Through experiments utilizing a large scale landfill model lysimeter it has been found that cover soil havethe purification capacity of organic pollutants. In the case of utilizing soil cover, as gas permeability of soil layer is lowerthan waste layer, anaerobic area in lysimeter was extended and stabilization of landfilled solid waste was late. In the caseof no cover, waste layer had a large purification capacity. In the case of foam cover (alternative daily cover), purificationcapacity of waste layer was same as at no cover

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To determine hydraulic property of solid waste materials, in situ intake rate measurements were conducted at surface of landfill. As object layers, incineration residue layers, refuse Layers, and incombustible waste layers were selected to measure. Intake rate of incineration residue decrease suddenly after infiltration started, and then rapidly reach to constant rate, so called final intake rate, within 300 to 500 sec. Refuse layer also indicates similar intake rate transition. To confirm the relationship between final intake rate and saturated hydraulic conductivity, constant head hydraulic conductivity test was carried out for the same samples brought back to laboratory in undisturbed condition. Since good agreements are identified between them, hydraulic conductivity was estimated from the rate. Determined hydraulic conductivity is 10^-4 to 10^-1cmis for incineration residue layer, 10^-2cm/s for refuse layer, and 10⁰cm/s for incombustible waste layer. For trying to investigate the influence of matric suction to the rate curve, unsaturated water movement was simulated based on Green and Ampt theory. In respect with the curve obtained from incineration residue layer, water movement may be dominated by not suction but gravity, due to the analyses which exhibit calculated curve agree well when less suction was assumed.

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Effective treatment of livestock feces and urine is required to prevent surface and ground water from being polluted. In this study, thermophilic oxic process (TOP) was applied to the treatment of swine waste. The purpose of this study is to investigate the treatment characteristics of swine waste by TOP in long-term operation. The results were summarized as follows: Though swine waste could be treated effectively until 60th day, the treatment performance was gradually declined after 60th day. 87% of carbon was converted to CO₂ on 45th day. 41% of carbon was converted to CO₂ on 85th day. It was recovered by replacing half of cedar chip by new one on 86th day. Under suitable condition of TOP, 90% of total input swine waste (40kg) and food oil (2kg) was removed in 60 days. The number of thermophilic bacteria was maintained about 10¹¹CFU·g_-1 during this period. The reason of the decline of treatment performance was considered thatthe activity of thermophilic bacteria come down due to the accumulation of some residue and deterioration of cedar chip.

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Effect of the influent total solid (TS) concentration on thermophlic methane fermentation of organic fraction of municipal solid waste (OFMSW) was investigated by using a semi-continuous flow completely-mixed reactor. The experiment was conducted at a temperature of 55°C and a constant retention time of 15 days by changing the influent TS level from 5% to 12%. The stoichiometric formula of the methane fermentation of OFMSW was identified as: C₁₇H₂₉O₁₀N+6.5H₂O→9.25CH₄+6.75CO₂+NH₄⁺ +HCO₃^-.The micro-nutrient was necessary for maintaining the reactor to be stable at the high influent TS level of 10% or more, otherwise methane fermentation tend to fail due to the accumulation of volatile fatty acid. By adding mineral nutrient to the feed, the reactor was successfully operated at the influent TS up to 12%, and no remarkable decrease in treatment performance was identified. The relationships between influent TS level and various operation parameter were determined quantitatively based on the experimental results.

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It is necessary to establish a generalized model to simulate the optimum operating condition of UASB process for controlling or predicting the actual operation. In this study, a model which was able to express unsteady growth of active and inert (decay biomass and extra cellular polymer) biomasses was developed based on the results of experiment to comprehend perpendicular distributions of biomass in UASB reactor. The developed model was demonstrated available in comparison with the experimental results. At first, the model was considered as a single layer model, and then it was developed to layered model. The single layer model could express unsteady growth of active and inert biomasses in UASB reactor. Furthermore, the layered model could also express the perpendicular distributions of biomass in UASB reactor.

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A novel multi-staged UASB (upflow anaerobic sludge blanket) reactor, which was originally developed by our research group, was applied to thermophilic treatment of a lipid-rich wastewater (dairy-milk). The reactor successfully reached a high COD loading of 35 kg COD/m³/d after 190 days operation, giving over 90% COD removal at a HRT of only 3.4 h for the influent 5000 mg COD/L, of which 50% is derived from lipid. This loading rate corresponds to two to three times as large as the maximum allowable loading rate of mesophilic conventional-type UASB reactor receiving the identical wastewater (our previousresult).
A severe deterioration of methane production occurred due to adsorption of LFA (long-chain fatty acids) to bacterial cell surfaces at the lower portion of sludge bed when the reactor temperature incidently dropped from 55°C to 45°C for a period of merely 12 hours. In order to clarify the mechanism of inhibitory effect of LFA adsorption, a separate vial-bottle activity test was conducted by using mesophilically-grown and thermophilically-grown granular sludge. Absorption of LFA caused more vital inhibition on the thermophilic sludge rather than the mesophilic sludge, due to cell lysis. Thermophilic acetate-utilizing methanogens were far more susceptible to LFA inhibition, compared with thermophilic hydrogen-utilizing methanogens.

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In watersheds, integrated water resources management becomes a key approach to meet increasing demands of residents such as avoiding water shortage and keeping landscape around streams in urban areas favorable. Reuse of treated wastewater and utilization of groundwater following its nourishment are potential measures to be taken for supplement of water supply, augmentation of stream flow rates, and so on. Requirements of the management are minimizing cost and LCE and maximizing residents' satisfaction. The GIS is a powerful and prospective supporting tool to obtain an optimal solution of water resources management in a watershed.
The objectives of this study are to develop a planning method for an optimal system of water resources utilization including reclamation recycling, and reuse in terms of LCE and cost minimum, and to apply it to the Hakata Bay watershed with water shortage, and to obtain an optimal solution for the management.
In conclusion, desalination or alternative measures, in addition to groundwater, is inevitable to avoid water shortagein this watershed. Desalination, however, has demerits of high LCE and cost, so that neap technologies to obtain alterntive water resources and to reduce water consumption are to be developed.

