water consumption alters a design maximum water consumption and a design intake rate. This matter changes not only the water source facility system but also the reliability of water supply. Thus the influences on water demand system by Global Warming are very serious. In this paper, we investigate a relationship between temperature and water consumption. Through a study of Temperature-Demand curve defined in this paper, we prove that their relationship is quadratic. Analysis of the temperature distribution reveals that there are some regional characteristics with regard to average temperature. Finally we propose a model to estimate water demandunder several scenarios and evaluate the change rate of water demand from present by the Global Warming.

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The numerical model for 3 dimensional atmospheric boundary layer was developed using hydrostatic, momentum and heat transport equations with boundary-fitted curvilinear coordinate along the shore line.The model was applied to Osaka Bay area for prediction of the sea and land breezes.The horizontal domain covers 100km×100km, and vertical height is 2600m. The simulations were carried out using the three different mesh grids. One was the mesh grid fitted to shore line (BFC) and others were the coarse (same mesh as BFC) and the fine mesh grid with the Cartesian coordinate (CMG; FMG). Both BFC and FMG results agreed reasonably but CMG results were some different. The results showed that boundary-fitted method could correctly predict in spite of the relatively coarse mesh grid and consume only one-forth the computer time needed for FMG

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For satellite remote sensing of red tides, a radiative transfer model for a coupled atmosphere-ocean system was developed to estimate upward flux of radiation from the polluted sea surface.Size distribution and the complex index of refraction of two kinds of red tide algae (Skeletonema costatum and Heterosigma akashiwo) were measured in batch cultures. The equation of radiative transfer in the coupled atmosphere-ocean system was solved by using Delta-P3 approximation method.Upward flux of radiation from the polluted sea surface which contained only the red tide algae decreased with the inclease of algae concentration.Whereas, in case of the sea which contained detritus in addition to the red tide algae, the upward flux had a peak at the wavelength of yellow region.It is, thus, important to determine the concentration and optical properties of detritus for the red tide remote sensing.Ratio of the upward flux at the wavelength of 410nm to one at 560nm decreased with the algae concentration.It is, then, possible to determine the red tide algae concentration by using the ratio of upward flux in satellite remote sensing.

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Experiments on a proposed dual-media filterwere conducted to investigate the effect of sand size on its perfomance in direct filtration with coagulation for secondary wastewater effluent.Aluminum sulfate was used as a coagulant to remove soluble substances and improve turbidity removal.
The results obtained are summerized as follows:(1) The over-all removal efficiency of the filter for turbidity, color and phosphate did not change too much with sand size at the filtration rate of 120m/d, but decreased with an increase in sand size at 240m/d and over.(2) On condition that the criteria for the limiting head loss and for the limiting filtrate turbidity were 3m and 5mg/l, respectively, the length of the filter run depended on the head loss limit regardless of the filtration rate in the case of a sand size of 0.59-0.71mm. In the case of sand size larger than 0.85-1.00mm, it depended on the head loss limit at 120m/d and on the filtrate concentration limit at 240m/d and over.(3) The optimum sand sizes were larger than 1.00-1.20mm at 120m/d and 0.71-0.85mm at 240m/d and over.(4) The reduction of porosity with specific deposit (mass of deposit/unit filter volume) did not change too much regardless of sand size, but became smaller with an increase in filtration rate.

