Several experiments for investigating the behavior of water and pollutants in a bed (column) of the residual ash of incinerated municipal wastes were performed under the conditions simulating actual state, and the discrete type models which were basically derived from the diference approximation of mass balance and rate equations were adopted to simulate the experimental results. Summaries are as follows.
1) When an unsaturated ash column had a saturated water table in a very large depth, forced evaporation from the top surface decreased the initial water content of ash througout the column. This change was simulated well by a discrete type model describing unsaturated infiltration.
2) According to the upward transport of water in the column, solutes were carried upward and concentrated within a shin surface layer (0.5cm). This phenomenan was nealy predicted by a discrete type model system describing unsaturated infiltration and solute elution and transport.
3) When water infiltrated intermittently in an unsaturated ash column, and when a new ash bed was instantly put on an. unsaturated ash bed being constantly infiltrated and the whole stratified bed was successively infiltrated, the solute concentration of leaching water changed up and down again. These phenomena were predicted on the whole by modifying the above model on the assumption that saturated channel filtration occured when the water content ratio became larger than some critical one.

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Laboratory batch experiments was conducted to elucidate sorption property of trichloroethylene (TCE) in water, nonionic organic compound, by waste components of solid waste landfill site and the following conclusions were obtained, consequently. 1) Sorption isotherms of TCE by waste components can also be described by the linear equation, which has been used to describe sorption isotherms of nonionic compounds by soil and sediment. 2) Partition coefficients (K_p) of incinerator residues which included 3 kinds (ash A, B, and landfilled ash) and 15 samples (12 samples were classified by 4 steps of particle size below 4mm and 3 samples were all below 4mm) were found to be nearly proportional to organic contents (f_om), i. e., K_p=130f_om^0.93(r=0.626, 0.062≤f_om≤0.142). 3) Partition coefficients of mixed wastes can be calculated simply by the weighted summation of partition coefficient of each component. 4) Among all of investigated waste components of which organic contents were over 0.9, K_p values of plastics such as polyvinylchloride tube and polyethylene film (P. E. film) were high in comparison to papers and wood. 5) Those of ashes and source separated and size reducted refuse (S. R. R.) were also high in comparison to cover soils and sand. 6) There were no effects of tetrachloroethylene which dissolved together at the same level as sorbate and dissolved organic (as dissolved organic carbon) and inorganic (as Cl^-) material within the concentration of this experiment, i.e., up to ca. 700 and 2000 mg/l individually on K_p of TCE. 7) K_p values of TCE by ashes increased somewhat by the increase of temperature within 15 to 30°C, however, those by S. R. R. and P. E. film were not changed ralatively.

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A chemical behavior of cadmium in sanitary landfill layer was studied by investigating timevariations of the total concentration of dissolved cadmium, [Cd_t] in leachate from lysimeters. One of two kinds of solid waste, artificial refuse (pseudo mixed refuse) and incinerator residue, was packed in each lysimeter and three experimental conditions, semiaerobic and unsaturated, anaerobic and saturated with seawater, and anaerobic and unsaturated were employed, that is, six lysimeters were experimented. In all the lysimeters, a rapid decrease of [Cd_t] was observed. It was found that such decrease resulted from Cd ²⁺ precipitation reaction with S^2- which was supplied by both biological decomposition of protein and reduction of sulfate. A model for calculating time-variation of [Cd_t] was proposed, in which the production rate of S^2- and CdS precipitation equiliburium were considered. The model could explain the decrease of [Cd_t] by properly choosing the effective coefficient γ which is the ratio of S^2- involved in CdS precipitation reaction to S^2- produced.

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Temperature distribution in sanitary landfill layer was theoretically studied. By modeling the phenomena of heat and mass transfer in landfill layer, one dimensional energy equation was formulated. The thermal properties of landfill layer (heat production rate by biodegradation of refuse, specific heat and thermal conductivity, etc.) were estimated. The temperature distribution in the depth of landfill layer was simulated for several landfill conditions. Consequently, the following main conclusions are obtained.
(1) The temperature distribution can be evaluated by a simple equation.(2) The maximum temperature in anaerobic sanitary landfill layer of mixed refuse can rise to about 50°C and above.(3) The depth of landfill layer and heat production rate have great influence on the maximum temperature.(4) The temperature in landfill layer can be used as an index to estimate the stabilization of landfill.