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Combined sewer overflows (CSOs) have made water quality of receiving water bodies, including rivers and lakes, worse year by year. A new distributed runoff simulation model of storm water and pollutants in urban sewer pipe systems, which can be used to investigate appropriate counter measures for the CSOs and evaluate the effects of the measures, is proposed. In this model, PWRI Model, which is a lumped model and was proposed by the Public Works Research Institute, Ministry of Construction, Japan, is improved to a distributed model and used to simulate pollutant runoff. SLOT Model, which can treat both open-channel and pressurized flows, is employed to simulate stormwater runoff with surcharge.
The distributed model was applied to a combined sewer pipe system with a pumping station and the applicability of the model was investigated on the basis of the comparison of simulated pollutographs and observed ones. As a result, it was pointed out that the model is very useful and practical one and can reproduce well runoff characteristics of stormwater and pollutants in combined sewer pipe systems with pumping stations.

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The water quality of forest rivers in central Hokkaido was researched to understand the runoff characteristics of nutrient loads from forest basins. Four forest rivers whose basins are contiguous to each other were surveyed simultaneously. The resultsare as follows.
1) The concentrations of nitrogen and phosphorus are high enough (0.2-0.3mgN/ I, 0.01-0.02mgP/ I) to cause eutrophication downstream.
2) In the period of storm runoff, nutrient loads were discharged in abundance from the forest basin.
3) Types of nutrients in runoff were arranged by L=C×Q=c×Qⁿ (L: specific nutrient load, C: concentration, Q: specific flow, c, n: constants). The runoff characteristic of nitrogen was WASH OUT type (n>1, concentration increases with increase of flow). The characteristic of phosphorus was the same, especially particulate phosphorus (n>2).
4) Principie component analysis of the data of water quality of four rivers suggested that the main factors that characterize the water quality of forest rivers are the condition of the surface soil layer at the forest basin and the degree of flow rate variation.

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In this study, application of geographic information system, GIS, to development of a framework for pollutant load analysis in Onga area was discussed. Total-nitrogen, total-phosphate, and chemical oxygen demand were used for analysing pollutant load. The pollutants density and/or distribution of point and non-point sources in Onga area were demonstrated by using GIS data. The concentrations of T-N and T-P in the Onga River are affected by the area ratio of paddy field to forest. The ratio of population to forest area influences COD concentrations in the Onga River.

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General methods for the biomass measurements in algal growth inhibition tests are cell counting, absorbance, and fluorescence, but a standard method is not restricted by the standard procedures. The possibilityof the different evaluation is present in the toxicity test by different biomass determinations.In this study, the toxicity of copper (Cu) and monochloramine (NH₂Cl) as reference toxic substances wereevaluated from the algal growth inhibition test using green alga Selenasturum capricornutum. To determine thebiomass changes, direct cell counting, turbidity, chlorophyll with fluorescence, and ATP methods were used andthe effective concentration of Cu and NH₂Cl were evaluated with each results. The most sensitive method of theevaluation was direct cell counting, then LOEC and EC₅₀ of Cu were 10 and 7 μg/l, and LOEC and EC₅₀ of NH₂Cl were 7 and 19 μg-Cl₂/l, respectively. Turbidity and fluorescence methods showed the same sensitivity for Cu, whereas these were not sensitive for NH₂Cl. In contrast, the sensitivity of ATP method was not good for bothtoxic substances, and the evaluated values of LOEC and EC₅₀ with ATP were several times higher than withcounting method. It is necessary to recognize that the method for biomass measurements in algal growth test hasan effect on the estimation.

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Excessive algal growth in drinking water sources like lakes and reservoirs is responsiblefor filter-clogging, undesirable taste and odor, disinfection-by-product formation and toxingeneration. Although various methods are currently being used to control algal bloom, theirsuccesses are limited. Many water utilities routinely use copper sulfate to control excessive algalgrowth. But there is a growing concern against its use mainly because it is non-specific to targetalgae and kills many non-target species. In this study, the scope of using UV-radiation to controlalgal growth was assessed using Microcystis aeruginosa and Anabena vulgaris as test species. Forboth of these species, an incident UV-dose of 450-m Ws/cm² was found to be lethal. A smaller doseof 180-m Ws/cm² prevented growth for about 7-days. It was also observed that UV-radiation onalgal extracellular products has a significant residual effect and can contribute to algal growthcontrol. The extent of residual effect depends on the UV-dose and can continue even for 7-days.

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Chromosomal aberration test was carried out to evaluate mutagenicity of organophosphoruspesticides during drinking water chlorination. Pesticides tested were fenitrothion (MEP), isofenphos, and diazinon which are P=S type;and dichlorvos (DDVP) which is P=O type.The respectiveoxygen analogs (P=O) were the major chlorination by-products of thiophosphorus (P=S) pesticides. It was found that the reaction with chlorine rather than hydrolysis was the main reason ofdecrease in oxygen analogs and DDVP in the actual drinking water supply process. Chromosomalaberration tests suggested that mutagenicity of MEP and isofenphos increase during chlorination. There was also the same variation tendency between the oxygen analog and activity inducing chromosomalaberrations of MEP after chlorination. MEP disappears by the reaction with chlorine, however, activity inducing aberrations of chlorinated water can be found. The large part of activity inducingaberrations of chlorinated MEP can be attributed to the oxygen analog. On the other hand, there wasnot a relationship between TOX and activity inducing aberrations of MEP. Weak activity inducingaberrations of diazinon was found just after chlorination and decreased gradually. Activity inducingaberrations of DDVP decreased with the decrease of DDVP itself and TOX.

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The sorption capacity of a synthetic polymer, polypropylene (PPL), and polypropylene coated with nhexane (PPL-HEX) for hydrophobic organic compounds (HOCs) was evaluated from equilibrium batch sorptionexperiments. Three polycyclic aromatic hydrocarbons (PAHs), namely, phenanthrene, fluorene and naphthalenewere used as HOCs. PAHs were quantified by the fluorescence quenching method. The effects of pH, ionicstrength, and dissolved organic matter (DOM) on the sorption were investigated. Considering sorption capacity (as measured by the conditional sorption coefficient, K_s^c) and sorption rate, PPL-HEX is the better adsorbent for PAHs than PPL. Ionic strength and pH did not have any effect on K_s^c. Neither PPL nor PPP-HEX sorb DOM, and the presence of DOM in the aqueous phase did not show any significant effect on the K_s^c for sorption of PAHs onto PPL-HEX. The main advantage of using PPL or PPL-HEX as adsorbents is that since they do notsorb DOM, target HOCs do not compete with DOM for sorption onto PPL and PPL-HEX, as opposed to sorptiononto activated carbon.