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The dynamics of spatial distribution of particulate components in mixed population biofilms was investigated using lμm fluorescent microparticles as tracer. Shifts of the tracer bead spatial distribution in the biofilm were measured by sectioning the biofilm with a microslicer and were compared with model simulations to evaluate the growthadvection concept in the existing biofilm models. The tracer beads could traverse throughout a 360 μm thick biofilm within 23 minutes, could be attributed to advective transport via water channels and pores. The release of the entrapped beads were much slower than predicted by a one dimensional model due to spatial and temporal changes in cell density in the biofilm. This evidence implied that cell growth and advection was not balanced due to the presence of biofilm heterogeneity (e. g., pores and voids). Three dimensional observation by a confocal scanning laser microscope clearly indicated that the biofilm consisted of semicountiguous base film and relatively high thickness variation of loose surface film. The substratum was not uniformly covered by the biofilm and cell-free spaces and voids were observed near the substratum. This suggested that the pores, voids and cell-free spaces in the biofilm were firstly filled with growing biomass, thereafter displacement of the tracer beads took place once the cell density reached certain levels. Model assumptions of constant cell density and a continuum concept (flat biomass) are clearly over simplified and should be revised. It was concluded that microbial population dynamics in the biofilm can be determined by not only microbial growth kinetics and physiology, but also by the biofilm structure and growth pattern. One dimensional approach (modeling) is, therefore, adequate to predict biofilm accumulation and its performance, but inadequate to accurately describe the microbial population dynamics in the biofilm.

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The adsorption and bioregeneration of biological activated carbon (BAC) were investigated using denitrifying fluidized bed reactors. Laboratory scale column packed with granular activated carbon (GAC) and artificial light aggregate (ALA) were fed with nitrate and saccharose in various modes. Saccharose was fed as a single carbon source and hydrogen donor for denitrifying bacteria. The empty bed contact time (EBCT) of the continuous feed experiments was 40 minutes. Adsorption capacity for BAC were 73.7 to 71.6% of that for GAC, and adsorption rate for BAC was 30.4% of that for GAC. The amount of bioregeneration for BAC was higher than that of desorption calculated from adsorption isotherm. The adsorption isotherm is not as same as desorption isotherm if the bulk concentration is lower than 30mg/L.

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Batch experiments on activated carbon adsorption of background organics of unknown composition were conducted. A few specific characteristics of the adsorption equilibria, such as the dependence of the overall isotherms on the overall initial concentrations, were demonstrated. Accordingly, a new approach was developed to mathematically describe the overall adsorption isotherms. This method consists of an overall adsorption isotherm expression derived from the ideal adsorbed solution theory (IAST) and a technique of fractionating the background organics into a multicomponent mixture in terms of the adsorptive strength described by the Freundlich parameters. Once the composition was determined by fitting the calculated overall isotherms to experimental data, the distribution of organics in both the liquid and the solid phases was calculated, and its relationship with the characteristic behavior of the overall adsorption isotherms was discussed.

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Photocatalytic degradation of phenol and inactivation of phage Qβ wereinvestigated in aqueous solution using a batch scale reactor with immobilized TiO₂ catalyst. Phenol was degraded and Qβ was inactivated photocatalytically under black light irradiation. The reaction of phenol degradation followed the Langmuir-Hinshellwood kinetics in the range of 0.1-10mg/1., while the inactivation of Qβ followed first-order kinetics apparently, in the range of 2.5×10⁴-3×10⁶ pfu/ml. Results from the comparative studies using TiO₂ slurry also showed the same characteristics of the reaction kinetics. Under germicidal light irradiation, no noticeable difference was observed in Qβ inactivation between with and without immobilized TiO₂ at the light intensity of 0.6×10^-3 W/cm². However, in the case of phenol degradation with germicidal lamp, photocatalytic effect was distinguished at the relative low intensity of germicidal light (0.46-0.88×10^-3W/cm²).

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The waste water reclamation system using a rotating membrane UF module, has beenstudied by adding a powdered activated carbon to a biological treatment process to remove the organic colored matter.
In this system, the powdered activated carbon dosage of 50 mg/l, and retention time of 4.5 hours, have been required to stably obtain a treated water with the color of less than 5 degrees.
It was found that the activated sludge filterability could be improved by adding the powdered activated carbon and the rotating membrane UF module could operate at a permeation flux of 1.0m³/m² d for about one and half years.