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Gas production characteristics of anaerobic and unsaturated solid wastelayer were studied by using 10 small lysimeters. One of 3 kinds of solid waste, i. e., artificial refuse (pseudo-mixed-refuse), in cinerator residue and mixture of both, was packed in each lysimeter. In Exp. A, aneffect of anaerobic microbes adding into lysimeters was investigated with 20°C and anaerobic conditionby measuring gas production rate and composition within 729 days. After about 100 days, active methanefermentation was observed only in lysimeters added anaerobes. In Exp. B, 8 lysimeters after Exp. A were used, but leachate was circulated with 20 or 30°C and anaerobic condition. In Exp. B1, it was investigated the relationship between gas production rate and characteristics of leachate circulated. In Exp. B2 and B3, by iteration of 1 ml acetic acid injection, it was obtained the influence of pH and temperature on methane fermentation and kinetic constants of methane fermentation, such as maximum value of specific growth rate constant, yield and half saturation constant.

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This study examines the procedure for development of an autoregressive (AR) model for a municipal refuse incinerator. Development of an effective model requires iteration between identification tests and procedures for selection of model variables and model fitting. Appropriate variables are selected using covariance and spectral density functions. After fitting, the model is evaluated objectively using simulations. Subjective evaluation is accomplished using system analysis procedures including step simulations and calculation of relative power contributions. Ultimate suitability of the model requires an evaluation based on knowledge of the plant. Using these procedures a six variable AR model was developed under lowand high load conditions. Based on system analysis the models were found to be qualitatively and quantitatively representative of the actual plant. There was little difference between the models identified at low and high load.

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Linear alkylbenzenesulfonate (LAS) was detected in 15 of 28 shallow, polluted lake sediments in Japan. Vertical profiles of the LAS homologues (C₁₁-C₁₄) and isomers (2φ, 3φ, 4φ, 5φ-7φ) found in the sediment cores were analyzed. Results showed that both the component rate of homologues with the longer alkyl chain (C₁₃, C₁₄) and the rate of the 2φ isomers were greater in the sediments than in to water. Moreover, it was seen that, while the concentration of all the homologues and isomers, the composition of 2φ isomers in the sediments were related to those in the water, there was little relationship between the composition of the homologues in the sediments and that in the water. The selective adsorption of the homologues with the longer alkyl chain to the sediments was expected. LAS was detected at more than 20-cm depth in some lake sediments, and vertical profiles varied with the lake. Inflow loadings, biodegradation, biological and physical disturbance, and sorptiondesorption reaction were all expected to influence the vertical profiles. The longitudinal changes of LAS in the sediments showed a marked decrease, but the composition of the homologues hardly changed longitudinally due to the effect of selective adsorption. LAS content in the lake sediments was related to the presence of anthropogenic pollutant, such as Zn and Cu, and also related to such watershed characteristics as population density.

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Concentrations of 16 elements were analyzed for sediments and suspended particulate matter samples obtained in Japanese 28 eutrophic lakes. Using some statistical analysis methods, those concentrations in sediments were grouped into 1) alkali metals and alkaline earth metals (Na, Mg, Ca, Sr, K), 2) elements originated from soil particle or rock (Ti, Fe), 3) elements having significant anthropogenic inputs (P, Cr, Cu, Zn), and 4) organic carbon and nitrogen. The ratio of suspended particulate matter to sediments decreased in the order of group 3), 4), 1), and 2). Elements belong in group 3) had larger variations in not only sediments concentrations but also suspended particulate matter concentrations in the 28 lakes than elements of other groups. Some significant factors were pointed out to explain sediments concentrations of respective groups; group 1) dissolved Na concentration in lake water, 2) Ti concentration in suspended particulate matter which reflects the inflow rate of soil particles from watershed, 3) TP concentration in lake water representing the degree of anthropogenic loads, and 4) chlorophyll-a concentration in lake water divided by the areal ratio ofdrainage to lake surface, deducible simply from the budget of organic matter in sediments.