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Adsorption and desorption of asulam, a polar herbicide, on decomposed granite (DG), two sand size fractions of DG (0.212-0.425mm and 0.075-0.150mm), and two natural loam soils werestudied under both batch and transport conditions. In the batch experiments, equilibrium was obtainedwithin the first 10 minutes in the DG soils and after 36 hours in the organic matter-rich loam soils.Freundlich isotherm models best describe the measured adsorption/desorption data. Asulam adsorptionwas highly correlated with Cation Exchange Capacity (CEC) for the five soils, suggesting that both soilorganic matter and clay minerals controlled sorption. Different sorption time-dependency (kinetics) wereobserved when comparing initially non-polluted with initially already asulam-polluted soil. During thetransport (micro-column) experiments, significant differences in the shape and tailing of the breakthroughcurves and in asulam retardation were observed for the two soil types. A Two-Sites Non-Equilibrium (TNE) model was used to describe and interpret the transport measurements. Pronounced non-equilibriumsorption and transport processes in the more organic and clay-rich loam soil gave a significant tailing ofbreakthrough curves while a symmetric breakthrough was seen for the more coarse-tetured DG, probablydue to the immediate sorption equilibrium in the DG. Slightly different values of pesticide retardationfactors were obtained from the batch and transport experiments in the case of loam soil, likely due to theobserved sorption non-equilibrium, sorption non-linearity, and sorption hysteresis processes.

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Dry deposition of particulate matter, organic carbon and toxic chemical substances e. g. heavy metals, PAHs (polycyclic aromatic hydrocarbons) on urban area and their runoff were measured and compared. The measured deposition rates differed according to the shape of the sampling plate, the setting height and the sampling duration. In order to compare with the amount of runoff, we used the deposition rate obtained by the plate with very low edge placed on the ground during no precipitation period. The runoff amounts of toxic chemical substances varied with the discharge and suspended solids (SS) concentration, whereas their contents in particulate matter were inversely proportional to SS concentrations. In the case of heavy rain, the ratios of runoff amount to dry and wet deposition rates were largely greater than unity for SS and heavy metals mainly originated from soil (Fe, Mn), and were around unity for air-originated ones (Zn, Pb). In contrast, the ratios of all substances (heavy metals, Benzo (a) pyrene, organic carbon) nearly equaled to unity in case of weak rain.

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Antimony concentrations in the environment around a smelter were determined and some basic elution tests from soils were carried out. The soil samples were collected around the antimony smelter which was known as a source of antimony pollution. Antimony concentration in the soil was measured by Instrumental Neutron Activation Analysis (INAA) and found very high concentration of ca.250mgSb/kg-soil. Elution tests, with purified water or calcium chloride solution or tartaric acid for solvent, were performed in the laboratory. The liquid samples from elution tests were measured by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). It was found that the antimony amount which was eluted form the soil was small, and that the difference between with purified water and with calcium chloride solution was little.

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The objectives of this study is to determine the level of environmental contamination by antimony around a smelter at the present time through a field survey, to discuss about dynamic behaviors of antimony in soil-plant system, and to evaluate the potential health risks of residents near the smelter which might be induced by antimony intake based on the field observations and reported data with metabolic model. Soils, farm products, groundwater, suspended particulate and urines, hairs and nails of residents were collected at several spots around the smelter, to determine antimony concentrations.
The results obtained in this study can be summarized as follows;
1) Antimony concentrations in farm soils around the smelter were still considerably higher than the natural abundance.
2) Except for children, antimony concentrations in urine of residents around the smelter are larger than the references.
3) Antimony concentrations in a human body of the resident were estimated three to ten times larger than the reference Japanese.
4) The critical pathways of antimony exposure to residents around the smelter were identified to be a vegetable intake and inhalation. For the children, accidental soil ingestion must be taken into an account as a potentially high exposure pathway.
5) The critical group of the antimony dose might be children. Eventual Soil ingestions by children might cause larger dose over the limit.

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An advanced wastewater treatment with the pre-coagulation process is going to be developed to achieve the high removal efficiency for nitrogen and phosphorus, energy conservation, and recycling of generated sludge in acompact facility. In this study, the influence of the pre-coagulation process on the sewage sludge treatment was investigated by a pilot plant.
We used ferric chloride, polyaluminium chloride (PAC) and aluminium sulfate as the coagulant to the primary sedimentation tank. The characteristics of sludge generated from the pre-coagulation process were examined by agravity thickening test, a dewatering test using a simple belt-press machine and a melting test.
The results are summarized as follows:
1) The quantity of pre-coagulated sludge became about twice as large as that of control sludge.
2) The dewatering test indicated that pre-coagulated sludge cake contained the sameamount of water as the control sludge cake using most suitable polymer.
3) The melting point of pre-coagulated sludge ash by ferric chloride was lower than that of control sludge ash and precoagulated sludge ash by PAC and aluminium sulfate.
Finally, the running costs were estimated in the case of wastewater treatment with or without the pre-coagulation process using the presented results and the published data.

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Oxygen uptake rate was considered as an index for determining the biodegradability of sewage sludgeunder thermophilic oxic process. The degradation efficiency of sewage sludge was examined from the difference of oxygen consumed in two experiments in which waste food oil, the mixture of waste food oil and sewage sludge wereadded, respectively. The sewage sludge was more degradable than waste food oil, and was degraded firstly from thedifference of oxygen consumed in initial period of thermophilic oxic process. At the same conditions of addition withwaste food oil, the total degradation efficiencies for each test were certified as 62.7%, 86.8%, and 82.4% respectively. Excepting the waste food oil, the degradation efficiencies for excess sludge, thickened sludge and dewatered sludge cakewere 99.4%, 99.6% and 82.1% respectively. Larger than 80% of degradation efficiency was determined when the C/Nratio of mixture was adjusted to 20.