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Effect of turbulence of water on the performance of hollowfiber membrane modules wereinvestigated under both steady flow and oscillating flow conditions. Hollowfiber membrane module end of the fiber fixed to a plate and with the other side kept free in flow, so that it resembles aquatic plants.Two open channels, one is for steady flow condition and theother is for oscillatory flow condition, were prepared, in which the membrane modules were submerged and suspended from the top. Velocity and turbulence near the modules was measuredby a Laser Doppler Velocimeter. Kaoline was mixed in the channel water and increase of filtration registance of membrane was measured in both of the conditions of flow. The increase of the registance was slower in higher turbulence condition, which suggests the importance of turbulence of water for removing accumulated particles from membrane under both steady flow and oscillating flow conditions.

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Low pressure reverse osmosis (LPRO) is considered as a possible tertiary treatment process providing good water quality, high permeation of water and high rejection of solutes. It is very important separation process of not only inorganic substances as calcium and chloride but also organic substances as recalcitrant substances including aromatic compounds. The development of new-generation LPRO as thin film composite membranes has provided the possibility to separate substances selectively under lower operating pressures than those obtained with the traditional ones. However, little information is obtained on the operation of the LPRO in separating organic and inorganic solutes under very low prerssure.
In this research, the LPRO experiments were made with solutions of organic substances in different pH levels. The experimental results showed that the solute separation in LPRO depends on molecular weight, pH and pKa in many cases.

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Pseudomonas putida KN1 is a phenol-utilizing bacterium, of which phenol hydroxylase (PH) capable of decomposing TCE is produced inducibly by phenol. After determining a region necessary for PH production, an insertion of the tac promoter in front of the PH gene in the chromosome was carried out by using homologous recombination. Although the modified strain, P. putida KN1-10A, constitutively degraded TCE, the TCE degradation rate of the modified strain was very low comparing to that of the parent strain. The strength of the native promoter induced by phenol and the tac promoter were compared each other by using luxAB of Vibrio harveyi as a reporter gene. Results showed that the tac promoter led a stronger expression than the native promoter. Accordingly it was suggested that more PH was produced in P. putida KN1-10A than P. putida KN1. Thus other factors affecting TCE degradation rate were shown to be exist. TCE transport can be a rate limiting step on TCE degradation by P. putida KN1-10A.

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Reuse of treated wastewater has been generalized especially in urban area. Under this situation, water quality of reclaimed wastewater is requiring new standard on health related microorganisms. Actual pathogenic microorganisms have been interested by hygienists and sanitary engineers. However, another important attention should be taken for opportunistic infection, because an unspecified number of people including handicapped persons in health are eventually exposed to water born opportunistically infeztious microorganisms.
In this paper, the authors present new detection method of sewage Legionella pneumophila, which is an important waterborne opportunistic-infection bacteria and causes legionnaire disease. Polymerase chain reaction (PCR) and DNA-DNA hybridization methods were employed to detect L. pneumophila and PCR method was improved to be applied to quantitative detection of L. pneumophila. The results from PCR-DNA hybridization test show the possibility that L. pneumophila survives through secondary sewage treatment and disinfection process. For sewage sample, conventional selective media method for L. pneumophila are not available. The experimental data of PCR-MPN for L. pneumophila shows good correlation to the enumeration data obtained by fluorescence stained direct count of this bacteria.

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From the standpoint of improving biological wastewater treatments by biochemical and genetic methods, the biodegradation and dehalogenation of haloaromatic pollutants were investigated. The crude enzyme extracted from 2, 4-D (2, 4-Dichlorophenoxyacetate) degrading strain was effective for the dehalogenation of 2-halo acid, especially 2-Chloropropionate (DL2-CPA). Based on the activity staining of this crude enzyme extract, it was found that only one dehalogenase was produced in this 2, 4-D degrading strain. The 2-halo acid dehalogenase was purified using FPLC, and it exhibited maximum activity at 45-50°C and pH 9-10, respectively. This enzyme had a molecukar weight of 68.5kDa and appeared to be composed of two identical subunits of 34kDa. Enzymatic activity of this dehalogenase was only detected with 2-halo acid which had carbons less than three, such as Bromoacetate, Iodoacetate, 2, 3-Dichloropropionate, DL-2-CPA, but no dehalogenation was detected for haloaromatic substrates, such as 2, 4-D or MCPA (4-Chloro-2-methylphenoxyacetate).

