The coagulation behaviors of two widely used model clay particles, kaolin and bentonite were investigated by using ferric chloride as coagulant in this paper. Through experiment, the effects of their suspension concentrations, alkalinity and charge properties on the coagulation behaviors were discussed. The results presented in this paper demonstrated that bentonite possesses very large negative surface charge comparing with kaolin particles. This determined its coagulation behavior shows great difference with that of kaolin. Initial colloid charge and alkalinity of raw water are regarded to be the most important factors influencing coagulant dosage. Eventually, using these two parameters, a formula was proposed for coagulant dosage control for the first time. Optimal dosage estimated by the formula showed a high correlation with jar-test data.
It is necessary to estimate kinetic parameters and distinguish between several wastewater components in terms of the Activated Sludge Models (ASM). To determine these parameters and components of Hachinohe Technical College wastewater, the oxygen uptake rates were measured in two batch experiments at high and low F/M rat io (initial ratio between wastewater and biomass). The calibration of the ASM No.1 simplified by Kappeler and Gujer and the ASM No.3 with the batch experiments estimated the kinetic parameters of heterotrophic organisms and the initial concentrations in COD biodegradable fractions. These calculations showed that the concentration of a hydrolysable fraction, Xs, 0 was adversely proportional to hydrolysis rate coefficient, kh of the simplified ASM No.1 and two condi t ions at different F/M ratio resulted in a great change only in kh and saturation coefficient, Ks of the both ASM models. The concentration of Xs, 0 measured in around 40% of total COD in the both models was low compared with European municipal wastewater.
Sludge settling tests using activated sludge from various types of municipal and industrial wastewater treatment plants were carried out to collect the data for zone-settling velocity. The data from 97 separate runs covering 11 different treatment plants were analyzed and the empirical parameters of V0 and k in Vesilind's equation were estimated. The value of maximum settling velocity (V0) was found to be almost constant at 7.8m/hr. On the other hand, value of k was observed to vary and possible to be expressed by a linear function of either Stirred SVI (SSVI) or Diluted SVI (DSVI). These relationships between value of k and SSVI (or DSVI) were observed to be in close agreement to relationships suggested insome earlier reports that were mainly based on data from municipal sludge. These results suggested that suchrelationships could be valid when further extended to activated sludges of industrial nature. Based on Flux theory and the empirical relations obtained in this study, attainable Sludge Loading Rates (SLRmax) in a secondary settling tank were estimated and compared with those predicted through relationships by earlier reports. Based on the comparison studies using SSVI based relationship, a reliable prediction of SIRmax can be expected for activated sludge having SSVI value of more than 80ml/g.
This work experimentally elucidated a system for reducing the amount of excess sludge by solubilization of return sludge using an ultrasonic wave process. In this system, part of the return sludge is sent to an ultrasonic reactor, and solubilized sludge is biodegraded in the aeration tank. This study examined (1) solubilization and destruction characteristics of treated activated sludge by ultrasonic wave under practical conditions;(2) reduction of excess sludge production under various conditions on a laboratory scale;(3) field tests; and (4) greenhouse gas emissions. Consequently, the following results were obtained;(1) Even though some bacteria were destroyed, activated sludge treated by ultrasonic waves are not reduced to single cells, but to the smallest flocs under 5μm. Treated activated sludge was scarcely solubilized and their activity levels were scarcely changed.(2) Laboratory scale experiments showed that this system is available for wastewater treatment system. Maximal reduction ratio of excess sludge is about 80%, and it was shown that its ratio is changed not only by exposure power and time but also by retention time in the aeration tank (3) Field tests showed that this system can reduce excess sludge and the maximal reduction ratio was 85%.(4) Greenhouse gas emissions of this system are about 40% lower than those of commonly used methods of sludge treat.
The characteristics of solubilization of the excess sludge by hydrothermal reaction and the biodegradability of hydrothermally treated sludge were investigated and the parameters, which are needed for a simulation, was determined. The amount of reduction of sludge and the water quality of treated water were predicted in the simulation. And the simulation results were compared with the results of the continuous experiment. Consequently, the following results were obtained.(1) In order to determine operation conditions, depolymerizention does not have the necessity of taking into consideration and it is good to make solubilization into the index for deciding of operation conditions.(2) Parameters of the hydrothermally treated sludge obtained k2=2.5 (1/day), Ks2=1, 000 (mg/L), a2-=0.5 (mg/L), b =0.05 (1/day).(3) It was identified that excess sludge is reducible by an activated sludge process without excess sludge production using hydrothermal reaction process and that the amount of reduction of sludge can be correctly predicted by this research model.(4) It was suggested that the amount of reduct on of sludge by this process and the amount of solubilization of the excess sludge by hydrothermal reaction process are equal.(5) The water quality of treated water was indicated almost the same level as that of a conventional activated sludge process.