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In the activated sludge plants, the excess sludge is currently processed at considerable costs, and, the reduction of it is a major concern. Reducing weight, volume and organic content has beenconventionally achieved through biological digestion techniques, but these require long and uneconomicalperiod to reach stabilization. In this study, the efficiencies of alkaline, acid and thermal methods inminimizing the sludge have been investigated and compared with the traditional methods of treating theexcess sludge. Maximum possible MLSS reduction was 68% when the alkaline treated sludge wasautoclaved at 121°C for 30 mins. The higher the pH, the higher the MLSS reduction with maximum of 64% at pH of 12.5 after 24 hours. The lower the pH, higher the MLSS reduction with maximum of 28% at pH 2.5 at room temperature. Alkaline solubilization yielded higher reduction of MLSS compared toacid solubilization due to the reasons that alkaline solubilization solubilized most of the protein in MLSSwhereas acid solubilized carbohydrate portion of the sludge and that MLSS contained around 10 to 15% carbohydrate and 35 to 40% of protein COD. The higher the temperature, the higher is the soluble COD yield. And thermal hydrolysis at 121°C and 1 bar, yielded solubilization of 44% and 41% of protein andcarbohydrate COD respectively.

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An automated measurement system is developed to monitor Peroxyacetyl Nitrate (PAN). This systemis made of an automatic valve device and a gas chromatograph with a ⁶³Ni electron capture detector. A 5ml airsample is directly introduced in the gas chromatograph without any focusing process. Continuous measurements of PAN concentration were made in Sapporo from July 1997 to April 1998. Medianconcentration of PAN for each month show seasonal variation with a maximum of 0.37ppb in spring. Thisvariation resembles background PAN variation measured in England. However on warm sunny days in summer, PAN showed a distinct diurnal variation and local formation of PAN was apparent. Whereas, in spring andwinter, PAN concentration showed little diurnal variation. Moreover monthly maximum concentration in springwas as high as that in summer. During winter and spring, it is so cold in Sapporo that PAN production in theurban atmosphere is rather limited. Thus variation of PAN concentration during winter and spring is affectedby large scale air pollution.

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Gaseous concentrations and particulate ones of DBP and DEHP in some surrounding atmospheres weremeasured. Then, the concentrations of them in the environment were estimated using the level II fugacity model, and itseffectiveness was studied by the comparison of the estimates and measured values. The measurement results showed: theconcentrations of DBP and DEHP were usually higher indoors than outdoors; there is considerable volatilization from aplastic processing plant; their concentrations in the atmosphere considerably differ from each other depending on places;the ratio of gaseous concentration and particulate one seemed to be greatly affected by the quality and the quantity ofsuspended particles and environmental conditions such as temperature and ventilation. The comparison of the concentrationsestimated using fugacity model and the measured ones showed that level II fugacity model was effective to estimatethe concentration of DBP and DEHP in the environment.

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Resuspended particulate matter and its contribution to algal growth in Lake Barato, ashallow lake of three lake basins, were researched.
Resuspension caused by lake currents was researched by a sediment-trap method. The densitydistributions of seston, resuspended matter and sediment were analyzed by a density gradientcentrifugation method. Turbidity and concentration of particulate iron increased with increases indepth-averaged current velocity in Lake Barato. This indicates that the resuspended particulatematter is mainly from sediment, because the sediment is rich in iron. The particulate matter containsmore organic material of lower densities and phosphorus than does the sediment. Bio-availablephosphorus content is higher in sediment of the upper lake basin than in that of the lower lake basin, and when the particulate matter of sediment is resuspended, it can provide phosphorus for algae inthe upper lake basin. These results indicate that resuspended particulate nutrients can not beneglected in the study of eutrophication of shallow lakes.

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The dominating factors of freshwater red tides caused by a dinoflagellate Peridinium bipes werestudied by means of the cultivations of algae in the Asahi reservoir which was a mesotrophic or oligotrophic lake.Targeted species of study were Peridinium bipes (clonal and axenic population), Melosira granulata (clonal andaxenic population), Nitzschia sp.(mono-population), Ankistrodesmus falcatus (mono-population), and Synechococcus sp.(mono-population) which were collected from the Asahi reservoir except for M. granulata. Cultivations were conducted by use of synthetic mediums (AFH, C, and Csi).
The multiplication curve of P. bipes to light showed that P. bipes was adapted to stronger light intensity than othertested algae, though the response to water temperature was analogous to other tested algae. Half-saturationconstants of P. bipes for nitrate and β-glycerophosphate were 0.055mgN·L^-1 and 0.0015mgP·L^-1 which was nearlyequal to those of M. granulata and lower than those of the other algae. These results indicated that P. bipes wasable to be superior to the other algae in the surface layer in the Asahi reservoir. This estimation was confirmedfrom the monthly vertical distributions of P. bipes and M. granulata in the Asahi reservoir from April 1995 toMarch 1996. Although the vertical distributions of P. bipes were not necessarily determined only by the specificgrowth rate because of its positive phototaxis and negative geotaxis, P. bipes was considered to get the taxis formaking a best use of the above-mentioned physiological advantages. Therefore, the multiplication characteristic in P. bipes should be useful to forming freshwater red tides.

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A numerical model in consideration of microsites which have particulate organic matter (POM) in their cores as energy source for bacteria is developed to simulate vertical concentration profiles in sediments and compared with a general vertically one-dimensional transport-reaction model (called M-S model and V-l model, respectively). In the M-S model, it is assumed that the POMs are in spherical form with 50μm to 500μm in radius and follow a logarithmic normal distribution. As aresult of the M-S model runs, it was demonstrated that the concentration profiles in the aerobic zone of the sediments, especially NO₃-N, were variable by the POM size and distribution if the total POM concentration in the sediment surface was constant because the difference of POM size leads to the difference of denitrification rate. The V-1 model could not show any differences.So if the microsite is not considered, anoxic and anaerobic reaction rates in the upper layer of the sediments would be underestimated.
Although the POM distributions influence on the saturation coefficient for oxygen inhibition in denitrification (K_{S, IN}) in the V-1 model, it is actually difficult to measure relationships between POM size and their numbers. Thus, the approximate variation range of K_{S, IN} was demonstrated to estimate more exact rates of denitrification in the aerobic zone of the sediments.