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White Rot Fungus Phanerochaete chrysosporium was immobilized in polyetheleneglycol (PEG) gel and on nylon, aspen chips and polyuretane foam in shallow stationary cultures. And the polyurethane foam was found to be the best carrier of P. chrysosporium according to the results of extracellilar enzymes {lignin perowddase (LiP) and manganese peroxidase (MnP)} production and the azo dye decolorization rate. The behaviors of P. chrysosporium immobilized on polyuretane foam was also investigated in 900mL batch reactors in carbon-limited media with different pH (pH5, pH6 and pH7). The LiP and MnP production was obtained under pH5 and pH6, and the mixture of three kinds of azo dyes were also decolorized simultaneously. No LP and little MnP production was detected under pH7, and the azo dye decolorization rate was poor, either. The P. chrysosporium immobilized on aspen chips was inoculated in heavy oil contaminated soils, and the removal rates of about 20% was obtained in 2 weeks.

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In a thermophilically-grown anaerobic sludge consortium acetate degradation can be performed either by acetate splitting reaction by acetate-utilizing methanogens (A-MPB), or by a symbiosis between acetate-oxidizing bacteria (AOB) and hydrogen-utilizing methanogens (H-MPB). The contribution of acetate consumption via hydrogen formation by the symbiosis between AOB and H-MPB was experimentally estimated using a sludge consortium grown in a thermophilic (55°C) UASB reactor operated over 20 months on a mixture of sucrose and volatile fatty acids. Acetate-fed and H2/CO2-fed methanogenic activities of the retained sludge increased with increasing vial-test temperature, exhibiting optima at 65°C.
Acetate degradation vial tests were conducted at 45, 55 and 65°C by varying hydrogen partial pr essure of headspace of individual vials so as to arbitrarily set at different ΔG' values for acetate oxidizing (hydrogen forming) reaction. Acetoclastic cleavage by A-MPB entirely dominated methanogenesis at 45°C At higher temperatures the symbiotic methanogenesis through hydrogen formation became prominent: electron distribution to the symbiotic methanogenesis was accounted for by 42% at 55°C, and 74% at 65°C.These results suggest that the syntrophic association of AOB and H-MPB becomes significant in acetate conversion to methane under thermophilic conditions.

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The ecotoxicological potential of 18 industrial effluents and 2 sewage effluents in Toyama Prefecture was assessed by using 5 small-scale bioassays (Microtox test, Daphnia magna immobilization test, freshwater crustacean immobilization test Thmnotoxkitf, Hydra attenuata acute test and Selenastrum capricornutum growth inhibition test). Algal assay and hydra acute sublethal assay had the most sensitive detection capacity and showed positive results out of 80% and 60% effluents tested, respectively. The comparison of 6 metal bioassay results and measured concentrations in effluents suggested the significant contribution of two metals (Zn²⁺, Cu²⁺) to the toxicity of effluent from surface processing factory. This suggestion was supported by the results of detoxification experiments with chelating agent. Other factors contributing effluent toxicity were found to be pH and volatile matters. By integrating the results of 5 bioassay in each effluents, the relative ecotoxicological potencies were compared. Finally, the comparison of toxic loading (potency×flow) showed the relatively high contributions from several large dischargers to the aquatic environment.

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The main purpose of this study is to evaluate dietary intake of heavy metals by Japanese based on the environmental monitoring data and to analyze their accumulation in human tissues. A compartment model was developed and heavy metals concentration in human tissues were used for evaluation of Japanese health risks.
The results obtained under the limits considered can be summarized as follows;
1) Rice and marine products are the largest dietary intake pathways of both Pb and Cd, and over 80% of those metals is supplied with domestic foods. No larger than 20% of those metals is supplied from foreign countries though Japanese depend about 70% foods on the abroads.
2) The compartment model was proposed and examined for evaluating metabolism of heavy metals in human body.
3) The present Pb concentration level in Japanese foods is enough low and no adverse health effects are expected on Japanese.
4) The Cd concentration level also causes no adverse health effects. However, Cd in kidney may reach the critical concentration to cause the renal dysfunction within 10 years, if people in high-risk zones continue to eat 1.0 ppm of rice produced there.
5) Continuous monitoring over 100 years is essential to evaluate human health risks caused by Pb and Cd.