The development of hydrogen fermentation from organic waste has drawn much attention because it contributes the formation of the recycling society. It was often observed, however, that hydrogen fermentation from organic waste was suddenly terminated, and one of the possible reasons is the inhibitory effect of lactic acid bacteria. Therefore, this paper focused on the effect of lactic acid bacteria, which is Lactobacillus paracasei isolated from the waste in the bean curd manufacturing, on hydrogen fermentation with respect to theinfluence of pH. The coculture of Lb. paracasei inhibited the hydrogen fermentation by Cl. acetobutylicum. This inhibition was more significant under pH 4.5 than pH 6.5. It was found that the supernatant of the culture medium of Lb. paracasei also inhibited the hydrogen fermentation and that this inhibition was visible under less than pH 5 and disappeared under more than pH 6.2. And the results of the agar well diffusion test where chymotrypsin and trypsin were applied as proteases clarified that Lb. paracasei excreted a bacteriocin and that it stopped the growth of hydrogen producing bacteria. The molecular weight of the bacteriocin in the supernatant of the culture medium of Lb. paracasei seemed to be between 1, 350 and 17, 000.
The objective of this study was to enhance the process of granulation in the anaerobic reactor using the method of over loading. At over loading, the oversupplied substrate is supposed to stimulate the microorganisms to excrete extracellular polymer, which acts as a bridge between the small flocculent sludge particles. It helps to develop the granular sludge so that the granulation process could be achieved in a relatively shorter time. In this study, the over loading was applied according to the thought that the biomass can be kept better at a fixed flow rate while the coagulation of sludge can be easier at unchanged substrate concentration. As a result, granulation was achieved in about 30 days while about 90 days were necessary when the reactor runs at the ordinary low loading rate. It is found that the content of extracellular polymer increased after the over loading was applied and then decreased gradually after the formation of granular sludge. The specific gravity of wet sludge changed in the same trend with the variation of extracellular polymer content in the sludge. Besides, the sludge particle size distribution changed from a normal distribution to a bimodal distribution and the coefficient of variation came to be a quantitative parameter to assess granulation at over loading condition.
Process performance of thermophilic multi-staged UASB reactor was investigated by feeding a Shochu stillage wastewater. The reactor was seeded with mesophilic sewage digested sludge, and operated at 55° over 900 days. Granulation successfully accomplished within the first three months. As a result, the reactor steadily allowed a super high rate COD loading rate of 100 kg COD ·m-3·d-1, which is equivalent to the influent strength of 10, 000 mg COD·1-1at a HRT of only 2.4 h, keeping COD removal of above 90%. Microbial consortia analys s of the retained sludge by 16S rRNA approach revealed that drastic microbial composition shift from mesophilic methanogens to thermophilic methanogens during 300 days operation under thermophilic conditions: Predominance of Methanosaeta concilii and Methanospirillum hungatei in the initial stage (mesophilically grown sludge) was thoroughly replaced by Methanosaeta thermophila and Methanothermobacter thermautotrophicus.
A two phase reaction kinetic model was proposed to describe the fate of endocrine disruptors in activated sludge process. The water-sludge partition coefficients, the water-sludge transfer rate constants and the degradation rate constants in the model were determined for 17β-estradiol (E2), estrone (El), 17α-ethynilestradiol (EE2) and Bisphenol A (BPA). The calculation by the parameters determined in the model showed that the removal of E2 and BPA increased with the increase in HRT and MLSS, though the removal of EE2 was less than 38% even at infinite SRT. The effect of complete removal of suspended solids by membrane separation activated sludge process was negligible, because the target compounds were less adsorbed onto sludge particles. However higher MLSS operation in the membrane process is advantageous for the efficient removal of endocrine disruptors even if it is operated with short HRT.
To investigate whether male fish are really feminized by estrogen-like substances exist in effluent of sewage treatment plants, eight-week exposure tests were performed using carp in water tanks received effluent from a sewage treatment plant. Serum vitellogenin (VTG) was selected as a biomarker of feminization. When the first run of the tests launched in the early spring of 2000, male and female carp were exposed in the same tank receiving treated sewage, VTG concentrations of male carp exposed to the effluent increased with time, while it reduced after the cease of exposure to the effluents. In the control experiment using dechlorinated tap water, increase in VTG was not recognized in male carp. Two more runs of the test were performed in the summer of 2000 and early spring 2001. However, significant increase in VTG could not be observed in male carp. The estrogenic activities in the effluents were almost in the same level throughout all the tests; therefore, the seasonal timing of exposure might be important for understanding this inconsistent phenomenon.
The collaboration among administrator, citizens and specialists is needed to approach stream environmental management in Japan. The society's attitude towards streams has changed from flood control and effective utilization of water resources to restoration of biological conditions. In this study, we conclude that biomonitoring based on indicator biology and habitat diversity index such as MILFm97 and HIMm98 effectively assesses the whole aspects of stream environment.
Food waste disposers (FWDs) in domestic sinks are banned or self regulated in most local communities in Japan. The ban is based on the belief that the direct discharge of raw organic wastes will increase water consumption, impact sludge management, and during wet weather will increase inflow loads to combined sewer systems causing overflow water to spill into water bodies. In an aging society one assumption is that FWDs will lead to the decrease of solid waste levels and improve general living standards. However, what will be the effect of FWDs on the environment? The introduction of FWDs to support a sustainable recycling program covering all facets of society requires careful selection of a system which complements the infrastructure. Building codes and local and regional characteristics must also be assessed, including the impact on users, garbage collection and disposal, and waste water systems. Ogasawara Village on Bonin Island, a part of Tokyo, was chosen for this study. In this simulation, it will be assumed that FWDs are installed in every residence on the island. This analysis is designed to assess the impact of FWDs on garbage and disposal systems, wastewater treatment plants, and other environmental issues. Finally the effect of FWDs on the economy, quantity of heat, energy consumption and CO2 emission levels will be analyzed.