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The dissolved manganese was oxidized by four kinds of oxidants and filtrated by five kinds of membranes. Oxidants used in experiments were Air, Cl₂, ClO₂ and KMnO₄. The dissolved manganese was not removed perfectly except by KMnO₄. The deposited particle size oxidized by KMnO₄ was larger than the deposited particle size of ClO₂, but it was less than 0.45μm. It was not removed perfectly by the 0.45μm pore size MF membrane filtration. The reaction time of removal for the dissolved manganese under the presence of MnO₂ was less than 10 seconds.
Next, the dissolved manganese in raw water was filtrated by membranes after the manganese sand column. The difference of the removal ratio between up-flow and down-flow by membrane fitration after the manganese sand column was very little under 500 m/d filtration rate.

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Reject ion characteristics of metals by nanofilteration membranes were examined. Chloride ions, sulfate ions, and organic compounds represented by TOC, which are found in high concentration in the landfill leachate, were more highly rejected by nanofiltration membranes than metals. Separation coefficient, which is the ratio of the metal permeation rate to the chloride ion or TOC permeation rate, was introduced to consider the rejection characteristics of various heavy metals in the leachate by the nanofiltration membrane. In spite of different materials and different nominal salt rejection of nanofiltration membrane used, the rejection tendency of every metals in the leachate was nearly the same. In part icular, the separation coefficient of arsenic against chloride ion and TOC was larger than any other separation coefficient of heavy metals. That is to say, arsenic is easy to go through the nanofilteration membrane. To certify why the rejection of arsenic is low in nanofilteration membrane, the rejection characteristics of arsenic spieces such as arsenite, arsenate, and DMAA, was investigated in nanofilteration membranes. Both arsenate and arsenite showed high rejection in the pH range where they exist in ion form. In the case of DMAA, the high rejection was always observed in wide range of pH. A high rejection of DMAA by nanofilteration membranes might be caused by a certain mutual interaction between membrane and solute.

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This study was investigated the effect of ozone aeration on flux recovery in anaerobic membrane bioreactor. The results show (1) ozone aeration was more effective than only oxygen on the prevention of permeation resistance increase caused by particle accumulation on membrane surface.(2) The flux recovery was more effective when ozone aeration was conducted without circulation of suspension compared than with circulation of suspension simultaneously.(3) Under the same quantity of ozone injection, extended contact time was more effective than increasing injection dose rate in the occurrence of constant ozone concentration among operation parameters.(4) In continuous operation, the average permeation flux was 0.69 (m³/m²/d) during the period of no ozone aeration. After intermittent ozone injection for 60 days, the average permeation flux was kept 1.18 (m³/m²d) of 1.7 times of that in no ozone aeration.(5) no great inhibition effect was observed to the VFAs forming bacteria by ozone injection for consecutive experimental period. Consequently, on the carbon recovery process from pre-coagulated raw sludge, membrane anaerobic bioreactor coupled with ozone aeration is available to overcome flux decline that is generally pointed out as a problem of membrane processes.

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Water environment in the River Akagawa which receives the effluent from a mine drainage treatment plant was investigated based on the data on water quality and benthic fauna. The water quality of the River Akagawa was characterized by the low pH and the high concentration of metals such as Al, Ca, Ni and Pb. The loads of Cu, Mn, Zn, T-N, T-P and TOC increased downstream whereas those of As and Fe increased and then decreased downstream and that of Pb decreased downstream, which shows that the main pollution source was the effluent from the treatment plant. It was found that the predominant benthic animals in the upper stream were Protonemura sp., Nemoura sp., Rhyacophila articulata and Chironomide and the number of spieces and individuals increased downstream. However, its number was small compared with that of natural rivers, which showed that the effluent affects the water environment in the River Akagawa. The predominant order of benthic animals was found to change from Plecoptera to Diptera and to Trichoptera downstream. It was concluded that the reduction of load from St. 1 to St. 2 is essential to recover sound water environment in the River Akagawa.

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Morphological transition and fishfauna were studied in the 2 wando-pools, midstream of the Tama-gawa River, Tokyo. During this study, 24 fish species and subspecies were captured in 4 sampling sites. Wand-pools are located at erosional zone of the stream, accordingly wandpool was scoured by overflow running water in swelling period as planned.

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We created wetland type biotope with recycled water in the industrial open space near the bay coast at Sakai City, Osaka Pref., Japan. We studied structure of vegetation, water quality and inhabits of insects and birds at the biotope. As a result, some species of insects inhabited; such as Ischnura senegalensis and Anax parthenope jilius, by preparing environmental conditions at the biotope. Concentration of nitrogen, phosphorus and potassium in the water flowed out from the pond were less than that of flowing into. Some aquatic insects; I. senegalensi, Crocothemis servilia, A.panhenope jilius, Orthetrum albistylum speciosum, Diplonychus japonicus and so on, inhabited with eutrophication water quality. For example DO was 1.4-7.0mg/l, BOD was 0.5-4.0mg/l, nitrogen was 8.8-25.2mg/l, phosphorus was 1.3-4.0mg/l, and potassium was 13-20mg/l.

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The sensitivities of the bioassays using various aquatic organisms to sewage samples were compared. The sewage samples used here were the influent and the secondary effluent obtained from the sewage treatment plant that receives industrial effluent. The aquatic organisms used in this study were Vihrio fischeri (MICROTOX®), Selenastrum capricornutum, Daphnia magna, Daphnia pulex, Daphnia carinata, Ceriodaphnia dubia, Moina macrocopa, Thamnocephalus platyurus (TOXKIT®), Paratya compressa improvisa, Tanichthys albonubes, Xenopus laevis, and Brachydanio rerio. The 50% effective concentration (EC50) values of influent were ranged from 5.6%(48h-EC50 of C. dubia) to 38.0%(48h-LC50 of T. albonubes), and the EC50 values of secondary effluent were ranged from 8.0%(48h-EC50 of C. dubia) to 92.3%(5min-EC50 of MICROTOX®). Among the acute toxicity tests, the tests using C dubia, T platyurus, and frog embryo were relatively sensitive to the sewage samples. The toxicity values for the sewage samples obtained from reproduction tests using D. magna, M. macrocopa, and C. dubia were in the same level. Moreover, we examined the data variation of D. magna acute toxicity test. The coefficient of variation (C. V. value) of the data obtained from 4 different organizations (companies) were about 30%.