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The following two novel devices, pH microelectrode and glucose-enzyme microelectrode were originally fabricated in this study, to clarify pH and substrate in situ profiles within anaerobically grown microbial-aggregates. The glucose microsensor consists of double glass-tips in order to eliminate an effect of pH, and has a measurement range of 0-500 mg/L. The inner glass-tip of 10 μm diameter was coated with glucose oxidase and covered with the outer glass-tip of 30μm diameter. The pH microsensor has a 10 μm diameter of glass-tip which was filled with ion selective membrane liquid, and covers the pH range of 4-10.
Both microelectrodes were applied to anaerobic granular sludge having a diameter of approximately 2 mm harvested from an UASB (upflow anaerobic sludge blanket) reactor treating an artificial wastewater. It proved that the pH profile in the granule tended to firstly decrease toward granule depth, and then to increase after attaining a minimum point at which the glucose concentration decreased to around zero. With higher glucose concentration in the bulk liquid, pH gradient within granules became steeper and the minimum pH value dropped more significantly.
A simple mathematical model consisting of diffusion and consumption of substrate was developedto estimate substrate profiles within granule. The model could simulate well thepH and glucose profiles measured by the microelectrodes. The results of measurements and simulations suggests that acetogenic bacteria should dominate near the granule surface, on the other hand methanogenic bacteria should be dominate inside of the granule.

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Two laboratory-scale biological filters were operated to investigate the nitrateremoval by sulfur oxidizing denitrifiers under different influent alkalinity conditions. The raw water containing nitrate (20 mg-N/1) and thiosulfate was supplied to the top of 90cm column bed filled with granular anthracites at 20°C.The downward velocity of filtration was 4m/day. High nitrite concentration was observed in low alkalinity cases, although nitrate was completely reduced to nitrite at the top part of the filter for each case. The accumulation seemed to be due toinhibitory effect by pH drop along the filter. Monitoring data of pH and nitrite profiles along the column indicated that complete denitrification was maintained when the pH in the filter was kept at higher than 7.2. After the continuous operation we divided the filter bed into 4 parts along the column. The collected biomass was used for denitrification activity test and quinone profile analysis. Denitrification activities of the attached biomass were different at the depth along the column. However, all quinone profile of the samples were almost same, which indicated that the most predominant quinone was Q-8 and that they had a little menaquinones.

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Influence of sulfide on the activities of sulfate-reducing bacteria (SRB) and hydrogenproducing proton-reducing bacteria (PRB) in anaerobic degradation of palmitate and propionate was investigated using four anaerobic sludge consortia (referred to as R1 through R4) derived from different sources.Four sludge consortia were categorized as follows according to the type of reactor and the level of sulfide for sludge cultivation: R1 as CSTR-low sulfide, R2 as CSTR-high sulfide, R3 as UASB-low sulfide, and R4 as UASB-high sulfide.
As for R1 sludge (CSTR, low sulfide), palmitate degradation activity (Pal-DA) by a symbiosis between palmitate-degrading PRB (Pal-PRB) and hydrogen-scavenging SRB (H-SRB) was 2.6 times as large as that by palmitate-oxidizing SRB (Pal-SRB).Pal-DA of R2 sludge (CSTR, high sulfide) by the symbiosis of Pal-SRB with H-SRB was only one-fifth of that of R1 sludge.As for R3 sludge (UASB, low sulfide), a symbiosis between PRB and hydrogen-scavenging methanogens (H-MPB) performed the same magnitude of propionate degradation activity (Pro-DA) as propionate-oxidizing SRB (Pro-SRB) did. Pro-DA of R4 sludge (UASB, high sulfide) was entirely attributable by Pro-SRB solely.
Two distinctive patterns were observed with respect to sulfide effect on Pal-DA and Pro-DA.Highsulfide sludge consortia, R2 and R4 showed a tendency to consistently decrease Pal-DA and Pro-DA, respectively, with increasing sulfide concentration.On the contrary, Pal-DA and Pro-DA of low-sulfide sludge, R1 and R3 possessed optima around 50 mg H²S-S·l_-1, above which point both activities inhibited by sulfide in the same manner as the case of high-sulfide sludge.