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The combination system of a centrifugal thickening and a centrifugal dewtering is planned to be adopted in a large scale sludge treatment plant which collects a large amount of sludge in a wide area. Because this system needs the smallest land requirement for installation and it produces a minimum amount of sidestream . Centrifuge has two functions which are liquid-solids separation and condensed solids conveyance. The ability of solids conveying increases according to.the scale-up of centrifugal dewatering. Therefore it is very rational to be set a centrifugal thickening before a centrifugal dewatering in a large scale plant. A small amount of polymer addition in a centrifugal thickening process improves centrate quality quite well. It is essential to keep sidestream quality well enough to be accepted by a neighbor waste- water treatment plant. This study presents an improved combination system which can get low water content in cake and high SS capture rate totally.

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The grains of binary or ternary-media water filters are cleansed by backwashing with water at a rate sufficient to fluidize the entire bed without mixing two or three kinds of filter media. Theoretical study which regards a backwashing of filters as a binary or ternary solid liquid fluidized bed shows that superficial velocity of backwashing water must be (1) greater than the minimum fluidization velocity of grain, (2) less than the terminal velocity, (3) less than the velocity at which bulk density of the heavier and smaller grain's layer is equal to that of the lighter and larger grain's layer and (4) less than the critical velocity at which mixing of different kinds of grains begins. In order to calculate the critical velocity, the model is developed on the basis of the force balance equations of each grain and validity of the model is confirmed by experimental results. The range of superficial velocity and diameters satisfying the segregation conditions of sand, anthracite and garnet are illustrated.

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As for the substrate uptake characteristics of activated sludge under aerobic condition, the significance of those two factors as SRT and substrate C/N ratio was estimated on the basis of mass balance equations regarding TOC and TN specific uptake rates, and then, the effects of the factors were examined by use of a CSTR unit operating with various SRTs and feeding synthetic substrates.
Accordingly, the results obtained are in the following;
(1) The significance of SRT control is considered to be the factor affecting nitrogen specific uptake rate, which increases as a result of decrease in SRT
(2) The oxidation extent of the TOC uptaken is referred to substrate C/N ratio, resulting in an increase of the TOC oxidation extent with increasing substrate C/N ratio and/or SRT.
(3) The composition properties of activated sludge are also affected directly by substrate C/N ratio and TOC oxidation extent.

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This paper deals with the evaluation of the substrate selectivity of the activated sludge as heterogeneous bacterial population. The substrate selectivity was evaluated by the substrate selectivity index (SSI) that was defined by the following equation. SSI=c/(a+b). Here, a, b, and c: the utilization rates of substrate A, B, and A·B mixture, respectively. For example, SSI=100% means that there are no metabolic competitions between the substrates and the utilization rate of each substrate is not influenced by the presence of other substrates. SSI=50% means that there exists the complete enzymatic inhibition as is known glucose effect.
The amino acids of 13 species were used for energy sources, because the matabolic path ways of these compounds are well known and the activated sludge was acclimated to peptone. SSI=55% was measured for a mixture of alanine and serine, 75% for glutamate and aspartate. The SSIs of more than 90% were measured for a mixture of two each essential amino acids . It was observed that the longer the metabolic pass ways of the amino acids to the TCA cycle intermediates, the larger the SSI. The extent of the substrate selectivity of the activated sludge was interpreted by the length of the metabolic pass ways of substrates to the TCA cycle intermediates.

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Ultrafiltration membrane have been studied of its application to activated sludge process, regarding the filtration rates as functions of membrane pore size, pressure difference, liquid velocity of direction along membrane surface, mixed liquor viscosity, and MLSS concentration. The membrane module investigated was of plate type.
Under high MLSS concentration, the activated sludge accumulates on the membrane surface and depressed the filtration rate, because of the increase in mixed liquor viscosity. The behavior of viscosity of the mixed liquor was found to be formulated similarly to the high polymer solution.
The Ruth equation can be applied to the filtration rate for the membrane pore size of 50000 molecular weight and under, while for pore size of 10, 000 and more it needs modification in term of pore clogging. The optimum pore size for the activated sludge system was found to be of 50, 000.