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The Bacillus subtilis rec-assay has been carried out using Monod tube (MT method) for evaluating DNA damaging toxicity. However, MT method has some drawbacks. We developed a new method with a microplate (MP method) for improving those drawbacks.
In this research, both MT and MP methods were applied for eight chemicals. The experimental results indicated that there was no difference between both methods in terms of DNA damaging toxicity, and that the sensitivity increased in MP method. Also it was found that the logarithmic values of LC50 had a linear relationship between the two methods. Furthermore, it was possible to make the required experiment time shorter and the required sample volume smaller (i.e., 1/10) in MP method. Based on these results, we can say that MP method is more effective and useful todetect DNA damaging toxicity of environmental samples.

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The objectives of this study are to evaluate the variation of biological activities of sludge and to estimate the optimal MLSS concentration in highly concentrated activated sludge process coupled with rotary disk type UF membrane fed with artificial wastewater and fermentation wastewater, respectively. Based on the results of experiment, high TOC or COD_Cr removal and high nitrification were obtained. It demonstrated the possibility of advanced wastewater treatment by this process. Furthermore, the floc of sludge broke at high MLSS concentration and kinds of bacteria changed to small ones judging from microscope and SEM observations. The optimal MLSS concentration was about 20, 000mg/l in both cases using artificial wastewater and fermentation wastewater according to the removal efficiencies of TOC, COD_Cr, NH₄-N, and variation of biological activities of sludge.

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Biofilm mechanical strength could be categorized into two different concepts, tensile strength and adhesion strength. The former and the latter can be defined, respectively, as biofilm internal force that is resistant to erosion and as that resistant to sloughing at biofilm/substratum interface, when external force is imposed. In this study a novel methodology is proposed to evaluate separately these two different biofilm strengths by using a tensile test device. Test biofilms consisting of denitrifiers were formed on the outer surfaces of tygon-made tubes (diameter 4.76 mm, connected with each other by 2 cm length) submerged in a rectangular open-channel reactor.
The results demonstrated that biofilm tensile strength consistently increased up to about 1000 Pa as biofilm formation proceeded, accompanied with variations in biofilm thickness from 0.4 to 2.9 mm and in biofilm dry density from 2.0 to 8.5 mg SS/cm³ for a period of 50 days reactor operation. Whereas biofilm adhesion strength drastically dropped to below 50 Pa as the biofilm became aged. The live-cell ratio of the biofilm determined by INT method decreased to about 40% with biofilm maturation. This suggests that dead-cell is likely responsible for lessening the adhesion strength. For tensile test, biofilm body is assumed to behave as an elastic material. Elastic index of the biofilm was considerably related to the tensile strength and to the density. However, the behavior of extracellular biopolymer content (ECP) was not dependent on the tensile strength. SEM observations also suggested that rather than the biofilm physiological properties such as ECP content, the biofilm structural properties such as elastic index are more determinative factors for the tensile strength.

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A reject water treatment system was developed for treating reject water from a centrailized sludge treatment process and trasmitting the effluent to an adjacent sewage treatment plant. This system comprises a pretreatment process, featuring a pellet blanket separator with thickener for SS and phosphorous removal, and a biofiltration process, featuring the use of floating media for removal of organic pollutants and nitrogen. Studies were made using a pilot plant (treatment capacity: about 1m³/hr) and the reject water was drawn from a mixed sludge centrifugal thickening process. A high sludge concentration of 3% was observed after 3 hours of thickening during pre-treatment (solid load: 50-200kg/m² per day). The effective inorganic coagulant (aluminium sulfate) dosage for attaining the target water quality was found to depend on influent SS and phosphorus concentrations (either 0.05mg Al₂O₃/mgSS or 1.8mg Al₂O₃/mgPO₄-P, used depending on whichever concentration was higher). As for the biofiltration process, a high denitrification rate (exceedig 1.3kg-N/m³ per day) was achieved in the denitrification column at a low water temperature of 15°C Residual S-BOD, after completion of the denitrification column. Moreover, a nitrification rate of 0.3kg-N/m³ per day was achieved in the nitrification column by reducing the S-BOD load to below 1kg-BOD/m³ per day. Such results of the reject water treatment system demonstrated that this system was capable of effectively treating reject water from a centrailized sludge treatment process, to a quality equivalent to that of primary settling tank effluent.

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We cultivated fatty oil decomposing micro-organisms by feeding with fatty oil alone in an activated sludge process combined with membrane separation. Isolation and identification were performed to examine flora by bacteriological methods. Batch experiments were performed to examine decomposition characteristics of this micro-organism and identification. Consequently, the following results were obtained.(1) Fatty oil decomposing micro-organisms more decomposed fatty oil than the control. This organism is considered possess 10 times more fatty oil decomposing bacteria than the control.(2) Based on the results of long chain fatty acid measurement by gas chromatography, that hydrolystic ability of the fatty oil of this micro-organism was higher than the control.(3) Six out of 18 isolated bacteria were found to be related to decomposition of fatty oil Nocardia sp.(4) Three of these strains decomposed fatty oil from the results of the tween80 test and fatty oil decomposing test, respectively.

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Using two kinds of EBPR (enhanced biological phosphorus removal) activated sludge, we made aerobic batch studies to know temperature effects on PHA (polyhydroxyalkanoate) degradation and P (phosphorus) uptake. The activated sludges used were grown in two EBPR systems fed with wastewater of different P/C ratios. The onesludge had a P content of 13-14 % in P/MLSS ratio, and the other 5-6 %. Due to the short aerobic HRTs, both of them had relatively high contents (30-14 mg/g-VSS) of PHA. The aerobic batch studies were made in a pH-controlled thermostat reactor using the mixed liquor from the anaerobic reactor of the two systems. To avoid phosphorus limitation, the liquor was supplemented with an excessive amount of KH₂PO₄ and MgSO₄. The selected temperatures were 10, 22 (24), 30, 35, and 39 C. The PHA degradation was found to follow a quasifirst order reaction at any temperature except at 39 C, where P uptake and the PHA degradation ceased completely. The P uptake was closely correlated to PHA degradation with a slope value (Y_P/H) ranging from 4 to 6 (mol-P/mol-PHA monomers). The rate constant (K) of PHA degradation and the concurrent P uptake was found to increase with a temperature increase from 10 to at least 30 C. For the effect of the sludge P content, the sludge with higher P contents gave smaller Y_P/H values and larger K values.