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A simulation model was developed for a combined activated sludge and biofilm process which was developed to achieve nitrogen and phosphorus removal without extending the existing treatment facilities. The process consists of an A²O (anaerobic, anoxic and oxic) process and a biofilm process in the form of fluidized bed in the aerobic zone. In this process nitrification is carried out by the nitrifiers on the fluidized media and denitrification and phosphorus removal are performed by the activated sludge.
Firstly, a biofilm model was developed by modifying the components, biological processes and detachment mechanism of an existing model, using the experimental results of the fluidized bed process. Secondly, the biofilm model was incorporated into the IAWQ Activated Sludge Model No.2 with the addition of a mechanism of transferring detached biofilm to the activated sludge. The parameter values of this model were fitted using the data of a pilot plant during a period of no rainfall. The model was then evaluated with the pilot plant data for a period of rainfall.
The model developed for the combined activated sludge and biofilm process simulated the water quality of the pilot plant well. Necessary improvements were also discussed.

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The relations and effect of temperature among the sulfate reducing bacteria (SRB), poly-phosphate accumulating bacteria (PAB), denitrification bacteria (DNB) and the filamentous sulfur bacteria (FSB) were studied at 4, 20, 30 and 37°C using sludge from an anaerobic-oxic plant. The results indicated the coexistence of SRB and FSB in the sludge. Phosphate accumulated sludge tended to decrease sulfate reduction and the number of SRB, sulfide oxidizing rate and filament length tended to increase with sulfate reduction rate. Denitrification completely suppressed SRB and PAB activity over the temperature range while nitrate was present. Results from the application of the Arrhenius equation indicated that the denitrification was the the most sensitive to temperature changes, with a mean Q₁₀ value of 2.4, followed by sulfate reduction (1.84) and phosphate release (1.35).

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In this study, the slag viscosities of the basic system “SiO2-CaO-Al2O3” were measured and the effect of oxiside components on the viscosity was studied, from which an approximate viscosity formula was obtained. Also, measured values and estimated values were comparatively studied.
In addition, the reported data of the papers were analyzed and this analysis brought another formula which was more accurate and widely applicable. Then, a comparative study between the repoted data and estimated values was conducted, and equi-viscous lines on the phase diagram could be presented. From these studies, viscosity, that could only be shown on the graph in the past, can now be shown quantitatively as the estimation formula by the functions of componentsand temperature.
Lastly, we considered the two estimation formulae obtained.

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Nitrous oxide (N₂O) production by nitrification and denitrification is a subject of current concern in environmental engineering; it is a global warming gas and possibly involves in the decay of stratospheric ozone layers. Nitrification and denitriflcatin has been most extensively applied to nightsoil treatment in Japan. Accordingly, to inquire into possibilities of N₂O production in the nightsoil treatment, we operated a lab-scale reactor in a mode mimicking the SBR type high load nitrogen removal process, a prevalently used technology in the nightsoil treatment. The mode of operation features a high volume loading of nitrogen (0.8g/L/day), a high biomass concentration (15-20g VS/L), a high reactor temperature (33°C) and a short cycle (30 minutes).
The yield of N₂O-N per nitrogen removed was less than 5% under steady conditions but it reached 20% at the time nitrification rapidly improved after the accidental deterioration. Besides the reactor operation, we conducted batch tests to search for the mechanisms of the N₂O production. Results of the batch denitrification tests showed that nitrite was more prompt to emit N₂O than nitrate. The gas, however, was produced even by nitrate reduction under acidic conditions. The phenomena apparently resulted from the different pH dependency of the rate for nitrate, nitrite and nitrous oxide reduction.