Wastewater reclamation is one of most effective countermeasures for water shortage in the urbanized area. However, there are high infectious risks without the appropriate treatment of wastewater due to a huge number of pathogens. In this study, infectious risks by poliovirus through wastewater reclamation in the Abukuma watershed were evaluated under various scenarios. For predictive evaluation of water shortage in the watershed, fluctuations of river flow rate at the intake point of drinking water were represented with the matrix of simultaneous probability of flow rates in consecutive two days. Water qualities (total coliforms and SS) were also determined with matrices between river flow rate and them. When the inactivation efficiency of poliovirus by disinfectionwas higher than 3 logs, the damage of water shortage could be decreased by wastewater reclamation without any increase of infectious risk. In case of lower inactivation efficiency, infectious risks would exponentially increase with decrease of damage of water shortage. In the worst case in reclaiming secondary effluent, wastewater reclamation for decreasing 500 % day of damage of water shortage caused ten times as high infectious risk as that without reclamation.
Energy consumption in mixing and aeration process was examined for the energy saving of nitrogen and phosphorous removal system. Adoption of the intermittent aeration mixing system was estimated to reduce the energy consumption in anaerobic and anoxic tank by 9%. Adding immobilization media in the aeration tank gave higher overall volumetric oxygen transfer coefficient when nitrification proceeded. Performance of the aeration apparatus was the critical factor for energy saving in aerobic tank.
This study aims to measure environmental preservation benefit by using not only WTP (willingness to pay) but also WTW (willingness to work) in the context of CVM (contingent valuation method), to evaluate the value of time in the voluntary activity and to show reasonableness of WTP and WTW as the index of environment economic evaluation. As a result, environmental preservation benefit in the coastal area in Japan is 12, 486 yen per person by WTP or 21.37 voluntary days per person by WTW, and the value of time in the voluntary activity is 584.28 yen per day. Now, the value of time seems too low as compared with usual value of time in the recreation activity. This is caused by small value of WTP in one's whole life, where the value is too low in general CVM studies. The result indicates that the index of WTP in the long term has some kind of biast o evaluate benefilto w.
Spilled oil at sea spreads very rapidly and results in a serious impact on coastal activities. Thus oil spreading should be prevented at earlier stage of oil accidents. In this paper, a new concept of an oil boom, called folding type is introduced. The model is a self-inflatable type and a rhombus shape in its cross section. At each corner, springs are equipped for the oil fence to be self-inflatable at an installation stage. The oil fence has advantages in handling and storage sides compared to conventional oil-fences. The oil fence is believed to keep a stable condition at the sea state of up to 4 or 5 and the magnitude of metacenter height of the oil fence is over 2 m. In this work, a physical experiment is carried out in a two dimensional wave tank to check the dynamic behaviour of the oil fence for incident waves. The natural frequency of the model is obtained through the experiments. The amplitude ratio between wave and oil fence model is approximately 1.0 and the phase lag between them is nearly 11°. From this preliminary study, it is found that the static and dynamic stabilities of the model are acceptable for practical application.
The issue of acid rain is one of the global environmental problems. It is required for solution of this problem that the mechanisms of acid rain are understood well In this paper, water qualities of acid rain were analyzed based on the raindrop size distribution. Although the ion concentration of rain is influenced by rain intensity, this analysis method is able to get rid of the influence. Therefore, the effect of air substance amount on rainwater quality can be considered separately. Results showed the relation between rainwater quality and potential ozone. Furthermore, the effects of air substance formation on ion concentration could be estimated for each season. It was also suggested that the amount of NO3 and NH4+ controlled the acid rain quality in rainy season of Japan.
Rapida nd accuratem easuremenmt ethodsf or chemicals orptiono ntod ifferents oilt ypes are needed to evaluate transport and fate of hazardous chemicals in soils and for risk assessment of new chemicals. Retardation of seven Environmenta Ilm pact Chemicals (EICs) in five differents oilsw as measuredu sing a high performance liquid chromatograph (HPLC) micro-columnm ethod.The HPLC micro-columns ystemr equires only small amounts of soil (3g) and chemicals (0.02m Li mpulsei njection), and experiments are rapid and easy to perform compared to the traditional batch or larger-scale columne xperiments. Retardation factors for seven EICs (bentazone car bofuran, 2, 4-D, l inuron, simazine;all organicp esticides and nitrate and nitrite) were determined by HPLC micro-column method.The retardationf actors of the pesticides were mostly constant with varying flow velocity and concentration R.etardationf actorsf or five out of seven pesticidess howed a significant correlation with soil organic matter content. For comparison, traditional batch experiments were carried out for two pesticides and two soils.The retardation factor from batch experiments were generallyl arger than when determined by the micro-column method, suggesting non-equilibrium adsorption under the flow condition.