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SBR experiments were conducted to find the optimal step ratio and volume allocation for the step-feed anoxic oxic activated sludge process. The experimental results showed the proper step-ratio (influent allocation to the second) can produce better removal of nitrogen due to denitrificaiton in the second anoxic phase, and that the oxic time required for nitrification can be estimated by MLSS and nitrogen treated. Then, a theoretical analysis based on stoichiometry was introduced to formulate concentrations of nitrogen species in the system with indices derived from influent quality and operational conditions. The availability of the analysis was verified by the agreement of theoretical estimations to experimental observations. Finally, the theoretical analysis suggested that the step ratios used in most of experiments are 10-20 % less than the optimal value, and that the proportions of first tanks in whole oxic tank volumes are also 10-20% less.

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Effect of effective depth of the reactor on nitrogen removal from domestic sewage by a draft tube type reactor is discussed with the data from continuous-treatment experiments. More than 2 minutes of the circulating time in the annulus partis required to obtain more than 70% of TN removal efficiency. As effective depth affects on circulating time, the range of D_i/D_o (the ratio of draft tube diameter to diameter of the reactor), in which high TN removal efficiency can be obtained, increases as effective depth increases. More than 70% of TN removal efficiency can be obtained in the reactor with depth of 6m under D_i/D_o conditions of both 0.19 and 0.26, while it can be obtained only when D_i/D_o is 0.19 in the reactor with depth of 4m.

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Nitrate disappearance during settling was quantified and correlated with the sludge settling characteristics in an small size intermittently aerated sequencing batch reactor. For 2770 mg/L initial MLSS sludge with zone settling velocity 2.52 cm/min, the percentage of nitrogen removed during settling to that removed in the system was 30% compared to 19% for initial MLSS 1270 mg/L with zone settlin velocity 6.56 cm/min. In order to predict the fate of nitrate during settling, rate of endogenous denitrification considering biomass stratification is essenti l. A simple batch-settling model was proposed, which can provide stratified biomass concentration profile for predicting nitrate disappearance during settling in SBR. Furthermore, model simulations highlighted different factors affecting settler denitrification such as mass transfer limitations and residual DO.

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In this study, experiments were conducted to clarify the characteristics of the ceramics-formed contact carriers made by burning with calcium as its main component, to make clear the adaptability of contact carrier made from oyster shell used anaerobic-aerobic circulation biofilm process, as well as performing the stream purification process for effective biological nitrification and denitrification. Experiments were also carried out to evaluate the reuse of the carrier. The following results were obtained. During the period from the start-up to 200 days, dissolved phosphorus (D-P) removal ratio was about 60%, among which 70% was phosphorate (PO₄-P). It was suggested that hydroxyapatite formed by reaction between Ca (OH) ₂ and PO₄-P, and hydroxyapatite could adsorb Anmonia (NH₄-N) dissolved in domestic wastewater. After that, the removal ratio decreased with the time course. However the Ca-carrier could be easyly regenerated through acid washing. And the acid solution used by the regeneration of the lowered-adsorption capacity of Ca-carrier could be also collected as fertilizer components containing NH₄-N and PO₄-P.

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The objective of this study was to investigate the relation between water quality and the species composition of microorganism in the stream purification facilities. The results showed that the concentration of dissolved organic matters like dissolved organic nitrogen (DON), dissolved protein decreased as the wastewater flowed down. In August, the concentration of the DON was very little (0.19-0.43 mg.l_-1), among the three points the seed biofilm was fetched out, population of the bacteria raised in the media with inorganic nitrogen source was higher that with the organic ones. However, in February, media with organic nitrogen source led to higher bacteria population than those with inorganic nitrogen source inthe case that the seed biofilm was stripped out from the upstream point. On theother hand, the biofilm sampled from the middle-and down-stream area, the media with inorganic source resulted in higher bacterial population than the ones of organic source. In the upstream point where the organic concentration was higher, zoomastigophara was dominant protozoa. In February, the ciliate Colpidium sp. was the dominant species with the its population occupied 88-95% of the total protozoan population. It suggest that the occurrence of different dominant species should be the different characteristics of the bacteria assimilating the nitrogen. It was clarified that the microbial composition of the biofilm was affected bythe nitorogen composition and its concentration

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The preservation of water quality and environment is increasingly important among the industrialized society. Effluent discharge standards employed by the Bureau of Environmental, Japanese Federal Government have prevented rivers, lakes, and oceans from the pollution by human activities. The number of novel man-made hazardous substances produced by industries is increasing according to the year, resulted in conventional discharge standards ineffective to preserve natural ecological environment. A novel monitoring parameters to detect unknown pollutant sensitively are need to be investigated. In this study, a novel parameter, ecological co-inhabitance index (ECI), was proposed in order to evaluate the water quality for creatures that were actually living the environment. This parameter utilized the population change of benthic organisms. Benthic animals in rivers areknown to be sensitive for environmental change, and was selected as test organismsfor this study. Four typical rivers with different characteristics were selectedto apply to ECI. These rivers receive different kinds of pollution streams. The results indicated that ECI estimated the pollution correctly that enable to reflect changes of pollutants, seasonal environment, and physical conditions.