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Wastewater from sludge drying process in sludge melting system contains both ammonium trogen and dissolved organic compomds in high concentrations.It also contains inhibitory organic cnoimpounds to nitrification, which are biodegradable and absorbable to granulated activated carbon (GAC). The inhibition is transitory as nitrification acdvity recovers immediately after the inhibitory compounds are removed. With combination of several pretreatment methods for concentration and extraction such as Sep-Pak C₁₈ concentration, GACex action, vacuum evaporration and liquid-liquid extracdon, and GC-MS analysis, paramethylphenol (p-cresol) is determined as a main inhibitory organic compound to nitrificahon in the wastewater. From the inhibition test with standard reagent of p-cresol, the 90% inhihibitory concentration is detennined to be 10 mg·L^-1. P-cresol is also shown to be biodegradable and absorbable to GAC, that indicates the availability of treatment with biological activated carbon (BAC).

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Our previous investigations had revealed that the gas composition of the tiny bubbles found on the Abukuma river bed were 99.8% of nitrogen._{1), 2)} In this paper, nitrification and denitrification activities of the biomass on river bed stones at swift flowing area and sediments at where the water is stagnant, were determined by batch culture, during two months from March to April 1996.
The changes of nitrogen concentration with respect to time in the batch experiments were clearly explained by the Monod model. Nitrification rate in the biomass on river bed stones and sediment depth of 0-10mm were around 120-180 and 225-400mg/m²·day, respectively. On the other hand, denitrification rate were found to be around 35 and 350mg/m²·day, respectively.
Therefore nitrification and denitrification in surface sediment is considered to be an important process for nitrogen removal.

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Chemical and biological characterization of anaerobic sediments of a eutrophic brackish lake Barato, Sapporo were performed with emphases on sulfur cycle in the sediment. Vertical distributions of sulfide compounds (FeS, FeS₂ and S⁰) were measured and related to sediment oxygen demand (SOD). The SOD was divided into biological and chemical components by using specific inhibitors. The chemical SOD was further separated by ferrous, sulfide and manganous demands. The experimental results indicated that SOD ranged 0.3-1.4 mgO₂/cm³ and the major component was ferrous demand accounting for 29-75%(avg.=55.4%). The content of sulfide compounds accounted for 1-2% of total dry weight of the sediment, which was responsible for about 40-50% of total SOD. Sulfate reduction and methane production in the sediment were limited by fatty acid (i. e., acetate) production. The addition of molybdate and chloroform to inhibit sulfate reduction and methanogenesis, respectively, gave a quantitative measure of fatty acid utilization rates by sulfate reduction and methane production. The experimental results revealed that acetate, propionate and n-butyrate accounted for approximately 60%, 25%, and 10%, respectively, of the electron donors of the sulfate reducing bacteria in this sediment. Acetate accounted for 40-60% of the electron donor of methane producing bacteria. These experimental results imply that the oxidation of sulfide, generated by microbial sulfate reduction is a key process in the biogeochemistry of brackish sediments. The detail information on the sediment of lake Barato will be useful for development of a new means to improve the overlaying water quality.

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The pollution of lake sediments by organic micropollutants has been of growing environmental concern due to their suspected long term effects on both human health and the surrounding ecosystem. In this research, in order to search the indicator organic micro-contaminant (s) which can be usable for representing the micro-organic pollution, an analytical methodology consisting of freeze-drying, soxhlet extraction with di chloromethane, concentration by rotary-evaporator, purification by Sep-pak florigil cartridge, and quantification by GC/MS was formulated and applied to the lake sediments of Akanoi Bay, Lake Biwa. With the detection of two polycyclic aromatic hydrocarbons (PAHs)(i. e., fluoranthene and pyrene) in the sediment samples, it was concluded that these two PAHs can be the candidate of the indicator contaminants. Based on the horizontal distribution of these PAHs and the particle size distribution of the sediment samples, it was furthermore considered that the river inflows into the Bay are the main pollution sources.