The authorsp reviouslyp roposeda new type of manholeb for energy lossr eduction with a flat guide cover on the invert of a coventional manhole with right-angle pipes (2000).How ever, when rainfall in an urban area significantly exceeds the design valuef or rainfall on the storm sewer network, flood damage is unavoidable even if the energy losses at manholes in the area have been reduced. It might be possible to reduce floodd amage in these areas by increasinge nergy losses at manholesupstream, and the intentional overflow from these manholes may delay the spread of flow over the ground surface downstream.The authors also previously proposed a new type of manhole with a bafflep late at the manhole outlet in straight pipes in order to reduce the cross-sectionaal area of flow to the downstream pipe.Under steep solpeg round surface, “drop” is often set between upstream and downstream pipes. In this study, the energy loss coefficient, K is estimated by experimental data in manholes considering four kinds of baffle plates snd three kinds of drops. The energy loss coefficient, K ranges from 0.8 to 8.9 due to the experimental results.
The effect of tsunami run-up on the intake water in a river was estimated. Particularly, the salinity rise of river by tsunami run-up was investigated. The tsunami propagation at the onshore and offshore was calculated. The distribution of salinity density after tsunami disaster in the river was presumedby BOX model in which the tsunami elevation and the velocity taken by tsunami run-up calculation at the river were used. If the salinity density is more 200 ppm, the river water will not be able to take and supply in Japanese standard. The time of intake stop will be greatly influenced by the river flow. When the river flow was slow, the tsunami runs up to the upper reaches on the river, and conveys much salinity flow into the river.
The formation of thermal stratification during summer in dam reservoirs suppresses the vertical mixing of their water body. When a reservoir is thermally stratified, oxygen supply from water surface to the bottom layer is limited.Since oxygen consumption in the bottom layer is intensive due to the degradation of organic matter in eutrophicated reservoirs, anoxic bottom layer is likely to be seen in such reservoirs. This anoxic condition may lead to the release of nutrients and metals from bottom sediments. Stable stratification can also be suitable for the accumulation of nuisance algae such as blue-green algae. Destratification method is thus sometimes applied in eutrophicated dam reservoirs to remedy above mentioned problems. We have done a field experiment to see the effect of the destratification on water quality of Aono dam reservoir in Hyogo prefecture. The destratification operation was suspended for one month in summer during the experiment. We have observed the development of a significant bottom anoxia and phosphate release while the operation was suspended.With the aid of numerical simulation, we have discussed the effect of destratification on water quality in Aono dam reservoir.
Recently, the variety of agricultural chemicals is increasingly making complicity in the status of water environment Gravel-bed oxidation method has been used for improvement of river water quality in Japan. From the viewpoint of the “ZERO EMISSION” concept, applications of plastic media or contact media to the water purification systems have been studied recently. Several studies on removal mechanismof BOD, COD, and SS inthese water purification systems are reported, however, the removalm echanism of agricultural chemicalsh as not been clarified yet For main purpose to recycle the usable industry resources in Saga as the contact media, the purification mechanism of agricultural chemicals are investigated both in the batch experiment and the continuous flow experiment A.s a result, the contactm ediah ave littlee ffect on the reduction rate of agricultural chemicals.It is shown that major factor of removal efficiency of the agricultural chemicals is “n-octanol/water (partition coefficient)”. Also it is clear that the agricultural chemicals absorbed by SS can be removed with SS capture in the contact oxidation method.
The experimental study was conducted with model equipment in order to assess influence of benthic biota on organic matter dynamics in tidal flat. In the experiment, four different biota ecosystems were prepared; shaded system, unshaded system, unshaded and polychaete released system, and unshaded and bivalve released system. Throughout the experiment, the amount of organic matter in sediment tended to increase. The accumulation rate of organic matter was different among the systems. The accumulation rate was greatly higher in shaded system than the other unshaded systems. This result suggests that the effect of benthic microalgae on bacterial organic matter degradation with its supplying oxygen and extracellular matabolite was much greater than that of macrobenthos. Filter feeding by bivalve inhibited the accumulation of organic matter in sediment, which was attributed to decreasing deposition, and respiration and the growth of bivalve. Moreover, bivalve predominance enhanced the productivity of attached algae because of activation of PO4-P regeneration by bivalve.
In this study, water quality and mud property in inner part of the Ariake Sea were examined through analyzing field survey data and laboratory tests for the basic parameters. As a result, state of anaerobic and/or reduction in summer season is found to be significant phenomena in deeper water in western part area of the Ariake Sea. Averaged particle size of mud in western part of the sea is mostly silt-clay with high organic content. It shows that the deposit mud can be resuspended quickly because the water content of the mud is very high (about w=300%). Also the mud property of high organic content gives some possibility of oxygen consumption in relating with resuspension and sedimentation of the mud. Water quality simulations were carried out to analyze mass balance and major phenomena in this area. From some sensitive analysis on simulation parameters, monthly change of COD concentration in the inner part is affected by mud property and rate of algae production although total loading through main rivers is not so significant except rainy season.
The Ariake Sea is a typical semi-closed water body surrounded by lowlands. The area of tidal flat accounts for 40% of all those in Japan and both the tidal flat and the sea has high fishery production. In recent decades, there are progressive developments such as new harbor, land reclamation and enclosure of a bay. Recent fishery production is abruptly decreasing, and thus it is necessary to investigate the environmental status. In this study, after developing a two-dimensional water quality model in the Ariake Sea, the characteristics of water quality through the observed data and simulation results were examined. As a result, it was indicated that the tidal flat plays an important role especially in nutrients. The discharged pollutant loads affect the concentrations of COD in summer. However, these high concentrations occur for a short period before being flushed out to the open sea.