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In situ hybridization of 16S rRNA-targeted oligonucleotide probes was used to elucidate the spacial distribution of several microorganisms within two types of granular sludge, mesophilic (35°C) and thermophilic (55°C), in upflow anaerobicsludge blanket (UASB) reactors which have been adapted to the identical composition of artificial wastewater. To visualize the microbial distributions, sectionsof both granules were hybridized with fluorescent oligonucleotide probes, and viewed by confocal laser scanning microscopy (CLSM). Hybridization of oligonucleotide probes for Archaea and Bacteria with microbes in the granule sections clearly showed the layered structure of both granules, indicating that the outer layerof the granules harbors mainly bacterial cells, and the inward consists of mainly archaeal cells. Methanosaeta, Methanobacterium, Methanospirillum, and Methanosarcina-like cells were detected and localized by the probes for several phylogenetic groups of methanogens, in which the most dominant methanogens in both granules were related with the genus Methanosaeta. For the detection of some unknown bacteria which were suggested to be present in the granules by 16S rDNA-based cloning analysis, we designed probes specific for clonal 16S rDNAs relative to thegreen non-sulfur bacteria, and clonal rDNAs which are relatives of the Syntrophobacter species. Hybridization of the probes for both granule sections showed particular locations of the targeted cells. The cells related with the green non-sulfur bacteria were detected as filamentous, and located in the most outer layer of the thermophilic granule sections. On the other hand, the cells related with Syntrophobacter species were coccoides, and located in the inward of only the mesophilic granules. These observations demonstrated a part of the layered structure, and revealed the overall microbial topography of both granules.

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Wastewater treatment and biomass production system under illumination and anaerobic condition by purple nonsulfur bacteria, Rhodobacter sphaeroides, is expectedto be an effective system from the points of less green-house gas emission and production of valuable materials. However, purple nonsulfur bacteria are sensitive to sulfide which can be produced by sulfate reducing bacteria under anaerobic conditions. In this paper, we quantified the growth inhibition by sulfide and investigated the bacterial co-existence system to alleviate this inhibition. The results are obtained as follows;- Purple nonsulfur bacteria could not grow underthe presence of more than 20mgS/L of total sul - fide.- Purple nonsulfur bacteria could alleviate the sulfide growth inhibition, and purple nonsulfur bacteria could grow even under the presence of 60mgS/L of initial sulfide concentration.

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The ecological role of sulfate-reducingb acteria (SRB) in anaerobic degradation of propionate was investigated using two UASB reactors operated in parallel under different feed conditions. Both UASB reactors received the identical organic source with asugar-VFA mixture of 2000mgCOD·l^-1, but different levels of sulfate: the first one fed with 33mgS0^2-₄-S·l^-1 (sulfate poor, referred to as R1), and other one fed with 1000 mgS0^2-₄-S·l^-1 (sulfate rich, R2). Microbial activities in terms of methane production, propionate degradation and sulfate reduction were assessed using sludge samples harvested from the respective reactors after over two years operation.C ontributions of syntrophic proton-reducing acetogenic bacteria (PRB) and of SRB inpropionate oxidation into acetate were separately quantified by conducting specific vial-bottle tests, in which cultivation conditions were subsequently alteredaccording to the thermodynamic oncept.
Methanogenesis predominantly occurred in R1 reactor, and sulfate reducers contributed only 3% of the total COD removal. On the other hand, COD reduction in R2 reactor was performed solely by sulfidogenesis, as a consequence of complete inhibition of methanogenesis by high level sulfide. The major contributor of propionate oxidation in R1 sludge consortium wasa symbiosis between PRB and hydrogenotrophic methanogens, while in R2 sludge consortium SRB were the sole contributor.In spite of much less sulfate load some extent of propionate-oxidizing SRB proliferated in R1 sludge consortium.In the presence of sulfate propionate-oxidizing SRB exerted a oxidizing-potential of 0.84 fold as large as by the symbiosis of PRB and MPB. This finding suggests that propionate-oxidizing SRB mostly grew as fermentative bacteria under such low sulfate level as in R1 reactor.

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Environmental pollution by heavy metal is a very serious problem. Especially, mercury pollution causes severe damage of human health like Minamata disease. Minamata Bay is known as the site where a very severe methylmercury-poisoning incident occurred. Some bacteria living in such a mercury polluted environment are often resistantto mercury compounds. Isolation and characterization of mercury-resistant bacteria have been done only for the aerobic microorganisms so far. In many cases, however, sites polluted by mercury compounds are anaerobic environmentssuch as soil and sediment. These anaerobic mercury-resistant bacteria have possibility of development of new anaerobic treatment system and bioremediation in the polluted anaerobic sites. In this study, we tried to isolate anaerobic mercury-resistant bacteria from the sea sediment of Minamata Bay, and to elucidate themechanism of mercury-resistance of the isolated bacteria by using Polymerase Chain Reaction (PCR) method and Southern hybridization method. Twenty-six strains of the anaerobic mercury-resistant bacteria were isolated from Minamata Bay sediment. Those were spore-forming and rod-shaped anaerobic bacteria. Therefore, those are classified as the genus Clostridium. The results of PCR analysis showed that the PCR products of the 26 isolates were not the same gene to Bacillus sp. merA gene in size. However, Southern hybridization analysis showed that only one strain named MN21 of the twenty-six strains has a highly homologous gene to the Bacillus merA gene whereas no signal was detected in the remaining strains.

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The energy loss at manholes is not negligible for designing a storm sewer network. Some researchers have investigated energy losses at manholes experimentally. Storm sewers have been constructed along roads under the ground surface. Therefore, there are various kinds of horizontal pipe angles between upstream and downstream pipes at two-way manholes. However, in previous research, only a few researchers examined effects of horizontal pipe angles on energy loss at two-way manholes. The purposes of this study are (1) to investigate effects of horizontal pipe angles on energy loss at two-way circular drop manholes and (2) to develop a new type of manhole structure with an improved invert profile to reduce the energy loss at the manholes with 90° bending pipes (Type D). Experiments were carried out by using three types of horizontal pipe angles, that is, 180°(Type A), 135°(Type B) and 90°(Type C and Type D) between upstream and dowstream pipes. Major experimental results are as follows:(1) when the ratio of S/D_d (S is the distance between upstream and downstream pipe bottoms and D_d is the downstream pipe diameter) is equal to 0, the energy loss coefficient K of Type C is by 0.2 to 1.8 larger than that of Type A and is by 0.1 to 0.4 larger than that of Type B, (2) when the ratio of S/D_d is larger than 1, K of Type C is a little smaller than that of Type A and is nearly the same as that of Type B and (3) K of Type D reduces 0.1 to 0.8 than that of Type C due to the improvement of the invertprofile.

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