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Aquatic macrophytes form a “system” consisting of the macrophytes themselves and periphytons attached to them. The system has a significant role in purifying water. In this study, we evaluated such water purification functions of macrophytes-periphytons “system”, as removing nutrients of the river water prior the river flowing into a lake. Using the data obtained by a field survey and laboratory tests, we made a model of the water quality purification by macrophytes and the periphytons. As a result, we found (1) the “system” of aquatic macrophytes and periphytons play a role as “catalysis” to suspend the dissolved nutrients, and (2) a physical purification function by the aquatic macrophytes which act as a filter to remove suspended solid from the water. Also, we clarified the efficiency of these functions at the water surface.

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The iron concentration and its size fraction were investigated in 15 reservoirs which trophic levels varied from oligotrophic types to eutrophic ones. The T-Fe concentration ranged from 0.021 to 2.349 mg· 1^-1, and the average value of the concentration from the all samples (n=123) was 0. 200 mg· l^-1, The D-Fe (<0.45μm size) concentration was about 20% of T-Fe, but someti-mes appeared to be above 50% when the T-Fe concentration was relatively low. The relationship between T-Fe and Chlorophyll-a was not clear enough to obtain a specific correlation as compared with that of T-P or T-N and Chlorophyll-a. One significant factor of this scatter was the difer-ence of the iron contents between algal cell particle (0.24%) and non-algal cell particle (3. 9%).
The D-Fe (<0.45μm size) concentration showed poor relationship with DOC which was quantitative index of desolved organic matters. On the other hand, better relationship was showed with E260 or DOC/E260 value which were qualitative index of desolved organic matters.
The examination of the three fraction of iron under the size of 1.0 /μm size showed that about 20% of the iron was the size of both 1. 0-0. 45μm and 0. 45-0. 10μm, and also 60% was size of less than 0.10μm. It suggested the concentration of D-Fe must be carefully defined by the physical sieving size for the consideration of algal availability of iron.

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Degradation activity ofPseudomonaspaucimobilis which degrade the refractory organic matter in sea water effectively was examined with the original experimental plant of rock bed contact-purification. First, the performance of the experimental plant withoutP. paucimobiliswas investigated. Theexperimental plant could purify turbidity most effectively, and No-Fines concrete (NFC) is superior to ordinary concrete and tires in removing SS and DOC. Degradation activity of organic matter of NFC was estimated to be 15-26% of that of sandy beach. Next, it was found that NFC supplemented withP.paucimobilisdegraded organic matter 1.4 times as much as NFC itself did.

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Biofilms attached on permeable structures in coastal areas can purify the water.It's efficiency is dependent on mass transfer in permeable structures.Mass transfer mechanism in a permeable breakwater was studied in an experimental channel which have a permeable breakwater composed of 7.5cm-diameterstyrene-balls.
Velocity fluctuation in the permeable breakwater was measured by a Laser Doppler Velocimeter and was found to have both wave components and turbulent components. Dispersion coefficient in the breakwater was measured using a chloride-tracer method and was divided into dispersion component and diffusion component. The dispersion coefficient was expressed as the product of root-mean-square-velocity of the wave motion and the void scale while the diffusion coefficient was expressedas the product of turbulence and the void scale.

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Water pollution cased by eutrophication has been worse year after year. Conventional methods for purification of an eutrophicated water like fast filtration or flocculation cost quite high and some times they cause secondary pollution. In this paper very slow bottom-filter method is proposed for this purpose and experiments were carried out to evaluate the method. In theses experiments asand-filter and a gravel-filter were set on whole the bottom of tanks and the water in the tanks was circulated by a pump and a airliftpump through the filters.As the results, it is shown that water polluted by eutrophication can be purified thoroughly by a bottom-filter, remarkable clogging of the filters could not been observed, an airlift-pump can decrease pH to eliminate non-ionic ammonium which causes serious fishkill and the method can be expected not only to improve water quality but also sediment.

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