At Mt. Tanigawa which was one of the source of Tone River basin, rainfall and snowfall of the summit were continually collected, and each nitrogen component was analyzed. The nitrogen concentration of mountain stream water which escaped from Mt. Tanigawa was also continually collected and analyzed. Then the research of river water quality was carried out for 5 times per year from mountain stream to Tone Oozeki Barrage located in most downstream edge of Gunma pref., and the transition of nitrogen concentration was observed. At the Tone Oozeki Barrage, the great bulk of water was taken as water supply resource of the Metropolitan area. The nitrogen concentration at the summit rainfall and snowfall agreed well with that of mountain stream water. The nitrogen concentration of Tone River was over 1mg/1 from Numata city in the upstream area. At the Tone Oozeki Barrage, the nitrogen concentration was 2 to 3mg/1 through the year. These values were rather high as the resource of water supply.
Inorganic ions as well as nitrogen and phosphorus affect the eutrophication in a closed water area. To investigate the runoff characteristics of inorganic ions in Uji river basin in Kochi prefecture, Japan, continuous surveyswere conducted every one or two weeks during from June 2000 to June 2001. It was found through the survey that Na+and Cl-were diluted according to the increase of flow rate, while NO3--N and PO43--P concentrations increased oppositely. Principal component analysis revealed that 80% of the information in the original data set was integrated into 3 principal components;(1) dilution due to the increase of flow rate, (2) photosynthesis, and (3) nitrification. The analysis also demonstrated that the influence of the dilution was detected particularly at the day having a larger flow rate, that the effect of photosynthesis appeared more significantly from July to the beginning of September, and that nitrification did notoccur perfectly from February to May.
The Toyohira River, the source for Sapporo's waterworks, receives inflow discharged from mines and hot springs. The concentration of potentially hazardous substances in such inflow is high for some flow regimes, which raises concerns related to water quality management. We conducted a water quality survey during and after rainfall (Aug. 21-24, 2001). Rainfall totaled 79 mm. This report reviews the movement of arsenic identified from its runoff characteristics based on continuous observation of water quality during the rainfall. Dissolved arsenic was found to showpoint-type discharge (distilled) whereby the concentration decreased according to the increase in discharge. Suspended arsenic was found to show a non-point-type (outflow) discharge, as was true for suspended solids. Arsenic stored in thesilt and clay of bottom sediment at normal times is tracted by the turbulent flow that occurs during rainfall, becomes suspended, and flows down in high concentration.
Characterization of organic matter in return flow from sludge treatment processes is essential for their effective to use nutrient removal process. This characterization showed that (1) the return flows from sludge thickening unit and dewatering unit contain higher percentage of readily biodegradable organic matter than sewage, and (2) it is not adequate to use the return flows from anaerobic digestion unit and sludge incineration process because of their low concentration ofbiodegradable organic matter, high nitrogen content, and high soluble inert organic matter. Simulation based on the Activated sludge model showed that (1) separate application of return flow in a two stepanoxic-aerobic nitrogen removal process is effective, such that sewage is fed to first anoxic zone whereas the return flow is fed to second anoxic zone; and (2) the centralized sludge treatment plant processing the sludge from 650, 000m3/day-sewage treatment is required to treat the nitrogen contained in 50, 000m3/day-sewage.
Activated sludge process with submerged membrane separation is a high-efficient and energy-saving wastewater treatment process. Interest has been now growing particularly in a single-reactor membrane-separation system, because the system component is simple and nitrogen, which is a cause substance of the eutrophication problem, can be efficiently removed by operating the reactor with intermittent aeration. However, operational factors influencing on nitrogen removal and the permeate flux in this system have not been clarified yet. This study was conducted to investigate the effects of aeration cycle and sludge load on these performances by continuous operation of the reactors. First, the influence of aeration cycle was investigated. Reactors were operated under four different conditions ofaeration cycle. As the results, a cycle of 30 minutes aeration and 30 minutes non-aeration was most effective in both nitrogen removal and the maintenance of permeate flux. Next, the influence of sludge load was investigated. Operation with sludge drawing was compared with the operation without sludge drawing under high volumetric load conditions. It was revealed that the operation without sludge drawing, in which sludge load was decreasing with time, had the advantage in both of the performances.
It is well known that nutrient removal performance depends on the concentration of readily biodegradable organic matter in the influent. Installing primary sludge fermentation process is one of the candidates to supply such a biodegradable organic matter to biological reactors. The mathematical model was developed for describing primary sludge fermentation process, in the form that the model could be integrated with the Activated Sludge Model. The validity of the model was confirmed with data from lab-scale batch experiments with primary sludge from municipal wastewater treatment plant. Inorder to demonstrate the application of the model, primary sludge fermentation process combined with nutrient removal process model, steady and unsteady simulations were performed. The steady stateanalysis showed the procedure for setting required fermented sludge volume and SRT. The unsteady state simulation showed that installing primary sludge fermentation process improves the stability of phosphorous removal in rain event.