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Removals of coliform bacteria, enterococcus bacteria and coliphages in sewage treatment plants using activated sludge and trickling filter processes were investigated over a period of one year. Coliform and enterococcus bacteria were removed at almost equal efficiency, while coliphages were removed more efficiently by the activated sludge process.
Experimetal results on the elution of coliphages from the activated sludge and the trickling filter slime concluded that more removal of coliphages in the activated sludge process was mainly due to the difference between their adsorptive affinity for the activated sludge and that for the trickling filter slime.
The treated sludge was disinfected by the chlorine prior to discharge into the receiving water. No coliform bacteria were detected in the chlorinated discharge when it had chlorine residuals in the range of 0-0.52mg/1, while enterococcus bacteria were detected when chlorine residuals dropped below 0.59mg/1. However, coliphages were generally detected throughout the range of chlorine residuals.

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Deposits in sewer pipes, come from decrease of flow ability caused by diferential settlement, may bring maintenance problem such as generation of odor and corrosion.
To find the realstate of deposits, separate sewer pipes (diameter 250mm-400mm), constructed in residential area about 10 years ago, were surveyed and deposits from pipes were analyed.
Moving characteristics of deposits were observed using fullscale model and found that deposits were divided into inorganic matter, black sandy matter, and organic matter. Amounts of deposits depended on flow rate. The critical velocities of accumulation and transportation were calculated.

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This paper describes the bubble plumes along a wall surface. Experimentson the bubble plumes were systematially performed and thereafter, we analize the behavior of the bubble plume, using the following assumptions. As previously reported, the interference diffusion coefficient varies only in vertical direction, as a function of bubble density at the center of the plume. The bubbles have a constant velocity relative to the surrounding water in a plume. Wall friction velocity U_x is defined by U_x²=C_fU_o²/2 and skin friction coefficient c_f has a constant value. The eddy diffusivity is epxressed as the product of representaive mean velocity and width of bubble plumes. On the basis of the above assumptions, moment method is applicable for analysis. By the comparisons of the theory and the experiments, the coefficients of skin friction, interference diffusivity and eddy diffusivity were evaluated. By measurements of turbulence in bubble plumes, the turbulent intensity distribution has a peak near the point of the half width of velocity profile. Inertial subranges are found in the energy spectra of the velocity fluctuations.

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The technical feasibility of treatment of low strength wastewater by upflow anaerobic sludge blanket (UASB) reactor was experimentally investigated using an actual domestic wastewater at a HRT of 4.7 hrs in the temperature range of 25 to 13°C. The result obtained from a continuous flow experiment indicated a fairly promising system performance, i.e., the removal efficiencies of total COD_cr, solid COD_cr and BOD (based on influent total-BOD and effluent soluble-BOD) achieved to be 60-85%(70% in average), 73-83%(80%) and 66-92%(85%), respectively.
The removal rates of total COD and soluble COD depend on the influent strength, but not on the temperature. On the other hand the particulate organic matters in the influent were effectively removed by entrapment into the sludge bed. The hydrolysing rate of the entrapped organics within bed was significantly affected by temperature, that is, 58% of the entrapped particulate organics was liquefied at 25°C, whereas only 33% at 13°C.
The methanogenic activity of the sludge cultivated on the domestic wastewater at low loading rate (1.6 KgC0D_cr·m^-3·d^-1) decreased to 4%(for sucrose as a vial test substrate) and 10%(for acetate) of the seeded granular sludge which had been formed on carbohydrate at high loading rate (11 KgC0D_cr·m^-3·d^-1).
Similary, the contents of ATP and coenzyme F42O of the sludge decreased to 1/2-1/4 and 1/4 - 1/7, respectively, of the seeded granular sludge.
Furthermore, observation of morphological structure of the sludge fed on the domestic wastewater by scanning electrOn microscopy revealed that the granules had a tendency to be partly cracked and to be in a state of autolysis, even though remaining granular forms as a whole.

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Multi-Stage Reversing flow Bioreactor (MRB) is multi-stage sludge blankets type bioreactor for municipal wastewater treatment utilizing the symbiotic relationship between microaerofilic and anaerobic bacteria. The most interesting characteristic of MRB is the formation of the self granulated sludge consist of anaerobic bacteria including Sulfate Reducing Bacteria and Beggiatoa. The hypothetical mechanism of the granule formation and the results of one year operation is summarized.
(1) Once Sulfate Reducing Bacteria (SRB) are accumulated in the reactor, Beggiatoa utilize sulfide whitch is produceed by SRB, then wrup up the anaerobic bacteria frock, make the self granulated sludge.
(2) The effluent quality rose 30 mg - BOD /l in winter becouse of the slagging of the self granulated sludge though less than 20 mg/l in summer without the slagging.
(3) Sludge producing ratio was 0.22 (produced SS/removed BOD) and 0.43 produced SS/removed SS.