A magnesium ammonium phosphate (MAP) crystallization process that works by addition of magnesium seed crystals was used to phosphorus (PO4-P<50g·m-3) removal from side streams from sludge dewatering and thickening processes. Using a bench scale reactor, which consisted of a bubble column with draught and settling tubes, the optimum operational conditions were determined to be: reaction time 2hr, pH 8.9-9.1, molar ratio of Mg/P = 1.0 and an excess of NH4-N, under these conditions the maximum amount of crystallization occurred.
Biological phosphorus removal process have still some problems from viewpoint of stable performance and reuse of phosphorus of wastewater as limited sources. The authors propose that the crystallization process can be of appropriate phosphorus removal from return sludge. Also it is shown that the process is capable of reusing phosphorus of wastewater. In this study, the newly developed crystallization process was applied to high concentration of phosphorus in thickener effluent and phosphorus stripping process. The equipment of phosphorus recovery process is up-flow fluidized-bed reactor. The experimental results proved that the removal efficiency of phosphorus (efficiency of crystallization) 75%-80% can be obtained with adjusting appropriate pH value to control coagulation. It is shown that the crystallization is not almost affected by alkalinity ranging from 150mg/l to 500mg/l.
Artificial seed crystal of calcium silicate hydrate (5CaO·6SiO2·5H2O: tobermorite crystals) was developed for crystallization of calcium phosphate. The crystallization process using the seed material was examined to confirm the stable removal of phosphorus from secondary effluent of municipal wastewater. The effects of the operating parameters on the crystallization process were analyzed with long term experimental data. Water temperature, pH and concentration of calcium ion were selected as the parameters in order to control stable and high removal efficiency of phosphorus. The effect of the operating parameters on the efficiency of crystallization process was shown by the experimental results. It is shown that the crystallization reaction can be expressed as first-order equation. A practical operation of the crystallization process using calcium hydroxide was demonstrated to obtain the long-term performance under the appropriate condition of pH value. It was experimentally clarified that the rate constant of the crystallization reaction decreased in proportion to the decrease in the calcium ion concentrations.
Phosphorus in water is causing Eutrophication of lakes which is globally assumed as one of the environmental problems to be solved. This study focused on the development of low-cost adsorbent for phosphorus made of waste ceramics and application of the adsorbent to the real river water and to the phosphorus recovery system. To enhance the adsorption capacity of the ceramic material, several sulphate salts were applied and washed with pure water. One of the sulphate salt (iron) resulted in the great enhancement of adsorption capacity which was ten times higher than the material itself. Equations expressing adsorption kinetics were developed assuming that flow condition was complete mixing in the adsorbent column. Calculations and data obtained in the experiments showed good accordance but further investigation would be required to have a better estimation. Application of the adsorbent to the real river water resulted in an excellent result which showed the high removal rate of phosphorus from the water for more than 250 days. And phosphorus recovery from the adsorbent using alkali was about 95 %. All results suggests that adsorbent developed here can be a good agent for phosphorus removal from the water.
Ralstonia eutropha KT-1 is a bacterium that can grow on phenol or toluene. Strain KT-1 is also able to degrade trichloroethylene (TCE) after the induction with phenol or toluene. Approximately 2 kg (dry weight) of strain KT-1 induced by toluene was injected into groundwater at a TCE-contaminated site to degrade TCE. After the injection process was completed, the groundwater was pumped up for 51 days. Number of phenol-degrading bacteria in the groundwater was monitored by most probable number (MPN) method during that period. Changes of bacterial populations in the groundwater were also analyzed by molecular methods based on 16S rDNA to evaluate impacts of strain KT-1 injected on indigenous bacterial population. Analysis of 16S rDNA clone showed that 68% of clones obtained during the experiment belonged to Proteobacteria Alpha or Beta. Terminal restriction fragment length polymorphisms (T-RFLP) analysis of PCR-amplified 16S rDNAs indicated that indigenous bacteria phylogenetically close to Nitrosomonas and Azoarcus group disappeared from the groundwater after the injection of strain KT-1. However, they were observed again as dominants after 18 days of pumping up.A statistical analysis, multi-dimensional scaling (MDS), was applied to the data of T-RFLP in order to evaluate the changes of bacterial populations. The results showed that indigenous bacterial populations perturbed by strain KT-1 were well restored in 51 days.
Water pollution with pathogenic viruses has been frequently reported in recent years. Since conventionalwater and wastewater treament systems are not enough to inactivate or remove pathogenic viruses, a new technology for virus removal should be developed. In this study, virus-binding proteins (VBPs) were isolated from activated sludge culture with affinity chomatography. The ability of VBPs to capture intact particles of poliovirus I was confirmed with ELISA. SDS-PAGE analysis revealed that VBPs included a number of polypeptidesthat have molecular weight between 94.0 and 14.4k Da. The evaluation of surface charges of VBPs with ion exchange chromatography found that a majority of VBP molecules had a net negative charge under the condition of the affinity chromatography. On the other hand, the viral peptide, which was used as an affinity ligand, was expected to have a net negative charge. As a result, the VBPs must be captured by the viral peptide with stronger binding forces than the electrostatic repulsive force. The affinity adsorption could explain the strong attractive interaction between VBPs and viral peptide. These VBPs could be useful as an innovative material for the virus removal.
In order to detect enteric viruses from tap water and river water, a new virus concentration method wasdeveloped. Poliovirus type 1, LSc 2ab Sabin strain, was used as a model, and the concentration of poliovirus in waterwas determined by plaque assay using BGM cell line. We used a “cation-coated membrane, ” a negatively chargedmembrane coated with multivalent cations, for adsorption of viruses. For many enteric viruses have negative chargesin environmental samples, and they adsorb to a positively charged membrane. The procedure of rinsing this membraneby H2SO4 solution was applied for removing only multivalent cations, and poliovirus on the membrane was eluted by Na OH solution. By using a Millipore HA membrane and AlC13 solution, over 90% of poliovirus was recovered fromboth Milli Q water and tap water, while the recovery ratio from river water was low and unstable. This new methodenables us to know the behavior of enteric viruses in tap water.
Real-Time PCR and Competitive PCR were applied to quantify 16S ribosomal and ammoniamonooxygenase (amoA) genes in the genome of ammonia-oxidizing bacteria. Two sets of PCR primer targeting the 16Sribosomal gene and one set targeting amoA gene were selected to implement both PCR-based quantification methods. Alinear response was observed over more than 3 orders of magnitude at real time PCR using a dilution series of Nitrosomonas europaea DNA, ranging from 105 to 102 copy number of 16S ribosomal gene and from 10% to 0.01% tototal DNA, respectively. The DNAs extracted from nitrifying activated sludge sample contained 3.0×104 and 1.3×105 copies/ng in 16S ribosomal gene and 1.8×105 copies/ng in amoA gene, that corresponded to 16, 43 and 55% to the genes at a N.europaea DNA equivalent. The number of amoA gene in the DNA extracted from the activated sludgeincreased with increase in the ammonia-oxidizing activities determined by batch experiments, while the abundance of16S ribosomal gene showed almost constant.
The gasification and melting system was developed for solution of shortage of dumpyards and curbing dioxins emitted from incinerators. This system is spreading from enact newnormative guidelines for curbing dioxins emitted from incinerators and the wide-area waste disposaland recycling plan. However, the gasification and melting system is influenced by the difference ofwaste composition by socio-economic activity. In this study, we used several Refuse Derived Fuel (RDFs) for the pyrolysis experiments. We measured the mass balance of char, tar, and pyrolysisgases to understand their influence on different pyrolysis conditions and compositions of waste. Thefive following items, 1) lower calorific value of char and pyrolysis gas, 2) generation ratio of char, 3) processing speed of waste, 4) the fuel ratio of char, 5) pyrolysis temperature, were selected todetermine the most suitable pyrolysis condition for gasification melting system. It was found out thata pyrlysis temperature at 500°C was the most suitable condition.
Air pollutants which are emitted from municipal refuse incinerators, like chlorinated organic compounds, are generated according to the state of combustion in the furnace. The combustion behavior of waste is very complicatedbecause the solid waste consists of various kinds of components and its reaction such as drying and combustion proceedsfrom the surface to the center of the solid, with time. Therefore, the concentration of produced unburnt gas changesaccording to progress of waste combustion. In this study, papers and plastics (PVC, PE, PS and the mixed) were burnedin an actual batch combustor, and then the concentration of the total unburnt carbon and T3CP (tri-chlorinated phenol), and the other gaseous components were continuously measured on line in the experiment. Moreover, the gases werealso measured precisely in electric furnace, and the result was compared with the former one.
Recent years, a new recycling technology for ashes from municipal solid wastes incinerators as rawmaterials of cement has been developed. This technology is considered to prevent the environment from secondarypollution and reduce the volume of final disposed materials. However, there are still several unclear points about the elutionbehavior of the heavy metal from the cement. In this research, several kinds of cements were made with fly ash from municipal solid wastes incinerators as raw materials, and the elution behavior of these cements was examined. As a result, we found the burning conditions and generation ofalite in the cements made. In the leaching tests, it was found that Pb didn't observed. However, Cr (VI) was detected overenvironmental quality standard in Japan even from the cement with 10% of fly ash. Moreover, those heavy metals seemed tovaporized to the air through burning procedure.
The aim of this study is to develop the recovery system of heavy metals in fly ash from an ash meltingfurnace. Though some recovery processes of heavy metals from fly ash have been already proposed, they variedaccording to the composition of fly ash. In this study, we firstly performed sequential extraction for fly ash to understandthe effect of the chemical state of heavy metal in fly ash on recovery process. As the results of sequential extraction, aneffective recovery process was proposed. In the first extraction, 45wt% of Pb in fly ash was extracted by mixing the 20g of fly ash with 200m L distilled waterfor lh at the rotation of 90rpm. In the second extraction 80wt% of Zn in fly ash was extracted by mixing the residue ofthe first extraction with 1mol/L CH3COONH4 for lh at the rotation of 90rpm. We obtained two final products with 50% of Zn and 67% of Pb by precipitating heavy metals in the extracts respectively. The weight of the residue decreasedfinally to 16wt% compared with the weight of the original fly ash.