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It was investigated to treat the wastewater containing phenol and salicylate using both phenol degrading bacteria and recombinant degrading phenol and salicylate immobilized in polyvinyl alcohol (PVA). Immobilization of living cells was suggested to mitigate the inhibiting action of phenol. Using immobilized phenol degrading bacterial cells, high phenol loading operation could be achieved in comparison with suspended cells or activated sludge such as 3.0g/l·day of volumetric loading. Salicylate degrading gene from NAH plasmid was transformed into phenol degrading bacteria and recombinant degrading both phenol and salicylate was breeded. Using activated sludge with recombinant cells immobilized in PVA, wastewater containing both phenol and salicylate could be treated effectively. Stability of plasmid in the recombinat was also investigated under conditions with or without selection pressures. It was concluded that immobilization of special kinds of living cells such as phenol degrading bacteria and/or recombinants containing aromatic compounds degradation-genes has many advantages for wastewater treatment.

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The effect of on-off aeration control in term of ORP was studied for the nitrogen removal from sewage and night soil with the experiments conducted in bench and mini-plant scales.
The ORP was found to be as a function of ammonia concentration and to be a suitable barometer for the optimum on-off control of aeration in order to remove nitrogen. The nitrification and denitrification proceeded respectively when air .was applied and not, and the maximum removal of nitrogen was obtained at a certain ORP value which depended on the substrate concentration in the waste-water. The on-off aeration control in term of ORP was much more effective than in term of DO, because the rates of nitrification and denitrification is controlled more accurately by the former operation. The BOD/N substrate ratio was necessary to be 4 or more to remove 80% or more of nitrogen from the waste-water.

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In the batch operation of laboratory scale anaerobic-aerobic activated sludge (AS) process, two operating conditions were compared. In the case of “Supernatant Withdraw Operation (SWO)”-the normal operation of AS, supernatant was withdrawn as effluent. In the case of “ML Withdraw Operation (MWO)”-the normal operation of pure culture, only small amount of mixed liquor was withdrawn. Phosphorus removal reduced after the change of operating conditions from SWO to MWO. However, after ninety days of MWO, recovery of enhanced phosphorus removal was observed for a month. It was unable to maintain this phosphorus removal for longer period under MWO.
In the enhanced phosphorus removal ASs, 18 to 50% of total isolates were identified as Acinetobacter calcoaceticus var. lwoffi by the API20E System, while only one isolate was identified by the API20NE System. No isolate of low phosphorus removal AS was identified as Acinetobacter by either System. One of the bacteria playing a functional role on enhanced phosphorus removal may, therefore, be identified as Acinetobacter calcoaceticus var, lwoffi by the API20E System, but not by the API20NE System.
The isolates which could not be identified to the genus level was 52% of the total isolates. The cluster analyses were applied to classify all these isolates effectively. The enhanced and low phosphorus removal ASs were clearly distinguished by the Ward method.

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For rational design and operation of biofilm reactor for treatment of water and wastewater it is necessary to clarify the mechanism of biofilm formation and detachment and to estimate biomass hold-up retained within the reactor. In this study a relationship between the adhesive strength of cells, the biofilm detachment rate and the content of extracellular biopolymer was quantified to investigate what factors govern the phenomenon of biofilm detachment. Experimental biofilm which consisted of denitrifying microorganisms were established on inner surface of tubes. The critical value as Bingham fluid for biofilm which corresponds to adhesive strength between cells was much higher than fluid shear stress acting on biofilm surface. Therefore not only extrinsic factors like fluid shear stress but also intrinsic factors of biofilm physiological conditions may take a important role in biofilm mechanical structure and detachment. The high correlation between biofilm loss rate and biofilm mass per unit area was observed. With an increase in biofilm mass per unit area, the content of extracellular biopolymer decreased, whereas gas content within biofilm increased. The magnitude of biofilm detachment seemed to be attributable to the content of extracellular biopolymer and gas production.

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