Reduction of leachate reaching a landfill bottom is important for minimizing leakage risk.Usually, leachate reduction is achieved after final cover and adequate drainage facilities are installed at thelandfill surface. However, more active control of leachate movement inside of the landfill must be effective inorder to manage leachate. In this study, lateral water movement arising at the boundary of waste andintermediate cover layer was investigated. First, infiltration experiments were conducted under the condition ofwaste overlying intermediate cover layer. The lateral water flow in the condition was identified; that it is highlydependent on hydraulic conductivity of lower cover layer. Then, generation of capillary barrier at the boundaryof sand overlying waste layer was confirmed by experiments which were carried out for double layer of sandand waste. Result of large scale multi-layer rainfall experiments also exhibited lateral flow functioningeffectively for controlling vertical infiltration of leachate. Good agreement is confirmed between experimentaland simulation results.
As an effective utilization of waste stillage which will be banned from dumping into sea in the near future, theauthors have studied and succeeded in making sosei paper pots by using waste stillage from shochu distilleries. And thephysical, mechanical, and chemical properties of a sosei paper pot have so far been clarified. In this research, in order to investigate whether sosei paper pots can be effectively utilized as one of agriculture materials, thegrowth test of mini tomatoes was carried out using sosei paper pots, waste paper pots (conventional pots), and polyethylene pots.Consequently, after planted in the field, the growth of mini tomatoes in sosei paper division was greater than those in waste paperpots and polyethylene pots. Moreover, in the division with the sosei paper pots, the fertilizer was never found to run out duringthe cultivation. The roots broke through the sosei pot, spread radially in the soil, and the pot did not have any influence on thegrowth of the root. Also, in all divisions, no root was found rotten. N. B. sosei paper (sosei means reborn)
Environmental safety of the landfill sites is now highly requested. In this viewpoint, a new typelandfill sites called as ‘steel plate liner system’ is now developed. Steel plate is used as the liner facility insteadof the conventional rubber sheets. However, the corrosion of the steel plate can take place in the system.Especially, the corrosion of the inside steel plate is feared because waste or leachate is touching to the inside.Corrosion margin should be adopted as the protection method. In this method, the corrosion rate of steel plateuntil reclaimed waste reaches stable is estimated and the board thickness is determined in advance. However, no data has been reported about the corrosion rate of steel plate in landfill sites. In this study, the corrosionrate of a non-painted steel plate was measured and the performance of various types of painting for protectionwas checked by landfill site exposure tests. The required board thickness was determined by using themaximum value of annual corrosion rate of the non-painted piece in view of safety.
Efficient recovery of organic components from wastewater with communiters is a future techniqueto be developed for sustainable society. This paper discusses techniques to recover organics, suspended andsoluble, from communiter wastewater. In order to determine an optical screen mesh size to collect suspendedsolids, TC, TN, and TP of separated solids in several kinds of communiter wastewater are examined. Availabilityof activated carbon and charcoal as adsorption media is also examined to recover soluble organics efficiently.The conclusions are that the optimal screen mesh size is 0.850mm for effective recovery of suspended organics;more than 25mg/L of activated carbon is necessary for that of soluble organics; and 1g of charcoal in 2.00 to4.75mm of diameter adsorbs 0.5-0.75g of oil.
Recovery process of aquatic insect biota was studied through two years monitoring of water quality andaquatic insects in the river Yukiya where river improvement works have been carried out by considering waterenvironment. The water environment of the river Yukiya was sound judging from the water quality indices except for thecase of high turbidity, whereas it was not good from the biota of aquatic insect. Immediately after the river improvementworks the individual number and species of aquatic insects were very small and the burrowing type of insects waspredominant and then the net-spinning type dominant. It was found that the community structure of aquatic insect couldrecover in several months if the conditions of river bed, inflow of tributary and runup of aquatic insects were arrangedwell. In addition, it was shown that the high turbidity water caused by river improvement works did not damage the biotaof aquatic insects seriously.
Most of reed communities around Lake Biwa are still under difficult conditions to grow without propermaintenance. Various studies have been conducted on the reed communities, but a few studies targeted the relationbetween geological conditions and reed growth. The objective of this paper is to evaluate the influence factors on reedgrowth. Reed communities around Lake Biwa were investigated on August 2001 and the following results were drawn: 1) Average density of reed shoots was 52 shoots/m2, average reed height was 201cm, average diameter of reeds was6.0mm on Lake Biwa shore. 2) Average density of reed shoots was high on the groundbetween higher than -70cm andlower than -30cm of the Lake Biwa standard water level (B. S. L.). On the ground lower than B. S. L.-100cm and higherthan -30cm, average density of reed shoots was low. 3) Organic matter contents in soil on natural reed communities werelower than ones of reed plantation fields. 4) Analysis of variance between reed growth indices and geological indicesshowed that a coefficient of uniformity and contents of total phosphorus in soil on reed community have an influence onthe reed growth.
This study pays attention to Deiratonotus japonicus in the Kita River, Kyushu.Field surveys and laboratory experiments were carried out to grasp the factors from whichthe number of individuals changes, changes of the total number of the indeviduals and theconditions on habitation. Conclusions in this study are as follows:(1) D. japonicus mainlydistributes in the range from 4.8km to 6.4km from the river mouth;(2) The number change ofindividuals was characterized;(3) If D. japonicus can hide inside riverbed materials, it canbear the flow passing over the riverbed materials; and (4) D. japonicus eggs were hatchedand its early zoeal stage was shown.